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-rw-r--r--block/blk-mq-tag.c12
-rw-r--r--include/linux/sbitmap.h7
-rw-r--r--lib/sbitmap.c29
3 files changed, 34 insertions, 14 deletions
diff --git a/block/blk-mq-tag.c b/block/blk-mq-tag.c
index 336dde07b230..a4e58fc28a06 100644
--- a/block/blk-mq-tag.c
+++ b/block/blk-mq-tag.c
@@ -134,6 +134,8 @@ unsigned int blk_mq_get_tag(struct blk_mq_alloc_data *data)
ws = bt_wait_ptr(bt, data->hctx);
drop_ctx = data->ctx == NULL;
do {
+ struct sbitmap_queue *bt_prev;
+
/*
* We're out of tags on this hardware queue, kick any
* pending IO submits before going to sleep waiting for
@@ -159,6 +161,7 @@ unsigned int blk_mq_get_tag(struct blk_mq_alloc_data *data)
if (data->ctx)
blk_mq_put_ctx(data->ctx);
+ bt_prev = bt;
io_schedule();
data->ctx = blk_mq_get_ctx(data->q);
@@ -170,6 +173,15 @@ unsigned int blk_mq_get_tag(struct blk_mq_alloc_data *data)
bt = &tags->bitmap_tags;
finish_wait(&ws->wait, &wait);
+
+ /*
+ * If destination hw queue is changed, fake wake up on
+ * previous queue for compensating the wake up miss, so
+ * other allocations on previous queue won't be starved.
+ */
+ if (bt != bt_prev)
+ sbitmap_queue_wake_up(bt_prev);
+
ws = bt_wait_ptr(bt, data->hctx);
} while (1);
diff --git a/include/linux/sbitmap.h b/include/linux/sbitmap.h
index 0c4a9c242dd7..e6539536dea9 100644
--- a/include/linux/sbitmap.h
+++ b/include/linux/sbitmap.h
@@ -513,6 +513,13 @@ static inline struct sbq_wait_state *sbq_wait_ptr(struct sbitmap_queue *sbq,
void sbitmap_queue_wake_all(struct sbitmap_queue *sbq);
/**
+ * sbitmap_queue_wake_up() - Wake up some of waiters in one waitqueue
+ * on a &struct sbitmap_queue.
+ * @sbq: Bitmap queue to wake up.
+ */
+void sbitmap_queue_wake_up(struct sbitmap_queue *sbq);
+
+/**
* sbitmap_queue_show() - Dump &struct sbitmap_queue information to a &struct
* seq_file.
* @sbq: Bitmap queue to show.
diff --git a/lib/sbitmap.c b/lib/sbitmap.c
index e6d7d610778d..6fdc6267f4a8 100644
--- a/lib/sbitmap.c
+++ b/lib/sbitmap.c
@@ -352,8 +352,9 @@ static void sbitmap_queue_update_wake_batch(struct sbitmap_queue *sbq,
if (sbq->wake_batch != wake_batch) {
WRITE_ONCE(sbq->wake_batch, wake_batch);
/*
- * Pairs with the memory barrier in sbq_wake_up() to ensure that
- * the batch size is updated before the wait counts.
+ * Pairs with the memory barrier in sbitmap_queue_wake_up()
+ * to ensure that the batch size is updated before the wait
+ * counts.
*/
smp_mb__before_atomic();
for (i = 0; i < SBQ_WAIT_QUEUES; i++)
@@ -463,15 +464,6 @@ static bool __sbq_wake_up(struct sbitmap_queue *sbq)
unsigned int wake_batch;
int wait_cnt;
- /*
- * Pairs with the memory barrier in set_current_state() to ensure the
- * proper ordering of clear_bit()/waitqueue_active() in the waker and
- * test_and_set_bit_lock()/prepare_to_wait()/finish_wait() in the
- * waiter. See the comment on waitqueue_active(). This is __after_atomic
- * because we just did clear_bit_unlock() in the caller.
- */
- smp_mb__after_atomic();
-
ws = sbq_wake_ptr(sbq);
if (!ws)
return false;
@@ -507,17 +499,26 @@ static bool __sbq_wake_up(struct sbitmap_queue *sbq)
return false;
}
-static void sbq_wake_up(struct sbitmap_queue *sbq)
+void sbitmap_queue_wake_up(struct sbitmap_queue *sbq)
{
while (__sbq_wake_up(sbq))
;
}
+EXPORT_SYMBOL_GPL(sbitmap_queue_wake_up);
void sbitmap_queue_clear(struct sbitmap_queue *sbq, unsigned int nr,
unsigned int cpu)
{
sbitmap_clear_bit_unlock(&sbq->sb, nr);
- sbq_wake_up(sbq);
+ /*
+ * Pairs with the memory barrier in set_current_state() to ensure the
+ * proper ordering of clear_bit_unlock()/waitqueue_active() in the waker
+ * and test_and_set_bit_lock()/prepare_to_wait()/finish_wait() in the
+ * waiter. See the comment on waitqueue_active().
+ */
+ smp_mb__after_atomic();
+ sbitmap_queue_wake_up(sbq);
+
if (likely(!sbq->round_robin && nr < sbq->sb.depth))
*per_cpu_ptr(sbq->alloc_hint, cpu) = nr;
}
@@ -529,7 +530,7 @@ void sbitmap_queue_wake_all(struct sbitmap_queue *sbq)
/*
* Pairs with the memory barrier in set_current_state() like in
- * sbq_wake_up().
+ * sbitmap_queue_wake_up().
*/
smp_mb();
wake_index = atomic_read(&sbq->wake_index);