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| author | Christoph Hellwig <hch@infradead.org> | 2014-02-20 14:20:53 -0800 |
|---|---|---|
| committer | James Bottomley <JBottomley@Parallels.com> | 2014-03-15 10:19:24 -0700 |
| commit | 44b93b59d544919aba1aea6fa95f1418f2aa870f (patch) | |
| tree | 337da45d94fc70c43ae33a5f60cd65e8e063ed85 /drivers/scsi/scsi.c | |
| parent | df03c3f62837e20e936fe705aa480e8bee6bb3ca (diff) | |
| download | linux-44b93b59d544919aba1aea6fa95f1418f2aa870f.tar.gz linux-44b93b59d544919aba1aea6fa95f1418f2aa870f.tar.bz2 linux-44b93b59d544919aba1aea6fa95f1418f2aa870f.zip | |
[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.c | 11 |
1 files changed, 6 insertions, 5 deletions
diff --git a/drivers/scsi/scsi.c b/drivers/scsi/scsi.c index d8afec8317cf..fb86479ffd4a 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); |