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authorMike Christie <michaelc@cs.wisc.edu>2008-11-11 13:42:35 -0600
committerJames Bottomley <James.Bottomley@HansenPartnership.com>2008-11-16 08:13:58 -0600
commit2a3a59e5c977654d3aad5bc11cc0aca2303a7f44 (patch)
tree4449aa49696e54a3a62fc595449be8caa89188f1 /drivers/scsi/scsi_lib.c
parent9bf1a2445f3c569098b8de7097ca324e65abecc2 (diff)
[SCSI] Fix hang in starved list processing
Close possible infinite loop with interrupts off when devices are added back to the starved list. Fixes: http://bugzilla.kernel.org/show_bug.cgi?id=11898 Reported-by: <alex.shi@intel.com> Signed-off-by: Mike Christie <michaelc@cs.wisc.edu> Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>
Diffstat (limited to 'drivers/scsi/scsi_lib.c')
-rw-r--r--drivers/scsi/scsi_lib.c23
1 files changed, 11 insertions, 12 deletions
diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
index f5d3b96890dc..fa45a1a66867 100644
--- a/drivers/scsi/scsi_lib.c
+++ b/drivers/scsi/scsi_lib.c
@@ -567,15 +567,18 @@ static inline int scsi_host_is_busy(struct Scsi_Host *shost)
*/
static void scsi_run_queue(struct request_queue *q)
{
- struct scsi_device *starved_head = NULL, *sdev = q->queuedata;
+ struct scsi_device *sdev = q->queuedata;
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);
- while (!list_empty(&shost->starved_list) && !scsi_host_is_busy(shost)) {
+ list_splice_init(&shost->starved_list, &starved_list);
+
+ while (!list_empty(&starved_list)) {
int flagset;
/*
@@ -588,24 +591,18 @@ static void scsi_run_queue(struct request_queue *q)
* scsi_request_fn must get the host_lock before checking
* or modifying starved_list or starved_entry.
*/
- sdev = list_entry(shost->starved_list.next,
- struct scsi_device, starved_entry);
- /*
- * The *queue_ready functions can add a device back onto the
- * starved list's tail, so we must check for a infinite loop.
- */
- if (sdev == starved_head)
+ if (scsi_host_is_busy(shost))
break;
- if (!starved_head)
- starved_head = sdev;
+ 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);
continue;
}
- list_del_init(&sdev->starved_entry);
spin_unlock(shost->host_lock);
spin_lock(sdev->request_queue->queue_lock);
@@ -621,6 +618,8 @@ static void scsi_run_queue(struct request_queue *q)
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);