[SCSI] libsas: Handle SCSI commands that complete with failure codes

This patch moves the code that handles SAS failures out of the main EH
function and into a separate function.  It also detects commands that have
no sas_task (i.e. they completed, but with error data) and sends them into
scsi_error for processing.  This allows us to handle SCSI errors (and
enables auto-spinup as a side effect) instead of dropping them on the
floor and falling into an infinite loop.  It also requires the
implementation of a device reset function, which the SAS failure code has
been modified to employ for REQ_DEVICE_RESET.

Signed-off-by: Darrick J. Wong <djwong@us.ibm.com>
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>

2 files changed, 105 insertions, 44 deletions

diff --git a/drivers/scsi/libsas/sas_scsi_host.c b/drivers/scsi/libsas/sas_scsi_host.c
index 9ffe7605fb9d..eac1d2dde743 100644
--- a/drivers/scsi/libsas/sas_scsi_host.c
+++ b/drivers/scsi/libsas/sas_scsi_host.c
@@ -34,6 +34,7 @@
 #include <scsi/scsi_transport_sas.h>
 #include "../scsi_sas_internal.h"
 #include "../scsi_transport_api.h"
+#include "../scsi_priv.h"
 
 #include <linux/err.h>
 #include <linux/blkdev.h>
@@ -396,54 +397,80 @@ static int sas_recover_I_T(struct domain_device *dev)
         return res;
 }
 
-static int eh_reset_phy_helper(struct sas_phy *phy)
+/* Find the sas_phy that's attached to this device */
+struct sas_phy *find_local_sas_phy(struct domain_device *dev)
 {
-        int tmf_resp;
+        struct domain_device *pdev = dev->parent;
+        struct ex_phy *exphy = NULL;
+        int i;
+
+        /* Directly attached device */
+        if (!pdev)
+                return dev->port->phy;
 
-        tmf_resp = sas_phy_reset(phy, 1);
-        if (tmf_resp)
-                SAS_DPRINTK("Hard reset of phy %d failed 0x%x\n",
-                            phy->identify.phy_identifier,
-                            tmf_resp);
+        /* Otherwise look in the expander */
+        for (i = 0; i < pdev->ex_dev.num_phys; i++)
+                if (!memcmp(dev->sas_addr,
+                            pdev->ex_dev.ex_phy[i].attached_sas_addr,
+                            SAS_ADDR_SIZE)) {
+                        exphy = &pdev->ex_dev.ex_phy[i];
+                        break;
+                }
 
-        return tmf_resp;
+        BUG_ON(!exphy);
+        return exphy->phy;
 }
 
-void sas_scsi_recover_host(struct Scsi_Host *shost)
+/* Attempt to send a target reset message to a device */
+int sas_eh_device_reset_handler(struct scsi_cmnd *cmd)
+{
+        struct domain_device *dev = cmd_to_domain_dev(cmd);
+        struct sas_phy *phy = find_local_sas_phy(dev);
+        int res;
+
+        res = sas_phy_reset(phy, 1);
+        if (res)
+                SAS_DPRINTK("Device reset of %s failed 0x%x\n",
+                            phy->dev.kobj.k_name,
+                            res);
+        if (res == TMF_RESP_FUNC_SUCC || res == TMF_RESP_FUNC_COMPLETE)
+                return SUCCESS;
+
+        return FAILED;
+}
+
+/* Try to reset a device */
+static int try_to_reset_cmd_device(struct Scsi_Host *shost,
+                                   struct scsi_cmnd *cmd)
+{
+        if (!shost->hostt->eh_device_reset_handler)
+                return FAILED;
+
+        return shost->hostt->eh_device_reset_handler(cmd);
+}
+
+static int sas_eh_handle_sas_errors(struct Scsi_Host *shost,
+                                    struct list_head *work_q,
+                                    struct list_head *done_q)
 {
-        struct sas_ha_struct *ha = SHOST_TO_SAS_HA(shost);
-        unsigned long flags;
-        LIST_HEAD(error_q);
         struct scsi_cmnd *cmd, *n;
         enum task_disposition res = TASK_IS_DONE;
         int tmf_resp, need_reset;
         struct sas_internal *i = to_sas_internal(shost->transportt);
-        struct sas_phy *task_sas_phy = NULL;
-
-        spin_lock_irqsave(shost->host_lock, flags);
-        list_splice_init(&shost->eh_cmd_q, &error_q);
-        spin_unlock_irqrestore(shost->host_lock, flags);
-
-        SAS_DPRINTK("Enter %s\n", __FUNCTION__);
+        unsigned long flags;
+        struct sas_ha_struct *ha = SHOST_TO_SAS_HA(shost);
 
