On Mon, Nov 22, 2021 at 09:48:35AM +0200, Sagi Grimberg wrote: > > > > > + 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? Yeah, we can add one extra srcu pointer to request queue, but this way needs one extra fetch to q->srcu in fast path compared with current code base, so io_uring workload may be affected a bit. Thanks, Ming
