V4L/DVB (5818): CinergyT2: fix flush_workqueue() vs work->func() deadlock

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Spotted and tested by Thomas Sattler <tsattler@gmx.de>.

cinergyT2.c does cancel_delayed_work() + flush_scheduled_work() while
holding cinergyt2->sem. This leads to deadlock because work->func()
needs the same mutex to complete. Another bug is that this code in fact
can't reliably stop the re-arming delayed_work.

Convert this code to use cancel_rearming_delayed_work() and move it
out of ->sem. Another mutex, ->wq_sem, was added to protect against the
concurrent open/resume.

This patch is a horrible hack to fix the lockup which happens in practice.
As Dmitry Torokhov pointed out this driver has other problems and needs
further changes.

Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>

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This commit is contained in:

Oleg Nesterov 2007-07-02 12:26:20 -03:00 • committed by Mauro Carvalho Chehab

parent f057131fb6

commit 1e4597e8f0

1 changed files with 40 additions and 26 deletions

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drivers/media/dvb/cinergyT2/cinergyT2.c

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