WSL2-Linux-Kernel/arch/xtensa
Duoming Zhou 50f79a2abb arch: xtensa: platforms: Fix deadlock in rs_close()
[ Upstream commit eb5adc7075 ]

There is a deadlock in rs_close(), which is shown
below:

   (Thread 1)              |      (Thread 2)
                           | rs_open()
rs_close()                 |  mod_timer()
 spin_lock_bh() //(1)      |  (wait a time)
 ...                       | rs_poll()
 del_timer_sync()          |  spin_lock() //(2)
 (wait timer to stop)      |  ...

We hold timer_lock in position (1) of thread 1 and
use del_timer_sync() to wait timer to stop, but timer handler
also need timer_lock in position (2) of thread 2.
As a result, rs_close() will block forever.

This patch deletes the redundant timer_lock in order to
prevent the deadlock. Because there is no race condition
between rs_close, rs_open and rs_poll.

Signed-off-by: Duoming Zhou <duoming@zju.edu.cn>
Message-Id: <20220407154430.22387-1-duoming@zju.edu.cn>
Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
2022-05-09 09:14:40 +02:00
..
boot xtensa: fix DTC warning unit_address_format 2022-04-13 20:59:09 +02:00
configs
include xtensa: fix xtensa_wsr always writing 0 2022-04-08 14:23:03 +02:00
kernel xtensa: fix a7 clobbering in coprocessor context load/store 2022-04-27 14:38:59 +02:00
lib
mm
platforms arch: xtensa: platforms: Fix deadlock in rs_close() 2022-05-09 09:14:40 +02:00
variants
Kbuild
Kconfig
Kconfig.debug
Makefile