[SCSI] scsi_error: add target reset handler

The problem is that serveral drivers are sending a target reset from the
device reset handler, and if we have multiple devices a target reset gets
sent for each device when only one would be sufficient. And if we do a target
reset it affects all the commands on the target so the device reset handler
code only cleaning up one devices's commands makes programming the driver a
little more difficult than it should be.

This patch adds a target reset handler, which drivers can use to send
a target reset. If successful it cleans up the commands for a devices
accessed through that starget.

Signed-off-by: Mike Christie <michaelc@cs.wisc.edu>
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>

1 files changed, 104 insertions, 18 deletions

diff --git a/drivers/scsi/scsi_error.c b/drivers/scsi/scsi_error.c
index 045a0868fc7b..1221d2ca0c64 100644
--- a/drivers/scsi/scsi_error.c
+++ b/drivers/scsi/scsi_error.c
@@ -524,6 +524,41 @@ static int scsi_try_bus_reset(struct scsi_cmnd *scmd)
         return rtn;
 }
 
+static void __scsi_report_device_reset(struct scsi_device *sdev, void *data)
+{
+        sdev->was_reset = 1;
+        sdev->expecting_cc_ua = 1;
+}
+
+/**
+ * scsi_try_target_reset - Ask host to perform a target reset
+ * @scmd:       SCSI cmd used to send a target reset
+ *
+ * Notes:
+ *    There is no timeout for this operation.  if this operation is
+ *    unreliable for a given host, then the host itself needs to put a
+ *    timer on it, and set the host back to a consistent state prior to
+ *    returning.
+ */
+static int scsi_try_target_reset(struct scsi_cmnd *scmd)
+{
+        unsigned long flags;
+        int rtn;
+
+        if (!scmd->device->host->hostt->eh_target_reset_handler)
+                return FAILED;
+
+        rtn = scmd->device->host->hostt->eh_target_reset_handler(scmd);
+        if (rtn == SUCCESS) {
+                spin_lock_irqsave(scmd->device->host->host_lock, flags);
+                __starget_for_each_device(scsi_target(scmd->device), NULL,
+                                          __scsi_report_device_reset);
+                spin_unlock_irqrestore(scmd->device->host->host_lock, flags);
+        }
+
+        return rtn;
+}
+
 /**
  * scsi_try_bus_device_reset - Ask host to perform a BDR on a dev
  * @scmd:       SCSI cmd used to send BDR
@@ -542,11 +577,8 @@ static int scsi_try_bus_device_reset(struct scsi_cmnd *scmd)
                 return FAILED;
 
         rtn = scmd->device->host->hostt->eh_device_reset_handler(scmd);
-        if (rtn == SUCCESS) {
-                scmd->device->was_reset = 1;
-                scmd->device->expecting_cc_ua = 1;
-        }
-
+        if (rtn == SUCCESS)
+                __scsi_report_device_reset(scmd->device, NULL);
         return rtn;
 }
 
@@ -584,8 +616,9 @@ static void scsi_abort_eh_cmnd(struct scsi_cmnd *scmd)
 {
         if (__scsi_try_to_abort_cmd(scmd) != SUCCESS)
                 if (scsi_try_bus_device_reset(scmd) != SUCCESS)
-                        if (scsi_try_bus_reset(scmd) != SUCCESS)
-                                scsi_try_host_reset(scmd);
+                        if (scsi_try_target_reset(scmd) != SUCCESS)
+                                if (scsi_try_bus_reset(scmd) != SUCCESS)
+                                        scsi_try_host_reset(scmd);
 }
 
 /**
@@ -1060,6 +1093,56 @@ static int scsi_eh_bus_device_reset(struct Scsi_Host *shost,
 }
 
