No code that occurs between blk_mq_get_ctx() and blk_mq_put_ctx() depends
on preemption being disabled for its correctness. Since removing the CPU
preemption calls does not measurably affect performance, simplify the
blk-mq code by removing the blk_mq_put_ctx() function and also by not
disabling preemption in blk_mq_get_ctx().
Cc: Christoph Hellwig <hch@xxxxxxxxxxxxx>
Cc: Ming Lei <ming.lei@xxxxxxxxxx>
Cc: Hannes Reinecke <hare@xxxxxxxx>
Cc: Omar Sandoval <osandov@xxxxxx>
Signed-off-by: Bart Van Assche <bvanassche@xxxxxxx>
---
block/blk-mq-sched.c | 5 +----
block/blk-mq-tag.c | 8 --------
block/blk-mq.c | 16 +++-------------
block/blk-mq.h | 7 +------
block/kyber-iosched.c | 1 -
5 files changed, 5 insertions(+), 32 deletions(-)
diff --git a/block/blk-mq-sched.c b/block/blk-mq-sched.c
index 74c6bb871f7e..0daadb8d2274 100644
--- a/block/blk-mq-sched.c
+++ b/block/blk-mq-sched.c
@@ -326,10 +326,8 @@ bool __blk_mq_sched_bio_merge(struct request_queue *q, struct bio *bio)
bool ret = false;
enum hctx_type type;
- if (e && e->type->ops.bio_merge) {
- blk_mq_put_ctx(ctx);
+ if (e && e->type->ops.bio_merge)
return e->type->ops.bio_merge(hctx, bio);
- }
type = hctx->type;
if ((hctx->flags & BLK_MQ_F_SHOULD_MERGE) &&
@@ -340,7 +338,6 @@ bool __blk_mq_sched_bio_merge(struct request_queue *q, struct bio *bio)
spin_unlock(&ctx->lock);
}
- blk_mq_put_ctx(ctx);
return ret;
}
diff --git a/block/blk-mq-tag.c b/block/blk-mq-tag.c
index 7513c8eaabee..da19f0bc8876 100644
--- a/block/blk-mq-tag.c
+++ b/block/blk-mq-tag.c
@@ -113,7 +113,6 @@ unsigned int blk_mq_get_tag(struct blk_mq_alloc_data *data)
struct sbq_wait_state *ws;
DEFINE_SBQ_WAIT(wait);
unsigned int tag_offset;
- bool drop_ctx;
int tag;
if (data->flags & BLK_MQ_REQ_RESERVED) {
@@ -136,7 +135,6 @@ unsigned int blk_mq_get_tag(struct blk_mq_alloc_data *data)
return BLK_MQ_TAG_FAIL;
ws = bt_wait_ptr(bt, data->hctx);
- drop_ctx = data->ctx == NULL;
do {
struct sbitmap_queue *bt_prev;
@@ -161,9 +159,6 @@ unsigned int blk_mq_get_tag(struct blk_mq_alloc_data *data)
if (tag != -1)
break;
- if (data->ctx)
- blk_mq_put_ctx(data->ctx);
-
bt_prev = bt;
io_schedule();
@@ -189,9 +184,6 @@ unsigned int blk_mq_get_tag(struct blk_mq_alloc_data *data)
ws = bt_wait_ptr(bt, data->hctx);
} while (1);
- if (drop_ctx && data->ctx)
- blk_mq_put_ctx(data->ctx);
-
sbitmap_finish_wait(bt, ws, &wait);
found_tag:
diff --git a/block/blk-mq.c b/block/blk-mq.c
index 35948d45d7b9..00d572265aa3 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -359,13 +359,13 @@ static struct request *blk_mq_get_request(struct request_queue *q,
struct elevator_queue *e = q->elevator;
struct request *rq;
unsigned int tag;
- bool put_ctx_on_error = false;
+ bool clear_ctx_on_error = false;
blk_queue_enter_live(q);
data->q = q;
if (likely(!data->ctx)) {
