[PATCH 5/8] blk-mq: add tagset quiesce interface

[Bart Van Assche]

On 10/23/22 18:57, Chao Leng wrote:
> blk_mq_quiesce_tagset() support concurrency. blk_mq_quiesce_tagset() just
> check the flag(QUEUE_FLAG_SKIP_TAGSET_QUIESCE), it has no impact on 
> concurrency.

Hi Chao,

I think it depends on how the QUEUE_FLAG_SKIP_TAGSET_QUIESCE flag is 
set. I agree if that flag is set once and never modified that there is 
no race. What I'm wondering about is whether there could be a need for 
block drivers to set the QUEUE_FLAG_SKIP_TAGSET_QUIESCE flag just before 
blk_mq_quiesce_tagset() is called and cleared immediately after 
blk_mq_quiesce_tagset() returns? In that case I think there is a race 
condition.

Thanks,

Bart.