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From: Christoph Hellwig <hch@lst.de>
To: Jens Axboe <axboe@kernel.dk>
Cc: Tejun Heo <tj@kernel.org>,
	linux-block@vger.kernel.org, Ming Lei <ming.lei@redhat.com>,
	"Darrick J . Wong" <djwong@kernel.org>
Subject: [PATCH 5/5] block: keep q_usage_counter in atomic mode after del_gendisk
Date: Wed, 29 Sep 2021 09:12:41 +0200	[thread overview]
Message-ID: <20210929071241.934472-6-hch@lst.de> (raw)
In-Reply-To: <20210929071241.934472-1-hch@lst.de>

Don't switch back to percpu mode to avoid the double RCU grace period
when tearing down SCSI devices.  After removing the disk only passthrough
commands can be send anyway.

Suggested-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Tested-by: Darrick J. Wong <djwong@kernel.org>
---
 block/blk-mq.c | 9 ++++++++-
 block/blk.h    | 1 +
 block/genhd.c  | 3 ++-
 3 files changed, 11 insertions(+), 2 deletions(-)

diff --git a/block/blk-mq.c b/block/blk-mq.c
index 108a352051be5..bc026372de439 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -188,9 +188,11 @@ void blk_mq_freeze_queue(struct request_queue *q)
 }
 EXPORT_SYMBOL_GPL(blk_mq_freeze_queue);
 
-void blk_mq_unfreeze_queue(struct request_queue *q)
+void __blk_mq_unfreeze_queue(struct request_queue *q, bool force_atomic)
 {
 	mutex_lock(&q->mq_freeze_lock);
+	if (force_atomic)
+		q->q_usage_counter.data->force_atomic = true;
 	q->mq_freeze_depth--;
 	WARN_ON_ONCE(q->mq_freeze_depth < 0);
 	if (!q->mq_freeze_depth) {
@@ -199,6 +201,11 @@ void blk_mq_unfreeze_queue(struct request_queue *q)
 	}
 	mutex_unlock(&q->mq_freeze_lock);
 }
+
+void blk_mq_unfreeze_queue(struct request_queue *q)
+{
+	__blk_mq_unfreeze_queue(q, false);
+}
 EXPORT_SYMBOL_GPL(blk_mq_unfreeze_queue);
 
 /*
diff --git a/block/blk.h b/block/blk.h
index e2ed2257709ae..6c3c00a8fe19d 100644
--- a/block/blk.h
+++ b/block/blk.h
@@ -51,6 +51,7 @@ struct blk_flush_queue *blk_alloc_flush_queue(int node, int cmd_size,
 void blk_free_flush_queue(struct blk_flush_queue *q);
 
 void blk_freeze_queue(struct request_queue *q);
+void __blk_mq_unfreeze_queue(struct request_queue *q, bool force_atomic);
 void blk_queue_start_drain(struct request_queue *q);
 
 #define BIO_INLINE_VECS 4
diff --git a/block/genhd.c b/block/genhd.c
index b3c33495d7208..edd013a820879 100644
--- a/block/genhd.c
+++ b/block/genhd.c
@@ -596,7 +596,8 @@ void del_gendisk(struct gendisk *disk)
 	/*
 	 * Allow using passthrough request again after the queue is torn down.
 	 */
-	blk_mq_unfreeze_queue(q);
+	blk_queue_flag_clear(QUEUE_FLAG_INIT_DONE, q);
+	__blk_mq_unfreeze_queue(q, true);
 
 	if (!(disk->flags & GENHD_FL_HIDDEN)) {
 		sysfs_remove_link(&disk_to_dev(disk)->kobj, "bdi");
-- 
2.30.2


  parent reply	other threads:[~2021-09-29  7:18 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-09-29  7:12 tear down file system I/O in del_gendisk v3 Christoph Hellwig
2021-09-29  7:12 ` [PATCH 1/5] block: call submit_bio_checks under q_usage_counter Christoph Hellwig
2021-10-17  1:14   ` Jens Axboe
2021-09-29  7:12 ` [PATCH 2/5] block: factor out a blk_try_enter_queue helper Christoph Hellwig
2021-09-29  7:12 ` [PATCH 3/5] block: split bio_queue_enter from blk_queue_enter Christoph Hellwig
2021-09-29  7:12 ` [PATCH 4/5] block: drain file system I/O on del_gendisk Christoph Hellwig
2021-09-29  8:17   ` Ming Lei
2021-10-01  4:13     ` Christoph Hellwig
2021-10-05  2:15       ` Ming Lei
2021-09-29  7:12 ` Christoph Hellwig [this message]
2021-10-12  9:33 ` [PATCH 6/5] kyber: avoid q->disk dereferences in trace points Christoph Hellwig
2021-10-14 12:57   ` Ming Lei
2021-10-14  9:23 ` tear down file system I/O in del_gendisk v3 Yi Zhang
2021-10-17  1:14 ` Jens Axboe

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