summaryrefslogtreecommitdiffstats
path: root/drivers/scsi/scsi.c
diff options
context:
space:
mode:
authorChristoph Hellwig <hch@infradead.org>2014-02-20 14:20:53 -0800
committerJames Bottomley <JBottomley@Parallels.com>2014-03-15 10:19:24 -0700
commit44b93b59d544919aba1aea6fa95f1418f2aa870f (patch)
tree337da45d94fc70c43ae33a5f60cd65e8e063ed85 /drivers/scsi/scsi.c
parentdf03c3f62837e20e936fe705aa480e8bee6bb3ca (diff)
[SCSI] avoid useless free_list lock roundtrips
Avoid hitting the host-wide free_list lock unless we need to put a command back onto the freelist. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Hannes Reinecke <hare@suse.de> Signed-off-by: James Bottomley <JBottomley@Parallels.com>
Diffstat (limited to 'drivers/scsi/scsi.c')
-rw-r--r--drivers/scsi/scsi.c11
1 files changed, 6 insertions, 5 deletions
diff --git a/drivers/scsi/scsi.c b/drivers/scsi/scsi.c
index d8afec8317c..fb86479ffd4 100644
--- a/drivers/scsi/scsi.c
+++ b/drivers/scsi/scsi.c
@@ -320,13 +320,14 @@ void __scsi_put_command(struct Scsi_Host *shost, struct scsi_cmnd *cmd,
{
unsigned long flags;
- /* changing locks here, don't need to restore the irq state */
- spin_lock_irqsave(&shost->free_list_lock, flags);
if (unlikely(list_empty(&shost->free_list))) {
- list_add(&cmd->list, &shost->free_list);
- cmd = NULL;
+ spin_lock_irqsave(&shost->free_list_lock, flags);
+ if (list_empty(&shost->free_list)) {
+ list_add(&cmd->list, &shost->free_list);
+ cmd = NULL;
+ }
+ spin_unlock_irqrestore(&shost->free_list_lock, flags);
}
- spin_unlock_irqrestore(&shost->free_list_lock, flags);
if (likely(cmd != NULL))
scsi_pool_free_command(shost->cmd_pool, cmd);