diff options
| author | Bart Van Assche <[email protected]> | 2018-03-19 11:46:13 -0700 |
|---|---|---|
| committer | Jens Axboe <[email protected]> | 2018-03-19 12:50:10 -0600 |
| commit | 818e0fa293ca836eba515615c64680ea916fd7cd (patch) | |
| tree | e3f01a690b1d58a1e316b9f7588c04a43a9a972c | |
| parent | 5f2b18ec8e1643410a2369f06888951cdedea0bf (diff) | |
block: Change a rcu_read_{lock,unlock}_sched() pair into rcu_read_{lock,unlock}()
scsi_device_quiesce() uses synchronize_rcu() to guarantee that the
effect of blk_set_preempt_only() will be visible for percpu_ref_tryget()
calls that occur after the queue unfreeze by using the approach
explained in https://lwn.net/Articles/573497/. The rcu read lock and
unlock calls in blk_queue_enter() form a pair with the synchronize_rcu()
call in scsi_device_quiesce(). Both scsi_device_quiesce() and
blk_queue_enter() must either use regular RCU or RCU-sched.
Since neither the RCU-protected code in blk_queue_enter() nor
blk_queue_usage_counter_release() sleeps, regular RCU protection
is sufficient. Note: scsi_device_quiesce() does not have to be
modified since it already uses synchronize_rcu().
Reported-by: Tejun Heo <[email protected]>
Fixes: 3a0a529971ec ("block, scsi: Make SCSI quiesce and resume work reliably")
Signed-off-by: Bart Van Assche <[email protected]>
Acked-by: Tejun Heo <[email protected]>
Cc: Tejun Heo <[email protected]>
Cc: Hannes Reinecke <[email protected]>
Cc: Ming Lei <[email protected]>
Cc: Christoph Hellwig <[email protected]>
Cc: Johannes Thumshirn <[email protected]>
Cc: Oleksandr Natalenko <[email protected]>
Cc: Martin Steigerwald <[email protected]>
Cc: [email protected] # v4.15
Signed-off-by: Jens Axboe <[email protected]>
| -rw-r--r-- | block/blk-core.c | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/block/blk-core.c b/block/blk-core.c index 5e88c579e896..a0f675f84f86 100644 --- a/block/blk-core.c +++ b/block/blk-core.c @@ -917,7 +917,7 @@ int blk_queue_enter(struct request_queue *q, blk_mq_req_flags_t flags) bool success = false; int ret; - rcu_read_lock_sched(); + rcu_read_lock(); if (percpu_ref_tryget_live(&q->q_usage_counter)) { /* * The code that sets the PREEMPT_ONLY flag is @@ -930,7 +930,7 @@ int blk_queue_enter(struct request_queue *q, blk_mq_req_flags_t flags) percpu_ref_put(&q->q_usage_counter); } } - rcu_read_unlock_sched(); + rcu_read_unlock(); if (success) return 0; |