Re: [PATCH v3 26/48] scsi: iscsi: Stop using the SCSI pointer

Lee Duncan
2022-02-13T22:14:07Z

On 2/11/22 14:32, Bart Van Assche wrote:
> 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.
>
> Cc: Lee Duncan <lduncan@suse.com>
> Cc: Chris Leech <cleech@redhat.com>
> Cc: Sagi Grimberg <sagi@grimberg.me>
> Cc: Hannes Reinecke <hare@suse.de>
> Cc: Himanshu Madhani <himanshu.madhani@oracle.com>
> 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,
>

Reviewed-by: Lee Duncan <lduncan@suse.com>