scsi: qla2xxx: Add IOCB resource tracking

This patch tracks number of IOCB resources used in the I/O fast path. If
the number of used IOCBs reach a high water limit, driver would return the
I/O as busy and let upper layer retry. This prevents over subscription of
IOCB resources where any future error recovery command is unable to cut
through.  Enable IOCB throttling by default.

Link: https://lore.kernel.org/r/20200904045128.23631-12-njavali@marvell.com
Reviewed-by: Himanshu Madhani <himanshu.madhani@oracle.com>
Signed-off-by: Quinn Tran <qutran@marvell.com>
Signed-off-by: Arun Easi <aeasi@marvell.com>
Signed-off-by: Nilesh Javali <njavali@marvell.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

diff --git a/drivers/scsi/qla2xxx/qla_def.h b/drivers/scsi/qla2xxx/qla_def.h
index 234cc33..817234d 100644 (file)
--- a/drivers/scsi/qla2xxx/qla_def.h
+++ b/drivers/scsi/qla2xxx/qla_def.h
@@ -624,6 +624,12 @@ enum {
        TYPE_TGT_TMCMD,         /* task management */
 };
 
+struct iocb_resource {
+       u8 res_type;
+       u8 pad;
+       u16 iocb_cnt;
+};
+
 typedef struct srb {
        /*
         * Do not move cmd_type field, it needs to
@@ -631,6 +637,7 @@ typedef struct srb {
         */
        uint8_t cmd_type;
        uint8_t pad[3];
+       struct iocb_resource iores;
        struct kref cmd_kref;   /* need to migrate ref_count over to this */
        void *priv;
        wait_queue_head_t nvme_ls_waitq;
@@ -3577,6 +3584,15 @@ struct req_que {
        uint8_t req_pkt[REQUEST_ENTRY_SIZE];
 };
 
+struct qla_fw_resources {
+       u16 iocbs_total;
+       u16 iocbs_limit;
+       u16 iocbs_qp_limit;
+       u16 iocbs_used;
+};
+
+#define QLA_IOCB_PCT_LIMIT 95
+
 /*Queue pair data structure */
 struct qla_qpair {
        spinlock_t qp_lock;
@@ -3629,6 +3645,7 @@ struct qla_qpair {
        uint64_t retry_term_jiff;
        struct qla_tgt_counters tgt_counters;
        uint16_t cpuid;
+       struct qla_fw_resources fwres ____cacheline_aligned;
 };
 
 /* Place holder for FW buffer parameters */

diff --git a/drivers/scsi/qla2xxx/qla_dfs.c b/drivers/scsi/qla2xxx/qla_dfs.c
index 118f2b2..6f5f18f 100644 (file)
--- a/drivers/scsi/qla2xxx/qla_dfs.c
+++ b/drivers/scsi/qla2xxx/qla_dfs.c
@@ -261,6 +261,8 @@ qla_dfs_fw_resource_cnt_show(struct seq_file *s, void *unused)
        struct scsi_qla_host *vha = s->private;
        uint16_t mb[MAX_IOCB_MB_REG];
        int rc;
+       struct qla_hw_data *ha = vha->hw;
+       u16 iocbs_used, i;
 
        rc = qla24xx_res_count_wait(vha, mb, SIZEOF_IOCB_MB_REG);
        if (rc != QLA_SUCCESS) {
@@ -285,6 +287,18 @@ qla_dfs_fw_resource_cnt_show(struct seq_file *s, void *unused)
                    mb[23]);
        }
 
+       if (ql2xenforce_iocb_limit) {
+               /* lock is not require. It's an estimate. */
+               iocbs_used = ha->base_qpair->fwres.iocbs_used;
+               for (i = 0; i < ha->max_qpairs; i++) {
+                       if (ha->queue_pair_map[i])
+                               iocbs_used += ha->queue_pair_map[i]->fwres.iocbs_used;
+               }
+
+               seq_printf(s, "Driver: estimate iocb used [%d] high water limit [%d]\n",
+                          iocbs_used, ha->base_qpair->fwres.iocbs_limit);
+       }
+
        return 0;
 }
 

