[PATCH 3/3] Revert "block: Fix a lockdep complaint triggered by request queue flushing"

Ming Lei
2020-11-12T07:56:08Z

This reverts commit b3c6a59975415bde29cfd76ff1ab008edbf614a9.

Now we can avoid nvme-loop lockdep warning of 'lockdep possible recursive
locking' by nvme-loop's lock class, no need to apply dynamically
allocated lock class key, so revert commit b3c6a5997541("block: Fix a
lockdep complaint triggered by request queue flushing").

This way fixes horrible SCSI probe delay issue on megaraid_sas, and it
is reported the whole probe may take more than half an hour.

Reported-by: Qian Cai <cai@redhat.com>
Cc: Sumit Saxena <sumit.saxena@broadcom.com>
Cc: John Garry <john.garry@huawei.com>
Cc: Kashyap Desai <kashyap.desai@broadcom.com>
Cc: Bart Van Assche <bvanassche@acm.org>
Cc: Hannes Reinecke <hare@suse.de>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
---
block/blk-flush.c | 5 -----
block/blk.h | 1 -
2 files changed, 6 deletions(-)

diff --git a/block/blk-flush.c b/block/blk-flush.c
index 657743524e15..c64f049226f6 100644
--- a/block/blk-flush.c
+++ b/block/blk-flush.c
@@ -69,7 +69,6 @@
#include <linux/blkdev.h>
#include <linux/gfp.h>
#include <linux/blk-mq.h>
-#include <linux/lockdep.h>

#include "blk.h"
#include "blk-mq.h"
@@ -469,9 +468,6 @@ struct blk_flush_queue *blk_alloc_flush_queue(int node, int cmd_size,
INIT_LIST_HEAD(&fq->flush_queue[1]);
INIT_LIST_HEAD(&fq->flush_data_in_flight);

- lockdep_register_key(&fq->key);
- lockdep_set_class(&fq->mq_flush_lock, &fq->key);
-
return fq;

fail_rq:
@@ -486,7 +482,6 @@ void blk_free_flush_queue(struct blk_flush_queue *fq)
if (!fq)
return;

- lockdep_unregister_key(&fq->key);
kfree(fq->flush_rq);
kfree(fq);
}
diff --git a/block/blk.h b/block/blk.h
index dfab98465db9..806fd6537295 100644
--- a/block/blk.h
+++ b/block/blk.h
@@ -25,7 +25,6 @@ struct blk_flush_queue {
struct list_head flush_data_in_flight;
struct request *flush_rq;

- struct lock_class_key key;
spinlock_t mq_flush_lock;
};

--
2.25.4