From: Jens Axboe <axboe@kernel.dk>
Date: Mon, 1 Oct 2018 14:58:57 +0000 (-0600)
Subject: Merge tag 'v4.19-rc6' into for-4.20/block
X-Git-Tag: v4.20-rc1~191^2~115
X-Git-Url: http://git.osdn.net/view?a=commitdiff_plain;h=c0aac682fa6590cb660cb083dbc09f55e799d2d2;p=uclinux-h8%2Flinux.git

Merge tag 'v4.19-rc6' into for-4.20/block

Merge -rc6 in, for two reasons:

1) Resolve a trivial conflict in the blk-mq-tag.c documentation
2) A few important regression fixes went into upstream directly, so
   they aren't in the 4.20 branch.

Signed-off-by: Jens Axboe <axboe@kernel.dk>

* tag 'v4.19-rc6': (780 commits)
  Linux 4.19-rc6
  MAINTAINERS: fix reference to moved drivers/{misc => auxdisplay}/panel.c
  cpufreq: qcom-kryo: Fix section annotations
  perf/core: Add sanity check to deal with pinned event failure
  xen/blkfront: correct purging of persistent grants
  Revert "xen/blkfront: When purging persistent grants, keep them in the buffer"
  selftests/powerpc: Fix Makefiles for headers_install change
  blk-mq: I/O and timer unplugs are inverted in blktrace
  dax: Fix deadlock in dax_lock_mapping_entry()
  x86/boot: Fix kexec booting failure in the SEV bit detection code
  bcache: add separate workqueue for journal_write to avoid deadlock
  drm/amd/display: Fix Edid emulation for linux
  drm/amd/display: Fix Vega10 lightup on S3 resume
  drm/amdgpu: Fix vce work queue was not cancelled when suspend
  Revert "drm/panel: Add device_link from panel device to DRM device"
  xen/blkfront: When purging persistent grants, keep them in the buffer
  clocksource/drivers/timer-atmel-pit: Properly handle error cases
  block: fix deadline elevator drain for zoned block devices
  ACPI / hotplug / PCI: Don't scan for non-hotplug bridges if slot is not bridge
  drm/syncobj: Don't leak fences when WAIT_FOR_SUBMIT is set
  ...

Signed-off-by: Jens Axboe <axboe@kernel.dk>
---

c0aac682fa6590cb660cb083dbc09f55e799d2d2
diff --cc block/blk-mq-tag.c
index 40d1667bceac,41317c50a446..cfda95b85d34
--- a/block/blk-mq-tag.c
+++ b/block/blk-mq-tag.c
@@@ -378,17 -321,12 +378,14 @@@ void blk_mq_queue_tag_busy_iter(struct 
  	int i;
  
  	/*
 -	 * __blk_mq_update_nr_hw_queues will update the nr_hw_queues and
 -	 * queue_hw_ctx after freeze the queue, so we use q_usage_counter
 -	 * to avoid race with it.
 +	 * __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.
  	 */
- 	rcu_read_lock();
- 	if (percpu_ref_is_zero(&q->q_usage_counter)) {
- 		rcu_read_unlock();
+ 	if (!percpu_ref_tryget(&q->q_usage_counter))
  		return;
- 	}
  
  	queue_for_each_hw_ctx(q, hctx, i) {
  		struct blk_mq_tags *tags = hctx->tags;