Kubernetes[1] is going to stick with /proc/net/tcp for a while.
This commit reduces the scheduling latency introduced by
established_get_first(), similar to commit acffb584cd ("net: diag:
add a scheduling point in inet_diag_dump_icsk()").
In our environment, the scheduling latency affects the performance of
latency-sensitive services like Redis.
Changes in V2 :
- call cond_resched() before checking if a bucket is empty as
suggested by Eric Dumazet
- removed the delay of synchronize_net() from the commit message
[1] https://github.com/google/cadvisor/blob/v0.47.2/container/libcontainer/handler.go#L130
Signed-off-by: Jian Wen <wenjian1@xiaomi.com>
Reviewed-by: Simon Horman <simon.horman@corigine.com>
Link: https://lore.kernel.org/r/20230711032405.3253025-1-wenjian1@xiaomi.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Under certain circumstances, the tcp receive buffer memory limit
set by autotuning (sk_rcvbuf) is increased due to incoming data
packets as a result of the window not closing when it should be.
This can result in the receive buffer growing all the way up to
tcp_rmem[2], even for tcp sessions with a low BDP.
To reproduce: Connect a TCP session with the receiver doing
nothing and the sender sending small packets (an infinite loop
of socket send() with 4 bytes of payload with a sleep of 1 ms
in between each send()). This will cause the tcp receive buffer
to grow all the way up to tcp_rmem[2].
As a result, a host can have individual tcp sessions with receive
buffers of size tcp_rmem[2], and the host itself can reach tcp_mem
limits, causing the host to go into tcp memory pressure mode.
The fundamental issue is the relationship between the granularity
of the window scaling factor and the number of byte ACKed back
to the sender. This problem has previously been identified in
RFC 7323, appendix F [1].
The Linux kernel currently adheres to never shrinking the window.
In addition to the overallocation of memory mentioned above, the
current behavior is functionally incorrect, because once tcp_rmem[2]
is reached when no remediations remain (i.e. tcp collapse fails to
free up any more memory and there are no packets to prune from the
out-of-order queue), the receiver will drop in-window packets
resulting in retransmissions and an eventual timeout of the tcp
session. A receive buffer full condition should instead result
in a zero window and an indefinite wait.
In practice, this problem is largely hidden for most flows. It
is not applicable to mice flows. Elephant flows can send data
fast enough to "overrun" the sk_rcvbuf limit (in a single ACK),
triggering a zero window.
But this problem does show up for other types of flows. Examples
are websockets and other type of flows that send small amounts of
data spaced apart slightly in time. In these cases, we directly
encounter the problem described in [1].
RFC 7323, section 2.4 [2], says there are instances when a retracted
window can be offered, and that TCP implementations MUST ensure
that they handle a shrinking window, as specified in RFC 1122,
section 4.2.2.16 [3]. All prior RFCs on the topic of tcp window
management have made clear that sender must accept a shrunk window
from the receiver, including RFC 793 [4] and RFC 1323 [5].
This patch implements the functionality to shrink the tcp window
when necessary to keep the right edge within the memory limit by
autotuning (sk_rcvbuf). This new functionality is enabled with
the new sysctl: net.ipv4.tcp_shrink_window
Additional information can be found at:
https://blog.cloudflare.com/unbounded-memory-usage-by-tcp-for-receive-buffers-and-how-we-fixed-it/
[1] https://www.rfc-editor.org/rfc/rfc7323#appendix-F
[2] https://www.rfc-editor.org/rfc/rfc7323#section-2.4
[3] https://www.rfc-editor.org/rfc/rfc1122#page-91
[4] https://www.rfc-editor.org/rfc/rfc793
[5] https://www.rfc-editor.org/rfc/rfc1323
Signed-off-by: Mike Freemon <mfreemon@cloudflare.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Allow splice to undo the effects of MSG_MORE after prematurely ending a
splice/sendfile due to getting an EOF condition (->splice_read() returned
0) after splice had called sendmsg() with MSG_MORE set when the user didn't
set MSG_MORE.
For UDP, a pending packet will not be emitted if the socket is closed
before it is flushed; with this change, it be flushed by ->splice_eof().
For TCP, it's not clear that MSG_MORE is actually effective.
Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Link: https://lore.kernel.org/r/CAHk-=wh=V579PDYvkpnTobCLGczbgxpMgGmmhqiTyE34Cpi5Gg@mail.gmail.com/
Signed-off-by: David Howells <dhowells@redhat.com>
cc: Kuniyuki Iwashima <kuniyu@amazon.com>
cc: Willem de Bruijn <willemdebruijn.kernel@gmail.com>
cc: David Ahern <dsahern@kernel.org>
cc: Jens Axboe <axboe@kernel.dk>
cc: Matthew Wilcox <willy@infradead.org>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
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Merge tag 'for-netdev' of https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next
Daniel Borkmann says:
====================
pull-request: bpf-next 2023-05-26
We've added 54 non-merge commits during the last 10 day(s) which contain
a total of 76 files changed, 2729 insertions(+), 1003 deletions(-).
The main changes are:
1) Add the capability to destroy sockets in BPF through a new kfunc,
from Aditi Ghag.
2) Support O_PATH fds in BPF_OBJ_PIN and BPF_OBJ_GET commands,
from Andrii Nakryiko.
3) Add capability for libbpf to resize datasec maps when backed via mmap,
from JP Kobryn.
4) Move all the test kfuncs for CI out of the kernel and into bpf_testmod,
from Jiri Olsa.
5) Big batch of xsk selftest improvements to prep for multi-buffer testing,
from Magnus Karlsson.
6) Show the target_{obj,btf}_id in tracing link's fdinfo and dump it
via bpftool, from Yafang Shao.
7) Various misc BPF selftest improvements to work with upcoming LLVM 17,
from Yonghong Song.
8) Extend bpftool to specify netdevice for resolving XDP hints,
from Larysa Zaremba.
9) Document masking in shift operations for the insn set document,
from Dave Thaler.
10) Extend BPF selftests to check xdp_feature support for bond driver,
from Lorenzo Bianconi.
* tag 'for-netdev' of https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next: (54 commits)
bpf: Fix bad unlock balance on freeze_mutex
libbpf: Ensure FD >= 3 during bpf_map__reuse_fd()
libbpf: Ensure libbpf always opens files with O_CLOEXEC
selftests/bpf: Check whether to run selftest
libbpf: Change var type in datasec resize func
bpf: drop unnecessary bpf_capable() check in BPF_MAP_FREEZE command
libbpf: Selftests for resizing datasec maps
libbpf: Add capability for resizing datasec maps
selftests/bpf: Add path_fd-based BPF_OBJ_PIN and BPF_OBJ_GET tests
libbpf: Add opts-based bpf_obj_pin() API and add support for path_fd
bpf: Support O_PATH FDs in BPF_OBJ_PIN and BPF_OBJ_GET commands
libbpf: Start v1.3 development cycle
bpf: Validate BPF object in BPF_OBJ_PIN before calling LSM
bpftool: Specify XDP Hints ifname when loading program
selftests/bpf: Add xdp_feature selftest for bond device
selftests/bpf: Test bpf_sock_destroy
selftests/bpf: Add helper to get port using getsockname
bpf: Add bpf_sock_destroy kfunc
bpf: Add kfunc filter function to 'struct btf_kfunc_id_set'
bpf: udp: Implement batching for sockets iterator
...
====================
Link: https://lore.kernel.org/r/20230526222747.17775-1-daniel@iogearbox.net
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
When using IPv4/TCP, skb->hash comes from sk->sk_txhash except in
TIME_WAIT and SYN_RECV where it's not set in the reply skb from
ip_send_unicast_reply. Those packets will have a mismatched hash with
others from the same flow as their hashes will be 0. IPv6 does not have
the same issue as the hash is set from the socket txhash in those cases.
This commits sets the hash in the reply skb from ip_send_unicast_reply,
which makes the IPv4 code behaving like IPv6.
Signed-off-by: Antoine Tenart <atenart@kernel.org>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
The socket destroy kfunc is used to forcefully terminate sockets from
certain BPF contexts. We plan to use the capability in Cilium
load-balancing to terminate client sockets that continue to connect to
deleted backends. The other use case is on-the-fly policy enforcement
where existing socket connections prevented by policies need to be
forcefully terminated. The kfunc also allows terminating sockets that may
or may not be actively sending traffic.
The kfunc can currently be called only from BPF TCP and UDP iterators
where users can filter, and terminate selected sockets. More
specifically, it can only be called from BPF contexts that ensure
socket locking in order to allow synchronous execution of protocol
specific `diag_destroy` handlers. The previous commit that batches UDP
sockets during iteration facilitated a synchronous invocation of the UDP
destroy callback from BPF context by skipping socket locks in
`udp_abort`. TCP iterator already supported batching of sockets being
iterated. To that end, `tracing_iter_filter` callback filter is added so
that verifier can restrict the kfunc to programs with `BPF_TRACE_ITER`
attach type, and reject other programs.
The kfunc takes `sock_common` type argument, even though it expects, and
casts them to a `sock` pointer. This enables the verifier to allow the
sock_destroy kfunc to be called for TCP with `sock_common` and UDP with
`sock` structs. Furthermore, as `sock_common` only has a subset of
certain fields of `sock`, casting pointer to the latter type might not
always be safe for certain sockets like request sockets, but these have a
special handling in the diag_destroy handlers.
Additionally, the kfunc is defined with `KF_TRUSTED_ARGS` flag to avoid the
cases where a `PTR_TO_BTF_ID` sk is obtained by following another pointer.
eg. getting a sk pointer (may be even NULL) by following another sk
pointer. The pointer socket argument passed in TCP and UDP iterators is
tagged as `PTR_TRUSTED` in {tcp,udp}_reg_info. The TRUSTED arg changes
are contributed by Martin KaFai Lau <martin.lau@kernel.org>.
Signed-off-by: Aditi Ghag <aditi.ghag@isovalent.com>
Link: https://lore.kernel.org/r/20230519225157.760788-8-aditi.ghag@isovalent.com
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
This is a preparatory commit to replace `lock_sock_fast` with
`lock_sock`,and facilitate BPF programs executed from the TCP sockets
iterator to be able to destroy TCP sockets using the bpf_sock_destroy
kfunc (implemented in follow-up commits).
Previously, BPF TCP iterator was acquiring the sock lock with BH
disabled. This led to scenarios where the sockets hash table bucket lock
can be acquired with BH enabled in some path versus disabled in other.
