[PATCH 11/16] snic: allocate device reset command

[Hannes Reinecke <hare@suse.de>]

Allocate a command to send a device reset instead of relying
on using the command which triggered the device failure.

Signed-off-by: Hannes Reinecke <hare@suse.de>
---
 drivers/scsi/snic/snic_scsi.c | 72 +++++++++++++++++++----------------
 1 file changed, 40 insertions(+), 32 deletions(-)

diff --git a/drivers/scsi/snic/snic_scsi.c b/drivers/scsi/snic/snic_scsi.c
index f1ef781df837..1807f713504f 100644
--- a/drivers/scsi/snic/snic_scsi.c
+++ b/drivers/scsi/snic/snic_scsi.c
@@ -2091,70 +2091,78 @@ snic_unlink_and_release_req(struct snic *snic, struct scsi_cmnd *sc, int flag)
 int
 snic_device_reset(struct scsi_cmnd *sc)
 {
-	struct Scsi_Host *shost = sc->device->host;
+	struct scsi_device *sdev = sc->device;
+	struct Scsi_Host *shost = sdev->host;
 	struct snic *snic = shost_priv(shost);
+	struct request *req;
 	struct snic_req_info *rqi = NULL;
-	int tag = snic_cmd_tag(sc);
 	int start_time = jiffies;
 	int ret = FAILED;
 	int dr_supp = 0;
 
-	SNIC_SCSI_DBG(shost, "dev_reset:sc %p :0x%x :req = %p :tag = %d\n",
-		      sc, sc->cmnd[0], scsi_cmd_to_rq(sc),
-		      snic_cmd_tag(sc));
-	dr_supp = snic_dev_reset_supported(sc->device);
+	SNIC_SCSI_DBG(shost, "dev_reset\n");
+	dr_supp = snic_dev_reset_supported(sdev);
 	if (!dr_supp) {
 		/* device reset op is not supported */
 		SNIC_HOST_INFO(shost, "LUN Reset Op not supported.\n");
-		snic_unlink_and_release_req(snic, sc, SNIC_DEV_RST_NOTSUP);
-
-		goto dev_rst_end;
+		return ret;
 	}
 
 	if (unlikely(snic_get_state(snic) != SNIC_ONLINE)) {
-		snic_unlink_and_release_req(snic, sc, 0);
 		SNIC_HOST_ERR(shost, "Devrst: Parent Devs are not online.\n");
 
-		goto dev_rst_end;
+		return ret;
 	}
 
-	/* There is no tag when lun reset is issue through ioctl. */
-	if (unlikely(tag <= SNIC_NO_TAG)) {
-		SNIC_HOST_INFO(snic->shost,
-			       "Devrst: LUN Reset Recvd thru IOCTL.\n");
-
-		rqi = snic_req_init(snic, 0);
-		if (!rqi)
-			goto dev_rst_end;
-
-		memset(scsi_cmd_priv(sc), 0,
-			sizeof(struct snic_internal_io_state));
-		CMD_SP(sc) = (char *)rqi;
-		CMD_FLAGS(sc) = SNIC_NO_FLAGS;
+	rqi = snic_req_init(snic, 0);
+	if (!rqi)
+		return ret;
 
-		/* Add special tag for dr coming from user spc */
-		rqi->tm_tag = SNIC_TAG_IOCTL_DEV_RST;
-		rqi->sc = sc;
+	req = scsi_alloc_request(sdev->request_queue, REQ_OP_DRV_IN,
+				 BLK_MQ_REQ_NOWAIT);
+	if (!req) {
+		/*
+		 * Request allocation might fail, indicating that
+		 * all tags are busy.
+		 * But device reset will be called only from within
+		 * SCSI EH, at which time all I/O is stopped. So the
+		 * only active tags would be for failed I/O, but
+		 * when all I/O is failed it'll be better to escalate
+		 * to host reset anyway.
+		 */
+		SNIC_HOST_ERR(snic->shost,
+			      "Devrst: TMF busy, escalate to host reset\n");
+		goto dev_rst_end;
 	}
+	sc = blk_mq_rq_to_pdu(req);
+	memset(scsi_cmd_priv(sc), 0,
+	       sizeof(struct snic_internal_io_state));
+	CMD_SP(sc) = (char *)rqi;
+	CMD_FLAGS(sc) = SNIC_NO_FLAGS;
 
+	/* Add special tag for dr coming from user spc */
+	rqi->tm_tag = SNIC_TAG_IOCTL_DEV_RST;
+	rqi->sc = sc;
+	WRITE_ONCE(req->state, MQ_RQ_IN_FLIGHT);
 	ret = snic_send_dr_and_wait(snic, sc);
 	if (ret) {
 		SNIC_HOST_ERR(snic->shost,
 			      "Devrst: IO w/ Tag %x Failed w/ err = %d\n",
-			      tag, ret);
-
+			      snic_cmd_tag(sc), ret);
+		blk_mq_set_request_complete(req);
 		snic_unlink_and_release_req(snic, sc, 0);
 
 		goto dev_rst_end;
 	}
-
+	blk_mq_set_request_complete(req);
 	ret = snic_dr_finish(snic, sc);
 
 dev_rst_end:
-	SNIC_TRC(snic->shost->host_no, tag, (ulong) sc,
+	SNIC_TRC(snic->shost->host_no, snic_cmd_tag(sc), (ulong) sc,
 		 jiffies_to_msecs(jiffies - start_time),
 		 0, SNIC_TRC_CMD(sc), SNIC_TRC_CMD_STATE_FLAGS(sc));
-
+	if (req)
+		blk_mq_free_request(req);
 	SNIC_SCSI_DBG(snic->shost,
 		      "Devrst: Returning from Device Reset : %s\n",
 		      (ret == SUCCESS) ? "SUCCESS" : "FAILED");
-- 
2.35.3