On 07/04/2020 17:30, Christoph Hellwig wrote:Hold your horses.
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)
{
ÂÂÂÂ[ .. ]
ÂÂÂÂstarget = scsi_alloc_target(&shost->shost_gendev, 0, shost->this_id);
ÂÂÂÂ[ .. ]
and we have typically:
drivers/scsi/hisi_sas/hisi_sas_v3_hw.c: .this_idÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ = -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)
{
ÂÂÂÂstruct scsi_cmnd *scmd;
ÂÂÂÂstruct request *rq;
ÂÂÂÂstruct scsi_device *sdev = scsi_get_host_dev(shost);
ÂÂÂÂif (!sdev)
ÂÂÂÂÂÂÂ return NULL;
ÂÂÂÂrq = blk_mq_alloc_request(sdev->request_queue,
ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ REQ_OP_DRV_OUT | REQ_NOWAIT,
ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ BLK_MQ_REQ_RESERVED);
ÂÂÂÂif (IS_ERR(rq)) // fix tidy-up
ÂÂÂÂÂÂÂ return NULL;
ÂÂÂÂWARN_ON(rq->tag == -1);
ÂÂÂÂscmd = blk_mq_rq_to_pdu(rq);
ÂÂÂÂscmd->request = rq;
ÂÂÂÂscmd->device = sdev;
ÂÂÂÂreturn scmd;
}
EXPORT_SYMBOL_GPL(scsi_get_reserved_cmd);
void scsi_put_reserved_cmd(struct scsi_cmnd *scmd)
{
ÂÂÂÂstruct request *rq = blk_mq_rq_from_pdu(scmd);
ÂÂÂÂif (blk_mq_rq_is_reserved(rq)) {
ÂÂÂÂÂÂÂ struct scsi_device *sdev = scmd->device;
ÂÂÂÂÂÂÂ blk_mq_free_request(rq);
ÂÂÂÂÂÂÂ scsi_free_host_dev(sdev);
ÂÂÂÂ}
}
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)