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>.
Bug: 197804811
Change-Id: I4c19fc2c7d39235b0e95a622f26646a353a19ee9
[Upstream: cherry picked from commit a9ed27a764156929efe714033edb3e9023c5f321]
[Pradeep: Resolved conflicts in block/blk.h]
Signed-off-by: Pradeep P V K <pragalla@codeaurora.org>
Git-commit: ec1b6ab9fe80cf689780c9ee3b2cdb04cc11895e
Git-repo: https://android.googlesource.com/kernel/common/
Signed-off-by: Pradeep P V K <quic_pragalla@quicinc.com>
(cherry picked from commit 49724e13eb)
Change-Id: I866184c8fb0d5708fc582c1aff0c4084a911a291
Signed-off-by: Surapusetty Naresh Babu <snareshb@qti.qualcomm.com>
09de4ca5ab