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

[Hannes Reinecke <hare@suse.de>]

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@suse.de                              +49 911 74053 688
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