Messages in this thread | | | Subject | Re: [PATCH RFC v2 02/24] scsi: allocate separate queue for reserved commands | From | Hannes Reinecke <> | Date | Thu, 23 Apr 2020 16:49:00 +0200 |
| |
On 4/23/20 4:13 PM, John Garry wrote: > On 07/04/2020 17:30, Christoph Hellwig wrote: >> On Tue, Apr 07, 2020 at 04:00:10PM +0200, Hannes Reinecke wrote: >>> My concern is this: >>> >>> struct scsi_device *scsi_get_host_dev(struct Scsi_Host *shost) >>> { >>> [ .. ] >>> starget = scsi_alloc_target(&shost->shost_gendev, 0, >>> shost->this_id); >>> [ .. ] >>> >>> and we have typically: >>> >>> drivers/scsi/hisi_sas/hisi_sas_v3_hw.c: .this_id = -1, >>> >>> It's _very_ uncommon to have a negative number as the SCSI target >>> device; in >>> fact, it _is_ an unsigned int already. >>> >>> But alright, I'll give it a go; let's see what I'll end up with. >> >> But this shouldn't be exposed anywhere. And I prefer that over having >> magic requests/scsi_cmnd that do not have a valid ->device pointer. >> . >> > > (just looking at this again) > > Hi Christoph, > > So how would this look added in scsi_lib.c: > > struct scsi_cmnd *scsi_get_reserved_cmd(struct Scsi_Host *shost) > { > struct scsi_cmnd *scmd; > struct request *rq; > struct scsi_device *sdev = scsi_get_host_dev(shost); > > if (!sdev) > return NULL; > > rq = blk_mq_alloc_request(sdev->request_queue, > REQ_OP_DRV_OUT | REQ_NOWAIT, > BLK_MQ_REQ_RESERVED); > if (IS_ERR(rq)) // fix tidy-up > return NULL; > WARN_ON(rq->tag == -1); > scmd = blk_mq_rq_to_pdu(rq); > scmd->request = rq; > scmd->device = sdev; > > return scmd; > } > EXPORT_SYMBOL_GPL(scsi_get_reserved_cmd); > > void scsi_put_reserved_cmd(struct scsi_cmnd *scmd) > { > struct request *rq = blk_mq_rq_from_pdu(scmd); > > if (blk_mq_rq_is_reserved(rq)) { > struct scsi_device *sdev = scmd->device; > blk_mq_free_request(rq); > scsi_free_host_dev(sdev); > } > } > EXPORT_SYMBOL_GPL(scsi_put_reserved_cmd); > > Not sure if we want a static scsi_device per host, or alloc and free > dynamically. > > (@Hannes, I also have some proper patches for libsas if you want to add it) > Hold your horses. I'm currently preparing a patchset implementing things by improving the current scsi_get_host_dev() etc.
RFC should be ready by the end of the week.
Cheers,
Hannes -- Dr. Hannes Reinecke Teamlead Storage & Networking hare@suse.de +49 911 74053 688 SUSE Software Solutions GmbH, Maxfeldstr. 5, 90409 Nürnberg HRB 36809 (AG Nürnberg), Geschäftsführer: Felix Imendörffer
| |