In such situation, kernel issued a warning since it thinks that in the
BH enabled path the same bucket lock *might* be acquired again in the
softirq context (BH disabled), which will lead to a potential dead lock.
Since bpf_sock_destroy also happens in a process context, the potential
deadlock warning is likely a false alarm.
Here is a snippet of annotated stack trace that motivated this change:
```
Possible interrupt unsafe locking scenario:
CPU0 CPU1
---- ----
lock(&h->lhash2[i].lock);
local_bh_disable();
lock(&h->lhash2[i].lock);
kernel imagined possible scenario:
local_bh_disable(); /* Possible softirq */
lock(&h->lhash2[i].lock);
*** Potential Deadlock ***
process context:
lock_acquire+0xcd/0x330
_raw_spin_lock+0x33/0x40
------> Acquire (bucket) lhash2.lock with BH enabled
__inet_hash+0x4b/0x210
inet_csk_listen_start+0xe6/0x100
inet_listen+0x95/0x1d0
__sys_listen+0x69/0xb0
__x64_sys_listen+0x14/0x20
do_syscall_64+0x3c/0x90
entry_SYSCALL_64_after_hwframe+0x72/0xdc
bpf_sock_destroy run from iterator:
lock_acquire+0xcd/0x330
_raw_spin_lock+0x33/0x40
------> Acquire (bucket) lhash2.lock with BH disabled
inet_unhash+0x9a/0x110
tcp_set_state+0x6a/0x210
tcp_abort+0x10d/0x200
bpf_prog_6793c5ca50c43c0d_iter_tcp6_server+0xa4/0xa9
bpf_iter_run_prog+0x1ff/0x340
------> lock_sock_fast that acquires sock lock with BH disabled
bpf_iter_tcp_seq_show+0xca/0x190
bpf_seq_read+0x177/0x450
```
Also, Yonghong reported a deadlock for non-listening TCP sockets that
this change resolves. Previously, `lock_sock_fast` held the sock spin
lock with BH which was again being acquired in `tcp_abort`:
```
watchdog: BUG: soft lockup - CPU#0 stuck for 86s! [test_progs:2331]
RIP: 0010:queued_spin_lock_slowpath+0xd8/0x500
Call Trace:
<TASK>
_raw_spin_lock+0x84/0x90
tcp_abort+0x13c/0x1f0
bpf_prog_88539c5453a9dd47_iter_tcp6_client+0x82/0x89
bpf_iter_run_prog+0x1aa/0x2c0
? preempt_count_sub+0x1c/0xd0
? from_kuid_munged+0x1c8/0x210
bpf_iter_tcp_seq_show+0x14e/0x1b0
bpf_seq_read+0x36c/0x6a0
bpf_iter_tcp_seq_show
lock_sock_fast
__lock_sock_fast
spin_lock_bh(&sk->sk_lock.slock);
/* * Fast path return with bottom halves disabled and * sock::sk_lock.slock held.* */
...
tcp_abort
local_bh_disable();
spin_lock(&((sk)->sk_lock.slock)); // from bh_lock_sock(sk)
```
With the switch to `lock_sock`, it calls `spin_unlock_bh` before returning:
```
lock_sock
lock_sock_nested
spin_lock_bh(&sk->sk_lock.slock);
:
spin_unlock_bh(&sk->sk_lock.slock);
```
Acked-by: Yonghong Song <yhs@meta.com>
Acked-by: Stanislav Fomichev <sdf@google.com>
Signed-off-by: Aditi Ghag <aditi.ghag@isovalent.com>
Link: https://lore.kernel.org/r/20230519225157.760788-2-aditi.ghag@isovalent.com
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
Conflicts:
drivers/net/ethernet/freescale/fec_main.c
6ead9c98ca ("net: fec: remove the xdp_return_frame when lack of tx BDs")
144470c88c ("net: fec: using the standard return codes when xdp xmit errors")
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
When tcp_v4_send_reset() is called with @sk == NULL,
we do not change ctl_sk->sk_priority, which could have been
set from a prior invocation.
Change tcp_v4_send_reset() to set sk_priority and sk_mark
fields before calling ip_send_unicast_reply().
This means tcp_v4_send_reset() and tcp_v4_send_ack()
no longer have to clear ctl_sk->sk_mark after
their call to ip_send_unicast_reply().
Fixes: f6c0f5d209 ("tcp: honor SO_PRIORITY in TIME_WAIT state")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Antoine Tenart <atenart@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Currently the SYN RTO schedule follows an exponential backoff
scheme, which can be unnecessarily conservative in cases where
there are link failures. In such cases, it's better to
aggressively try to retransmit packets, so it takes routers
less time to find a repath with a working link.
We chose a default value for this sysctl of 4, to follow
the macOS and IOS backoff scheme of 1,1,1,1,1,2,4,8, ...
MacOS and IOS have used this backoff schedule for over
a decade, since before this 2009 IETF presentation
discussed the behavior:
https://www.ietf.org/proceedings/75/slides/tcpm-1.pdf
This commit makes the SYN RTO schedule start with a number of
linear backoffs given by the following sysctl:
* tcp_syn_linear_timeouts
This changes the SYN RTO scheme to be: init_rto_val for
tcp_syn_linear_timeouts, exp backoff starting at init_rto_val
For example if init_rto_val = 1 and tcp_syn_linear_timeouts = 2, our
backoff scheme would be: 1, 1, 1, 2, 4, 8, 16, ...
Signed-off-by: David Morley <morleyd@google.com>
Signed-off-by: Yuchung Cheng <ycheng@google.com>
Signed-off-by: Neal Cardwell <ncardwell@google.com>
Tested-by: David Morley <morleyd@google.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Link: https://lore.kernel.org/r/20230509180558.2541885-1-morleyd.kernel@gmail.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
While reviewing the udp-iter batching patches, noticed the bpf_iter_tcp
calling sock_put() is incorrect. It should call sock_gen_put instead
because bpf_iter_tcp is iterating the ehash table which has the req sk
and tw sk. This patch replaces all sock_put with sock_gen_put in the
bpf_iter_tcp codepath.
Fixes: 04c7820b77 ("bpf: tcp: Bpf iter batching and lock_sock")
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20230328004232.2134233-1-martin.lau@linux.dev
tcp_poll() reads sk->sk_err without socket lock held/owned.
We should used READ_ONCE() here, and update writers
to use WRITE_ONCE().
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This field can be read/written without lock synchronization.
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
kfree_rcu(1-arg) should be avoided as much as possible,
since this is only possible from sleepable contexts,
and incurr extra rcu barriers.
I wish the 1-arg variant of kfree_rcu() would
get a distinct name, like kfree_rcu_slow()
to avoid it being abused.
Fixes: 459837b522 ("net/tcp: Disable TCP-MD5 static key on tcp_md5sig_info destruction")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Paul E. McKenney <paulmck@kernel.org>
Reviewed-by: Pavan Chebbi <pavan.chebbi@broadcom.com>
Reviewed-by: Dmitry Safonov <dima@arista.com>
Link: https://lore.kernel.org/r/20221202052847.2623997-1-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
If the kernel was short on (atomic) memory and failed to allocate it -
don't proceed to creation of request socket. Otherwise the socket would
be unsigned and userspace likely doesn't expect that the TCP is not
MD5-signed anymore.
Signed-off-by: Dmitry Safonov <dima@arista.com>
Acked-by: Jakub Kicinski <kuba@kernel.org>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
To do that, separate two scenarios:
- where it's the first MD5 key on the system, which means that enabling
of the static key may need to sleep;
- copying of an existing key from a listening socket to the request
socket upon receiving a signed TCP segment, where static key was
already enabled (when the key was added to the listening socket).
Now the life-time of the static branch for TCP-MD5 is until:
- last tcp_md5sig_info is destroyed
- last socket in time-wait state with MD5 key is closed.
Which means that after all sockets with TCP-MD5 keys are gone, the
system gets back the performance of disabled md5-key static branch.
While at here, provide static_key_fast_inc() helper that does ref
counter increment in atomic fashion (without grabbing cpus_read_lock()
on CONFIG_JUMP_LABEL=y). This is needed to add a new user for
a static_key when the caller controls the lifetime of another user.
Signed-off-by: Dmitry Safonov <dima@arista.com>
Acked-by: Jakub Kicinski <kuba@kernel.org>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Add a helper to allocate tcp_md5sig_info, that will help later to
do/allocate things when info allocated, once per socket.
Signed-off-by: Dmitry Safonov <dima@arista.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Acked-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
When we call connect() for a socket bound to a wildcard address, we update
saddr locklessly. However, it could result in a data race; another thread
iterating over bhash might see a corrupted address.
Let's update saddr under the bhash bucket's lock.
Fixes: 3df80d9320 ("[DCCP]: Introduce DCCPv6")
Fixes: 7c657876b6 ("[DCCP]: Initial implementation")
Fixes: 1da177e4c3 ("Linux-2.6.12-rc2")
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Acked-by: Joanne Koong <joannelkoong@gmail.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
When connect() is called on a socket bound to the wildcard address,
we change the socket's saddr to a local address. If the socket
fails to connect() to the destination, we have to reset the saddr.
However, when an error occurs after inet_hash6?_connect() in
(dccp|tcp)_v[46]_conect(), we forget to reset saddr and leave
the socket bound to the address.
From the user's point of view, whether saddr is reset or not varies
with errno. Let's fix this inconsistent behaviour.
Note that after this patch, the repro [0] will trigger the WARN_ON()
in inet_csk_get_port() again, but this patch is not buggy and rather
fixes a bug papering over the bhash2's bug for which we need another
fix.
For the record, the repro causes -EADDRNOTAVAIL in inet_hash6_connect()
by this sequence:
s1 = socket()
s1.setsockopt(SOL_SOCKET, SO_REUSEADDR, 1)
s1.bind(('127.0.0.1', 10000))
s1.sendto(b'hello', MSG_FASTOPEN, (('127.0.0.1', 10000)))
# or s1.connect(('127.0.0.1', 10000))
s2 = socket()
s2.setsockopt(SOL_SOCKET, SO_REUSEADDR, 1)
s2.bind(('0.0.0.0', 10000))
s2.connect(('127.0.0.1', 10000)) # -EADDRNOTAVAIL
s2.listen(32) # WARN_ON(inet_csk(sk)->icsk_bind2_hash != tb2);
[0]: https://syzkaller.appspot.com/bug?extid=015d756bbd1f8b5c8f09
Fixes: 3df80d9320 ("[DCCP]: Introduce DCCPv6")
Fixes: 7c657876b6 ("[DCCP]: Initial implementation")
Fixes: 1da177e4c3 ("Linux-2.6.12-rc2")
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Acked-by: Joanne Koong <joannelkoong@gmail.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
The value of 'st->state' has been verified as "TCP_SEQ_STATE_LISTENING",
it's unnecessary to assign TCP_SEQ_STATE_LISTENING to it, so we can remove it.