 /**
+ * scsi_eh_target_reset - send target reset if needed
+ * @shost:      scsi host being recovered.
+ * @work_q:     &list_head for pending commands.
+ * @done_q:     &list_head for processed commands.
+ *
+ * Notes:
+ *    Try a target reset.
+ */
+static int scsi_eh_target_reset(struct Scsi_Host *shost,
+                                struct list_head *work_q,
+                                struct list_head *done_q)
+{
+        struct scsi_cmnd *scmd, *tgtr_scmd, *next;
+        unsigned int id;
+        int rtn;
+
+        for (id = 0; id <= shost->max_id; id++) {
+                tgtr_scmd = NULL;
+                list_for_each_entry(scmd, work_q, eh_entry) {
+                        if (id == scmd_id(scmd)) {
+                                tgtr_scmd = scmd;
+                                break;
+                        }
+                }
+                if (!tgtr_scmd)
+                        continue;
+
+                SCSI_LOG_ERROR_RECOVERY(3, printk("%s: Sending target reset "
+                                                  "to target %d\n",
+                                                  current->comm, id));
+                rtn = scsi_try_target_reset(tgtr_scmd);
+                if (rtn == SUCCESS) {
+                        list_for_each_entry_safe(scmd, next, work_q, eh_entry) {
+                                if (id == scmd_id(scmd))
+                                        if (!scsi_device_online(scmd->device) ||
+                                            !scsi_eh_tur(tgtr_scmd))
+                                                scsi_eh_finish_cmd(scmd,
+                                                                   done_q);
+                        }
+                } else
+                        SCSI_LOG_ERROR_RECOVERY(3, printk("%s: Target reset"
+                                                          " failed target: "
+                                                          "%d\n",
+                                                          current->comm, id));
+        }
+
+        return list_empty(work_q);
+}
+
+/**
  * scsi_eh_bus_reset - send a bus reset 
  * @shost:      &scsi host being recovered.
  * @work_q:     &list_head for pending commands.
@@ -1447,9 +1530,11 @@ void scsi_eh_ready_devs(struct Scsi_Host *shost,
 {
         if (!scsi_eh_stu(shost, work_q, done_q))
                 if (!scsi_eh_bus_device_reset(shost, work_q, done_q))
-                        if (!scsi_eh_bus_reset(shost, work_q, done_q))
-                                if (!scsi_eh_host_reset(work_q, done_q))
-                                        scsi_eh_offline_sdevs(work_q, done_q);
+                        if (!scsi_eh_target_reset(shost, work_q, done_q))
+                                if (!scsi_eh_bus_reset(shost, work_q, done_q))
+                                        if (!scsi_eh_host_reset(work_q, done_q))
+                                                scsi_eh_offline_sdevs(work_q,
+                                                                      done_q);
 }
 EXPORT_SYMBOL_GPL(scsi_eh_ready_devs);
 
@@ -1619,10 +1704,8 @@ void scsi_report_bus_reset(struct Scsi_Host *shost, int channel)
         struct scsi_device *sdev;
 
         __shost_for_each_device(sdev, shost) {
-                if (channel == sdev_channel(sdev)) {
-                        sdev->was_reset = 1;
-                        sdev->expecting_cc_ua = 1;
-                }
+                if (channel == sdev_channel(sdev))
+                        __scsi_report_device_reset(sdev, NULL);
         }
 }
 EXPORT_SYMBOL(scsi_report_bus_reset);
@@ -1655,10 +1738,8 @@ void scsi_report_device_reset(struct Scsi_Host *shost, int channel, int target)
 
         __shost_for_each_device(sdev, shost) {
                 if (channel == sdev_channel(sdev) &&
-                    target == sdev_id(sdev)) {
-                        sdev->was_reset = 1;
-                        sdev->expecting_cc_ua = 1;
-                }
+                    target == sdev_id(sdev))
+                        __scsi_report_device_reset(sdev, NULL);
         }
 }
 EXPORT_SYMBOL(scsi_report_device_reset);
@@ -1714,6 +1795,11 @@ scsi_reset_provider(struct scsi_device *dev, int flag)
                 if (rtn == SUCCESS)
                         break;
                 /* FALLTHROUGH */
+        case SCSI_TRY_RESET_TARGET:
+                rtn = scsi_try_target_reset(scmd);
+                if (rtn == SUCCESS)
+                        break;
+                /* FALLTHROUGH */
         case SCSI_TRY_RESET_BUS:
                 rtn = scsi_try_bus_reset(scmd);
                 if (rtn == SUCCESS)