From fb01a2932e81a1fb2273f87ff92dc8172b8880ee Mon Sep 17 00:00:00 2001 From: Ming Lei Date: Thu, 3 Dec 2020 09:26:36 +0800 Subject: blk-mq: add new API of blk_mq_hctx_set_fq_lock_class flush_end_io() may be called recursively from some driver, such as nvme-loop, so lockdep may complain 'possible recursive locking'. Commit b3c6a5997541("block: Fix a lockdep complaint triggered by request queue flushing") tried to address this issue by assigning dynamically allocated per-flush-queue lock class. This solution adds synchronize_rcu() for each hctx's release handler, and causes horrible SCSI MQ probe delay(more than half an hour on megaraid sas). Add new API of blk_mq_hctx_set_fq_lock_class() for these drivers, so we just need to use driver specific lock class for avoiding the lockdep warning of 'possible recursive locking'. Tested-by: Kashyap Desai Reported-by: Qian Cai Cc: Sumit Saxena Cc: John Garry Cc: Kashyap Desai Cc: Bart Van Assche Cc: Hannes Reinecke Signed-off-by: Ming Lei Reviewed-by: Hannes Reinecke Signed-off-by: Jens Axboe --- include/linux/blk-mq.h | 3 +++ 1 file changed, 3 insertions(+) (limited to 'include/linux/blk-mq.h') diff --git a/include/linux/blk-mq.h b/include/linux/blk-mq.h index 794b2a33a2c3..5f639240760e 100644 --- a/include/linux/blk-mq.h +++ b/include/linux/blk-mq.h @@ -5,6 +5,7 @@ #include #include #include +#include struct blk_mq_tags; struct blk_flush_queue; @@ -594,5 +595,7 @@ static inline void blk_mq_cleanup_rq(struct request *rq) } blk_qc_t blk_mq_submit_bio(struct bio *bio); +void blk_mq_hctx_set_fq_lock_class(struct blk_mq_hw_ctx *hctx, + struct lock_class_key *key); #endif -- cgit v1.2.3-58-ga151