diff --git a/drivers/scsi/qla2xxx/qla_gbl.h b/drivers/scsi/qla2xxx/qla_gbl.h
index 3360857..9c4d077 100644 (file)
--- a/drivers/scsi/qla2xxx/qla_gbl.h
+++ b/drivers/scsi/qla2xxx/qla_gbl.h
@@ -129,6 +129,8 @@ int qla2x00_reserve_mgmt_server_loop_id(scsi_qla_host_t *);
 void qla_rscn_replay(fc_port_t *fcport);
 void qla24xx_free_purex_item(struct purex_item *item);
 extern bool qla24xx_risc_firmware_invalid(uint32_t *);
+void qla_init_iocb_limit(scsi_qla_host_t *);
+
 
 /*
  * Global Data in qla_os.c source file.
@@ -175,6 +177,7 @@ extern int qla2xuseresexchforels;
 extern int ql2xexlogins;
 extern int ql2xdifbundlinginternalbuffers;
 extern int ql2xfulldump_on_mpifail;
+extern int ql2xenforce_iocb_limit;
 
 extern int qla2x00_loop_reset(scsi_qla_host_t *);
 extern void qla2x00_abort_all_cmds(scsi_qla_host_t *, int);

diff --git a/drivers/scsi/qla2xxx/qla_init.c b/drivers/scsi/qla2xxx/qla_init.c
index a2914e3..f71f3a1 100644 (file)
--- a/drivers/scsi/qla2xxx/qla_init.c
+++ b/drivers/scsi/qla2xxx/qla_init.c
@@ -3632,6 +3632,31 @@ out:
        return ha->flags.lr_detected;
 }
 
+void qla_init_iocb_limit(scsi_qla_host_t *vha)
+{
+       u16 i, num_qps;
+       u32 limit;
+       struct qla_hw_data *ha = vha->hw;
+
+       num_qps = ha->num_qpairs + 1;
+       limit = (ha->orig_fw_iocb_count * QLA_IOCB_PCT_LIMIT) / 100;
+
+       ha->base_qpair->fwres.iocbs_total = ha->orig_fw_iocb_count;
+       ha->base_qpair->fwres.iocbs_limit = limit;
+       ha->base_qpair->fwres.iocbs_qp_limit = limit / num_qps;
+       ha->base_qpair->fwres.iocbs_used = 0;
+       for (i = 0; i < ha->max_qpairs; i++) {
+               if (ha->queue_pair_map[i])  {
+                       ha->queue_pair_map[i]->fwres.iocbs_total =
+                               ha->orig_fw_iocb_count;
+                       ha->queue_pair_map[i]->fwres.iocbs_limit = limit;
+                       ha->queue_pair_map[i]->fwres.iocbs_qp_limit =
+                               limit / num_qps;
+                       ha->queue_pair_map[i]->fwres.iocbs_used = 0;
+               }
+       }
+}
+
 /**
  * qla2x00_setup_chip() - Load and start RISC firmware.
  * @vha: HA context
@@ -3731,6 +3756,7 @@ enable_82xx_npiv:
                                                    MIN_MULTI_ID_FABRIC - 1;
                                }
                                qla2x00_get_resource_cnts(vha);
+                               qla_init_iocb_limit(vha);
 
                                /*
                                 * Allocate the array of outstanding commands

diff --git a/drivers/scsi/qla2xxx/qla_inline.h b/drivers/scsi/qla2xxx/qla_inline.h
index 5b04da8..c7aae43 100644 (file)
--- a/drivers/scsi/qla2xxx/qla_inline.h
+++ b/drivers/scsi/qla2xxx/qla_inline.h
@@ -378,3 +378,58 @@ qla2xxx_get_fc4_priority(struct scsi_qla_host *vha)
 
