| Message ID | 20200919035425.3316563-1-yangerkun@huawei.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | block-mq: fix comments in blk_mq_queue_tag_busy_iter | expand |
Ping... 在 2020/9/19 11:54, yangerkun 写道: > 'f5bbbbe4d635 ("blk-mq: sync the update nr_hw_queues with > blk_mq_queue_tag_busy_iter")' introduce a bug what we may sleep between > rcu lock. Then '530ca2c9bd69 ("blk-mq: Allow blocking queue tag iter > callbacks")' fix it by get request_queue's ref. And 'a9a808084d6a ("block: > Remove the synchronize_rcu() call from __blk_mq_update_nr_hw_queues()")' > remove the synchronize_rcu in __blk_mq_update_nr_hw_queues. We need > update the confused comments in blk_mq_queue_tag_busy_iter. > > Signed-off-by: yangerkun <yangerkun@huawei.com> > --- > block/blk-mq-tag.c | 4 +--- > 1 file changed, 1 insertion(+), 3 deletions(-) > > diff --git a/block/blk-mq-tag.c b/block/blk-mq-tag.c > index 32d82e23b095..051227bd5a03 100644 > --- a/block/blk-mq-tag.c > +++ b/block/blk-mq-tag.c > @@ -398,9 +398,7 @@ void blk_mq_queue_tag_busy_iter(struct request_queue *q, busy_iter_fn *fn, > /* > * __blk_mq_update_nr_hw_queues() updates nr_hw_queues and queue_hw_ctx > * while the queue is frozen. So we can use q_usage_counter to avoid > - * racing with it. __blk_mq_update_nr_hw_queues() uses > - * synchronize_rcu() to ensure this function left the critical section > - * below. > + * racing with it. > */ > if (!percpu_ref_tryget(&q->q_usage_counter)) > return; >
On 9/18/20 9:54 PM, yangerkun wrote: > 'f5bbbbe4d635 ("blk-mq: sync the update nr_hw_queues with > blk_mq_queue_tag_busy_iter")' introduce a bug what we may sleep between > rcu lock. Then '530ca2c9bd69 ("blk-mq: Allow blocking queue tag iter > callbacks")' fix it by get request_queue's ref. And 'a9a808084d6a ("block: > Remove the synchronize_rcu() call from __blk_mq_update_nr_hw_queues()")' > remove the synchronize_rcu in __blk_mq_update_nr_hw_queues. We need > update the confused comments in blk_mq_queue_tag_busy_iter. Applied, thanks.
diff --git a/block/blk-mq-tag.c b/block/blk-mq-tag.c index 32d82e23b095..051227bd5a03 100644 --- a/block/blk-mq-tag.c +++ b/block/blk-mq-tag.c @@ -398,9 +398,7 @@ void blk_mq_queue_tag_busy_iter(struct request_queue *q, busy_iter_fn *fn, /* * __blk_mq_update_nr_hw_queues() updates nr_hw_queues and queue_hw_ctx * while the queue is frozen. So we can use q_usage_counter to avoid - * racing with it. __blk_mq_update_nr_hw_queues() uses - * synchronize_rcu() to ensure this function left the critical section - * below. + * racing with it. */ if (!percpu_ref_tryget(&q->q_usage_counter)) return;
'f5bbbbe4d635 ("blk-mq: sync the update nr_hw_queues with blk_mq_queue_tag_busy_iter")' introduce a bug what we may sleep between rcu lock. Then '530ca2c9bd69 ("blk-mq: Allow blocking queue tag iter callbacks")' fix it by get request_queue's ref. And 'a9a808084d6a ("block: Remove the synchronize_rcu() call from __blk_mq_update_nr_hw_queues()")' remove the synchronize_rcu in __blk_mq_update_nr_hw_queues. We need update the confused comments in blk_mq_queue_tag_busy_iter. Signed-off-by: yangerkun <yangerkun@huawei.com> --- block/blk-mq-tag.c | 4 +--- 1 file changed, 1 insertion(+), 3 deletions(-)