[PATCH v4 26/50] scsi: iscsi: Stop using the SCSI pointer

Bart Van Assche
2022-02-16T21:04:08Z

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
---
drivers/infiniband/ulp/iser/iscsi_iser.c | 1 +
drivers/scsi/be2iscsi/be_main.c | 3 ++-
drivers/scsi/bnx2i/bnx2i_iscsi.c | 1 +
drivers/scsi/cxgbi/cxgb3i/cxgb3i.c | 1 +
drivers/scsi/cxgbi/cxgb4i/cxgb4i.c | 1 +
drivers/scsi/iscsi_tcp.c | 1 +
drivers/scsi/libiscsi.c | 20 ++++++++++----------
drivers/scsi/qedi/qedi_fw.c | 4 ++--
drivers/scsi/qedi/qedi_iscsi.c | 1 +
drivers/scsi/qla4xxx/ql4_def.h | 16 +++++++++++++---
drivers/scsi/qla4xxx/ql4_os.c | 13 +++++++------
include/scsi/libiscsi.h | 12 ++++++++++++
12 files changed, 52 insertions(+), 22 deletions(-)

diff --git a/drivers/infiniband/ulp/iser/iscsi_iser.c b/drivers/infiniband/ulp/iser/iscsi_iser.c
index 07e47021a71f..f8d0bab4424c 100644
--- a/drivers/infiniband/ulp/iser/iscsi_iser.c
+++ b/drivers/infiniband/ulp/iser/iscsi_iser.c
@@ -971,6 +971,7 @@ static struct scsi_host_template iscsi_iser_sht = {
.proc_name = "iscsi_iser",
.this_id = -1,
.track_queue_depth = 1,
+ .cmd_size = sizeof(struct iscsi_cmd),
};

static struct iscsi_transport iscsi_iser_transport = {
diff --git a/drivers/scsi/be2iscsi/be_main.c b/drivers/scsi/be2iscsi/be_main.c
index ab55681145f8..3bb0adefbe06 100644
--- a/drivers/scsi/be2iscsi/be_main.c
+++ b/drivers/scsi/be2iscsi/be_main.c
@@ -218,7 +218,7 @@ static char const *cqe_desc[] = {

static int beiscsi_eh_abort(struct scsi_cmnd *sc)
{
- struct iscsi_task *abrt_task = (struct iscsi_task *)sc->SCp.ptr;
+ struct iscsi_task *abrt_task = iscsi_cmd(sc)->task;
struct iscsi_cls_session *cls_session;
struct beiscsi_io_task *abrt_io_task;
struct beiscsi_conn *beiscsi_conn;
@@ -403,6 +403,7 @@ static struct scsi_host_template beiscsi_sht = {
.cmd_per_lun = BEISCSI_CMD_PER_LUN,
.vendor_id = SCSI_NL_VID_TYPE_PCI | BE_VENDOR_ID,
.track_queue_depth = 1,
+ .cmd_size = sizeof(struct iscsi_cmd),
};

static struct scsi_transport_template *beiscsi_scsi_transport;
diff --git a/drivers/scsi/bnx2i/bnx2i_iscsi.c b/drivers/scsi/bnx2i/bnx2i_iscsi.c
index e21b053b4f3e..fe86fd61a995 100644
--- a/drivers/scsi/bnx2i/bnx2i_iscsi.c
+++ b/drivers/scsi/bnx2i/bnx2i_iscsi.c
@@ -2268,6 +2268,7 @@ static struct scsi_host_template bnx2i_host_template = {
.sg_tablesize = ISCSI_MAX_BDS_PER_CMD,
.shost_groups = bnx2i_dev_groups,
.track_queue_depth = 1,
+ .cmd_size = sizeof(struct iscsi_cmd),
};

struct iscsi_transport bnx2i_iscsi_transport = {
diff --git a/drivers/scsi/cxgbi/cxgb3i/cxgb3i.c b/drivers/scsi/cxgbi/cxgb3i/cxgb3i.c
index f949a4e00783..ff9d4287937a 100644
--- a/drivers/scsi/cxgbi/cxgb3i/cxgb3i.c
+++ b/drivers/scsi/cxgbi/cxgb3i/cxgb3i.c
@@ -98,6 +98,7 @@ static struct scsi_host_template cxgb3i_host_template = {
.dma_boundary = PAGE_SIZE - 1,
.this_id = -1,
.track_queue_depth = 1,
+ .cmd_size = sizeof(struct iscsi_cmd),
};