        return (data >> 6) & BIT_0 ? FC4_PRIORITY_FCP : FC4_PRIORITY_NVME;
 }
+
+enum {
+       RESOURCE_NONE,
+       RESOURCE_INI,
+};
+
+static inline int
+qla_get_iocbs(struct qla_qpair *qp, struct iocb_resource *iores)
+{
+       u16 iocbs_used, i;
+       struct qla_hw_data *ha = qp->vha->hw;
+
+       if (!ql2xenforce_iocb_limit) {
+               iores->res_type = RESOURCE_NONE;
+               return 0;
+       }
+
+       if ((iores->iocb_cnt + qp->fwres.iocbs_used) < qp->fwres.iocbs_qp_limit) {
+               qp->fwres.iocbs_used += iores->iocb_cnt;
+               return 0;
+       } else {
+               /* no need to acquire qpair lock. It's just rough calculation */
+               iocbs_used = ha->base_qpair->fwres.iocbs_used;
+               for (i = 0; i < ha->max_qpairs; i++) {
+                       if (ha->queue_pair_map[i])
+                               iocbs_used += ha->queue_pair_map[i]->fwres.iocbs_used;
+               }
+
+               if ((iores->iocb_cnt + iocbs_used) < qp->fwres.iocbs_limit) {
+                       qp->fwres.iocbs_used += iores->iocb_cnt;
+                       return 0;
+               } else {
+                       iores->res_type = RESOURCE_NONE;
+                       return -ENOSPC;
+               }
+       }
+}
+
+static inline void
+qla_put_iocbs(struct qla_qpair *qp, struct iocb_resource *iores)
+{
+       switch (iores->res_type) {
+       case RESOURCE_NONE:
+               break;
+       default:
+               if (qp->fwres.iocbs_used >= iores->iocb_cnt) {
+                       qp->fwres.iocbs_used -= iores->iocb_cnt;
+               } else {
+                       // should not happen
+                       qp->fwres.iocbs_used = 0;
+               }
+               break;
+       }
+       iores->res_type = RESOURCE_NONE;
+}

diff --git a/drivers/scsi/qla2xxx/qla_iocb.c b/drivers/scsi/qla2xxx/qla_iocb.c
index d69e16e..b60a332 100644 (file)
--- a/drivers/scsi/qla2xxx/qla_iocb.c
+++ b/drivers/scsi/qla2xxx/qla_iocb.c
@@ -1637,6 +1637,12 @@ qla24xx_start_scsi(srb_t *sp)
 
        tot_dsds = nseg;
        req_cnt = qla24xx_calc_iocbs(vha, tot_dsds);
+
+       sp->iores.res_type = RESOURCE_INI;
+       sp->iores.iocb_cnt = req_cnt;
+       if (qla_get_iocbs(sp->qpair, &sp->iores))
+               goto queuing_error;
+
        if (req->cnt < (req_cnt + 2)) {
                cnt = IS_SHADOW_REG_CAPABLE(ha) ? *req->out_ptr :
                    rd_reg_dword_relaxed(req->req_q_out);
@@ -1709,6 +1715,7 @@ queuing_error:
        if (tot_dsds)
                scsi_dma_unmap(cmd);
 
+       qla_put_iocbs(sp->qpair, &sp->iores);
        spin_unlock_irqrestore(&ha->hardware_lock, flags);
 
        return QLA_FUNCTION_FAILED;
@@ -1822,6 +1829,12 @@ qla24xx_dif_start_scsi(srb_t *sp)
        /* Total Data and protection sg segment(s) */
        tot_prot_dsds = nseg;
        tot_dsds += nseg;
+
+       sp->iores.res_type = RESOURCE_INI;
+       sp->iores.iocb_cnt = qla24xx_calc_iocbs(vha, tot_dsds);
+       if (qla_get_iocbs(sp->qpair, &sp->iores))
+               goto queuing_error;
+
        if (req->cnt < (req_cnt + 2)) {
                cnt = IS_SHADOW_REG_CAPABLE(ha) ? *req->out_ptr :
                    rd_reg_dword_relaxed(req->req_q_out);
@@ -1896,6 +1909,7 @@ queuing_error:
        }
        /* Cleanup will be performed by the caller (queuecommand) */
 
+       qla_put_iocbs(sp->qpair, &sp->iores);
        spin_unlock_irqrestore(&ha->hardware_lock, flags);
        return QLA_FUNCTION_FAILED;
 }
@@ -1957,6 +1971,12 @@ qla2xxx_start_scsi_mq(srb_t *sp)
 
        tot_dsds = nseg;
        req_cnt = qla24xx_calc_iocbs(vha, tot_dsds);
+
+       sp->iores.res_type = RESOURCE_INI;
+       sp->iores.iocb_cnt = req_cnt;
+       if (qla_get_iocbs(sp->qpair, &sp->iores))
+               goto queuing_error;
+
        if (req->cnt < (req_cnt + 2)) {
                cnt = IS_SHADOW_REG_CAPABLE(ha) ? *req->out_ptr :
                    rd_reg_dword_relaxed(req->req_q_out);
@@ -2029,6 +2049,7 @@ queuing_error:
        if (tot_dsds)
                scsi_dma_unmap(cmd);
 
