> -----Original Message----- > From: Ming Lei [mailto:ming.lei@xxxxxxxxxx] > Sent: Friday, December 7, 2018 3:50 PM > To: Kashyap Desai > Cc: Bart Van Assche; linux-block; Jens Axboe; linux-scsi; Suganath Prabu > Subramani; Sreekanth Reddy; Sathya Prakash Veerichetty > Subject: Re: +AFs-PATCH+AF0- blk-mq: Set request mapping to NULL in > blk+AF8-mq+AF8-put+AF8-driver+AF8-tag > > On Thu, Dec 06, 2018 at 11:15:13AM +0530, Kashyap Desai wrote: > > > > > > If the 'tag' passed to scsi_host_find_tag() is valid, I think there > > > shouldn't have such issue. > > > > > > If you want to find outstanding IOs, maybe you can try > > > blk_mq_queue_tag_busy_iter() > > > or blk_mq_tagset_busy_iter(), because you may not know if the passed > > 'tag' > > > to > > > scsi_host_find_tag() is valid or not. > > > > We tried quick change in mpt3sas driver using blk_mq_tagset_busy_iter and > > it returns/callback for valid requests (no stale entries are returned). > > Expected. > > Above two APIs are only for blk-mq. What about non-mq case ? Driver > > should use scsi_host_find_tag for non-mq and blk_mq_tagset_busy_iter for > > blk-mq case ? > > But your patch is only for blk-mq, is there same issue on non-mq case? Problematic part from below function is code path which goes from " shost_use_blk_mq(shost))". Non-mq path works fine because every IO completion set bqt->tag_index[tag] = NULL from blk_queue_end_tag(). I did similar things for mq path in this patch. static inline struct scsi_cmnd *scsi_host_find_tag(struct Scsi_Host *shost, int tag) { struct request *req = NULL; if (tag == SCSI_NO_TAG) return NULL; if (shost_use_blk_mq(shost)) { u16 hwq = blk_mq_unique_tag_to_hwq(tag); if (hwq < shost->tag_set.nr_hw_queues) { req = blk_mq_tag_to_rq(shost->tag_set.tags[hwq], blk_mq_unique_tag_to_tag(tag)); } } else { req = blk_map_queue_find_tag(shost->bqt, tag); } Kashyap > > Thanks, > Ming
