Re: [PATCH 17/24] snic: reserve tag for TMF

[Hannes Reinecke <hare@xxxxxxx>]

On 5/6/22 06:28, John Garry wrote:
> > diff --git a/drivers/scsi/snic/snic_main.c 
> > b/drivers/scsi/snic/snic_main.c
> > index 29d56396058c..f344cbc27923 100644
> > --- a/drivers/scsi/snic/snic_main.c
> > +++ b/drivers/scsi/snic/snic_main.c
> > @@ -512,6 +512,9 @@ snic_probe(struct pci_dev *pdev, const struct 
> > pci_device_id *ent)
> >                        max_t(u32, SNIC_MIN_IO_REQ, max_ios));
> >       snic->max_tag_id = shost->can_queue;
> > +    /* Reserve one reset command */
> > +    shost->can_queue--;
> > +    snic->tmf_tag_id = shost->can_queue;
> >       shost->max_lun = snic->config.luns_per_tgt;
> >       shost->max_id = SNIC_MAX_TARGET;
> > diff --git a/drivers/scsi/snic/snic_scsi.c 
> > b/drivers/scsi/snic/snic_scsi.c
> > index 5f17666f3e1d..e18c8c5e4b46 100644
> > --- a/drivers/scsi/snic/snic_scsi.c
> > +++ b/drivers/scsi/snic/snic_scsi.c
> > @@ -1018,17 +1018,6 @@ snic_hba_reset_cmpl_handler(struct snic *snic, 
> > struct snic_fw_req *fwreq)
> >                 "reset_cmpl: type = %x, hdr_stat = %x, cmnd_id = %x, 
> > hid = %x, ctx = %lx\n",
> >                 typ, hdr_stat, cmnd_id, hid, ctx);
> > -    /* spl case, host reset issued through ioctl */
> > -    if (cmnd_id == SCSI_NO_TAG) {
> > -        rqi = (struct snic_req_info *) ctx;
> > -        SNIC_HOST_INFO(snic->shost,
> > -                   "reset_cmpl:Tag %d ctx %lx cmpl stat %s\n",
> > -                   cmnd_id, ctx, snic_io_status_to_str(hdr_stat));
> > -        sc = rqi->sc;
> > -
> > -        goto ioctl_hba_rst;
> > -    }
> > -
> >       if (cmnd_id >= snic->max_tag_id) {
> >           SNIC_HOST_ERR(snic->shost,
> >                     "reset_cmpl: Tag 0x%x out of Range,HdrStat %s\n",
> > @@ -1039,7 +1028,6 @@ snic_hba_reset_cmpl_handler(struct snic *snic, 
> > struct snic_fw_req *fwreq)
> >       }
> >       sc = scsi_host_find_tag(snic->shost, cmnd_id);
> > -ioctl_hba_rst:
> >       if (!sc) {
> >           atomic64_inc(&snic->s_stats.io.sc_null);
> >           SNIC_HOST_ERR(snic->shost,
> > @@ -1725,7 +1713,7 @@ snic_dr_clean_single_req(struct snic *snic,
> >   {
> >       struct snic_req_info *rqi = NULL;
> >       struct snic_tgt *tgt = NULL;
> > -    struct scsi_cmnd *sc = NULL;
> > +    struct scsi_cmnd *sc;
> >       spinlock_t *io_lock = NULL;
> >       u32 sv_state = 0, tmf = 0;
> >       DECLARE_COMPLETION_ONSTACK(tm_done);
> > @@ -2238,13 +2226,6 @@ snic_issue_hba_reset(struct snic *snic, struct 
> > scsi_cmnd *sc)
> >           goto hba_rst_end;
> >       }
> > -    if (snic_cmd_tag(sc) == SCSI_NO_TAG) {
> > -        memset(scsi_cmd_priv(sc), 0,
> > -            sizeof(struct snic_internal_io_state));
> > -        SNIC_HOST_INFO(snic->shost, "issu_hr:Host reset thru ioctl.\n");
> > -        rqi->sc = sc;
> > -    }
> > -
> >       req = rqi_to_req(rqi);
> >       io_lock = snic_io_lock_hash(snic, sc);
> > @@ -2319,11 +2300,13 @@ snic_issue_hba_reset(struct snic *snic, struct 
> > scsi_cmnd *sc)
> >   } /* end of snic_issue_hba_reset */
> >   int
> > -snic_reset(struct Scsi_Host *shost, struct scsi_cmnd *sc)
> > +snic_reset(struct Scsi_Host *shost)
> >   {
> >       struct snic *snic = shost_priv(shost);
> > +    struct scsi_cmnd *sc = NULL;
> >       enum snic_state sv_state;
> >       unsigned long flags;
> > +    u32 start_time  = jiffies;
> >       int ret = FAILED;
> >       /* Set snic state as SNIC_FWRESET*/
> > @@ -2348,6 +2331,18 @@ snic_reset(struct Scsi_Host *shost, struct 
> > scsi_cmnd *sc)
> >       while (atomic_read(&snic->ios_inflight))
> >           schedule_timeout(msecs_to_jiffies(1));
> > +    sc = scsi_host_find_tag(shost, snic->tmf_tag_id);
>
> Maybe I am missing something but this does not seem right. As I see, 
> blk-mq has driver tags in range [0, snic->tmf_tag_id - 1], so we cannot 
> call scsi_host_find_tag() -> blk_mq_unique_tag_to_tag(snic->tmf_tag_id)
We do decrease 'can_queue' by '1' just at the start of this patch, hence 
the last tag is always available for TMF.

Cheers,

Hannes
--
Dr. Hannes Reinecke                Kernel Storage Architect
hare@xxxxxxx                              +49 911 74053 688
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