[SCSI] aic94xx SCSI timeout fix: SMP retry fix.

Updating DDB0 inside aic94xx driver itself caused SMP command timeout. I
hit this SMP timeout problem twice but I am not able to reproduce it since
then. Here is a fix that retries an SMP command.

Signed-off-by: Malahal Naineni <malahal@us.ibm.com>
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>

1 files changed, 47 insertions, 37 deletions

diff --git a/drivers/scsi/libsas/sas_expander.c b/drivers/scsi/libsas/sas_expander.c
index 30b8014bcc7a..e34a93435497 100644
--- a/drivers/scsi/libsas/sas_expander.c
+++ b/drivers/scsi/libsas/sas_expander.c
@@ -71,55 +71,65 @@ static void smp_task_done(struct sas_task *task)
 static int smp_execute_task(struct domain_device *dev, void *req, int req_size,
                             void *resp, int resp_size)
 {
-        int res;
-        struct sas_task *task = sas_alloc_task(GFP_KERNEL);
+        int res, retry;
+        struct sas_task *task = NULL;
         struct sas_internal *i =
                 to_sas_internal(dev->port->ha->core.shost->transportt);
 
-        if (!task)
-                return -ENOMEM;
-
-        task->dev = dev;
-        task->task_proto = dev->tproto;
-        sg_init_one(&task->smp_task.smp_req, req, req_size);
-        sg_init_one(&task->smp_task.smp_resp, resp, resp_size);
+        for (retry = 0; retry < 3; retry++) {
+                task = sas_alloc_task(GFP_KERNEL);
+                if (!task)
+                        return -ENOMEM;
 
-        task->task_done = smp_task_done;
+                task->dev = dev;
+                task->task_proto = dev->tproto;
+                sg_init_one(&task->smp_task.smp_req, req, req_size);
+                sg_init_one(&task->smp_task.smp_resp, resp, resp_size);
 
-        task->timer.data = (unsigned long) task;
-        task->timer.function = smp_task_timedout;
-        task->timer.expires = jiffies + SMP_TIMEOUT*HZ;
-        add_timer(&task->timer);
+                task->task_done = smp_task_done;
 
-        res = i->dft->lldd_execute_task(task, 1, GFP_KERNEL);
+                task->timer.data = (unsigned long) task;
+                task->timer.function = smp_task_timedout;
+                task->timer.expires = jiffies + SMP_TIMEOUT*HZ;
+                add_timer(&task->timer);
 
-        if (res) {
-                del_timer(&task->timer);
-                SAS_DPRINTK("executing SMP task failed:%d\n", res);
-                goto ex_err;
-        }
+                res = i->dft->lldd_execute_task(task, 1, GFP_KERNEL);
 
-        wait_for_completion(&task->completion);
-        res = -ETASK;
-        if ((task->task_state_flags & SAS_TASK_STATE_ABORTED)) {
-                SAS_DPRINTK("smp task timed out or aborted\n");
-                i->dft->lldd_abort_task(task);
-                if (!(task->task_state_flags & SAS_TASK_STATE_DONE)) {
-                        SAS_DPRINTK("SMP task aborted and not done\n");
+                if (res) {
+                        del_timer(&task->timer);
+                        SAS_DPRINTK("executing SMP task failed:%d\n", res);
                         goto ex_err;
                 }
+
+                wait_for_completion(&task->completion);
+                res = -ETASK;
+                if ((task->task_state_flags & SAS_TASK_STATE_ABORTED)) {
+                        SAS_DPRINTK("smp task timed out or aborted\n");
+                        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;
+                        }
+                }
+                if (task->task_status.resp == SAS_TASK_COMPLETE &&
+                    task->task_status.stat == SAM_GOOD) {
+                        res = 0;
+                        break;
+                } else {
+                        SAS_DPRINTK("%s: task to dev %016llx response: 0x%x "
+                                    "status 0x%x\n", __FUNCTION__,
+                                    SAS_ADDR(dev->sas_addr),
+                                    task->task_status.resp,
+                                    task->task_status.stat);
+                        sas_free_task(task);
+                        task = NULL;
+                }
         }
-        if (task->task_status.resp == SAS_TASK_COMPLETE &&
-            task->task_status.stat == SAM_GOOD)
-                res = 0;
-        else
-                SAS_DPRINTK("%s: task to dev %016llx response: 0x%x "
-                            "status 0x%x\n", __FUNCTION__,
-                            SAS_ADDR(dev->sas_addr),
-                            task->task_status.resp,
-                            task->task_status.stat);
 ex_err:
-        sas_free_task(task);
+        BUG_ON(retry == 3 && task != NULL);
+        if (task != NULL) {
+                sas_free_task(task);
+        }
         return res;
 }