static struct iscsi_transport cxgb3i_iscsi_transport = {
diff --git a/drivers/scsi/cxgbi/cxgb4i/cxgb4i.c b/drivers/scsi/cxgbi/cxgb4i/cxgb4i.c
index efb3e2b3398e..53d91bf9c12a 100644
--- a/drivers/scsi/cxgbi/cxgb4i/cxgb4i.c
+++ b/drivers/scsi/cxgbi/cxgb4i/cxgb4i.c
@@ -116,6 +116,7 @@ static struct scsi_host_template cxgb4i_host_template = {
.dma_boundary = PAGE_SIZE - 1,
.this_id = -1,
.track_queue_depth = 1,
+ .cmd_size = sizeof(struct iscsi_cmd),
};

static struct iscsi_transport cxgb4i_iscsi_transport = {
diff --git a/drivers/scsi/iscsi_tcp.c b/drivers/scsi/iscsi_tcp.c
index 1bc37593c88f..9fee70d6434a 100644
--- a/drivers/scsi/iscsi_tcp.c
+++ b/drivers/scsi/iscsi_tcp.c
@@ -1007,6 +1007,7 @@ static struct scsi_host_template iscsi_sw_tcp_sht = {
.proc_name = "iscsi_tcp",
.this_id = -1,
.track_queue_depth = 1,
+ .cmd_size = sizeof(struct iscsi_cmd),
};

static struct iscsi_transport iscsi_sw_tcp_transport = {
diff --git a/drivers/scsi/libiscsi.c b/drivers/scsi/libiscsi.c
index 059dae8909ee..d69203d19f2c 100644
--- a/drivers/scsi/libiscsi.c
+++ b/drivers/scsi/libiscsi.c
@@ -462,7 +462,7 @@ static void iscsi_free_task(struct iscsi_task *task)

if (sc) {
/* SCSI eh reuses commands to verify us */
- sc->SCp.ptr = NULL;
+ iscsi_cmd(sc)->task = NULL;
/*
* queue command may call this to free the task, so
* it will decide how to return sc to scsi-ml.
@@ -1344,10 +1344,10 @@ struct iscsi_task *iscsi_itt_to_ctask(struct iscsi_conn *conn, itt_t itt)
if (!task || !task->sc)
return NULL;

- if (task->sc->SCp.phase != conn->session->age) {
+ if (iscsi_cmd(task->sc)->age != conn->session->age) {
iscsi_session_printk(KERN_ERR, conn->session,
"task's session age %d, expected %d\n",
- task->sc->SCp.phase, conn->session->age);
+ iscsi_cmd(task->sc)->age, conn->session->age);
return NULL;
}

@@ -1645,8 +1645,8 @@ static inline struct iscsi_task *iscsi_alloc_task(struct iscsi_conn *conn,
(void *) &task, sizeof(void *)))
return NULL;

- sc->SCp.phase = conn->session->age;
- sc->SCp.ptr = (char *) task;
+ iscsi_cmd(sc)->age = conn->session->age;
+ iscsi_cmd(sc)->task = task;

refcount_set(&task->refcount, 1);
task->state = ISCSI_TASK_PENDING;
@@ -1683,7 +1683,7 @@ int iscsi_queuecommand(struct Scsi_Host *host, struct scsi_cmnd *sc)
struct iscsi_task *task = NULL;

sc->result = 0;
- sc->SCp.ptr = NULL;
+ iscsi_cmd(sc)->task = NULL;

ihost = shost_priv(host);

