[PATCH 2/8] blk-mq: protect completion path with RCU

[Tejun Heo]

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 <t...@kernel.org>
---
 block/blk-mq.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/block/blk-mq.c b/block/blk-mq.c
index ddc9261..6741c3e 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -584,11 +584,16 @@ static void hctx_lock(struct blk_mq_hw_ctx *hctx, int 
*srcu_idx)
 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;
+
+       hctx_lock(hctx, &srcu_idx);
        if (!blk_mark_rq_complete(rq))
                __blk_mq_complete_request(rq);
+       hctx_unlock(hctx, srcu_idx);
 }
 EXPORT_SYMBOL(blk_mq_complete_request);
 
-- 
2.9.5