Commit dcd6589b authored Mar 10, 2020 by Tejun Heo Committed by Jens Axboe Mar 10, 2020

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



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: 7caa4715 ("blkcg: implement blk-iocost")
Cc: stable@vger.kernel.org # v5.4+
Signed-off-by: Jens Axboe <axboe@kernel.dk>

parent 14afc593

block/blk-iocost.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -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;

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