[SCSI] libsas: pre-clean commands that won the eh vs completion race

When scrolling forward through the eh list (in a clear_q scenario) it is
possible to encounter commands that won the completion vs eh race.  Rather
than sprinkle more "if (!task)" throughout the handler just make a pass
through the list and delete the race winners before handling the rest.

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

diff --git a/drivers/scsi/libsas/sas_scsi_host.c b/drivers/scsi/libsas/sas_scsi_host.c
index 94ef763..731c892 100644 (file)
--- a/drivers/scsi/libsas/sas_scsi_host.c
+++ b/drivers/scsi/libsas/sas_scsi_host.c
@@ -249,8 +249,8 @@ out_done:
 
 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);
+       struct sas_task *task = TO_SAS_TASK(cmd);
 
        /* At this point, we only get called following an actual abort
         * of the task, so we should be guaranteed not to be racing with
@@ -267,9 +267,9 @@ static void sas_eh_finish_cmd(struct scsi_cmnd *cmd)
 
 static void sas_eh_defer_cmd(struct scsi_cmnd *cmd)
 {
-       struct sas_task *task = TO_SAS_TASK(cmd);
-       struct domain_device *dev = task->dev;
+       struct domain_device *dev = cmd_to_domain_dev(cmd);
        struct sas_ha_struct *ha = dev->port->ha;
+       struct sas_task *task = TO_SAS_TASK(cmd);
 
        if (!dev_is_sata(dev)) {
                sas_eh_finish_cmd(cmd);
@@ -530,8 +530,9 @@ static int sas_eh_handle_sas_errors(struct Scsi_Host *shost,
        struct sas_internal *i = to_sas_internal(shost->transportt);
        unsigned long flags;
        struct sas_ha_struct *ha = SHOST_TO_SAS_HA(shost);
+       LIST_HEAD(done);
 
-Again:
+       /* clean out any commands that won the completion vs eh race */
        list_for_each_entry_safe(cmd, n, work_q, eh_entry) {
                struct domain_device *dev = cmd_to_domain_dev(cmd);
                struct sas_task *task;
@@ -545,7 +546,12 @@ Again:
                spin_unlock_irqrestore(&dev->done_lock, flags);
 
                if (!task)
-                       continue;
+                       list_move_tail(&cmd->eh_entry, &done);
+       }
+
+ Again:
+       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);
 
@@ -649,15 +655,16 @@ Again:
                        goto clear_q;
                }
        }
+ out:
+       list_splice_tail(&done, work_q);
        list_splice_tail_init(&ha->eh_ata_q, work_q);
        return list_empty(work_q);
-clear_q:
+
+ clear_q:
        SAS_DPRINTK("--- Exit %s -- clear_q\n", __func__);
        list_for_each_entry_safe(cmd, n, work_q, eh_entry)
                sas_eh_finish_cmd(cmd);
-
-       list_splice_tail_init(&ha->eh_ata_q, work_q);
-       return list_empty(work_q);
+       goto out;
 }
 
 void sas_scsi_recover_host(struct Scsi_Host *shost)