data->ctx = blk_mq_get_ctx(q);
- put_ctx_on_error = true;
+ clear_ctx_on_error = true;
}
if (likely(!data->hctx))
data->hctx = blk_mq_map_queue(q, data->cmd_flags,
@@ -391,10 +391,8 @@ static struct request *blk_mq_get_request(struct request_queue *q,
tag = blk_mq_get_tag(data);
if (tag == BLK_MQ_TAG_FAIL) {
- if (put_ctx_on_error) {
- blk_mq_put_ctx(data->ctx);
+ if (clear_ctx_on_error)
data->ctx = NULL;
- }
blk_queue_exit(q);
return NULL;
}
@@ -431,8 +429,6 @@ struct request *blk_mq_alloc_request(struct request_queue *q, unsigned int op,
if (!rq)
return ERR_PTR(-EWOULDBLOCK);
- blk_mq_put_ctx(alloc_data.ctx);
-
rq->__data_len = 0;
rq->__sector = (sector_t) -1;
rq->bio = rq->biotail = NULL;
@@ -1975,7 +1971,6 @@ static blk_qc_t blk_mq_make_request(struct request_queue *q, struct bio *bio)
plug = current->plug;
if (unlikely(is_flush_fua)) {
- blk_mq_put_ctx(data.ctx);
blk_mq_bio_to_request(rq, bio);
/* bypass scheduler for flush rq */
@@ -1989,7 +1984,6 @@ static blk_qc_t blk_mq_make_request(struct request_queue *q, struct bio *bio)
unsigned int request_count = plug->rq_count;
struct request *last = NULL;
- blk_mq_put_ctx(data.ctx);
blk_mq_bio_to_request(rq, bio);
if (!request_count)
@@ -2023,8 +2017,6 @@ static blk_qc_t blk_mq_make_request(struct request_queue *q, struct bio *bio)
blk_add_rq_to_plug(plug, rq);
trace_block_plug(q);
- blk_mq_put_ctx(data.ctx);
-
if (same_queue_rq) {
data.hctx = same_queue_rq->mq_hctx;
trace_block_unplug(q, 1, true);
@@ -2033,11 +2025,9 @@ static blk_qc_t blk_mq_make_request(struct request_queue *q, struct bio *bio)
}
} else if ((q->nr_hw_queues > 1 && is_sync) || (!q->elevator &&
!data.hctx->dispatch_busy)) {
- blk_mq_put_ctx(data.ctx);
blk_mq_bio_to_request(rq, bio);
blk_mq_try_issue_directly(data.hctx, rq, &cookie);
} else {
- blk_mq_put_ctx(data.ctx);
blk_mq_bio_to_request(rq, bio);
blk_mq_sched_insert_request(rq, false, true, true);
}
diff --git a/block/blk-mq.h b/block/blk-mq.h
index 633a5a77ee8b..f4bf5161333e 100644
--- a/block/blk-mq.h
+++ b/block/blk-mq.h
@@ -151,12 +151,7 @@ static inline struct blk_mq_ctx *__blk_mq_get_ctx(struct request_queue *q,
*/
static inline struct blk_mq_ctx *blk_mq_get_ctx(struct request_queue *q)
{
- return __blk_mq_get_ctx(q, get_cpu());
-}
-
-static inline void blk_mq_put_ctx(struct blk_mq_ctx *ctx)
-{
- put_cpu();
+ return __blk_mq_get_ctx(q, raw_smp_processor_id());
}
struct blk_mq_alloc_data {
diff --git a/block/kyber-iosched.c b/block/kyber-iosched.c
index c3b05119cebd..71c7b07b645a 100644
--- a/block/kyber-iosched.c
+++ b/block/kyber-iosched.c
@@ -574,7 +574,6 @@ static bool kyber_bio_merge(struct blk_mq_hw_ctx *hctx, struct bio *bio)
spin_lock(&kcq->lock);
merged = blk_mq_bio_list_merge(hctx->queue, rq_list, bio);
spin_unlock(&kcq->lock);
- blk_mq_put_ctx(ctx);
return merged;
}
--
2.22.0.rc3