Signed-off-by: xu xin <xu.xin16@zte.com.cn>
Signed-off-by: David S. Miller <davem@davemloft.net>
Congestion control algorithms track PLB state and cause the connection
to trigger a path change when either of the 2 conditions is satisfied:
- No packets are in flight and (# consecutive congested rounds >=
sysctl_tcp_plb_idle_rehash_rounds)
- (# consecutive congested rounds >= sysctl_tcp_plb_rehash_rounds)
A round (RTT) is marked as congested when congestion signal
(ECN ce_ratio) over an RTT is greater than sysctl_tcp_plb_cong_thresh.
In the event of RTO, PLB (via tcp_write_timeout()) triggers a path
change and disables congestion-triggered path changes for random time
between (sysctl_tcp_plb_suspend_rto_sec, 2*sysctl_tcp_plb_suspend_rto_sec)
to avoid hopping onto the "connectivity blackhole". RTO-triggered
path changes can still happen during this cool-off period.
Signed-off-by: Mubashir Adnan Qureshi <mubashirq@google.com>
Signed-off-by: Yuchung Cheng <ycheng@google.com>
Signed-off-by: Neal Cardwell <ncardwell@google.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
PLB (Protective Load Balancing) is a host based mechanism for load
balancing across switch links. It leverages congestion signals(e.g. ECN)
from transport layer to randomly change the path of the connection
experiencing congestion. PLB changes the path of the connection by
changing the outgoing IPv6 flow label for IPv6 connections (implemented
in Linux by calling sk_rethink_txhash()). Because of this implementation
mechanism, PLB can currently only work for IPv6 traffic. For more
information, see the SIGCOMM 2022 paper:
https://doi.org/10.1145/3544216.3544226
This commit adds new sysctl knobs and sets their default values for
TCP PLB.
Signed-off-by: Mubashir Adnan Qureshi <mubashirq@google.com>
Signed-off-by: Yuchung Cheng <ycheng@google.com>
Signed-off-by: Neal Cardwell <ncardwell@google.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
The type of sk_rcvbuf and sk_sndbuf in struct sock is int, and
in tcp_add_backlog(), the variable limit is caculated by adding
sk_rcvbuf, sk_sndbuf and 64 * 1024, it may exceed the max value
of int and overflow. This patch reduces the limit budget by
halving the sndbuf to solve this issue since ACK packets are much
smaller than the payload.
Fixes: c9c3321257 ("tcp: add tcp_add_backlog()")
Signed-off-by: Lu Wei <luwei32@huawei.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Acked-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
The more sockets we have in the hash table, the longer we spend looking
up the socket. While running a number of small workloads on the same
host, they penalise each other and cause performance degradation.
The root cause might be a single workload that consumes much more
resources than the others. It often happens on a cloud service where
different workloads share the same computing resource.
On EC2 c5.24xlarge instance (196 GiB memory and 524288 (1Mi / 2) ehash
entries), after running iperf3 in different netns, creating 24Mi sockets
without data transfer in the root netns causes about 10% performance
regression for the iperf3's connection.
thash_entries sockets length Gbps
524288 1 1 50.7
24Mi 48 45.1
It is basically related to the length of the list of each hash bucket.
For testing purposes to see how performance drops along the length,
I set 131072 (1Mi / 8) to thash_entries, and here's the result.
thash_entries sockets length Gbps
131072 1 1 50.7
1Mi 8 49.9
2Mi 16 48.9
4Mi 32 47.3
8Mi 64 44.6
16Mi 128 40.6
24Mi 192 36.3
32Mi 256 32.5
40Mi 320 27.0
48Mi 384 25.0
To resolve the socket lookup degradation, we introduce an optional
per-netns hash table for TCP, but it's just ehash, and we still share
the global bhash, bhash2 and lhash2.
With a smaller ehash, we can look up non-listener sockets faster and
isolate such noisy neighbours. In addition, we can reduce lock contention.
We can control the ehash size by a new sysctl knob. However, depending
on workloads, it will require very sensitive tuning, so we disable the
feature by default (net.ipv4.tcp_child_ehash_entries == 0). Moreover,
we can fall back to using the global ehash in case we fail to allocate
enough memory for a new ehash. The maximum size is 16Mi, which is large
enough that even if we have 48Mi sockets, the average list length is 3,
and regression would be less than 1%.
We can check the current ehash size by another read-only sysctl knob,
net.ipv4.tcp_ehash_entries. A negative value means the netns shares
the global ehash (per-netns ehash is disabled or failed to allocate
memory).
# dmesg | cut -d ' ' -f 5- | grep "established hash"
TCP established hash table entries: 524288 (order: 10, 4194304 bytes, vmalloc hugepage)
# sysctl net.ipv4.tcp_ehash_entries
net.ipv4.tcp_ehash_entries = 524288 # can be changed by thash_entries
# sysctl net.ipv4.tcp_child_ehash_entries
net.ipv4.tcp_child_ehash_entries = 0 # disabled by default
# ip netns add test1
# ip netns exec test1 sysctl net.ipv4.tcp_ehash_entries
net.ipv4.tcp_ehash_entries = -524288 # share the global ehash
# sysctl -w net.ipv4.tcp_child_ehash_entries=100
net.ipv4.tcp_child_ehash_entries = 100
# ip netns add test2
# ip netns exec test2 sysctl net.ipv4.tcp_ehash_entries
net.ipv4.tcp_ehash_entries = 128 # own a per-netns ehash with 2^n buckets
When more than two processes in the same netns create per-netns ehash
concurrently with different sizes, we need to guarantee the size in
one of the following ways:
1) Share the global ehash and create per-netns ehash
First, unshare() with tcp_child_ehash_entries==0. It creates dedicated
netns sysctl knobs where we can safely change tcp_child_ehash_entries
and clone()/unshare() to create a per-netns ehash.
2) Control write on sysctl by BPF
We can use BPF_PROG_TYPE_CGROUP_SYSCTL to allow/deny read/write on
sysctl knobs.
Note that the global ehash allocated at the boot time is spread over
available NUMA nodes, but inet_pernet_hashinfo_alloc() will allocate
pages for each per-netns ehash depending on the current process's NUMA
policy. By default, the allocation is done in the local node only, so
the per-netns hash table could fully reside on a random node. Thus,
depending on the NUMA policy the netns is created with and the CPU the
current thread is running on, we could see some performance differences
for highly optimised networking applications.
Note also that the default values of two sysctl knobs depend on the ehash
size and should be tuned carefully:
tcp_max_tw_buckets : tcp_child_ehash_entries / 2
tcp_max_syn_backlog : max(128, tcp_child_ehash_entries / 128)
As a bonus, we can dismantle netns faster. Currently, while destroying
netns, we call inet_twsk_purge(), which walks through the global ehash.
It can be potentially big because it can have many sockets other than
TIME_WAIT in all netns. Splitting ehash changes that situation, where
it's only necessary for inet_twsk_purge() to clean up TIME_WAIT sockets
in each netns.
With regard to this, we do not free the per-netns ehash in inet_twsk_kill()
to avoid UAF while iterating the per-netns ehash in inet_twsk_purge().
Instead, we do it in tcp_sk_exit_batch() after calling tcp_twsk_purge() to
keep it protocol-family-independent.
In the future, we could optimise ehash lookup/iteration further by removing
netns comparison for the per-netns ehash.
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
While destroying netns, we call inet_twsk_purge() in tcp_sk_exit_batch()
and tcpv6_net_exit_batch() for AF_INET and AF_INET6. These commands
trigger the kernel to walk through the potentially big ehash twice even
though the netns has no TIME_WAIT sockets.
# ip netns add test
# ip netns del test
or
# unshare -n /bin/true >/dev/null
When tw_refcount is 1, we need not call inet_twsk_purge() at least
for the net. We can save such unneeded iterations if all netns in
net_exit_list have no TIME_WAIT sockets. This change eliminates
the tax by the additional unshare() described in the next patch to
guarantee the per-netns ehash size.
Tested:
# mount -t debugfs none /sys/kernel/debug/
# echo cleanup_net > /sys/kernel/debug/tracing/set_ftrace_filter
# echo inet_twsk_purge >> /sys/kernel/debug/tracing/set_ftrace_filter
# echo function > /sys/kernel/debug/tracing/current_tracer
# cat ./add_del_unshare.sh
for i in `seq 1 40`
do
(for j in `seq 1 100` ; do unshare -n /bin/true >/dev/null ; done) &
done
wait;
# ./add_del_unshare.sh
Before the patch:
# cat /sys/kernel/debug/tracing/trace_pipe
kworker/u128:0-8 [031] ...1. 174.162765: cleanup_net <-process_one_work
kworker/u128:0-8 [031] ...1. 174.240796: inet_twsk_purge <-cleanup_net
kworker/u128:0-8 [032] ...1. 174.244759: inet_twsk_purge <-tcp_sk_exit_batch
kworker/u128:0-8 [034] ...1. 174.290861: cleanup_net <-process_one_work
kworker/u128:0-8 [039] ...1. 175.245027: inet_twsk_purge <-cleanup_net
kworker/u128:0-8 [046] ...1. 175.290541: inet_twsk_purge <-tcp_sk_exit_batch
kworker/u128:0-8 [037] ...1. 175.321046: cleanup_net <-process_one_work
kworker/u128:0-8 [024] ...1. 175.941633: inet_twsk_purge <-cleanup_net
kworker/u128:0-8 [025] ...1. 176.242539: inet_twsk_purge <-tcp_sk_exit_batch
After:
# cat /sys/kernel/debug/tracing/trace_pipe
kworker/u128:0-8 [038] ...1. 428.116174: cleanup_net <-process_one_work
kworker/u128:0-8 [038] ...1. 428.262532: cleanup_net <-process_one_work
kworker/u128:0-8 [030] ...1. 429.292645: cleanup_net <-process_one_work
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
We will soon introduce an optional per-netns ehash.
