scsi: ppa: Move the SCSI pointer to private command data

Set .cmd_size in the SCSI host template instead of using the SCSI pointer
from struct scsi_cmnd. This patch prepares for removal of the SCSI pointer
from struct scsi_cmnd.

Link: https://lore.kernel.org/r/20220218195117.25689-41-bvanassche@acm.orgReviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: Himanshu Madhani <himanshu.madhani@oracle.com>
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

drivers/scsi/ppa.c

@@ -45,6 +45,11 @@ typedef struct {
 
 #include  "ppa.h"
 
+static struct scsi_pointer *ppa_scsi_pointer(struct scsi_cmnd *cmd)
+{
+	return scsi_cmd_priv(cmd);
+}
+
 static inline ppa_struct *ppa_dev(struct Scsi_Host *host)
 {
 	return *(ppa_struct **)&host->hostdata;
@@ -56,7 +61,7 @@ static void got_it(ppa_struct *dev)
 {
 	dev->base = dev->dev->port->base;
 	if (dev->cur_cmd)
-		dev->cur_cmd->SCp.phase = 1;
+		ppa_scsi_pointer(dev->cur_cmd)->phase = 1;
 	else
 		wake_up(dev->waiting);
 }
@@ -511,13 +516,14 @@ static inline int ppa_send_command(struct scsi_cmnd *cmd)
  * The driver appears to remain stable if we speed up the parallel port
  * i/o in this function, but not elsewhere.
  */
-static int ppa_completion(struct scsi_cmnd *cmd)
+static int ppa_completion(struct scsi_cmnd *const cmd)
 {
 	/* Return codes:
 	 * -1     Error
 	 *  0     Told to schedule
 	 *  1     Finished data transfer
 	 */
+	struct scsi_pointer *scsi_pointer = ppa_scsi_pointer(cmd);
 	ppa_struct *dev = ppa_dev(cmd->device->host);
 	unsigned short ppb = dev->base;
 	unsigned long start_jiffies = jiffies;
@@ -543,7 +549,7 @@ static int ppa_completion(struct scsi_cmnd *cmd)
 		if (time_after(jiffies, start_jiffies + 1))
 			return 0;
 
-		if ((cmd->SCp.this_residual <= 0)) {
+		if (scsi_pointer->this_residual <= 0) {
 			ppa_fail(dev, DID_ERROR);
 			return -1;	/* ERROR_RETURN */
 		}
@@ -572,28 +578,30 @@ static int ppa_completion(struct scsi_cmnd *cmd)
 		}
 
 		/* determine if we should use burst I/O */
-		fast = (bulk && (cmd->SCp.this_residual >= PPA_BURST_SIZE))
-		    ? PPA_BURST_SIZE : 1;
+		fast = bulk && scsi_pointer->this_residual >= PPA_BURST_SIZE ?
+			PPA_BURST_SIZE : 1;
 
 		if (r == (unsigned char) 0xc0)
-			status = ppa_out(dev, cmd->SCp.ptr, fast);
+			status = ppa_out(dev, scsi_pointer->ptr, fast);
 		else
-			status = ppa_in(dev, cmd->SCp.ptr, fast);
+			status = ppa_in(dev, scsi_pointer->ptr, fast);
 
-		cmd->SCp.ptr += fast;
-		cmd->SCp.this_residual -= fast;
+		scsi_pointer->ptr += fast;
+		scsi_pointer->this_residual -= fast;
 
 		if (!status) {
 			ppa_fail(dev, DID_BUS_BUSY);
 			return -1;	/* ERROR_RETURN */
 		}
-		if (cmd->SCp.buffer && !cmd->SCp.this_residual) {
+		if (scsi_pointer->buffer && !scsi_pointer->this_residual) {
 			/* if scatter/gather, advance to the next segment */
-			if (cmd->SCp.buffers_residual--) {
-				cmd->SCp.buffer = sg_next(cmd->SCp.buffer);
-				cmd->SCp.this_residual =
-				    cmd->SCp.buffer->length;
-				cmd->SCp.ptr = sg_virt(cmd->SCp.buffer);
+			if (scsi_pointer->buffers_residual--) {
+				scsi_pointer->buffer =
+					sg_next(scsi_pointer->buffer);
+				scsi_pointer->this_residual =
+				    scsi_pointer->buffer->length;
+				scsi_pointer->ptr =
+					sg_virt(scsi_pointer->buffer);
 			}
 		}
 		/* Now check to see if the drive is ready to comunicate */
@@ -658,7 +666,7 @@ static void ppa_interrupt(struct work_struct *work)
 	}
 #endif
 
