From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Date: Fri, 13 Feb 2015 11:01:26 +0100
Subject: block: blk-mq: Use swait
Git-repo: git://git.kernel.org/pub/scm/linux/kernel/git/rt/linux-rt-devel.git
Git-commit: 7d79d0aa12062994f97bd16e74eb19307aae0d3b
Patch-mainline: Queued in subsystem maintainer repository
References: SLE Realtime Extension

| 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
|  #2:  (&shost->scan_mutex){+.+.+.}, at: [<ffffffffa000faa3>] __scsi_add_device+0xa3/0x130 [scsi_mod]
|  #3:  (&set->tag_list_lock){+.+...}, at: [<ffffffff812f09fa>] blk_mq_init_queue+0x96a/0xa50
|  #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>
Signed-off-by: Mike Galbraith <mgalbraith@suse.de>
---
 block/blk-core.c       |    8 ++++----
 block/blk-mq.c         |    6 +++---
 include/linux/blkdev.h |    2 +-
 3 files changed, 8 insertions(+), 8 deletions(-)

--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -713,7 +713,7 @@ void blk_set_queue_dying(struct request_
 	}
 
 	/* Make blk_queue_enter() reexamine the DYING flag. */
-	wake_up_all(&q->mq_freeze_wq);
+	swake_up_all(&q->mq_freeze_wq);
 }
 EXPORT_SYMBOL_GPL(blk_set_queue_dying);
 
@@ -953,7 +953,7 @@ int blk_queue_enter(struct request_queue
 		 */
 		smp_rmb();
 
-		wait_event(q->mq_freeze_wq,
+		swait_event(q->mq_freeze_wq,
 			   (atomic_read(&q->mq_freeze_depth) == 0 &&
 			    (preempt || !blk_queue_preempt_only(q))) ||
 			   blk_queue_dying(q));
@@ -972,7 +972,7 @@ static void blk_queue_usage_counter_rele
 	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(struct timer_list *t)
@@ -1063,7 +1063,7 @@ struct request_queue *blk_alloc_queue_no
 	q->bypass_depth = 1;
 	queue_flag_set_unlocked(QUEUE_FLAG_BYPASS, q);
 
-	init_waitqueue_head(&q->mq_freeze_wq);
+	init_swait_queue_head(&q->mq_freeze_wq);
 	mutex_init(&q->mq_freeze_lock);
 
 	/*
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -153,14 +153,14 @@ 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);
 }
@@ -204,7 +204,7 @@ void blk_mq_unfreeze_queue(struct reques
 	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);
 	}
 	mutex_unlock(&q->mq_freeze_lock);
 }
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -654,7 +654,7 @@ 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;