[PATCH 1/6] blk-mq: protect completion path with RCU
From: Tejun Heo <tj@kernel.org>
Date: 2017-12-12 19:01:52
Also in:
lkml
Subsystem:
block layer, the rest · Maintainers:
Jens Axboe, Linus Torvalds
Currently, blk-mq protects only the issue path with RCU. This patch puts the completion path under the same RCU protection. This will be used to synchronize issue/completion against timeout by later patches, which will also add the comments. Signed-off-by: Tejun Heo <tj@kernel.org> --- block/blk-mq.c | 16 ++++++++++++++-- 1 file changed, 14 insertions(+), 2 deletions(-)
diff --git a/block/blk-mq.c b/block/blk-mq.c
index 1109747..acf4fbb 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c@@ -568,11 +568,23 @@ static void __blk_mq_complete_request(struct request *rq) void blk_mq_complete_request(struct request *rq) { struct request_queue *q = rq->q; + struct blk_mq_hw_ctx *hctx = blk_mq_map_queue(q, rq->mq_ctx->cpu); + int srcu_idx; if (unlikely(blk_should_fake_timeout(q))) return; - if (!blk_mark_rq_complete(rq)) - __blk_mq_complete_request(rq); + + if (!(hctx->flags & BLK_MQ_F_BLOCKING)) { + rcu_read_lock(); + if (!blk_mark_rq_complete(rq)) + __blk_mq_complete_request(rq); + rcu_read_unlock(); + } else { + srcu_idx = srcu_read_lock(hctx->queue_rq_srcu); + if (!blk_mark_rq_complete(rq)) + __blk_mq_complete_request(rq); + srcu_read_unlock(hctx->queue_rq_srcu, srcu_idx); + } } EXPORT_SYMBOL(blk_mq_complete_request);
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2.9.5