This means we cannot use tcp_hashinfo directly in most places.
Instead, access it via net->ipv4.tcp_death_row.hashinfo.
The access will be valid only while initialising tcp_hashinfo
itself and creating/destroying each netns.
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
We will soon introduce an optional per-netns ehash.
This means we cannot use the global sk->sk_prot->h.hashinfo
to fetch a TCP hashinfo.
Instead, set NULL to sk->sk_prot->h.hashinfo for TCP and get
a proper hashinfo from net->ipv4.tcp_death_row.hashinfo.
Note that we need not use sk->sk_prot->h.hashinfo if DCCP is
disabled.
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
We will soon introduce an optional per-netns ehash and access hash
tables via net->ipv4.tcp_death_row->hashinfo instead of &tcp_hashinfo
in most places.
It could harm the fast path because dereferences of two fields in net
and tcp_death_row might incur two extra cache line misses. To save one
dereference, let's place tcp_death_row back in netns_ipv4 and fetch
hashinfo via net->ipv4.tcp_death_row"."hashinfo.
Note tcp_death_row was initially placed in netns_ipv4, and commit
fbb8295248 ("tcp: allocate tcp_death_row outside of struct netns_ipv4")
changed it to a pointer so that we can fire TIME_WAIT timers after freeing
net. However, we don't do so after commit 04c494e68a ("Revert "tcp/dccp:
get rid of inet_twsk_purge()""), so we need not define tcp_death_row as a
pointer.
Also, we move refcount_dec_and_test(&tw_refcount) from tcp_sk_exit() to
tcp_sk_exit_batch() as a debug check.
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This patch adds no functional change and cleans up some functions
that the following patches touch around so that we make them tidy
and easy to review/revert. The changes are
- Keep reverse christmas tree order
- Remove unnecessary init of port in inet_csk_find_open_port()
- Use req_to_sk() once in reqsk_queue_unlink()
- Use sock_net(sk) once in tcp_time_wait() and tcp_v[46]_connect()
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Because per host rate limiting has been proven problematic (side channel
attacks can be based on it), per host rate limiting of challenge acks ideally
should be per netns and turned off by default.
This is a long due followup of following commits:
083ae30828 ("tcp: enable per-socket rate limiting of all 'challenge acks'")
f2b2c582e8 ("tcp: mitigate ACK loops for connections as tcp_sock")
75ff39ccc1 ("tcp: make challenge acks less predictable")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Jason Baron <jbaron@akamai.com>
Acked-by: Neal Cardwell <ncardwell@google.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
The current bind hashtable (bhash) is hashed by port only.
In the socket bind path, we have to check for bind conflicts by
traversing the specified port's inet_bind_bucket while holding the
hashbucket's spinlock (see inet_csk_get_port() and
inet_csk_bind_conflict()). In instances where there are tons of
sockets hashed to the same port at different addresses, the bind
conflict check is time-intensive and can cause softirq cpu lockups,
as well as stops new tcp connections since __inet_inherit_port()
also contests for the spinlock.
This patch adds a second bind table, bhash2, that hashes by
port and sk->sk_rcv_saddr (ipv4) and sk->sk_v6_rcv_saddr (ipv6).
Searching the bhash2 table leads to significantly faster conflict
resolution and less time holding the hashbucket spinlock.
Please note a few things:
* There can be the case where the a socket's address changes after it
has been bound. There are two cases where this happens:
1) The case where there is a bind() call on INADDR_ANY (ipv4) or
IPV6_ADDR_ANY (ipv6) and then a connect() call. The kernel will
assign the socket an address when it handles the connect()
2) In inet_sk_reselect_saddr(), which is called when rebuilding the
sk header and a few pre-conditions are met (eg rerouting fails).
In these two cases, we need to update the bhash2 table by removing the
entry for the old address, and add a new entry reflecting the updated
address.
* The bhash2 table must have its own lock, even though concurrent
accesses on the same port are protected by the bhash lock. Bhash2 must
have its own lock to protect against cases where sockets on different
ports hash to different bhash hashbuckets but to the same bhash2
hashbucket.
This brings up a few stipulations:
1) When acquiring both the bhash and the bhash2 lock, the bhash2 lock
will always be acquired after the bhash lock and released before the
bhash lock is released.
2) There are no nested bhash2 hashbucket locks. A bhash2 lock is always
acquired+released before another bhash2 lock is acquired+released.
* The bhash table cannot be superseded by the bhash2 table because for
bind requests on INADDR_ANY (ipv4) or IPV6_ADDR_ANY (ipv6), every socket
bound to that port must be checked for a potential conflict. The bhash
table is the only source of port->socket associations.
Signed-off-by: Joanne Koong <joannelkoong@gmail.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
While reading sysctl_tcp_reflect_tos, it can be changed concurrently.
Thus, we need to add READ_ONCE() to its readers.
Fixes: ac8f1710c1 ("tcp: reflect tos value received in SYN to the socket")
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Acked-by: Wei Wang <weiwan@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
While reading sysctl_tcp_tw_reuse, it can be changed concurrently.
Thus, we need to add READ_ONCE() to its reader.
Fixes: 1da177e4c3 ("Linux-2.6.12-rc2")
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
If we set XFRM security policy by calling setsockopt with option
IPV6_XFRM_POLICY, the policy will be stored in 'sock_policy' in 'sock'
struct. However tcp_v6_send_response doesn't look up dst_entry with the
actual socket but looks up with tcp control socket. This may cause a
problem that a RST packet is sent without ESP encryption & peer's TCP
socket can't receive it.
This patch will make the function look up dest_entry with actual socket,
if the socket has XFRM policy(sock_policy), so that the TCP response
packet via this function can be encrypted, & aligned on the encrypted
TCP socket.
Tested: We encountered this problem when a TCP socket which is encrypted
in ESP transport mode encryption, receives challenge ACK at SYN_SENT
state. After receiving challenge ACK, TCP needs to send RST to
establish the socket at next SYN try. But the RST was not encrypted &
peer TCP socket still remains on ESTABLISHED state.
So we verified this with test step as below.
[Test step]
1. Making a TCP state mismatch between client(IDLE) & server(ESTABLISHED).
2. Client tries a new connection on the same TCP ports(src & dst).
3. Server will return challenge ACK instead of SYN,ACK.
4. Client will send RST to server to clear the SOCKET.
5. Client will retransmit SYN to server on the same TCP ports.
[Expected result]
The TCP connection should be established.
Cc: Maciej Żenczykowski <maze@google.com>
Cc: Eric Dumazet <edumazet@google.com>
Cc: Steffen Klassert <steffen.klassert@secunet.com>
Cc: Sehee Lee <seheele@google.com>
Signed-off-by: Sewook Seo <sewookseo@google.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
drivers/net/ethernet/microchip/sparx5/sparx5_switchdev.c
9c5de246c1 ("net: sparx5: mdb add/del handle non-sparx5 devices")
fbb89d02e3 ("net: sparx5: Allow mdb entries to both CPU and ports")
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
When the third packet of 3WHS connection establishment
contains payload, it is added into socket receive queue
without the XFRM check and the drop of connection tracking
context.
This means that if the data is left unread in the socket
receive queue, conntrack module can not be unloaded.
As most applications usually reads the incoming data
immediately after accept(), bug has been hiding for
quite a long time.
Commit 68822bdf76 ("net: generalize skb freeing
deferral to per-cpu lists") exposed this bug because
even if the application reads this data, the skb
with nfct state could stay in a per-cpu cache for
an arbitrary time, if said cpu no longer process RX softirqs.
Many thanks to Ilya Maximets for reporting this issue,
and for testing various patches:
https://lore.kernel.org/netdev/20220619003919.394622-1-i.maximets@ovn.org/
Note that I also added a missing xfrm4_policy_check() call,
although this is probably not a big issue, as the SYN
packet should have been dropped earlier.
Fixes: b59c270104 ("[NETFILTER]: Keep conntrack reference until IPsec policy checks are done")
Reported-by: Ilya Maximets <i.maximets@ovn.org>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Florian Westphal <fw@strlen.de>
Cc: Pablo Neira Ayuso <pablo@netfilter.org>
Cc: Steffen Klassert <steffen.klassert@secunet.com>
Tested-by: Ilya Maximets <i.maximets@ovn.org>
Reviewed-by: Ilya Maximets <i.maximets@ovn.org>
Link: https://lore.kernel.org/r/20220623050436.1290307-1-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Each protocol having a ->memory_allocated pointer gets a corresponding
per-cpu reserve, that following patches will use.
Instead of having reserved bytes per socket,
we want to have per-cpu reserves.
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Shakeel Butt <shakeelb@google.com>
Acked-by: Soheil Hassas Yeganeh <soheil@google.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Fix the following build warning when CONFIG_IPV6 is not set:
In function ‘fortify_memcpy_chk’,
inlined from ‘tcp_md5_do_add’ at net/ipv4/tcp_ipv4.c:1210:2:
./include/linux/fortify-string.h:328:4: error: call to ‘__write_overflow_field’ declared with attribute warning: detected write beyond size of field (1st parameter); maybe use struct_group()? [-Werror=attribute-warning]
328 | __write_overflow_field(p_size_field, size);
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Suggested-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: huhai <huhai@kylinos.cn>
Reviewed-by: David Ahern <dsahern@kernel.org>
Link: https://lore.kernel.org/r/20220526101213.2392980-1-zhanggenjian@kylinos.cn
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
The 'drop_reason' that passed to kfree_skb_reason() in tcp_v4_rcv()
and tcp_v6_rcv() can be SKB_NOT_DROPPED_YET(0), as it is used as the
return value of tcp_inbound_md5_hash().
And it can panic the kernel with NULL pointer in
net_dm_packet_report_size() if the reason is 0, as drop_reasons[0]
is NULL.
Fixes: 1330b6ef33 ("skb: make drop reason booleanable")
Reviewed-by: Jiang Biao <benbjiang@tencent.com>
Reviewed-by: Hao Peng <flyingpeng@tencent.com>
Signed-off-by: Menglong Dong <imagedong@tencent.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This reverts commits:
0dad4087a8 ("tcp/dccp: get rid of inet_twsk_purge()")
d507204d3c ("tcp/dccp: add tw->tw_bslot")
As Leonard pointed out, a newly allocated netns can happen
to reuse a freed 'struct net'.
