On 2020-05-27 11:06, Christoph Hellwig wrote:
> --- a/block/blk-mq-tag.c
> +++ b/block/blk-mq-tag.c
> @@ -180,6 +180,14 @@ unsigned int blk_mq_get_tag(struct blk_mq_alloc_data *data)
> sbitmap_finish_wait(bt, ws, &wait);
>
> found_tag:
> + /*
> + * Give up this allocation if the hctx is inactive. The caller will
> + * retry on an active hctx.
> + */
> + if (unlikely(test_bit(BLK_MQ_S_INACTIVE, &data->hctx->state))) {
> + blk_mq_put_tag(tags, data->ctx, tag + tag_offset);
> + return -1;
> + }
> return tag + tag_offset;
> }
The code that has been added in blk_mq_hctx_notify_offline() will only
work correctly if blk_mq_get_tag() tests BLK_MQ_S_INACTIVE after the
store instructions involved in the tag allocation happened. Does this
mean that a memory barrier should be added in the above function before
the test_bit() call?
Thanks,
Bart.
