Ido Schimmel 6aff7cbfe7 netdevsim: Block until all devices are released ... Like other buses, devices on the netdevsim bus have a release callback that is invoked when the reference count of the device drops to zero. However, unlike other buses such as PCI, the release callback is not necessarily built into the kernel, as netdevsim can be built as a module. The above is problematic as nothing prevents the module from being unloaded before the release callback has been invoked, which can happen asynchronously. One such example can be found in commit a380687200 ("devlink: take device reference for devlink object") where devlink calls put_device() from an RCU callback. The issue is not theoretical and the reproducer in [1] can reliably crash the kernel. The conclusion of this discussion was that the issue should be solved in netdevsim, which is what this patch is trying to do. Add a reference count that is increased when a device is added to the bus and decreased when a device is released. Signal a completion when the reference count drops to zero and wait for the completion when unloading the module so that the module will not be unloaded before all the devices were released. The reference count is initialized to one so that completion is only signaled when unloading the module. With this patch, the reproducer in [1] no longer crashes the kernel. [1] https://lore.kernel.org/netdev/20230619125015.1541143-2-idosch@nvidia.com/ Fixes: a380687200 ("devlink: take device reference for devlink object") Signed-off-by: Ido Schimmel <idosch@nvidia.com> Reviewed-by: Jiri Pirko <jiri@nvidia.com> Link: https://lore.kernel.org/r/20231026083343.890689-1-idosch@nvidia.com Signed-off-by: Jakub Kicinski <kuba@kernel.org>		2023-10-27 14:48:36 -07:00
..
bpf.c	bpf: Introduce device-bound XDP programs	2023-01-23 09:38:10 -08:00
bus.c	netdevsim: Block until all devices are released	2023-10-27 14:48:36 -07:00
dev.c	netdevsim: fix uninitialized data in nsim_dev_trap_fa_cookie_write()	2023-07-12 12:46:35 -07:00
ethtool.c	net: netdevsim: use mock PHC driver	2023-08-09 15:59:21 -07:00
fib.c	Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net	2022-08-03 09:04:55 +02:00
health.c	netdevsim: devlink health: use retained error fmsg API	2023-10-20 11:34:49 +01:00
hwstats.c	netdevsim: Fix hwstats debugfs file permissions	2022-09-19 14:40:38 -07:00
ipsec.c	netdevsim: Fill IPsec state validation failure reason	2023-01-26 16:28:48 -08:00
macsec.c	netdevsim: add dummy macsec offload	2023-07-14 09:16:53 +01:00
Makefile	netdevsim: add dummy macsec offload	2023-07-14 09:16:53 +01:00
netdev.c	net: netdevsim: mimic tc-taprio offload	2023-08-09 15:59:21 -07:00
netdevsim.h	net: netdevsim: use mock PHC driver	2023-08-09 15:59:21 -07:00
psample.c	netdevsim: Only use sampling truncation length when valid	2021-04-22 13:23:56 -07:00
udp_tunnels.c	netdevsim: set .owner to THIS_MODULE	2020-11-17 14:08:59 -08:00