On Wed, Nov 03, 2021 at 06:45:34AM -0700, Bart Van Assche wrote: > > But more importantly: SCSI LLDDs have absolutel no business calling > > blk_get_request or blk_mq_alloc_request directly, but as usual UFS is > > completely fucked up here. > > As explained by Adrian, the UFS protocol uses a single tag space for SCSI > commands and UFS device commands. blk_mq_alloc_request() is used in this > context to allocate a tag only from the shared tag space only. I think using > blk_mq_alloc_request() for that purpose is fine. The problem is not the shared tag space, the problem is that it is poking through layers. IFF we have good use cases for just allocating a tag (and we don't want to reserve it, which does make sense for many things like task management) we need a SCSI layer API that returns just the tag (and preferably also poisons the request in some way).