+       qla_put_iocbs(sp->qpair, &sp->iores);
        spin_unlock_irqrestore(&qpair->qp_lock, flags);
 
        return QLA_FUNCTION_FAILED;
@@ -2157,6 +2178,12 @@ qla2xxx_dif_start_scsi_mq(srb_t *sp)
        /* Total Data and protection sg segment(s) */
        tot_prot_dsds = nseg;
        tot_dsds += nseg;
+
+       sp->iores.res_type = RESOURCE_INI;
+       sp->iores.iocb_cnt = qla24xx_calc_iocbs(vha, tot_dsds);
+       if (qla_get_iocbs(sp->qpair, &sp->iores))
+               goto queuing_error;
+
        if (req->cnt < (req_cnt + 2)) {
                cnt = IS_SHADOW_REG_CAPABLE(ha) ? *req->out_ptr :
                    rd_reg_dword_relaxed(req->req_q_out);
@@ -2234,6 +2261,7 @@ queuing_error:
        }
        /* Cleanup will be performed by the caller (queuecommand) */
 
+       qla_put_iocbs(sp->qpair, &sp->iores);
        spin_unlock_irqrestore(&qpair->qp_lock, flags);
        return QLA_FUNCTION_FAILED;
 }

diff --git a/drivers/scsi/qla2xxx/qla_isr.c b/drivers/scsi/qla2xxx/qla_isr.c
index 4d59d5b..4baa839 100644 (file)
--- a/drivers/scsi/qla2xxx/qla_isr.c
+++ b/drivers/scsi/qla2xxx/qla_isr.c
@@ -2901,6 +2901,7 @@ qla2x00_status_entry(scsi_qla_host_t *vha, struct rsp_que *rsp, void *pkt)
                }
                return;
        }
+       qla_put_iocbs(sp->qpair, &sp->iores);
 
        if (sp->cmd_type != TYPE_SRB) {
                req->outstanding_cmds[handle] = NULL;
@@ -3313,6 +3314,7 @@ qla2x00_error_entry(scsi_qla_host_t *vha, struct rsp_que *rsp, sts_entry_t *pkt)
        default:
                sp = qla2x00_get_sp_from_handle(vha, func, req, pkt);
                if (sp) {
+                       qla_put_iocbs(sp->qpair, &sp->iores);
                        sp->done(sp, res);
                        return 0;
                }

diff --git a/drivers/scsi/qla2xxx/qla_os.c b/drivers/scsi/qla2xxx/qla_os.c
index 78936b5..4a5a5e4 100644 (file)
--- a/drivers/scsi/qla2xxx/qla_os.c
+++ b/drivers/scsi/qla2xxx/qla_os.c
@@ -40,6 +40,11 @@ module_param(ql2xfulldump_on_mpifail, int, S_IRUGO | S_IWUSR);
 MODULE_PARM_DESC(ql2xfulldump_on_mpifail,
                 "Set this to take full dump on MPI hang.");
 
+int ql2xenforce_iocb_limit = 1;
+module_param(ql2xenforce_iocb_limit, int, S_IRUGO | S_IWUSR);
+MODULE_PARM_DESC(ql2xenforce_iocb_limit,
+                "Enforce IOCB throttling, to avoid FW congestion. (default: 0)");
+
 /*
  * CT6 CTX allocation cache
  */
@@ -3316,6 +3321,7 @@ qla2x00_probe_one(struct pci_dev *pdev, const struct pci_device_id *id)
                for (i = 0; i < ha->max_qpairs; i++)
                        qla2xxx_create_qpair(base_vha, 5, 0, startit);
        }
+       qla_init_iocb_limit(base_vha);
 
        if (ha->flags.running_gold_fw)
                goto skip_dpc;