@@ -1997,7 +1997,7 @@ enum blk_eh_timer_return iscsi_eh_cmd_timed_out(struct scsi_cmnd *sc)

spin_lock_bh(&session->frwd_lock);
spin_lock(&session->back_lock);
- task = (struct iscsi_task *)sc->SCp.ptr;
+ task = iscsi_cmd(sc)->task;
if (!task) {
/*
* Raced with completion. Blk layer has taken ownership
@@ -2260,7 +2260,7 @@ int iscsi_eh_abort(struct scsi_cmnd *sc)
* if session was ISCSI_STATE_IN_RECOVERY then we may not have
* got the command.
*/
- if (!sc->SCp.ptr) {
+ if (!iscsi_cmd(sc)->task) {
ISCSI_DBG_EH(session, "sc never reached iscsi layer or "
"it completed.\n");
spin_unlock_bh(&session->frwd_lock);
@@ -2273,7 +2273,7 @@ int iscsi_eh_abort(struct scsi_cmnd *sc)
* then let the host reset code handle this
*/
if (!session->leadconn || session->state != ISCSI_STATE_LOGGED_IN ||
- sc->SCp.phase != session->age) {
+ iscsi_cmd(sc)->age != session->age) {
spin_unlock_bh(&session->frwd_lock);
mutex_unlock(&session->eh_mutex);
ISCSI_DBG_EH(session, "failing abort due to dropped "
@@ -2282,7 +2282,7 @@ int iscsi_eh_abort(struct scsi_cmnd *sc)
}

spin_lock(&session->back_lock);
- task = (struct iscsi_task *)sc->SCp.ptr;
+ task = iscsi_cmd(sc)->task;
if (!task || !task->sc) {
/* task completed before time out */
ISCSI_DBG_EH(session, "sc completed while abort in progress\n");
diff --git a/drivers/scsi/qedi/qedi_fw.c b/drivers/scsi/qedi/qedi_fw.c
index 5916ed7662d5..4e99508ff95d 100644
--- a/drivers/scsi/qedi/qedi_fw.c
+++ b/drivers/scsi/qedi/qedi_fw.c
@@ -603,9 +603,9 @@ static void qedi_scsi_completion(struct qedi_ctx *qedi,
goto error;
}

- if (!sc_cmd->SCp.ptr) {
+ if (!iscsi_cmd(sc_cmd)->task) {
QEDI_WARN(&qedi->dbg_ctx,
- "SCp.ptr is NULL, returned in another context.\n");
+ "NULL task pointer, returned in another context.\n");
goto error;
}

diff --git a/drivers/scsi/qedi/qedi_iscsi.c b/drivers/scsi/qedi/qedi_iscsi.c
index 282ecb4e39bb..8196f89f404e 100644
--- a/drivers/scsi/qedi/qedi_iscsi.c
+++ b/drivers/scsi/qedi/qedi_iscsi.c
@@ -59,6 +59,7 @@ struct scsi_host_template qedi_host_template = {
.dma_boundary = QEDI_HW_DMA_BOUNDARY,
.cmd_per_lun = 128,
.shost_groups = qedi_shost_groups,
+ .cmd_size = sizeof(struct iscsi_cmd),
};

static void qedi_conn_free_login_resources(struct qedi_ctx *qedi,
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",
diff --git a/include/scsi/libiscsi.h b/include/scsi/libiscsi.h
index 4ee233e5a6ff..cb805ed9cbf1 100644
--- a/include/scsi/libiscsi.h
+++ b/include/scsi/libiscsi.h
@@ -19,6 +19,7 @@
#include <linux/refcount.h>
#include <scsi/iscsi_proto.h>
#include <scsi/iscsi_if.h>
+#include <scsi/scsi_cmnd.h>
#include <scsi/scsi_transport_iscsi.h>

struct scsi_transport_template;
@@ -152,6 +153,17 @@ static inline bool iscsi_task_is_completed(struct iscsi_task *task)
task->state == ISCSI_TASK_ABRT_SESS_RECOV;
}

+/* Private data associated with struct scsi_cmnd. */
+struct iscsi_cmd {
+ struct iscsi_task *task;
+ int age;
+};
+
+static inline struct iscsi_cmd *iscsi_cmd(struct scsi_cmnd *cmd)
+{
+ return scsi_cmd_priv(cmd);
+}
+
/* Connection's states */
enum {
ISCSI_CONN_INITIAL_STAGE,