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authorChris Wilson <chris@chris-wilson.co.uk>2020-03-10 16:23:19 +0000
committerTejun Heo <tj@kernel.org>2020-03-12 14:26:50 -0400
commit00d5d15b0641f4ae463253eba06c836d56c2ce42 (patch)
treee3e206c15d3ab9fad053303d930fe8190ac5aca9 /kernel/workqueue.c
parent2333e829952fb437db915bbb17f4d8c43127d438 (diff)
workqueue: Mark up unlocked access to wq->first_flusher
[ 7329.671518] BUG: KCSAN: data-race in flush_workqueue / flush_workqueue [ 7329.671549] [ 7329.671572] write to 0xffff8881f65fb250 of 8 bytes by task 37173 on cpu 2: [ 7329.671607] flush_workqueue+0x3bc/0x9b0 (kernel/workqueue.c:2844) [ 7329.672527] [ 7329.672540] read to 0xffff8881f65fb250 of 8 bytes by task 37175 on cpu 0: [ 7329.672571] flush_workqueue+0x28d/0x9b0 (kernel/workqueue.c:2835) Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk> Cc: Tejun Heo <tj@kernel.org> Cc: Lai Jiangshan <jiangshanlai@gmail.com> Signed-off-by: Tejun Heo <tj@kernel.org>
Diffstat (limited to 'kernel/workqueue.c')
-rw-r--r--kernel/workqueue.c4
1 files changed, 2 insertions, 2 deletions
diff --git a/kernel/workqueue.c b/kernel/workqueue.c
index 5afa9ad45eba..40a4ba39ad5e 100644
--- a/kernel/workqueue.c
+++ b/kernel/workqueue.c
@@ -2832,7 +2832,7 @@ void flush_workqueue(struct workqueue_struct *wq)
* First flushers are responsible for cascading flushes and
* handling overflow. Non-first flushers can simply return.
*/
- if (wq->first_flusher != &this_flusher)
+ if (READ_ONCE(wq->first_flusher) != &this_flusher)
return;
mutex_lock(&wq->mutex);
@@ -2841,7 +2841,7 @@ void flush_workqueue(struct workqueue_struct *wq)
if (wq->first_flusher != &this_flusher)
goto out_unlock;
- wq->first_flusher = NULL;
+ WRITE_ONCE(wq->first_flusher, NULL);
WARN_ON_ONCE(!list_empty(&this_flusher.list));
WARN_ON_ONCE(wq->flush_color != this_flusher.flush_color);