dm io: fix a race condition in the wake up code for sync_io

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commit 10f1d5d111 upstream.

There's a race condition between the atomic_dec_and_test(&io->count)
in dec_count() and the waking of the sync_io() thread.  If the thread
is spuriously woken immediately after the decrement it may exit,
making the on stack io struct invalid, yet the dec_count could still
be using it.

Fix this race by using a completion in sync_io() and dec_count().

Reported-by: Minfei Huang <huangminfei@ucloud.cn>
Signed-off-by: Joe Thornber <thornber@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Acked-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

...

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Joe Thornber 2014-06-27 15:29:04 -04:00 • committed by Greg Kroah-Hartman

parent 2a0dd0a658

commit 99c4b20adc

1 changed files with 8 additions and 14 deletions

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drivers/md/dm-io.c

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