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-rw-r--r--block/blk-mq.c4
1 files changed, 4 insertions, 0 deletions
diff --git a/block/blk-mq.c b/block/blk-mq.c
index 12bb7a49c5ba..c28d6b3088a0 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -2314,6 +2314,9 @@ static void blk_mq_realloc_hw_ctxs(struct blk_mq_tag_set *set,
struct blk_mq_hw_ctx **hctxs = q->queue_hw_ctx;
blk_mq_sysfs_unregister(q);
+
+ /* protect against switching io scheduler */
+ mutex_lock(&q->sysfs_lock);
for (i = 0; i < set->nr_hw_queues; i++) {
int node;
@@ -2358,6 +2361,7 @@ static void blk_mq_realloc_hw_ctxs(struct blk_mq_tag_set *set,
}
}
q->nr_hw_queues = i;
+ mutex_unlock(&q->sysfs_lock);
blk_mq_sysfs_register(q);
}