[PATCH] blk-mq: add missing call to srcu_barrier() in blk_mq_free_tag_set()

Commit 05c3e88488ed ("srcu: Queue sdp->work when the delay timer is
successfully deleted") added a check in cleanup_srcu_struct() if the
call to srcu_barrier() has been made before calling it, which
revealed a missing call to srcu_barrier() before calling
cleanup_srcu_struct(set->srcu). Fix this.

Signed-off-by: Marek Szyprowski <[email protected]>
---
This fixes the following issue observed recently in linux-next:
------------[ cut here ]------------
 WARNING: kernel/rcu/srcutree.c:706 at cleanup_srcu_struct+0x194/0x3d4, CPU#1: kworker/1:2/156
 Modules linked in: s5p_mfc exynos_gsc s5p_jpeg videobuf2_dma_contig v4l2_mem2mem videobuf2_memops videobuf2_v4l2 videobuf2_common videodev mc
 CPU: 1 UID: 0 PID: 156 Comm: kworker/1:2 Not tainted 7.2.0-rc3-00006-g05c3e88488ed-dirty #13430 PREEMPT
 Hardware name: Samsung Exynos (Flattened Device Tree)
 Workqueue: usb_hub_wq hub_event
 Call trace:
  unwind_backtrace from show_stack+0x10/0x14
  show_stack from dump_stack_lvl+0x6c/0x8c
  dump_stack_lvl from __warn+0x90/0x204
  __warn from warn_slowpath_fmt+0x1b4/0x1bc
  warn_slowpath_fmt from cleanup_srcu_struct+0x194/0x3d4
  cleanup_srcu_struct from blk_mq_free_tag_set+0x138/0x158
  blk_mq_free_tag_set from scsi_mq_free_tags+0x10/0x1c
  scsi_mq_free_tags from scsi_remove_host+0x14c/0x170
  scsi_remove_host from uas_disconnect+0x70/0x84
  uas_disconnect from usb_unbind_interface+0x78/0x2b4
  usb_unbind_interface from device_release_driver_internal+0x194/0x208
  device_release_driver_internal from bus_remove_device+0xf8/0x1c8
  bus_remove_device from device_del+0x138/0x3b0
  device_del from usb_disable_device+0xec/0x22c
  usb_disable_device from usb_disconnect+0xf8/0x2bc
  usb_disconnect from hub_event+0x9a8/0x1c3c
  hub_event from process_one_work+0x258/0x798
  process_one_work from worker_thread+0x1bc/0x3cc
  worker_thread from kthread+0x138/0x16c
  kthread from ret_from_fork+0x14/0x28
 Exception stack(0xf0dfdfb0 to 0xf0dfdff8)
 dfa0:                                     00000000 00000000 00000000 00000000
 dfc0: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
 dfe0: 00000000 00000000 00000000 00000000 00000013 00000000
 irq event stamp: 23097
 hardirqs last  enabled at (23109): [<c0100bf8>] __irq_svc+0xb8/0xd0
 hardirqs last disabled at (23118): [<c0100b94>] __irq_svc+0x54/0xd0
 softirqs last  enabled at (23094): [<c013ef54>] handle_softirqs+0x32c/0x58c
 softirqs last disabled at (23065): [<c013f360>] __irq_exit_rcu+0x144/0x1f0
 ---[ end trace 0000000000000000 ]---
---
 block/blk-mq.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/block/blk-mq.c b/block/blk-mq.c
index 2c850330a32b..a26a11c73ee3 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -4975,6 +4975,7 @@ void blk_mq_free_tag_set(struct blk_mq_tag_set *set)
 	srcu_barrier(&set->tags_srcu);
 	cleanup_srcu_struct(&set->tags_srcu);
 	if (set->flags & BLK_MQ_F_BLOCKING) {
+		srcu_barrier(set->srcu);
 		cleanup_srcu_struct(set->srcu);
 		kfree(set->srcu);
 	}
-- 
2.43.0