[SCSI] libsas: prevent double completion of scmds from eh

We invoke task->task_done() to free the task in the eh case, but at this
point we are prepared for scsi_eh_flush_done_q() to finish off the scmd.

Introduce sas_end_task() to capture the final response status from the
lldd and free the task.

Also take the opportunity to kill this warning.
drivers/scsi/libsas/sas_scsi_host.c: In function ‘sas_end_task’:
drivers/scsi/libsas/sas_scsi_host.c:102:3: warning: case value ‘2’ not in enumerated type ‘enum exec_status’ [-Wswitch]

Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>

2 files changed, 37 insertions, 29 deletions

diff --git a/drivers/scsi/libsas/sas_scsi_host.c b/drivers/scsi/libsas/sas_scsi_host.c
index ba5876ccd29a..50db8f971a06 100644
--- a/drivers/scsi/libsas/sas_scsi_host.c
+++ b/drivers/scsi/libsas/sas_scsi_host.c
@@ -49,27 +49,12 @@
 #include <linux/scatterlist.h>
 #include <linux/libata.h>
 
-/* ---------- SCSI Host glue ---------- */
-
-static void sas_scsi_task_done(struct sas_task *task)
+/* record final status and free the task */
+static void sas_end_task(struct scsi_cmnd *sc, struct sas_task *task)
 {
         struct task_status_struct *ts = &task->task_status;
-        struct scsi_cmnd *sc = task->uldd_task;
         int hs = 0, stat = 0;
 
-        if (unlikely(task->task_state_flags & SAS_TASK_STATE_ABORTED)) {
-                /* Aborted tasks will be completed by the error handler */
-                SAS_DPRINTK("task done but aborted\n");
-                return;
-        }
-
-        if (unlikely(!sc)) {
-                SAS_DPRINTK("task_done called with non existing SCSI cmnd!\n");
-                list_del_init(&task->list);
-                sas_free_task(task);
-                return;
-        }
-
         if (ts->resp == SAS_TASK_UNDELIVERED) {
                 /* transport error */
                 hs = DID_NO_CONNECT;
@@ -124,10 +109,32 @@ static void sas_scsi_task_done(struct sas_task *task)
                         break;
                 }
         }
-        ASSIGN_SAS_TASK(sc, NULL);
+
         sc->result = (hs << 16) | stat;
+        ASSIGN_SAS_TASK(sc, NULL);
         list_del_init(&task->list);
         sas_free_task(task);
+}
+
+static void sas_scsi_task_done(struct sas_task *task)
+{
+        struct scsi_cmnd *sc = task->uldd_task;
+
+        if (unlikely(task->task_state_flags & SAS_TASK_STATE_ABORTED)) {
+                /* Aborted tasks will be completed by the error handler */
+                SAS_DPRINTK("task done but aborted\n");
+                return;
+        }
+
+        if (unlikely(!sc)) {
+                SAS_DPRINTK("task_done called with non existing SCSI cmnd!\n");
+                list_del_init(&task->list);
+                sas_free_task(task);
+                return;
+        }
+
+        ASSIGN_SAS_TASK(sc, NULL);
+        sas_end_task(sc, task);
         sc->scsi_done(sc);
 }
 
@@ -236,18 +243,16 @@ static void sas_eh_finish_cmd(struct scsi_cmnd *cmd)
         struct sas_task *task = TO_SAS_TASK(cmd);
         struct sas_ha_struct *sas_ha = SHOST_TO_SAS_HA(cmd->device->host);
 
-        /* remove the aborted task flag to allow the task to be
-         * completed now. At this point, we only get called following
-         * an actual abort of the task, so we should be guaranteed not
-         * to be racing with any completions from the LLD (hence we
-         * don't need the task state lock to clear the flag) */
-        task->task_state_flags &= ~SAS_TASK_STATE_ABORTED;
-        /* Now call task_done.  However, task will be free'd after
-         * this */
-        task->task_done(task);
+        /* At this point, we only get called following an actual abort
+         * of the task, so we should be guaranteed not to be racing with
+         * any completions from the LLD.  Task is freed after this.
+         */
+        sas_end_task(cmd, task);
+
         /* now finish the command and move it on to the error
          * handler done list, this also takes it off the
-         * error handler pending list */
+         * error handler pending list.
+         */
         scsi_eh_finish_cmd(cmd, &sas_ha->eh_done_q);
 }
 
diff --git a/include/scsi/libsas.h b/include/scsi/libsas.h
index 10eb2ea74431..071041b290d6 100644
--- a/include/scsi/libsas.h
+++ b/include/scsi/libsas.h
@@ -452,7 +452,10 @@ enum service_response {
 };
 
 enum exec_status {
-        /* The SAM_STAT_.. codes fit in the lower 6 bits */
+        /* The SAM_STAT_.. codes fit in the lower 6 bits, alias some of
+         * them here to silence 'case value not in enumerated type' warnings
+         */
+        __SAM_STAT_CHECK_CONDITION = SAM_STAT_CHECK_CONDITION,
 
         SAS_DEV_NO_RESPONSE = 0x80,
         SAS_DATA_UNDERRUN,