-	if (cmd->SCp.phase > 1)
+	if (ppa_scsi_pointer(cmd)->phase > 1)
 		ppa_disconnect(dev);
 
 	ppa_pb_dismiss(dev);
@@ -670,6 +678,7 @@ static void ppa_interrupt(struct work_struct *work)
 
 static int ppa_engine(ppa_struct *dev, struct scsi_cmnd *cmd)
 {
+	struct scsi_pointer *scsi_pointer = ppa_scsi_pointer(cmd);
 	unsigned short ppb = dev->base;
 	unsigned char l = 0, h = 0;
 	int retv;
@@ -680,7 +689,7 @@ static int ppa_engine(ppa_struct *dev, struct scsi_cmnd *cmd)
 	if (dev->failed)
 		return 0;
 
-	switch (cmd->SCp.phase) {
+	switch (scsi_pointer->phase) {
 	case 0:		/* Phase 0 - Waiting for parport */
 		if (time_after(jiffies, dev->jstart + HZ)) {
 			/*
@@ -715,7 +724,7 @@ static int ppa_engine(ppa_struct *dev, struct scsi_cmnd *cmd)
 					return 1;	/* Try again in a jiffy */
 				}
 			}
-			cmd->SCp.phase++;
+			scsi_pointer->phase++;
 		}
 		fallthrough;
 
@@ -724,7 +733,7 @@ static int ppa_engine(ppa_struct *dev, struct scsi_cmnd *cmd)
 			ppa_fail(dev, DID_NO_CONNECT);
 			return 0;
 		}
-		cmd->SCp.phase++;
+		scsi_pointer->phase++;
 		fallthrough;
 
 	case 3:		/* Phase 3 - Ready to accept a command */
@@ -734,21 +743,22 @@ static int ppa_engine(ppa_struct *dev, struct scsi_cmnd *cmd)
 
 		if (!ppa_send_command(cmd))
 			return 0;
-		cmd->SCp.phase++;
+		scsi_pointer->phase++;
 		fallthrough;
 
 	case 4:		/* Phase 4 - Setup scatter/gather buffers */
 		if (scsi_bufflen(cmd)) {
-			cmd->SCp.buffer = scsi_sglist(cmd);
-			cmd->SCp.this_residual = cmd->SCp.buffer->length;
-			cmd->SCp.ptr = sg_virt(cmd->SCp.buffer);
+			scsi_pointer->buffer = scsi_sglist(cmd);
+			scsi_pointer->this_residual =
+				scsi_pointer->buffer->length;
+			scsi_pointer->ptr = sg_virt(scsi_pointer->buffer);
 		} else {
-			cmd->SCp.buffer = NULL;
-			cmd->SCp.this_residual = 0;
-			cmd->SCp.ptr = NULL;
+			scsi_pointer->buffer = NULL;
+			scsi_pointer->this_residual = 0;
+			scsi_pointer->ptr = NULL;
 		}
-		cmd->SCp.buffers_residual = scsi_sg_count(cmd) - 1;
-		cmd->SCp.phase++;
+		scsi_pointer->buffers_residual = scsi_sg_count(cmd) - 1;
+		scsi_pointer->phase++;
 		fallthrough;
 
 	case 5:		/* Phase 5 - Data transfer stage */
@@ -761,7 +771,7 @@ static int ppa_engine(ppa_struct *dev, struct scsi_cmnd *cmd)
 			return 0;
 		if (retv == 0)
 			return 1;
-		cmd->SCp.phase++;
+		scsi_pointer->phase++;
 		fallthrough;
 
 	case 6:		/* Phase 6 - Read status/message */
@@ -798,7 +808,7 @@ static int ppa_queuecommand_lck(struct scsi_cmnd *cmd)
 	dev->jstart = jiffies;
 	dev->cur_cmd = cmd;
 	cmd->result = DID_ERROR << 16;	/* default return code */
-	cmd->SCp.phase = 0;	/* bus free */
+	ppa_scsi_pointer(cmd)->phase = 0;	/* bus free */
 
 	schedule_delayed_work(&dev->ppa_tq, 0);
 
@@ -839,7 +849,7 @@ static int ppa_abort(struct scsi_cmnd *cmd)
 	 * have tied the SCSI_MESSAGE line high in the interface
 	 */
 
-	switch (cmd->SCp.phase) {
+	switch (ppa_scsi_pointer(cmd)->phase) {
 	case 0:		/* Do not have access to parport */
 	case 1:		/* Have not connected to interface */
 		dev->cur_cmd = NULL;	/* Forget the problem */
@@ -861,7 +871,7 @@ static int ppa_reset(struct scsi_cmnd *cmd)
 {
 	ppa_struct *dev = ppa_dev(cmd->device->host);
 
-	if (cmd->SCp.phase)
+	if (ppa_scsi_pointer(cmd)->phase)
 		ppa_disconnect(dev);
 	dev->cur_cmd = NULL;	/* Forget the problem */
 
@@ -976,6 +986,7 @@ static struct scsi_host_template ppa_template = {
 	.sg_tablesize		= SG_ALL,
 	.can_queue		= 1,
 	.slave_alloc		= ppa_adjust_queue,
+	.cmd_size		= sizeof(struct scsi_pointer),
 };
 
 /***************************************************************************