block: blk-mq: Use swait

| BUG: sleeping function called from invalid context at kernel/locking/rtmutex.c:914
| in_atomic(): 1, irqs_disabled(): 0, pid: 255, name: kworker/u257:6
| 5 locks held by kworker/u257:6/255:
|  #0:  ("events_unbound"){.+.+.+}, at: [<ffffffff8108edf1>] process_one_work+0x171/0x5e0
|  #1:  ((&entry->work)){+.+.+.}, at: [<ffffffff8108edf1>] process_one_work+0x171/0x5e0
|  raspberrypi#2:  (&shost->scan_mutex){+.+.+.}, at: [<ffffffffa000faa3>] __scsi_add_device+0xa3/0x130 [scsi_mod]
|  raspberrypi#3:  (&set->tag_list_lock){+.+...}, at: [<ffffffff812f09fa>] blk_mq_init_queue+0x96a/0xa50
|  raspberrypi#4:  (rcu_read_lock_sched){......}, at: [<ffffffff8132887d>] percpu_ref_kill_and_confirm+0x1d/0x120
| Preemption disabled at:[<ffffffff812eff76>] blk_mq_freeze_queue_start+0x56/0x70
|
| CPU: 2 PID: 255 Comm: kworker/u257:6 Not tainted 3.18.7-rt0+ #1
| Workqueue: events_unbound async_run_entry_fn
|  0000000000000003 ffff8800bc29f998 ffffffff815b3a12 0000000000000000
|  0000000000000000 ffff8800bc29f9b8 ffffffff8109aa16 ffff8800bc29fa28
|  ffff8800bc5d1bc8 ffff8800bc29f9e8 ffffffff815b8dd4 ffff880000000000
| Call Trace:
|  [<ffffffff815b3a12>] dump_stack+0x4f/0x7c
|  [<ffffffff8109aa16>] __might_sleep+0x116/0x190
|  [<ffffffff815b8dd4>] rt_spin_lock+0x24/0x60
|  [<ffffffff810b6089>] __wake_up+0x29/0x60
|  [<ffffffff812ee06e>] blk_mq_usage_counter_release+0x1e/0x20
|  [<ffffffff81328966>] percpu_ref_kill_and_confirm+0x106/0x120
|  [<ffffffff812eff76>] blk_mq_freeze_queue_start+0x56/0x70
|  [<ffffffff812f0000>] blk_mq_update_tag_set_depth+0x40/0xd0
|  [<ffffffff812f0a1c>] blk_mq_init_queue+0x98c/0xa50
|  [<ffffffffa000dcf0>] scsi_mq_alloc_queue+0x20/0x60 [scsi_mod]
|  [<ffffffffa000ea35>] scsi_alloc_sdev+0x2f5/0x370 [scsi_mod]
|  [<ffffffffa000f494>] scsi_probe_and_add_lun+0x9e4/0xdd0 [scsi_mod]
|  [<ffffffffa000fb26>] __scsi_add_device+0x126/0x130 [scsi_mod]
|  [<ffffffffa013033f>] ata_scsi_scan_host+0xaf/0x200 [libata]
|  [<ffffffffa012b5b6>] async_port_probe+0x46/0x60 [libata]
|  [<ffffffff810978fb>] async_run_entry_fn+0x3b/0xf0
|  [<ffffffff8108ee81>] process_one_work+0x201/0x5e0

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>

block/blk-core.c

@@ -794,7 +794,7 @@ int blk_queue_enter(struct request_queue *q, bool nowait)
  */
  smp_rmb();
 
- ret = wait_event_interruptible(q->mq_freeze_wq,
+ ret = swait_event_interruptible(q->mq_freeze_wq,
  !atomic_read(&q->mq_freeze_depth) ||
  blk_queue_dying(q));
  if (blk_queue_dying(q))
@@ -814,7 +814,7 @@ static void blk_queue_usage_counter_release(struct percpu_ref *ref)
  struct request_queue *q =
  container_of(ref, struct request_queue, q_usage_counter);
 
- wake_up_all(&q->mq_freeze_wq);
+ swake_up_all(&q->mq_freeze_wq);
 }
 
 static void blk_rq_timed_out_timer(unsigned long data)
@@ -890,7 +890,7 @@ struct request_queue *blk_alloc_queue_node(gfp_t gfp_mask, int node_id)
  q->bypass_depth = 1;
  __set_bit(QUEUE_FLAG_BYPASS, &q->queue_flags);
 
- init_waitqueue_head(&q->mq_freeze_wq);
+ init_swait_queue_head(&q->mq_freeze_wq);
 
  /*
  * Init percpu_ref in atomic mode so that it's faster to shutdown.

block/blk-mq.c

@@ -132,14 +132,14 @@ EXPORT_SYMBOL_GPL(blk_freeze_queue_start);
 
 void blk_mq_freeze_queue_wait(struct request_queue *q)
 {
- wait_event(q->mq_freeze_wq, percpu_ref_is_zero(&q->q_usage_counter));
+ swait_event(q->mq_freeze_wq, percpu_ref_is_zero(&q->q_usage_counter));
 }
 EXPORT_SYMBOL_GPL(blk_mq_freeze_queue_wait);
 
 int blk_mq_freeze_queue_wait_timeout(struct request_queue *q,
  unsigned long timeout)
 {
- return wait_event_timeout(q->mq_freeze_wq,
+ return swait_event_timeout(q->mq_freeze_wq,
  percpu_ref_is_zero(&q->q_usage_counter),
  timeout);
 }
@@ -180,7 +180,7 @@ void blk_mq_unfreeze_queue(struct request_queue *q)
  WARN_ON_ONCE(freeze_depth < 0);
  if (!freeze_depth) {
  percpu_ref_reinit(&q->q_usage_counter);
- wake_up_all(&q->mq_freeze_wq);
+ swake_up_all(&q->mq_freeze_wq);
  }
 }
 EXPORT_SYMBOL_GPL(blk_mq_unfreeze_queue);
@@ -261,7 +261,7 @@ void blk_mq_wake_waiters(struct request_queue *q)
  * dying, we need to ensure that processes currently waiting on
  * the queue are notified as well.
  */
- wake_up_all(&q->mq_freeze_wq);
+ swake_up_all(&q->mq_freeze_wq);
 }
 
 bool blk_mq_can_queue(struct blk_mq_hw_ctx *hctx)

include/linux/blkdev.h

@@ -598,7 +598,7 @@ struct request_queue {
  struct throtl_data *td;
 #endif
  struct rcu_head rcu_head;
- wait_queue_head_t mq_freeze_wq;
+ struct swait_queue_head mq_freeze_wq;
  struct percpu_ref q_usage_counter;
  struct list_head all_q_node;