[libata] add ata_queued_cmd completion hook

drivers/scsi/libata-core.c

@@ -2293,8 +2293,8 @@ struct ata_queued_cmd *ata_qc_new_init(struct ata_port *ap,
 void ata_qc_complete(struct ata_queued_cmd *qc, u8 drv_stat)
 {
 	struct ata_port *ap = qc->ap;
-	struct scsi_cmnd *cmd = qc->scsicmd;
 	unsigned int tag, do_clear = 0;
+	int rc;
 
 	assert(qc != NULL);	/* ata_qc_from_tag _might_ return NULL */
 	assert(qc->flags & ATA_QCFLAG_ACTIVE);
@@ -2302,18 +2302,14 @@ void ata_qc_complete(struct ata_queued_cmd *qc, u8 drv_stat)
 	if (likely(qc->flags & ATA_QCFLAG_SG))
 		ata_sg_clean(qc);
 
-	if (cmd) {
-		if (unlikely(drv_stat & (ATA_ERR | ATA_BUSY | ATA_DRQ))) {
-			if (is_atapi_taskfile(&qc->tf))
-				cmd->result = SAM_STAT_CHECK_CONDITION;
-			else
-				ata_to_sense_error(qc);
-		} else {
-			cmd->result = SAM_STAT_GOOD;
-		}
+	/* call completion callback */
+	rc = qc->complete_fn(qc, drv_stat);
 
-		qc->scsidone(cmd);
-	}
+	/* if callback indicates not to complete command (non-zero),
+	 * return immediately
+	 */
+	if (rc != 0)
+		return;
 
 	qc->flags = 0;
 	tag = qc->tag;

drivers/scsi/libata-scsi.c

@@ -335,6 +335,24 @@ static unsigned int ata_scsi_rw_xlat(struct ata_queued_cmd *qc, u8 *scsicmd)
 	return 1;
 }
 
+static int ata_scsi_qc_complete(struct ata_queued_cmd *qc, u8 drv_stat)
+{
+	struct scsi_cmnd *cmd = qc->scsicmd;
+
+	if (unlikely(drv_stat & (ATA_ERR | ATA_BUSY | ATA_DRQ))) {
+		if (is_atapi_taskfile(&qc->tf))
+			cmd->result = SAM_STAT_CHECK_CONDITION;
+		else
+			ata_to_sense_error(qc);
+	} else {
+		cmd->result = SAM_STAT_GOOD;
+	}
+
+	qc->scsidone(cmd);
+
+	return 0;
+}
+
 /**
  *	ata_scsi_translate - Translate then issue SCSI command to ATA device
  *	@ap: ATA port to which the command is addressed
@@ -379,6 +397,8 @@ static void ata_scsi_translate(struct ata_port *ap, struct ata_device *dev,
 		qc->flags |= ATA_QCFLAG_SG; /* data is present; dma-map it */
 	}
 
+	qc->complete_fn = ata_scsi_qc_complete;
+
 	if (xlat_func(qc, scsicmd))
 		goto err_out;
 

include/linux/libata.h

@@ -158,7 +158,7 @@ struct ata_port;
 struct ata_queued_cmd;
 
 /* typedefs */
-typedef void (*ata_qc_cb_t) (struct ata_queued_cmd *qc, unsigned int flags);
+typedef int (*ata_qc_cb_t) (struct ata_queued_cmd *qc, u8 drv_stat);
 
 struct ata_ioports {
 	unsigned long		cmd_addr;
@@ -224,7 +224,7 @@ struct ata_queued_cmd {
 
 	struct scatterlist	*sg;
 
-	ata_qc_cb_t		callback;
+	ata_qc_cb_t		complete_fn;
 
 	struct completion	*waiting;