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Yu-Ting Tseng d579b04a52 binder: frozen notification
Frozen processes present a significant challenge in binder transactions.
When a process is frozen, it cannot, by design, accept and/or respond to
binder transactions. As a result, the sender needs to adjust its
behavior, such as postponing transactions until the peer process
unfreezes. However, there is currently no way to subscribe to these
state change events, making it impossible to implement frozen-aware
behaviors efficiently.

Introduce a binder API for subscribing to frozen state change events.
This allows programs to react to changes in peer process state,
mitigating issues related to binder transactions sent to frozen
processes.

Implementation details:
For a given binder_ref, the state of frozen notification can be one of
the followings:
1. Userspace doesn't want a notification. binder_ref->freeze is null.
2. Userspace wants a notification but none is in flight.
   list_empty(&binder_ref->freeze->work.entry) = true
3. A notification is in flight and waiting to be read by userspace.
   binder_ref_freeze.sent is false.
4. A notification was read by userspace and kernel is waiting for an ack.
   binder_ref_freeze.sent is true.

When a notification is in flight, new state change events are coalesced into
the existing binder_ref_freeze struct. If userspace hasn't picked up the
notification yet, the driver simply rewrites the state. Otherwise, the
notification is flagged as requiring a resend, which will be performed
once userspace acks the original notification that's inflight.

See https://r.android.com/3070045 for how userspace is going to use this
feature.

Signed-off-by: Yu-Ting Tseng <yutingtseng@google.com>
Acked-by: Carlos Llamas <cmllamas@google.com>
Link: https://lore.kernel.org/r/20240709070047.4055369-4-yutingtseng@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-07-31 13:56:00 +02:00
arch minmax: add a few more MIN_T/MAX_T users 2024-07-28 13:41:14 -07:00
block block: fix deadlock between sd_remove & sd_release 2024-07-24 09:51:21 -06:00
certs kbuild: use $(src) instead of $(srctree)/$(src) for source directory 2024-05-10 04:34:52 +09:00
crypto crypto: testmgr - generate power-of-2 lengths more often 2024-07-13 11:50:28 +12:00
Documentation CXL for v6.11 merge window 2024-07-28 09:33:28 -07:00
drivers binder: frozen notification 2024-07-31 13:56:00 +02:00
fs This pull request contains updates (actually, just fixes) for UBI and UBIFS: 2024-07-28 11:51:51 -07:00
include binder: frozen notification 2024-07-31 13:56:00 +02:00
init Rust changes for v6.11 2024-07-27 13:44:54 -07:00
io_uring io_uring/napi: pass ktime to io_napi_adjust_timeout 2024-07-26 08:31:59 -06:00
ipc sysctl: treewide: constify the ctl_table argument of proc_handlers 2024-07-24 20:59:29 +02:00
kernel Fixes and minor updates for the timer migration code: 2024-07-27 10:19:55 -07:00
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LICENSES LICENSES: Add the copyleft-next-0.3.1 license 2022-11-08 15:44:01 +01:00
mm mm/page_alloc: fix pcp->count race between drain_pages_zone() vs __rmqueue_pcplist() 2024-07-26 14:33:09 -07:00
net minmax: add a few more MIN_T/MAX_T users 2024-07-28 13:41:14 -07:00
rust Rust changes for v6.11 2024-07-27 13:44:54 -07:00
samples Driver core changes for 6.11-rc1 2024-07-25 10:42:22 -07:00
scripts Kbuild fixes for v6.11 2024-07-28 14:02:48 -07:00
security apparmor-pr-2024-07-24 PR 2024-07-25 2024-07-27 13:28:39 -07:00
sound Devicetree fixes for 6.11, part 1 2024-07-27 12:46:16 -07:00
tools turbostat release 2024.07.26 2024-07-28 10:52:15 -07:00
usr initramfs: shorten cmd_initfs in usr/Makefile 2024-07-16 01:07:52 +09:00
virt KVM generic changes for 6.11 2024-07-16 09:51:36 -04:00
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.cocciconfig
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.get_maintainer.ignore Add Jeff Kirsher to .get_maintainer.ignore 2024-03-08 11:36:54 +00:00
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.mailmap MAINTAINERS: mailmap: update James Clark's email address 2024-07-26 14:32:35 -07:00
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Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS CXL for v6.11 merge window 2024-07-28 09:33:28 -07:00
Makefile Linux 6.11-rc1 2024-07-28 14:19:55 -07:00
README README: Fix spelling 2024-03-18 03:36:32 -06:00

Linux kernel

There are several guides for kernel developers and users. These guides can be rendered in a number of formats, like HTML and PDF. Please read Documentation/admin-guide/README.rst first.

In order to build the documentation, use make htmldocs or make pdfdocs. The formatted documentation can also be read online at:

https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory, several of them using the reStructuredText markup notation.

Please read the Documentation/process/changes.rst file, as it contains the requirements for building and running the kernel, and information about the problems which may result by upgrading your kernel.