[PATCH] block: Fix possible sleep in invalid context

[Sujit Reddy Thumma <sthumma@codeaurora.org>]

When block runtime PM is enabled following warning is seen
while resuming the device.

BUG: sleeping function called from invalid context at
.../drivers/base/power/runtime.c:923
in_atomic(): 1, irqs_disabled(): 128, pid: 12, name: kworker/0:1
[<c0014448>] (unwind_backtrace+0x0/0x120) from
[<c03120e4>] (__pm_runtime_suspend+0x34/0xa0) from
[<c021c33c>] (blk_post_runtime_resume+0x4c/0x5c) from
[<c03297cc>] (scsi_runtime_resume+0x90/0xb4) from
[<c0310940>] (__rpm_callback+0x30/0x58) from
[<c0310980>] (rpm_callback+0x18/0x28) from
[<c0311ab0>] (rpm_resume+0x3dc/0x540) from
[<c03120a4>] (pm_runtime_work+0x8c/0x98) from
[<c007767c>] (process_one_work+0x238/0x3e4) from
[<c0077b90>] (worker_thread+0x1ac/0x2ac) from
[<c007cfdc>] (kthread+0x88/0x94) from
[<c000ece0>] (kernel_thread_exit+0x0/0x8)

Fix this by releasing spin_lock_irq() before calling
pm_runtime_autosuspend() in blk_post_runtime_resume().

Signed-off-by: Sujit Reddy Thumma <sthumma@codeaurora.org>
Cc: stable@vger.kernel.org
---
 block/blk-core.c |    6 ++++--
 1 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/block/blk-core.c b/block/blk-core.c
index 33c33bc..2456116 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -3159,16 +3159,18 @@ EXPORT_SYMBOL(blk_pre_runtime_resume);
  */
 void blk_post_runtime_resume(struct request_queue *q, int err)
 {
-	spin_lock_irq(q->queue_lock);
 	if (!err) {
+		spin_lock_irq(q->queue_lock);
 		q->rpm_status = RPM_ACTIVE;
 		__blk_run_queue(q);
 		pm_runtime_mark_last_busy(q->dev);
+		spin_unlock_irq(q->queue_lock);
 		pm_runtime_autosuspend(q->dev);
 	} else {
+		spin_lock_irq(q->queue_lock);
 		q->rpm_status = RPM_SUSPENDED;
+		spin_unlock_irq(q->queue_lock);
 	}
-	spin_unlock_irq(q->queue_lock);
 }
 EXPORT_SYMBOL(blk_post_runtime_resume);
 #endif
-- 
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