On Fri, Mar 22, 2019 at 10:48:18PM +0800, Yufen Yu wrote:
> We convert 'active_queues' from atomic_t to newly provied
> refcount_t type and API, which can prevent accidental counter
> overflows and underflows.
There is no initialization using refcount_set(), which leads me to
believe we're 0 initialized and then it's broken again.
> Signed-off-by: Yufen Yu <yuyufen@xxxxxxxxxx>
> ---
> block/blk-mq-debugfs.c | 2 +-
> block/blk-mq-tag.c | 6 +++---
> block/blk-mq-tag.h | 2 +-
> 3 files changed, 5 insertions(+), 5 deletions(-)
>
> diff --git a/block/blk-mq-debugfs.c b/block/blk-mq-debugfs.c
> index 81536b7201be..48f0cc2c90ba 100644
> --- a/block/blk-mq-debugfs.c
> +++ b/block/blk-mq-debugfs.c
> @@ -473,7 +473,7 @@ static void blk_mq_debugfs_tags_show(struct seq_file *m,
> seq_printf(m, "nr_tags=%u\n", tags->nr_tags);
> seq_printf(m, "nr_reserved_tags=%u\n", tags->nr_reserved_tags);
> seq_printf(m, "active_queues=%d\n",
> - atomic_read(&tags->active_queues));
> + refcount_read(&tags->active_queues));
>
> seq_puts(m, "\nbitmap_tags:\n");
> sbitmap_queue_show(&tags->bitmap_tags, m);
> diff --git a/block/blk-mq-tag.c b/block/blk-mq-tag.c
> index 3fcb15fa6398..1d713f221bf7 100644
> --- a/block/blk-mq-tag.c
> +++ b/block/blk-mq-tag.c
> @@ -31,7 +31,7 @@ bool __blk_mq_tag_busy(struct blk_mq_hw_ctx *hctx)
> {
> if (!test_bit(BLK_MQ_S_TAG_ACTIVE, &hctx->state) &&
> !test_and_set_bit(BLK_MQ_S_TAG_ACTIVE, &hctx->state))
> - atomic_inc(&hctx->tags->active_queues);
> + refcount_inc(&hctx->tags->active_queues);
>
> return true;
> }
> @@ -57,7 +57,7 @@ void __blk_mq_tag_idle(struct blk_mq_hw_ctx *hctx)
> if (!test_and_clear_bit(BLK_MQ_S_TAG_ACTIVE, &hctx->state))
> return;
>
> - atomic_dec(&tags->active_queues);
> + refcount_dec(&tags->active_queues);
>
> blk_mq_tag_wakeup_all(tags, false);
> }
> @@ -82,7 +82,7 @@ static inline bool hctx_may_queue(struct blk_mq_hw_ctx *hctx,
> if (bt->sb.depth == 1)
> return true;
>
> - users = atomic_read(&hctx->tags->active_queues);
> + users = refcount_read(&hctx->tags->active_queues);
> if (!users)
> return true;
>
> diff --git a/block/blk-mq-tag.h b/block/blk-mq-tag.h
> index 61deab0b5a5a..e948b4833a2a 100644
> --- a/block/blk-mq-tag.h
> +++ b/block/blk-mq-tag.h
> @@ -11,7 +11,7 @@ struct blk_mq_tags {
> unsigned int nr_tags;
> unsigned int nr_reserved_tags;
>
> - atomic_t active_queues;
> + refcount_t active_queues;
>
> struct sbitmap_queue bitmap_tags;
> struct sbitmap_queue breserved_tags;
> --
> 2.16.2.dirty
>