While TCP TW timers were covered by my patches, other things were not:
1) Lookups in rx path (INET_MATCH() and INET6_MATCH()), as they look
at 4-tuple plus the 'struct net' pointer.
2) /proc/net/tcp[6] and inet_diag, same reason.
3) hashinfo->bhash[], same reason.
Fixing all this seems risky, lets instead revert.
In the future, we might have a per netns tcp hash table, or
a per netns list of timewait sockets...
Fixes: 0dad4087a8 ("tcp/dccp: get rid of inet_twsk_purge()")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: Leonard Crestez <cdleonard@gmail.com>
Tested-by: Leonard Crestez <cdleonard@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
The listen sk is currently stored in two hash tables,
listening_hash (hashed by port) and lhash2 (hashed by port and address).
After commit 0ee58dad5b ("net: tcp6: prefer listeners bound to an address")
and commit d9fbc7f643 ("net: tcp: prefer listeners bound to an address"),
the TCP-SYN lookup fast path does not use listening_hash.
The commit 05c0b35709 ("tcp: seq_file: Replace listening_hash with lhash2")
also moved the seq_file (/proc/net/tcp) iteration usage from
listening_hash to lhash2.
There are still a few listening_hash usages left.
One of them is inet_reuseport_add_sock() which uses the listening_hash
to search a listen sk during the listen() system call. This turns
out to be very slow on use cases that listen on many different
VIPs at a popular port (e.g. 443). [ On top of the slowness in
adding to the tail in the IPv6 case ]. The latter patch has a
selftest to demonstrate this case.
This patch takes this chance to move all remaining listening_hash
usages to lhash2 and then retire listening_hash.
Since most changes need to be done together, it is hard to cut
the listening_hash to lhash2 switch into small patches. The
changes in this patch is highlighted here for the review
purpose.
1. Because of the listening_hash removal, lhash2 can use the
sk->sk_nulls_node instead of the icsk->icsk_listen_portaddr_node.
This will also keep the sk_unhashed() check to work as is
after stop adding sk to listening_hash.
The union is removed from inet_listen_hashbucket because
only nulls_head is needed.
2. icsk->icsk_listen_portaddr_node and its helpers are removed.
3. The current lhash2 users needs to iterate with sk_nulls_node
instead of icsk_listen_portaddr_node.
One case is in the inet[6]_lhash2_lookup().
Another case is the seq_file iterator in tcp_ipv4.c.
One thing to note is sk_nulls_next() is needed
because the old inet_lhash2_for_each_icsk_continue()
does a "next" first before iterating.
4. Move the remaining listening_hash usage to lhash2
inet_reuseport_add_sock() which this series is
trying to improve.
inet_diag.c and mptcp_diag.c are the final two
remaining use cases and is moved to lhash2 now also.
Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Logic added in commit f35f821935 ("tcp: defer skb freeing after socket
lock is released") helped bulk TCP flows to move the cost of skbs
frees outside of critical section where socket lock was held.
But for RPC traffic, or hosts with RFS enabled, the solution is far from
being ideal.
For RPC traffic, recvmsg() has to return to user space right after
skb payload has been consumed, meaning that BH handler has no chance
to pick the skb before recvmsg() thread. This issue is more visible
with BIG TCP, as more RPC fit one skb.
For RFS, even if BH handler picks the skbs, they are still picked
from the cpu on which user thread is running.
Ideally, it is better to free the skbs (and associated page frags)
on the cpu that originally allocated them.
This patch removes the per socket anchor (sk->defer_list) and
instead uses a per-cpu list, which will hold more skbs per round.
This new per-cpu list is drained at the end of net_action_rx(),
after incoming packets have been processed, to lower latencies.
In normal conditions, skbs are added to the per-cpu list with
no further action. In the (unlikely) cases where the cpu does not
run net_action_rx() handler fast enough, we use an IPI to raise
NET_RX_SOFTIRQ on the remote cpu.
Also, we do not bother draining the per-cpu list from dev_cpu_dead()
This is because skbs in this list have no requirement on how fast
they should be freed.
Note that we can add in the future a small per-cpu cache
if we see any contention on sd->defer_lock.
Tested on a pair of hosts with 100Gbit NIC, RFS enabled,
and /proc/sys/net/ipv4/tcp_rmem[2] tuned to 16MB to work around
page recycling strategy used by NIC driver (its page pool capacity
being too small compared to number of skbs/pages held in sockets
receive queues)
Note that this tuning was only done to demonstrate worse
conditions for skb freeing for this particular test.
These conditions can happen in more general production workload.
10 runs of one TCP_STREAM flow
Before:
Average throughput: 49685 Mbit.
Kernel profiles on cpu running user thread recvmsg() show high cost for
skb freeing related functions (*)
57.81% [kernel] [k] copy_user_enhanced_fast_string
(*) 12.87% [kernel] [k] skb_release_data
(*) 4.25% [kernel] [k] __free_one_page
(*) 3.57% [kernel] [k] __list_del_entry_valid
1.85% [kernel] [k] __netif_receive_skb_core
1.60% [kernel] [k] __skb_datagram_iter
(*) 1.59% [kernel] [k] free_unref_page_commit
(*) 1.16% [kernel] [k] __slab_free
1.16% [kernel] [k] _copy_to_iter
(*) 1.01% [kernel] [k] kfree
(*) 0.88% [kernel] [k] free_unref_page
0.57% [kernel] [k] ip6_rcv_core
0.55% [kernel] [k] ip6t_do_table
0.54% [kernel] [k] flush_smp_call_function_queue
(*) 0.54% [kernel] [k] free_pcppages_bulk
0.51% [kernel] [k] llist_reverse_order
0.38% [kernel] [k] process_backlog
(*) 0.38% [kernel] [k] free_pcp_prepare
0.37% [kernel] [k] tcp_recvmsg_locked
(*) 0.37% [kernel] [k] __list_add_valid
0.34% [kernel] [k] sock_rfree
0.34% [kernel] [k] _raw_spin_lock_irq
(*) 0.33% [kernel] [k] __page_cache_release
0.33% [kernel] [k] tcp_v6_rcv
(*) 0.33% [kernel] [k] __put_page
(*) 0.29% [kernel] [k] __mod_zone_page_state
0.27% [kernel] [k] _raw_spin_lock
After patch:
Average throughput: 73076 Mbit.
Kernel profiles on cpu running user thread recvmsg() looks better:
81.35% [kernel] [k] copy_user_enhanced_fast_string
1.95% [kernel] [k] _copy_to_iter
1.95% [kernel] [k] __skb_datagram_iter
1.27% [kernel] [k] __netif_receive_skb_core
1.03% [kernel] [k] ip6t_do_table
0.60% [kernel] [k] sock_rfree
0.50% [kernel] [k] tcp_v6_rcv
0.47% [kernel] [k] ip6_rcv_core
0.45% [kernel] [k] read_tsc
0.44% [kernel] [k] _raw_spin_lock_irqsave
0.37% [kernel] [k] _raw_spin_lock
0.37% [kernel] [k] native_irq_return_iret
0.33% [kernel] [k] __inet6_lookup_established
0.31% [kernel] [k] ip6_protocol_deliver_rcu
0.29% [kernel] [k] tcp_rcv_established
0.29% [kernel] [k] llist_reverse_order
v2: kdoc issue (kernel bots)
do not defer if (alloc_cpu == smp_processor_id()) (Paolo)
replace the sk_buff_head with a single-linked list (Jakub)
add a READ_ONCE()/WRITE_ONCE() for the lockless read of sd->defer_list
Signed-off-by: Eric Dumazet <edumazet@google.com>
Acked-by: Paolo Abeni <pabeni@redhat.com>
Link: https://lore.kernel.org/r/20220422201237.416238-1-eric.dumazet@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Now that ip_rt_fix_tos() doesn't reset ->flowi4_scope unconditionally,
we don't have to rely on the RTO_ONLINK bit to properly set the scope
of a flowi4 structure. We can just set ->flowi4_scope explicitly and
avoid using RTO_ONLINK in ->flowi4_tos.
This patch converts callers of ip_route_connect(). Instead of setting
the tos parameter with RT_CONN_FLAGS(sk), as all callers do, we can:
1- Drop the tos parameter from ip_route_connect(): its value was
entirely based on sk, which is also passed as parameter.
2- Set ->flowi4_scope depending on the SOCK_LOCALROUTE socket option
instead of always initialising it with RT_SCOPE_UNIVERSE (let's
define ip_sock_rt_scope() for this purpose).
3- Avoid overloading ->flowi4_tos with RTO_ONLINK: since the scope is
now properly initialised, we don't need to tell ip_rt_fix_tos() to
adjust ->flowi4_scope for us. So let's define ip_sock_rt_tos(),
which is the same as RT_CONN_FLAGS() but without the RTO_ONLINK
bit overload.
Note:
In the original ip_route_connect() code, __ip_route_output_key()
might clear the RTO_ONLINK bit of fl4->flowi4_tos (because of
ip_rt_fix_tos()). Therefore flowi4_update_output() had to reuse the
original tos variable. Now that we don't set RTO_ONLINK any more,
this is not a problem and we can use fl4->flowi4_tos in
flowi4_update_output().
Signed-off-by: Guillaume Nault <gnault@redhat.com>
Reviewed-by: David Ahern <dsahern@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
We had various bugs over the years with code
breaking the assumption that tp->snd_cwnd is greater
than zero.
Lately, syzbot reported the WARN_ON_ONCE(!tp->prior_cwnd) added
in commit 8b8a321ff7 ("tcp: fix zero cwnd in tcp_cwnd_reduction")
can trigger, and without a repro we would have to spend
considerable time finding the bug.
Instead of complaining too late, we want to catch where
and when tp->snd_cwnd is set to an illegal value.
Signed-off-by: Eric Dumazet <edumazet@google.com>
Suggested-by: Yuchung Cheng <ycheng@google.com>
Cc: Neal Cardwell <ncardwell@google.com>
Acked-by: Yuchung Cheng <ycheng@google.com>
Link: https://lore.kernel.org/r/20220405233538.947344-1-eric.dumazet@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Back when tcp_tso_autosize() and TCP pacing were introduced,
our focus was really to reduce burst sizes for long distance
flows.
The simple heuristic of using sk_pacing_rate/1024 has worked
well, but can lead to too small packets for hosts in the same
rack/cluster, when thousands of flows compete for the bottleneck.
