Re: [PATCH 1/5] blk-mq: move srcu from blk_mq_hw_ctx to request_queue

Sagi Grimberg
2021-11-22T07:48:39Z

>>> + bool alloc_srcu;
>>
>> I found the following statement multiple times in this patch:
>>
>> WARN_ON_ONCE(q->alloc_srcu != !!(q->tag_set->flags & BLK_MQ_F_BLOCKING));
>>
>> Does this mean that the new q->alloc_srcu member variable can be left out
>> and that it can be replaced with the following test?
>>
>> q->tag_set->flags & BLK_MQ_F_BLOCKING
>
> q->tag_set can't be used anymore after blk_cleanup_queue() returns,
> and we need the flag for freeing request_queue instance.

Why not just look at the queue->srcu pointer? it is allocated only
for BLK_MQ_F_BLOCKING no?