[SCSI] libsas: add mutex for SMP task execution

SAS does not tag SMP requests, and at least one lldd (isci) does not permit
more than one in-flight request at a time.

[jejb: fix sas_init_dev tab issues while we're at it]
Signed-off-by: Jeff Skirvin <jeffrey.d.skirvin@intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>

2 files changed, 32 insertions, 28 deletions

diff --git a/drivers/scsi/libsas/sas_discover.c b/drivers/scsi/libsas/sas_discover.c
index bad5eba4a92b..c56cc6400819 100644
--- a/drivers/scsi/libsas/sas_discover.c
+++ b/drivers/scsi/libsas/sas_discover.c
@@ -37,21 +37,22 @@
 
 void sas_init_dev(struct domain_device *dev)
 {
-        switch (dev->dev_type) {
-        case SAS_END_DEV:
-                break;
-        case EDGE_DEV:
-        case FANOUT_DEV:
-                INIT_LIST_HEAD(&dev->ex_dev.children);
-                break;
-        case SATA_DEV:
-        case SATA_PM:
-        case SATA_PM_PORT:
-                INIT_LIST_HEAD(&dev->sata_dev.children);
-                break;
-        default:
-                break;
-        }
+        switch (dev->dev_type) {
+        case SAS_END_DEV:
+                break;
+        case EDGE_DEV:
+        case FANOUT_DEV:
+                INIT_LIST_HEAD(&dev->ex_dev.children);
+                mutex_init(&dev->ex_dev.cmd_mutex);
+                break;
+        case SATA_DEV:
+        case SATA_PM:
+        case SATA_PM_PORT:
+                INIT_LIST_HEAD(&dev->sata_dev.children);
+                break;
+        default:
+                break;
+        }
 }
 
 /* ---------- Domain device discovery ---------- */
diff --git a/drivers/scsi/libsas/sas_expander.c b/drivers/scsi/libsas/sas_expander.c
index d3c1a29b8a2a..7c59f97c0287 100644
--- a/drivers/scsi/libsas/sas_expander.c
+++ b/drivers/scsi/libsas/sas_expander.c
@@ -72,11 +72,13 @@ static int smp_execute_task(struct domain_device *dev, void *req, int req_size,
         struct sas_internal *i =
                 to_sas_internal(dev->port->ha->core.shost->transportt);
 
+        mutex_lock(&dev->ex_dev.cmd_mutex);
         for (retry = 0; retry < 3; retry++) {
                 task = sas_alloc_task(GFP_KERNEL);
-                if (!task)
-                        return -ENOMEM;
-
+                if (!task) {
+                        res = -ENOMEM;
+                        break;
+                }
                 task->dev = dev;
                 task->task_proto = dev->tproto;
                 sg_init_one(&task->smp_task.smp_req, req, req_size);
@@ -94,7 +96,7 @@ static int smp_execute_task(struct domain_device *dev, void *req, int req_size,
                 if (res) {
                         del_timer(&task->timer);
                         SAS_DPRINTK("executing SMP task failed:%d\n", res);
-                        goto ex_err;
+                        break;
                 }
 
                 wait_for_completion(&task->completion);
@@ -104,21 +106,23 @@ static int smp_execute_task(struct domain_device *dev, void *req, int req_size,
                         i->dft->lldd_abort_task(task);
                         if (!(task->task_state_flags & SAS_TASK_STATE_DONE)) {
                                 SAS_DPRINTK("SMP task aborted and not done\n");
-                                goto ex_err;
+                                break;
                         }
                 }
                 if (task->task_status.resp == SAS_TASK_COMPLETE &&
                     task->task_status.stat == SAM_STAT_GOOD) {
                         res = 0;
                         break;
-                } if (task->task_status.resp == SAS_TASK_COMPLETE &&
-                      task->task_status.stat == SAS_DATA_UNDERRUN) {
+                }
+                if (task->task_status.resp == SAS_TASK_COMPLETE &&
+                    task->task_status.stat == SAS_DATA_UNDERRUN) {
                         /* no error, but return the number of bytes of
                          * underrun */
                         res = task->task_status.residual;
                         break;
-                } if (task->task_status.resp == SAS_TASK_COMPLETE &&
-                      task->task_status.stat == SAS_DATA_OVERRUN) {
+                }
+                if (task->task_status.resp == SAS_TASK_COMPLETE &&
+                    task->task_status.stat == SAS_DATA_OVERRUN) {
                         res = -EMSGSIZE;
                         break;
                 } else {
@@ -131,11 +135,10 @@ static int smp_execute_task(struct domain_device *dev, void *req, int req_size,
                         task = NULL;
                 }
         }
-ex_err:
+        mutex_unlock(&dev->ex_dev.cmd_mutex);
+
         BUG_ON(retry == 3 && task != NULL);
-        if (task != NULL) {
-                sas_free_task(task);
-        }
+        sas_free_task(task);
         return res;
 }