It seems that check for host busy is deserved before scanning the starved list.
And list operation is simplified.
Signed-off-by: Hillf Danton <dhillf@xxxxxxxxx>
---
--- o/linux-2.6.36-rc4/drivers/scsi/scsi_lib.c 2010-09-13
07:07:38.000000000 +0800
+++ m/linux-2.6.36-rc4/drivers/scsi/scsi_lib.c 2010-09-19
20:32:34.000000000 +0800
@@ -399,18 +399,20 @@ static inline int scsi_host_is_busy(stru
*/
static void scsi_run_queue(struct request_queue *q)
{
- struct scsi_device *sdev = q->queuedata;
+ struct scsi_device *sdev = q->queuedata, *safe;
struct Scsi_Host *shost = sdev->host;
- LIST_HEAD(starved_list);
unsigned long flags;
if (scsi_target(sdev)->single_lun)
scsi_single_lun_run(sdev);
spin_lock_irqsave(shost->host_lock, flags);
- list_splice_init(&shost->starved_list, &starved_list);
-
- while (!list_empty(&starved_list)) {
+ if (scsi_host_is_busy(shost)) {
+ spin_unlock_irqrestore(shost->host_lock, flags);
+ return;
+ }
+ list_for_each_entry_safe(sdev, safe, &shost->starved_list,
+ starved_entry) {
int flagset;
/*
@@ -426,14 +428,10 @@ static void scsi_run_queue(struct reques
if (scsi_host_is_busy(shost))
break;
- sdev = list_entry(starved_list.next,
- struct scsi_device, starved_entry);
- list_del_init(&sdev->starved_entry);
- if (scsi_target_is_busy(scsi_target(sdev))) {
- list_move_tail(&sdev->starved_entry,
- &shost->starved_list);
+ if (scsi_target_is_busy(scsi_target(sdev)))
continue;
- }
+
+ list_del_init(&sdev->starved_entry);
spin_unlock(shost->host_lock);
@@ -450,8 +448,6 @@ static void scsi_run_queue(struct reques
spin_lock(shost->host_lock);
}
- /* put any unprocessed entries back */
- list_splice(&starved_list, &shost->starved_list);
spin_unlock_irqrestore(shost->host_lock, flags);
blk_run_queue(q);
--
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