-        /* All tasks on this list were marked SAS_TASK_STATE_ABORTED
-         * by sas_scsi_timed_out() callback.
-         */
 Again:
-        SAS_DPRINTK("going over list...\n");
-        list_for_each_entry_safe(cmd, n, &error_q, eh_entry) {
+        list_for_each_entry_safe(cmd, n, work_q, eh_entry) {
                 struct sas_task *task = TO_SAS_TASK(cmd);
-                list_del_init(&cmd->eh_entry);
 
-                if (!task) {
-                        SAS_DPRINTK("%s: taskless cmd?!\n", __FUNCTION__);
+                if (!task)
                         continue;
-                }
+
+                list_del_init(&cmd->eh_entry);
 
                 spin_lock_irqsave(&task->task_state_lock, flags);
                 need_reset = task->task_state_flags & SAS_TASK_NEED_DEV_RESET;
-                if (need_reset)
-                        task_sas_phy = task->dev->port->phy;
                 spin_unlock_irqrestore(&task->task_state_lock, flags);
 
                 SAS_DPRINTK("trying to find task 0x%p\n", task);
@@ -457,14 +484,14 @@ Again:
                                     task);
                         task->task_done(task);
                         if (need_reset)
-                                eh_reset_phy_helper(task_sas_phy);
+                                try_to_reset_cmd_device(shost, cmd);
                         continue;
                 case TASK_IS_ABORTED:
                         SAS_DPRINTK("%s: task 0x%p is aborted\n",
                                     __FUNCTION__, task);
                         task->task_done(task);
                         if (need_reset)
-                                eh_reset_phy_helper(task_sas_phy);
+                                try_to_reset_cmd_device(shost, cmd);
                         continue;
                 case TASK_IS_AT_LU:
                         SAS_DPRINTK("task 0x%p is at LU: lu recover\n", task);
@@ -476,8 +503,8 @@ Again:
                                             cmd->device->lun);
                                 task->task_done(task);
                                 if (need_reset)
-                                        eh_reset_phy_helper(task_sas_phy);
-                                sas_scsi_clear_queue_lu(&error_q, cmd);
+                                        try_to_reset_cmd_device(shost, cmd);
+                                sas_scsi_clear_queue_lu(work_q, cmd);
                                 goto Again;
                         }
                         /* fallthrough */
@@ -491,8 +518,8 @@ Again:
                                             SAS_ADDR(task->dev->sas_addr));
                                 task->task_done(task);
                                 if (need_reset)
-                                        eh_reset_phy_helper(task_sas_phy);
-                                sas_scsi_clear_queue_I_T(&error_q, task->dev);
+                                        try_to_reset_cmd_device(shost, cmd);
+                                sas_scsi_clear_queue_I_T(work_q, task->dev);
                                 goto Again;
                         }
                         /* Hammer time :-) */
@@ -506,8 +533,8 @@ Again:
                                                     "succeeded\n", port->id);
                                         task->task_done(task);
                                         if (need_reset)
-                                                eh_reset_phy_helper(task_sas_phy);
-                                        sas_scsi_clear_queue_port(&error_q,
+                                                try_to_reset_cmd_device(shost, cmd);
+                                        sas_scsi_clear_queue_port(work_q,
                                                                   port);
                                         goto Again;
                                 }
@@ -520,7 +547,7 @@ Again:
                                                     "succeeded\n");
                                         task->task_done(task);
                                         if (need_reset)
-                                                eh_reset_phy_helper(task_sas_phy);
+                                                try_to_reset_cmd_device(shost, cmd);
                                         goto out;
                                 }
                         }
@@ -535,21 +562,53 @@ Again:
 
