linux/arch/xtensa/platforms
Duoming Zhou eb5adc7075 arch: xtensa: platforms: Fix deadlock in rs_close()
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>
2022-04-13 03:36:34 -07:00
..
iss arch: xtensa: platforms: Fix deadlock in rs_close() 2022-04-13 03:36:34 -07:00
xt2000 treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152 2019-05-30 11:26:32 -07:00
xtfpga xtensa: xtfpga: Try software restart before simulating CPU reset 2021-10-05 12:19:05 -07:00
Makefile xtensa: move core-y in arch/xtensa/Makefile to arch/xtensa/Kbuild 2021-08-11 11:37:13 -07:00