scsi: mpt3sas: Proper handling of set/clear of "ATA command pending" flag.

1. In IO path, setting of "ATA command pending" flag early before device
   removal, invalid device handle etc., checks causes any new commands
   to be always returned with SAM_STAT_BUSY and when the driver removes
   the drive the SML issues SYNC Cache command and that command is
   always returned with SAM_STAT_BUSY and thus making SYNC Cache command
   to requeued.

2. If the driver gets an ATA PT command for a SATA drive then the driver
   set "ATA command pending" flag in device specific data structure not
   to allow any further commands until the ATA PT command is completed.
   However, after setting the flag if the driver decides to return the
   command back to upper layers without actually issuing to the firmware
   (i.e., returns from qcmd failure return paths) then the corresponding
   flag is not cleared and this prevents the driver from sending any new
   commands to the drive.

This patch fixes above two issues by setting of "ATA command pending"
flag after checking for whether device deleted, invalid device handle,
device busy with task management. And by setting "ATA command pending"
flag to false in all of the qcmd failure return paths after setting the
flag.

Signed-off-by: Chaitra P B <[email protected]>
Signed-off-by: Suganath Prabu S <[email protected]>
Signed-off-by: Martin K. Petersen <[email protected]>

Author: Chaitra P B

drivers/scsi/mpt3sas/mpt3sas_scsih.c

@@ -4758,19 +4758,6 @@ scsih_qcmd(struct Scsi_Host *shost, struct scsi_cmnd *scmd)
 		return 0;
 	}
 
-	/*
-	 * Bug work around for firmware SATL handling.  The loop
-	 * is based on atomic operations and ensures consistency
-	 * since we're lockless at this point
-	 */
-	do {
-		if (test_bit(0, &sas_device_priv_data->ata_command_pending)) {
-			scmd->result = SAM_STAT_BUSY;
-			scmd->scsi_done(scmd);
-			return 0;
-		}
-	} while (_scsih_set_satl_pending(scmd, true));
-
 	sas_target_priv_data = sas_device_priv_data->sas_target;
 
 	/* invalid device handle */
@@ -4796,6 +4783,19 @@ scsih_qcmd(struct Scsi_Host *shost, struct scsi_cmnd *scmd)
 	    sas_device_priv_data->block)
 		return SCSI_MLQUEUE_DEVICE_BUSY;
 
+	/*
+	 * Bug work around for firmware SATL handling.  The loop
+	 * is based on atomic operations and ensures consistency
+	 * since we're lockless at this point
+	 */
+	do {
+		if (test_bit(0, &sas_device_priv_data->ata_command_pending)) {
+			scmd->result = SAM_STAT_BUSY;
+			scmd->scsi_done(scmd);
+			return 0;
+		}
+	} while (_scsih_set_satl_pending(scmd, true));
+
 	if (scmd->sc_data_direction == DMA_FROM_DEVICE)
 		mpi_control = MPI2_SCSIIO_CONTROL_READ;
 	else if (scmd->sc_data_direction == DMA_TO_DEVICE)
@@ -4823,6 +4823,7 @@ scsih_qcmd(struct Scsi_Host *shost, struct scsi_cmnd *scmd)
 	if (!smid) {
 		pr_err(MPT3SAS_FMT "%s: failed obtaining a smid\n",
 		    ioc->name, __func__);
+		_scsih_set_satl_pending(scmd, false);
 		goto out;
 	}
 	mpi_request = mpt3sas_base_get_msg_frame(ioc, smid);
@@ -4854,6 +4855,7 @@ scsih_qcmd(struct Scsi_Host *shost, struct scsi_cmnd *scmd)
 		pcie_device = sas_target_priv_data->pcie_dev;
 		if (ioc->build_sg_scmd(ioc, scmd, smid, pcie_device)) {
 			mpt3sas_base_free_smid(ioc, smid);
+			_scsih_set_satl_pending(scmd, false);
 			goto out;
 		}
 	} else