drivers: net: hippi: Fix deadlock in rr_close()

stable inclusion
from stable-v5.10.114
commit ac3d0770437eedd6639271abeb5b49fd0b9941a4
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I5IY1V

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=ac3d0770437eedd6639271abeb5b49fd0b9941a4



--------------------------------

[ Upstream commit bc6de287 ]

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

   (Thread 1)                |      (Thread 2)
                             | rr_open()
rr_close()                   |  add_timer()
 spin_lock_irqsave() //(1)   |  (wait a time)
 ...                         | rr_timer()
 del_timer_sync()            |  spin_lock_irqsave() //(2)
 (wait timer to stop)        |  ...

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

This patch extracts del_timer_sync() from the protection of
spin_lock_irqsave(), which could let timer handler to obtain
the needed lock.

Signed-off-by: Duoming Zhou <duoming@zju.edu.cn>
Link: https://lore.kernel.org/r/20220417125519.82618-1-duoming@zju.edu.cn


Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Zheng Zengkai <zhengzengkai@huawei.com>
Acked-by: Xie XiuQi <xiexiuqi@huawei.com>