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

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 <[email protected]>
Signed-off-by: Joe Thornber <[email protected]>
Signed-off-by: Mike Snitzer <[email protected]>
Acked-by: Mikulas Patocka <[email protected]>
Cc: [email protected]

0 files changed, 0 insertions, 0 deletions