Neal Cardwell had the idea of making the TSO burst size
a function of both sk_pacing_rate and tcp_min_rtt()
Indeed, for local flows, sending bigger bursts is better
to reduce cpu costs, as occasional losses can be repaired
quite fast.
This patch is based on Neal Cardwell implementation
done more than two years ago.
bbr is adjusting max_pacing_rate based on measured bandwidth,
while cubic would over estimate max_pacing_rate.
/proc/sys/net/ipv4/tcp_tso_rtt_log can be used to tune or disable
this new feature, in logarithmic steps.
Tested:
100Gbit NIC, two hosts in the same rack, 4K MTU.
600 flows rate-limited to 20000000 bytes per second.
Before patch: (TSO sizes would be limited to 20000000/1024/4096 -> 4 segments per TSO)
~# echo 0 >/proc/sys/net/ipv4/tcp_tso_rtt_log
~# nstat -n;perf stat ./super_netperf 600 -H otrv6 -l 20 -- -K dctcp -q 20000000;nstat|egrep "TcpInSegs|TcpOutSegs|TcpRetransSegs|Delivered"
96005
Performance counter stats for './super_netperf 600 -H otrv6 -l 20 -- -K dctcp -q 20000000':
65,945.29 msec task-clock # 2.845 CPUs utilized
1,314,632 context-switches # 19935.279 M/sec
5,292 cpu-migrations # 80.249 M/sec
940,641 page-faults # 14264.023 M/sec
201,117,030,926 cycles # 3049769.216 GHz (83.45%)
17,699,435,405 stalled-cycles-frontend # 8.80% frontend cycles idle (83.48%)
136,584,015,071 stalled-cycles-backend # 67.91% backend cycles idle (83.44%)
53,809,530,436 instructions # 0.27 insn per cycle
# 2.54 stalled cycles per insn (83.36%)
9,062,315,523 branches # 137422329.563 M/sec (83.22%)
153,008,621 branch-misses # 1.69% of all branches (83.32%)
23.182970846 seconds time elapsed
TcpInSegs 15648792 0.0
TcpOutSegs 58659110 0.0 # Average of 3.7 4K segments per TSO packet
TcpExtTCPDelivered 58654791 0.0
TcpExtTCPDeliveredCE 19 0.0
After patch:
~# echo 9 >/proc/sys/net/ipv4/tcp_tso_rtt_log
~# nstat -n;perf stat ./super_netperf 600 -H otrv6 -l 20 -- -K dctcp -q 20000000;nstat|egrep "TcpInSegs|TcpOutSegs|TcpRetransSegs|Delivered"
96046
Performance counter stats for './super_netperf 600 -H otrv6 -l 20 -- -K dctcp -q 20000000':
48,982.58 msec task-clock # 2.104 CPUs utilized
186,014 context-switches # 3797.599 M/sec
3,109 cpu-migrations # 63.472 M/sec
941,180 page-faults # 19214.814 M/sec
153,459,763,868 cycles # 3132982.807 GHz (83.56%)
12,069,861,356 stalled-cycles-frontend # 7.87% frontend cycles idle (83.32%)
120,485,917,953 stalled-cycles-backend # 78.51% backend cycles idle (83.24%)
36,803,672,106 instructions # 0.24 insn per cycle
# 3.27 stalled cycles per insn (83.18%)
5,947,266,275 branches # 121417383.427 M/sec (83.64%)
87,984,616 branch-misses # 1.48% of all branches (83.43%)
23.281200256 seconds time elapsed
TcpInSegs 1434706 0.0
TcpOutSegs 58883378 0.0 # Average of 41 4K segments per TSO packet
TcpExtTCPDelivered 58878971 0.0
TcpExtTCPDeliveredCE 9664 0.0
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Neal Cardwell <ncardwell@google.com>
Link: https://lore.kernel.org/r/20220309015757.2532973-1-eric.dumazet@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
We have a number of cases where function returns drop/no drop
decision as a boolean. Now that we want to report the reason
code as well we have to pass extra output arguments.
We can make the reason code evaluate correctly as bool.
I believe we're good to reorder the reasons as they are
reported to user space as strings.
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Reviewed-by: David Ahern <dsahern@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
The functions do essentially the same work to verify TCP-MD5 sign.
Code can be merged into one family-independent function in order to
reduce copy'n'paste and generated code.
Later with TCP-AO option added, this will allow to create one function
that's responsible for segment verification, that will have all the
different checks for MD5/AO/non-signed packets, which in turn will help
to see checks for all corner-cases in one function, rather than spread
around different families and functions.
Cc: Eric Dumazet <edumazet@google.com>
Cc: Hideaki YOSHIFUJI <yoshfuji@linux-ipv6.org>
Signed-off-by: Dmitry Safonov <dima@arista.com>
Reviewed-by: David Ahern <dsahern@kernel.org>
Link: https://lore.kernel.org/r/20220223175740.452397-1-dima@arista.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Replace kfree_skb() used in tcp_v4_do_rcv() and tcp_v6_do_rcv() with
kfree_skb_reason().
Reviewed-by: Mengen Sun <mengensun@tencent.com>
Reviewed-by: Hao Peng <flyingpeng@tencent.com>
Signed-off-by: Menglong Dong <imagedong@tencent.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: David Ahern <dsahern@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Pass the address of drop_reason to tcp_add_backlog() to store the
reasons for skb drops when fails. Following drop reasons are
introduced:
SKB_DROP_REASON_SOCKET_BACKLOG
Reviewed-by: Mengen Sun <mengensun@tencent.com>
Reviewed-by: Hao Peng <flyingpeng@tencent.com>
Signed-off-by: Menglong Dong <imagedong@tencent.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: David Ahern <dsahern@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Pass the address of drop reason to tcp_v4_inbound_md5_hash() and
tcp_v6_inbound_md5_hash() to store the reasons for skb drops when this
function fails. Therefore, the drop reason can be passed to
kfree_skb_reason() when the skb needs to be freed.
Following drop reasons are added:
SKB_DROP_REASON_TCP_MD5NOTFOUND
SKB_DROP_REASON_TCP_MD5UNEXPECTED
SKB_DROP_REASON_TCP_MD5FAILURE
SKB_DROP_REASON_TCP_MD5* above correspond to LINUX_MIB_TCPMD5*
Reviewed-by: Mengen Sun <mengensun@tencent.com>
Reviewed-by: Hao Peng <flyingpeng@tencent.com>
Signed-off-by: Menglong Dong <imagedong@tencent.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: David Ahern <dsahern@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Use kfree_skb_reason() for some path in tcp_v4_rcv() that missed before,
including:
SKB_DROP_REASON_SOCKET_FILTER
SKB_DROP_REASON_XFRM_POLICY
Reviewed-by: Mengen Sun <mengensun@tencent.com>
Reviewed-by: Hao Peng <flyingpeng@tencent.com>
Signed-off-by: Menglong Dong <imagedong@tencent.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: David Ahern <dsahern@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Current release - new code bugs:
- tcp: add a missing sk_defer_free_flush() in tcp_splice_read()
- tcp: add a stub for sk_defer_free_flush(), fix CONFIG_INET=n
- nf_tables: set last expression in register tracking area
- nft_connlimit: fix memleak if nf_ct_netns_get() fails
- mptcp: fix removing ids bitmap setting
- bonding: use rcu_dereference_rtnl when getting active slave
- fix three cases of sleep in atomic context in drivers: lan966x, gve
- handful of build fixes for esoteric drivers after netdev->dev_addr
was made const
Previous releases - regressions:
- revert "ipv6: Honor all IPv6 PIO Valid Lifetime values", it broke
Linux compatibility with USGv6 tests
- procfs: show net device bound packet types
- ipv4: fix ip option filtering for locally generated fragments
- phy: broadcom: hook up soft_reset for BCM54616S
Previous releases - always broken:
- ipv4: raw: lock the socket in raw_bind()
- ipv4: decrease the use of shared IPID generator to decrease the
chance of attackers guessing the values
- procfs: fix cross-netns information leakage in /proc/net/ptype
- ethtool: fix link extended state for big endian
- bridge: vlan: fix single net device option dumping
- ping: fix the sk_bound_dev_if match in ping_lookup
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
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Merge tag 'net-5.17-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net
Pull networking fixes from Jakub Kicinski:
"Including fixes from netfilter and can.
Current release - new code bugs:
- tcp: add a missing sk_defer_free_flush() in tcp_splice_read()
- tcp: add a stub for sk_defer_free_flush(), fix CONFIG_INET=n
- nf_tables: set last expression in register tracking area
- nft_connlimit: fix memleak if nf_ct_netns_get() fails
- mptcp: fix removing ids bitmap setting
- bonding: use rcu_dereference_rtnl when getting active slave
- fix three cases of sleep in atomic context in drivers: lan966x, gve
- handful of build fixes for esoteric drivers after netdev->dev_addr
was made const
Previous releases - regressions:
- revert "ipv6: Honor all IPv6 PIO Valid Lifetime values", it broke
Linux compatibility with USGv6 tests
- procfs: show net device bound packet types
- ipv4: fix ip option filtering for locally generated fragments
- phy: broadcom: hook up soft_reset for BCM54616S
Previous releases - always broken:
- ipv4: raw: lock the socket in raw_bind()
- ipv4: decrease the use of shared IPID generator to decrease the
chance of attackers guessing the values
- procfs: fix cross-netns information leakage in /proc/net/ptype
- ethtool: fix link extended state for big endian
- bridge: vlan: fix single net device option dumping
- ping: fix the sk_bound_dev_if match in ping_lookup"
* tag 'net-5.17-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net: (86 commits)
net: bridge: vlan: fix memory leak in __allowed_ingress
net: socket: rename SKB_DROP_REASON_SOCKET_FILTER
ipv4: remove sparse error in ip_neigh_gw4()
ipv4: avoid using shared IP generator for connected sockets
ipv4: tcp: send zero IPID in SYNACK messages
ipv4: raw: lock the socket in raw_bind()
MAINTAINERS: add missing IPv4/IPv6 header paths
MAINTAINERS: add more files to eth PHY
net: stmmac: dwmac-sun8i: use return val of readl_poll_timeout()
net: bridge: vlan: fix single net device option dumping
net: stmmac: skip only stmmac_ptp_register when resume from suspend
net: stmmac: configure PTP clock source prior to PTP initialization
Revert "ipv6: Honor all IPv6 PIO Valid Lifetime values"
connector/cn_proc: Use task_is_in_init_pid_ns()
pid: Introduce helper task_is_in_init_pid_ns()
gve: Fix GFP flags when allocing pages
net: lan966x: Fix sleep in atomic context when updating MAC table
net: lan966x: Fix sleep in atomic context when injecting frames
ethernet: seeq/ether3: don't write directly to netdev->dev_addr
ethernet: 8390/etherh: don't write directly to netdev->dev_addr
...
