diff options
| author | Ming Lei <ming.lei@redhat.com> | 2021-08-18 04:09:25 +0300 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2021-09-12 09:58:27 +0300 |
| commit | cad6239f5080fdb1acdfb7faeaa8b252125a68d1 (patch) | |
| tree | 4eac4825848b15e9680fa89725e00afe8685abda /block | |
| parent | ceffaa61b5bb5296e07cb7f4f494377eb659058f (diff) | |
| download | linux-cad6239f5080fdb1acdfb7faeaa8b252125a68d1.tar.xz | |
blk-mq: fix is_flush_rq
commit a9ed27a764156929efe714033edb3e9023c5f321 upstream.
is_flush_rq() is called from bt_iter()/bt_tags_iter(), and runs the
following check:
hctx->fq->flush_rq == req
but the passed hctx from bt_iter()/bt_tags_iter() may be NULL because:
1) memory re-order in blk_mq_rq_ctx_init():
rq->mq_hctx = data->hctx;
...
refcount_set(&rq->ref, 1);
OR
2) tag re-use and ->rqs[] isn't updated with new request.
Fix the issue by re-writing is_flush_rq() as:
return rq->end_io == flush_end_io;
which turns out simpler to follow and immune to data race since we have
ordered WRITE rq->end_io and refcount_set(&rq->ref, 1).
Fixes: 2e315dc07df0 ("blk-mq: grab rq->refcount before calling ->fn in blk_mq_tagset_busy_iter")
Cc: "Blank-Burian, Markus, Dr." <blankburian@uni-muenster.de>
Cc: Yufen Yu <yuyufen@huawei.com>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Link: https://lore.kernel.org/r/20210818010925.607383-1-ming.lei@redhat.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Cc: Yi Zhang <yi.zhang@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'block')
| -rw-r--r-- | block/blk-flush.c | 5 | ||||
| -rw-r--r-- | block/blk-mq.c | 2 | ||||
| -rw-r--r-- | block/blk.h | 6 |
3 files changed, 7 insertions, 6 deletions
diff --git a/block/blk-flush.c b/block/blk-flush.c index 040d9adf8789..70f1d02135ed 100644 --- a/block/blk-flush.c +++ b/block/blk-flush.c @@ -263,6 +263,11 @@ static void flush_end_io(struct request *flush_rq, blk_status_t error) spin_unlock_irqrestore(&fq->mq_flush_lock, flags); } +bool is_flush_rq(struct request *rq) +{ + return rq->end_io == flush_end_io; +} + /** * blk_kick_flush - consider issuing flush request * @q: request_queue being kicked diff --git a/block/blk-mq.c b/block/blk-mq.c index 044d0e3a15ad..94436e0a508c 100644 --- a/block/blk-mq.c +++ b/block/blk-mq.c @@ -929,7 +929,7 @@ static bool blk_mq_req_expired(struct request *rq, unsigned long *next) void blk_mq_put_rq_ref(struct request *rq) { - if (is_flush_rq(rq, rq->mq_hctx)) + if (is_flush_rq(rq)) rq->end_io(rq, 0); else if (refcount_dec_and_test(&rq->ref)) __blk_mq_free_request(rq); diff --git a/block/blk.h b/block/blk.h index dfab98465db9..ecfd523c68d0 100644 --- a/block/blk.h +++ b/block/blk.h @@ -44,11 +44,7 @@ static inline void __blk_get_queue(struct request_queue *q) kobject_get(&q->kobj); } -static inline bool -is_flush_rq(struct request *req, struct blk_mq_hw_ctx *hctx) -{ - return hctx->fq->flush_rq == req; -} +bool is_flush_rq(struct request *req); struct blk_flush_queue *blk_alloc_flush_queue(int node, int cmd_size, gfp_t flags); |