                         task->task_done(task);
                         if (need_reset)
-                                eh_reset_phy_helper(task_sas_phy);
+                                try_to_reset_cmd_device(shost, cmd);
                         goto clear_q;
                 }
         }
 out:
-        scsi_eh_flush_done_q(&ha->eh_done_q);
-        SAS_DPRINTK("--- Exit %s\n", __FUNCTION__);
-        return;
+        return list_empty(work_q);
 clear_q:
         SAS_DPRINTK("--- Exit %s -- clear_q\n", __FUNCTION__);
-        list_for_each_entry_safe(cmd, n, &error_q, eh_entry) {
+        list_for_each_entry_safe(cmd, n, work_q, eh_entry) {
                 struct sas_task *task = TO_SAS_TASK(cmd);
                 list_del_init(&cmd->eh_entry);
                 task->task_done(task);
         }
+        return list_empty(work_q);
+}
+
+void sas_scsi_recover_host(struct Scsi_Host *shost)
+{
+        struct sas_ha_struct *ha = SHOST_TO_SAS_HA(shost);
+        unsigned long flags;
+        LIST_HEAD(eh_work_q);
+
+        spin_lock_irqsave(shost->host_lock, flags);
+        list_splice_init(&shost->eh_cmd_q, &eh_work_q);
+        spin_unlock_irqrestore(shost->host_lock, flags);
+
+        SAS_DPRINTK("Enter %s\n", __FUNCTION__);
+        /*
+         * Deal with commands that still have SAS tasks (i.e. they didn't
+         * complete via the normal sas_task completion mechanism)
+         */
+        if (sas_eh_handle_sas_errors(shost, &eh_work_q, &ha->eh_done_q))
+                goto out;
+
+        /*
+         * Now deal with SCSI commands that completed ok but have a an error
+         * code (and hopefully sense data) attached.  This is roughly what
+         * scsi_unjam_host does, but we skip scsi_eh_abort_cmds because any
+         * command we see here has no sas_task and is thus unknown to the HA.
+         */
+        if (!scsi_eh_get_sense(&eh_work_q, &ha->eh_done_q))
+                scsi_eh_ready_devs(shost, &eh_work_q, &ha->eh_done_q);
+
+out:
+        scsi_eh_flush_done_q(&ha->eh_done_q);
+        SAS_DPRINTK("--- Exit %s\n", __FUNCTION__);
+        return;
 }
 
 enum scsi_eh_timer_return sas_scsi_timed_out(struct scsi_cmnd *cmd)
@@ -914,3 +973,4 @@ EXPORT_SYMBOL_GPL(__sas_task_abort);
 EXPORT_SYMBOL_GPL(sas_task_abort);
 EXPORT_SYMBOL_GPL(sas_phy_reset);
 EXPORT_SYMBOL_GPL(sas_phy_enable);
+EXPORT_SYMBOL_GPL(sas_eh_device_reset_handler);
diff --git a/include/scsi/libsas.h b/include/scsi/libsas.h
index ca393929c10b..b200233cc6f4 100644
--- a/include/scsi/libsas.h
+++ b/include/scsi/libsas.h
@@ -660,5 +660,6 @@ void sas_init_dev(struct domain_device *);
 
 void sas_task_abort(struct sas_task *);
 int __sas_task_abort(struct sas_task *);
+int sas_eh_device_reset_handler(struct scsi_cmnd *cmd);
 
 #endif /* _SASLIB_H_ */