Rename SKB_DROP_REASON_SOCKET_FILTER, which is used
as the reason of skb drop out of socket filter before
it's part of a released kernel. It will be used for
more protocols than just TCP in future series.
Signed-off-by: Menglong Dong <imagedong@tencent.com>
Reviewed-by: David Ahern <dsahern@kernel.org>
Link: https://lore.kernel.org/all/20220127091308.91401-2-imagedong@tencent.com/
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
TCP ipv4 uses per-cpu/per-netns ctl sockets in order to send
RST and some ACK packets (on behalf of TIMEWAIT sockets).
This adds memory and cpu costs, which do not seem needed.
Now typical servers have 256 or more cores, this adds considerable
tax to netns users.
tcp sockets are used from BH context, are not receiving packets,
and do not store any persistent state but the 'struct net' pointer
in order to be able to use IPv4 output functions.
Note that I attempted a related change in the past, that had
to be hot-fixed in commit bdbbb8527b ("ipv4: tcp: get rid of ugly unicast_sock")
This patch could very well surface old bugs, on layers not
taking care of sk->sk_kern_sock properly.
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Prior patches in the series made sure tw_timer_handler()
can be fired after netns has been dismantled/freed.
We no longer have to scan a potentially big TCP ehash
table at netns dismantle.
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Remove PDE_DATA() completely and replace it with pde_data().
[akpm@linux-foundation.org: fix naming clash in drivers/nubus/proc.c]
[akpm@linux-foundation.org: now fix it properly]
Link: https://lkml.kernel.org/r/20211124081956.87711-2-songmuchun@bytedance.com
Signed-off-by: Muchun Song <songmuchun@bytedance.com>
Acked-by: Christian Brauner <christian.brauner@ubuntu.com>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Alexey Gladkov <gladkov.alexey@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Replace kfree_skb() with kfree_skb_reason() in tcp_v4_rcv(). Following
drop reasons are added:
SKB_DROP_REASON_NO_SOCKET
SKB_DROP_REASON_PKT_TOO_SMALL
SKB_DROP_REASON_TCP_CSUM
SKB_DROP_REASON_TCP_FILTER
After this patch, 'kfree_skb' event will print message like this:
$ TASK-PID CPU# ||||| TIMESTAMP FUNCTION
$ | | | ||||| | |
<idle>-0 [000] ..s1. 36.113438: kfree_skb: skbaddr=(____ptrval____) protocol=2048 location=(____ptrval____) reason: NO_SOCKET
The reason of skb drop is printed too.
Signed-off-by: Menglong Dong <imagedong@tencent.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
The return value of BPF_CGROUP_RUN_PROG_INET{4,6}_POST_BIND() in
__inet_bind() is not handled properly. While the return value
is non-zero, it will set inet_saddr and inet_rcv_saddr to 0 and
exit:
err = BPF_CGROUP_RUN_PROG_INET4_POST_BIND(sk);
if (err) {
inet->inet_saddr = inet->inet_rcv_saddr = 0;
goto out_release_sock;
}
Let's take UDP for example and see what will happen. For UDP
socket, it will be added to 'udp_prot.h.udp_table->hash' and
'udp_prot.h.udp_table->hash2' after the sk->sk_prot->get_port()
called success. If 'inet->inet_rcv_saddr' is specified here,
then 'sk' will be in the 'hslot2' of 'hash2' that it don't belong
to (because inet_saddr is changed to 0), and UDP packet received
will not be passed to this sock. If 'inet->inet_rcv_saddr' is not
specified here, the sock will work fine, as it can receive packet
properly, which is wired, as the 'bind()' is already failed.
To undo the get_port() operation, introduce the 'put_port' field
for 'struct proto'. For TCP proto, it is inet_put_port(); For UDP
proto, it is udp_lib_unhash(); For icmp proto, it is
ping_unhash().
Therefore, after sys_bind() fail caused by
BPF_CGROUP_RUN_PROG_INET4_POST_BIND(), it will be unbinded, which
means that it can try to be binded to another port.
Signed-off-by: Menglong Dong <imagedong@tencent.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20220106132022.3470772-2-imagedong@tencent.com
tcp recvmsg() (or rx zerocopy) spends a fair amount of time
freeing skbs after their payload has been consumed.
A typical ~64KB GRO packet has to release ~45 page
references, eventually going to page allocator
for each of them.
Currently, this freeing is performed while socket lock
is held, meaning that there is a high chance that
BH handler has to queue incoming packets to tcp socket backlog.
This can cause additional latencies, because the user
thread has to process the backlog at release_sock() time,
and while doing so, additional frames can be added
by BH handler.
This patch adds logic to defer these frees after socket
lock is released, or directly from BH handler if possible.
Being able to free these skbs from BH handler helps a lot,
because this avoids the usual alloc/free assymetry,
when BH handler and user thread do not run on same cpu or
NUMA node.
One cpu can now be fully utilized for the kernel->user copy,
and another cpu is handling BH processing and skb/page
allocs/frees (assuming RFS is not forcing use of a single CPU)
Tested:
100Gbit NIC
Max throughput for one TCP_STREAM flow, over 10 runs
MTU : 1500
Before: 55 Gbit
After: 66 Gbit
MTU : 4096+(headers)
Before: 82 Gbit
After: 95 Gbit
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Instead of using a full netdev_features_t, we can use a single bit,
as sk_route_nocaps is only used to remove NETIF_F_GSO_MASK from
sk->sk_route_cap.
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
If packet is going to be coalesced, sk_sndbuf/sk_rcvbuf values
are not used. Defer their access to the point we need them.
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
RFC 5082 IP_MINTTL option is rarely used on hosts.
Add a static key to remove from TCP fast path useless code,
and potential cache line miss to fetch inet_sk(sk)->min_ttl
Note that once ip4_min_ttl static key has been enabled,
it stays enabled until next boot.
Signed-off-by: Eric Dumazet <edumazet@google.com>
Acked-by: Soheil Hassas Yeganeh <soheil@google.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
No report yet from KCSAN, yet worth documenting the races.
Signed-off-by: Eric Dumazet <edumazet@google.com>
Acked-by: Soheil Hassas Yeganeh <soheil@google.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Increase cache locality by moving rx_dst_ifindex next to sk->sk_rx_dst
This is part of an effort to reduce cache line misses in TCP fast path.
This removes one cache line miss in early demux.
Signed-off-by: Eric Dumazet <edumazet@google.com>
Acked-by: Soheil Hassas Yeganeh <soheil@google.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Multiple VRFs are generally meant to be "separate" but right now md5
keys for the default VRF also affect connections inside VRFs if the IP
addresses happen to overlap.
So far the combination of TCP_MD5SIG_FLAG_IFINDEX with tcpm_ifindex == 0
was an error, accept this to mean "key only applies to default VRF".
This is what applications using VRFs for traffic separation want.
Signed-off-by: Leonard Crestez <cdleonard@gmail.com>
Reviewed-by: David Ahern <dsahern@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
With net.ipv4.tcp_l3mdev_accept=1 it is possible for a listen socket to
accept connection from the same client address in different VRFs. It is
also possible to set different MD5 keys for these clients which differ
only in the tcpm_l3index field.
This appears to work when distinguishing between different VRFs but not
between non-VRF and VRF connections. In particular:
* tcp_md5_do_lookup_exact will match a non-vrf key against a vrf key.
This means that adding a key with l3index != 0 after a key with l3index
== 0 will cause the earlier key to be deleted. Both keys can be present
if the non-vrf key is added later.
* _tcp_md5_do_lookup can match a non-vrf key before a vrf key. This
casues failures if the passwords differ.
Fix this by making tcp_md5_do_lookup_exact perform an actual exact
comparison on l3index and by making __tcp_md5_do_lookup perfer
vrf-bound keys above other considerations like prefixlen.
Fixes: dea53bb80e ("tcp: Add l3index to tcp_md5sig_key and md5 functions")
Signed-off-by: Leonard Crestez <cdleonard@gmail.com>
Reviewed-by: David Ahern <dsahern@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
This reverts the following patches :
- commit 2e05fcae83 ("tcp: fix compile error if !CONFIG_SYSCTL")
- commit 4f661542a4 ("tcp: fix zerocopy and notsent_lowat issues")
- commit 472c2e07ee ("tcp: add one skb cache for tx")
- commit 8b27dae5a2 ("tcp: add one skb cache for rx")
Having a cache of one skb (in each direction) per TCP socket is fragile,
since it can cause a significant increase of memory needs,
and not good enough for high speed flows anyway where more than one skb
is needed.
We want instead to add a generic infrastructure, with more flexible
per-cpu caches, for alien NUMA nodes.
Acked-by: Paolo Abeni <pabeni@redhat.com>
Acked-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Andrii Nakryiko says:
====================
bpf-next 2021-07-30
We've added 64 non-merge commits during the last 15 day(s) which contain
a total of 83 files changed, 5027 insertions(+), 1808 deletions(-).
The main changes are:
1) BTF-guided binary data dumping libbpf API, from Alan.
2) Internal factoring out of libbpf CO-RE relocation logic, from Alexei.
3) Ambient BPF run context and cgroup storage cleanup, from Andrii.
4) Few small API additions for libbpf 1.0 effort, from Evgeniy and Hengqi.
5) bpf_program__attach_kprobe_opts() fixes in libbpf, from Jiri.
6) bpf_{get,set}sockopt() support in BPF iterators, from Martin.
7) BPF map pinning improvements in libbpf, from Martynas.
8) Improved module BTF support in libbpf and bpftool, from Quentin.
9) Bpftool cleanups and documentation improvements, from Quentin.
10) Libbpf improvements for supporting CO-RE on old kernels, from Shuyi.
11) Increased maximum cgroup storage size, from Stanislav.
12) Small fixes and improvements to BPF tests and samples, from various folks.
