scsi: iscsi: Stop using the SCSI pointer

Instead of storing the iSCSI task pointer and the session age in the SCSI
pointer, use command-private variables. This patch prepares for removal of
the SCSI pointer from struct scsi_cmnd.

The list of iSCSI drivers has been obtained as follows:
$ git grep -lw iscsi_host_alloc
drivers/infiniband/ulp/iser/iscsi_iser.c
drivers/scsi/be2iscsi/be_main.c
drivers/scsi/bnx2i/bnx2i_iscsi.c
drivers/scsi/cxgbi/libcxgbi.c
drivers/scsi/iscsi_tcp.c
drivers/scsi/libiscsi.c
drivers/scsi/qedi/qedi_main.c
drivers/scsi/qla4xxx/ql4_os.c
include/scsi/libiscsi.h

Note: it is not clear to me how the qla4xxx driver can work without this
patch since it uses the scsi_cmnd::SCp.ptr member for two different
purposes:
- The qla4xxx driver uses this member to store a struct srb pointer.
- libiscsi uses this member to store a struct iscsi_task pointer.

Reviewed-by: Lee Duncan <lduncan@suse.com>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Himanshu Madhani <himanshu.madhani@oracle.com>
Cc: Chris Leech <cleech@redhat.com>
Cc: Sagi Grimberg <sagi@grimberg.me>
Cc: Nilesh Javali <njavali@marvell.com>
Cc: Manish Rangankar <mrangankar@marvell.com>
Cc: Karen Xie <kxie@chelsio.com>
Cc: Ketan Mukadam <ketan.mukadam@broadcom.com>
Signed-off-by: Bart Van Assche <bvanassche@acm.org>

iscsi

Link: https://lore.kernel.org/r/20220218195117.25689-26-bvanassche@acm.org
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

2 files changed, 20 insertions, 9 deletions

diff --git a/drivers/scsi/qla4xxx/ql4_def.h b/drivers/scsi/qla4xxx/ql4_def.h
index 69a590546bf9..5f82c8afd5e0 100644
--- a/drivers/scsi/qla4xxx/ql4_def.h
+++ b/drivers/scsi/qla4xxx/ql4_def.h
@@ -216,11 +216,21 @@
 #define IDC_COMP_TOV			5
 #define LINK_UP_COMP_TOV		30
 
-#define CMD_SP(Cmnd)			((Cmnd)->SCp.ptr)
+/*
+ * Note: the data structure below does not have a struct iscsi_cmd member since
+ * the qla4xxx driver does not use libiscsi for SCSI I/O.
+ */
+struct qla4xxx_cmd_priv {
+	struct srb *srb;
+};
+
+static inline struct qla4xxx_cmd_priv *qla4xxx_cmd_priv(struct scsi_cmnd *cmd)
+{
+	return scsi_cmd_priv(cmd);
+}
 
 /*
- * SCSI Request Block structure	 (srb)	that is placed
- * on cmd->SCp location of every I/O	 [We have 22 bytes available]
+ * SCSI Request Block structure (srb) that is associated with each scsi_cmnd.
  */
 struct srb {
 	struct list_head list;	/* (8)	 */
diff --git a/drivers/scsi/qla4xxx/ql4_os.c b/drivers/scsi/qla4xxx/ql4_os.c
index 0ae936d839f1..d64eda961412 100644
--- a/drivers/scsi/qla4xxx/ql4_os.c
+++ b/drivers/scsi/qla4xxx/ql4_os.c
@@ -226,6 +226,7 @@ static struct scsi_host_template qla4xxx_driver_template = {
 	.name			= DRIVER_NAME,
 	.proc_name		= DRIVER_NAME,
 	.queuecommand		= qla4xxx_queuecommand,
+	.cmd_size		= sizeof(struct qla4xxx_cmd_priv),
 
 	.eh_abort_handler	= qla4xxx_eh_abort,
 	.eh_device_reset_handler = qla4xxx_eh_device_reset,
@@ -4054,7 +4055,7 @@ static struct srb* qla4xxx_get_new_srb(struct scsi_qla_host *ha,
 	srb->ddb = ddb_entry;
 	srb->cmd = cmd;
 	srb->flags = 0;
-	CMD_SP(cmd) = (void *)srb;
+	qla4xxx_cmd_priv(cmd)->srb = srb;
 
 	return srb;
 }
@@ -4067,7 +4068,7 @@ static void qla4xxx_srb_free_dma(struct scsi_qla_host *ha, struct srb *srb)
 		scsi_dma_unmap(cmd);
 		srb->flags &= ~SRB_DMA_VALID;
 	}
-	CMD_SP(cmd) = NULL;
+	qla4xxx_cmd_priv(cmd)->srb = NULL;
 }
 
 void qla4xxx_srb_compl(struct kref *ref)
@@ -4640,7 +4641,7 @@ static int qla4xxx_cmd_wait(struct scsi_qla_host *ha)
 			 * the scsi/block layer is going to prevent
 			 * the tag from being released.
 			 */
-			if (cmd != NULL && CMD_SP(cmd))
+			if (cmd != NULL && qla4xxx_cmd_priv(cmd)->srb)
 				break;
 		}
 		spin_unlock_irqrestore(&ha->hardware_lock, flags);
@@ -9079,7 +9080,7 @@ struct srb *qla4xxx_del_from_active_array(struct scsi_qla_host *ha,
 	if (!cmd)
 		return srb;
 
-	srb = (struct srb *)CMD_SP(cmd);
+	srb = qla4xxx_cmd_priv(cmd)->srb;
 	if (!srb)
 		return srb;
 
@@ -9121,7 +9122,7 @@ static int qla4xxx_eh_wait_on_command(struct scsi_qla_host *ha,
 
 	do {
 		/* Checking to see if its returned to OS */
-		rp = (struct srb *) CMD_SP(cmd);
+		rp = qla4xxx_cmd_priv(cmd)->srb;
 		if (rp == NULL) {
 			done++;
 			break;
@@ -9215,7 +9216,7 @@ static int qla4xxx_eh_abort(struct scsi_cmnd *cmd)
 	}
 
 	spin_lock_irqsave(&ha->hardware_lock, flags);
-	srb = (struct srb *) CMD_SP(cmd);
+	srb = qla4xxx_cmd_priv(cmd)->srb;
 	if (!srb) {
 		spin_unlock_irqrestore(&ha->hardware_lock, flags);
 		ql4_printk(KERN_INFO, ha, "scsi%ld:%d:%llu: Specified command has already completed.\n",