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blk-iocost: fix incorrect vtime comparison in iocg_is_idle() 

commit dcd6589b11 upstream.

vtimes may wrap and time_before/after64() should be used to determine
whether a given vtime is before or after another. iocg_is_idle() was
incorrectly using plain "<" comparison do determine whether done_vtime
is before vtime. Here, the only thing we're interested in is whether
done_vtime matches vtime which indicates that there's nothing in
flight. Let's test for inequality instead.

Signed-off-by: Tejun Heo <tj@kernel.org>
Fixes: 7caa47151a ("blkcg: implement blk-iocost")
Cc: stable@vger.kernel.org # v5.4+
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
5.4-rM2-2.2.x-imx-squashed
Tejun Heo 2020-03-10 13:07:46 -04:00 committed by Greg Kroah-Hartman
parent 0c47d02ad4
commit b7e54dd751
1 changed files with 1 additions and 1 deletions
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block/blk-iocost.c
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@ -1318,7 +1318,7 @@ static bool iocg_is_idle(struct ioc_gq *iocg)
return false;
/* is something in flight? */
if (atomic64_read(&iocg->done_vtime) < atomic64_read(&iocg->vtime))
if (atomic64_read(&iocg->done_vtime) != atomic64_read(&iocg->vtime))
return false;
return true;