* https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next: (64 commits)
tools: bpftool: Complete metrics list in "bpftool prog profile" doc
tools: bpftool: Document and add bash completion for -L, -B options
selftests/bpf: Update bpftool's consistency script for checking options
tools: bpftool: Update and synchronise option list in doc and help msg
tools: bpftool: Complete and synchronise attach or map types
selftests/bpf: Check consistency between bpftool source, doc, completion
tools: bpftool: Slightly ease bash completion updates
unix_bpf: Fix a potential deadlock in unix_dgram_bpf_recvmsg()
libbpf: Add btf__load_vmlinux_btf/btf__load_module_btf
tools: bpftool: Support dumping split BTF by id
libbpf: Add split BTF support for btf__load_from_kernel_by_id()
tools: Replace btf__get_from_id() with btf__load_from_kernel_by_id()
tools: Free BTF objects at various locations
libbpf: Rename btf__get_from_id() as btf__load_from_kernel_by_id()
libbpf: Rename btf__load() as btf__load_into_kernel()
libbpf: Return non-null error on failures in libbpf_find_prog_btf_id()
bpf: Emit better log message if bpf_iter ctx arg btf_id == 0
tools/resolve_btfids: Emit warnings and patch zero id for missing symbols
bpf: Increase supported cgroup storage value size
libbpf: Fix race when pinning maps in parallel
...
====================
Link: https://lore.kernel.org/r/20210730225606.1897330-1-andrii@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This patch allows bpf tcp iter to call bpf_(get|set)sockopt.
To allow a specific bpf iter (tcp here) to call a set of helpers,
get_func_proto function pointer is added to bpf_iter_reg.
The bpf iter is a tracing prog which currently requires
CAP_PERFMON or CAP_SYS_ADMIN, so this patch does not
impose other capability checks for bpf_(get|set)sockopt.
Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Acked-by: Kuniyuki Iwashima <kuniyu@amazon.co.jp>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20210701200619.1036715-1-kafai@fb.com
This patch does batching and lock_sock for the bpf tcp iter.
It does not affect the proc fs iteration.
With bpf-tcp-cc, new algo rollout happens more often. Instead of
restarting the application to pick up the new tcp-cc, the next patch
will allow bpf iter to do setsockopt(TCP_CONGESTION). This requires
locking the sock.
Also, unlike the proc iteration (cat /proc/net/tcp[6]), the bpf iter
can inspect all fields of a tcp_sock. It will be useful to have a
consistent view on some of the fields (e.g. the ones reported in
tcp_get_info() that also acquires the sock lock).
Double lock: locking the bucket first and then locking the sock could
lead to deadlock. This patch takes a batching approach similar to
inet_diag. While holding the bucket lock, it batch a number of sockets
into an array first and then unlock the bucket. Before doing show(),
it then calls lock_sock_fast().
In a machine with ~400k connections, the maximum number of
sk in a bucket of the established hashtable is 7. 0.02% of
the established connections fall into this bucket size.
For listen hash (port+addr lhash2), the bucket is usually very
small also except for the SO_REUSEPORT use case which the
userspace could have one SO_REUSEPORT socket per thread.
While batching is used, it can also minimize the chance of missing
sock in the setsockopt use case if the whole bucket is batched.
This patch will start with a batch array with INIT_BATCH_SZ (16)
which will be enough for the most common cases. bpf_iter_tcp_batch()
will try to realloc to a larger array to handle exception case (e.g.
the SO_REUSEPORT case in the lhash2).
Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Acked-by: Kuniyuki Iwashima <kuniyu@amazon.co.jp>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20210701200613.1036157-1-kafai@fb.com
This patch moves the tcp seq_file iteration on listeners
from the port only listening_hash to the port+addr lhash2.
When iterating from the bpf iter, the next patch will need to
lock the socket such that the bpf iter can call setsockopt (e.g. to
change the TCP_CONGESTION). To avoid locking the bucket and then locking
the sock, the bpf iter will first batch some sockets from the same bucket
and then unlock the bucket. If the bucket size is small (which
usually is), it is easier to batch the whole bucket such that it is less
likely to miss a setsockopt on a socket due to changes in the bucket.
However, the port only listening_hash could have many listeners
hashed to a bucket (e.g. many individual VIP(s):443 and also
multiple by the number of SO_REUSEPORT). We have seen bucket size in
tens of thousands range. Also, the chance of having changes
in some popular port buckets (e.g. 443) is also high.
The port+addr lhash2 was introduced to solve this large listener bucket
issue. Also, the listening_hash usage has already been replaced with
lhash2 in the fast path inet[6]_lookup_listener(). This patch follows
the same direction on moving to lhash2 and iterates the lhash2
instead of listening_hash.
Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Acked-by: Kuniyuki Iwashima <kuniyu@amazon.co.jp>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20210701200606.1035783-1-kafai@fb.com
The current listening_get_next() is overloaded by passing
NULL to the 2nd arg, like listening_get_next(seq, NULL), to
mean get_first().
This patch moves some logic from the listening_get_next() into
a new function listening_get_first(). It will be equivalent
to the current established_get_first() and established_get_next()
setup. get_first() is to find a non empty bucket and return
the first sk. get_next() is to find the next sk of the current
bucket and then resorts to get_first() if the current bucket is
exhausted.
The next patch is to move the listener seq_file iteration from
listening_hash (port only) to lhash2 (port+addr).
Separating out listening_get_first() from listening_get_next()
here will make the following lhash2 changes cleaner and easier to
follow.
Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Acked-by: Kuniyuki Iwashima <kuniyu@amazon.co.jp>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20210701200600.1035353-1-kafai@fb.com
A following patch will create a separate struct to store extra
bpf_iter state and it will embed the existing tcp_iter_state like this:
struct bpf_tcp_iter_state {
struct tcp_iter_state state;
/* More bpf_iter specific states here ... */
}
As a prep work, this patch removes the
"struct tcp_seq_afinfo *bpf_seq_afinfo" where its purpose is
to tell if it is iterating from bpf_iter instead of proc fs.
Currently, if "*bpf_seq_afinfo" is not NULL, it is iterating from
bpf_iter. The kernel should not filter by the addr family and
leave this filtering decision to the bpf prog.
Instead of adding a "*bpf_seq_afinfo" pointer, this patch uses the
"seq->op == &bpf_iter_tcp_seq_ops" test to tell if it is iterating
from the bpf iter.
The bpf_iter_(init|fini)_tcp() is left here to prepare for
the change of a following patch.
Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Acked-by: Kuniyuki Iwashima <kuniyu@amazon.co.jp>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20210701200554.1034982-1-kafai@fb.com
This patch refactors the net and family matching into
two new helpers, seq_sk_match() and seq_file_family().
seq_file_family() is in the later part of the file to prepare
the change of a following patch.
Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Acked-by: Kuniyuki Iwashima <kuniyu@amazon.co.jp>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20210701200548.1034629-1-kafai@fb.com
st->bucket stores the current bucket number.
st->offset stores the offset within this bucket that is the sk to be
seq_show(). Thus, st->offset only makes sense within the same
st->bucket.
These two variables are an optimization for the common no-lseek case.
When resuming the seq_file iteration (i.e. seq_start()),
tcp_seek_last_pos() tries to continue from the st->offset
at bucket st->bucket.
However, it is possible that the bucket pointed by st->bucket
has changed and st->offset may end up skipping the whole st->bucket
without finding a sk. In this case, tcp_seek_last_pos() currently
continues to satisfy the offset condition in the next (and incorrect)
bucket. Instead, regardless of the offset value, the first sk of the
next bucket should be returned. Thus, "bucket == st->bucket" check is
added to tcp_seek_last_pos().
The chance of hitting this is small and the issue is a decade old,
so targeting for the next tree.
Fixes: a8b690f98b ("tcp: Fix slowness in read /proc/net/tcp")
Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Acked-by: Kuniyuki Iwashima <kuniyu@amazon.co.jp>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20210701200541.1033917-1-kafai@fb.com
Multiple complaints have been raised from the TFO users on the internet
stating that the TFO blackhole logic is too aggressive and gets falsely
triggered too often.
(e.g. https://blog.apnic.net/2021/07/05/tcp-fast-open-not-so-fast/)
Considering that most middleboxes no longer drop TFO packets, we decide
to disable the blackhole logic by setting
/proc/sys/net/ipv4/tcp_fastopen_blackhole_timeout_set to 0 by default.
Fixes: cf1ef3f071 ("net/tcp_fastopen: Disable active side TFO in certain scenarios")
Signed-off-by: Wei Wang <weiwan@google.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Acked-by: Neal Cardwell <ncardwell@google.com>
Acked-by: Soheil Hassas Yeganeh <soheil@google.com>
Acked-by: Yuchung Cheng <ycheng@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
While tp->mtu_info is read while socket is owned, the write
sides happen from err handlers (tcp_v[46]_mtu_reduced)
which only own the socket spinlock.
Fixes: 563d34d057 ("tcp: dont drop MTU reduction indications")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This patch introduces a function wrapper to call the sk_error_report
callback. That will prepare to add additional handling whenever
sk_error_report is called, for example to trace socket errors.
Signed-off-by: Alexander Aring <aahringo@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This patch also changes the code to call reuseport_migrate_sock() and
inet_reqsk_clone(), but unlike the other cases, we do not call
inet_reqsk_clone() right after reuseport_migrate_sock().
Currently, in the receive path for TCP_NEW_SYN_RECV sockets, its listener
has three kinds of refcnt:
(A) for listener itself
(B) carried by reuqest_sock
(C) sock_hold() in tcp_v[46]_rcv()
While processing the req, (A) may disappear by close(listener). Also, (B)
can disappear by accept(listener) once we put the req into the accept
queue. So, we have to hold another refcnt (C) for the listener to prevent
use-after-free.
For socket migration, we call reuseport_migrate_sock() to select a listener
with (A) and to increment the new listener's refcnt in tcp_v[46]_rcv().
This refcnt corresponds to (C) and is cleaned up later in tcp_v[46]_rcv().
Thus we have to take another refcnt (B) for the newly cloned request_sock.
In inet_csk_complete_hashdance(), we hold the count (B), clone the req, and
try to put the new req into the accept queue. By migrating req after
winning the "own_req" race, we can avoid such a worst situation:
CPU 1 looks up req1
CPU 2 looks up req1, unhashes it, then CPU 1 loses the race
CPU 3 looks up req2, unhashes it, then CPU 2 loses the race
...
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.co.jp>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Link: https://lore.kernel.org/bpf/20210612123224.12525-8-kuniyu@amazon.co.jp
