diff options
| author | Bart Van Assche <bart.vanassche@wdc.com> | 2018-04-10 17:02:40 -0600 |
|---|---|---|
| committer | Jens Axboe <axboe@kernel.dk> | 2018-04-10 17:46:40 -0600 |
| commit | 37f9579f4c31a6d698dbf3016d7bf132f9288d30 (patch) | |
| tree | 3b3add4672c9e0391bead53a764718e92d131983 | |
| parent | a93f00b3762026dd8231f473fae9346bda07db03 (diff) | |
blk-mq: Avoid that submitting a bio concurrently with device removal triggers a crash
Because blkcg_exit_queue() is now called from inside blk_cleanup_queue()
it is no longer safe to access cgroup information during or after the
blk_cleanup_queue() call. Hence protect the generic_make_request_checks()
call with blk_queue_enter() / blk_queue_exit().
Reported-by: Ming Lei <ming.lei@redhat.com>
Fixes: a063057d7c73 ("block: Fix a race between request queue removal and the block cgroup controller")
Signed-off-by: Bart Van Assche <bart.vanassche@wdc.com>
Cc: Ming Lei <ming.lei@redhat.com>
Cc: Joseph Qi <joseph.qi@linux.alibaba.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
| -rw-r--r-- | block/blk-core.c | 35 |
1 files changed, 29 insertions, 6 deletions
diff --git a/block/blk-core.c b/block/blk-core.c index abcb8684ba67..806ce2442819 100644 --- a/block/blk-core.c +++ b/block/blk-core.c @@ -2385,8 +2385,20 @@ blk_qc_t generic_make_request(struct bio *bio) * yet. */ struct bio_list bio_list_on_stack[2]; + blk_mq_req_flags_t flags = 0; + struct request_queue *q = bio->bi_disk->queue; blk_qc_t ret = BLK_QC_T_NONE; + if (bio->bi_opf & REQ_NOWAIT) + flags = BLK_MQ_REQ_NOWAIT; + if (blk_queue_enter(q, flags) < 0) { + if (!blk_queue_dying(q) && (bio->bi_opf & REQ_NOWAIT)) + bio_wouldblock_error(bio); + else + bio_io_error(bio); + return ret; + } + if (!generic_make_request_checks(bio)) goto out; @@ -2423,11 +2435,22 @@ blk_qc_t generic_make_request(struct bio *bio) bio_list_init(&bio_list_on_stack[0]); current->bio_list = bio_list_on_stack; do { - struct request_queue *q = bio->bi_disk->queue; - blk_mq_req_flags_t flags = bio->bi_opf & REQ_NOWAIT ? - BLK_MQ_REQ_NOWAIT : 0; + bool enter_succeeded = true; + + if (unlikely(q != bio->bi_disk->queue)) { + if (q) + blk_queue_exit(q); + q = bio->bi_disk->queue; + flags = 0; + if (bio->bi_opf & REQ_NOWAIT) + flags = BLK_MQ_REQ_NOWAIT; + if (blk_queue_enter(q, flags) < 0) { + enter_succeeded = false; + q = NULL; + } + } - if (likely(blk_queue_enter(q, flags) == 0)) { + if (enter_succeeded) { struct bio_list lower, same; /* Create a fresh bio_list for all subordinate requests */ @@ -2435,8 +2458,6 @@ blk_qc_t generic_make_request(struct bio *bio) bio_list_init(&bio_list_on_stack[0]); ret = q->make_request_fn(q, bio); - blk_queue_exit(q); - /* sort new bios into those for a lower level * and those for the same level */ @@ -2463,6 +2484,8 @@ blk_qc_t generic_make_request(struct bio *bio) current->bio_list = NULL; /* deactivate */ out: + if (q) + blk_queue_exit(q); return ret; } EXPORT_SYMBOL(generic_make_request); |