[SCSI] do not manipulate device reference counts in scsi_get/put_command

Many callers won't need this and we can optimize them away.  In addition
the handling in the __-prefixed variants was inconsistant to start with.

Based on an earlier patch from Bart Van Assche.

[jejb: fix kerneldoc probelm picked up by Fengguang Wu]
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>

diff --git a/drivers/scsi/scsi.c b/drivers/scsi/scsi.c
index fb86479ffd4ae214bdf304a344e99f25d25fab8f..2b12983d2b2d193a2df93c3db4a2e27f5406b7cd 100644 (file)
--- a/drivers/scsi/scsi.c
+++ b/drivers/scsi/scsi.c
@@ -284,27 +284,19 @@ EXPORT_SYMBOL_GPL(__scsi_get_command);
  */
 struct scsi_cmnd *scsi_get_command(struct scsi_device *dev, gfp_t gfp_mask)
 {
-       struct scsi_cmnd *cmd;
+       struct scsi_cmnd *cmd = __scsi_get_command(dev->host, gfp_mask);
+       unsigned long flags;
 
-       /* Bail if we can't get a reference to the device */
-       if (!get_device(&dev->sdev_gendev))
+       if (unlikely(cmd == NULL))
                return NULL;
 
-       cmd = __scsi_get_command(dev->host, gfp_mask);
-
-       if (likely(cmd != NULL)) {
-               unsigned long flags;
-
-               cmd->device = dev;
-               INIT_LIST_HEAD(&cmd->list);
-               INIT_DELAYED_WORK(&cmd->abort_work, scmd_eh_abort_handler);
-               spin_lock_irqsave(&dev->list_lock, flags);
-               list_add_tail(&cmd->list, &dev->cmd_list);
-               spin_unlock_irqrestore(&dev->list_lock, flags);
-               cmd->jiffies_at_alloc = jiffies;
-       } else
-               put_device(&dev->sdev_gendev);
-
+       cmd->device = dev;
+       INIT_LIST_HEAD(&cmd->list);
+       INIT_DELAYED_WORK(&cmd->abort_work, scmd_eh_abort_handler);
+       spin_lock_irqsave(&dev->list_lock, flags);
+       list_add_tail(&cmd->list, &dev->cmd_list);
+       spin_unlock_irqrestore(&dev->list_lock, flags);
+       cmd->jiffies_at_alloc = jiffies;
        return cmd;
 }
 EXPORT_SYMBOL(scsi_get_command);
@@ -313,10 +305,8 @@ EXPORT_SYMBOL(scsi_get_command);
  * __scsi_put_command - Free a struct scsi_cmnd
  * @shost: dev->host
  * @cmd: Command to free
- * @dev: parent scsi device
  */
-void __scsi_put_command(struct Scsi_Host *shost, struct scsi_cmnd *cmd,
-                       struct device *dev)
+void __scsi_put_command(struct Scsi_Host *shost, struct scsi_cmnd *cmd)
 {
        unsigned long flags;
 
@@ -331,8 +321,6 @@ void __scsi_put_command(struct Scsi_Host *shost, struct scsi_cmnd *cmd,
 
        if (likely(cmd != NULL))
                scsi_pool_free_command(shost->cmd_pool, cmd);
-
-       put_device(dev);
 }
 EXPORT_SYMBOL(__scsi_put_command);
 
@@ -346,7 +334,6 @@ EXPORT_SYMBOL(__scsi_put_command);
  */
 void scsi_put_command(struct scsi_cmnd *cmd)
 {
-       struct scsi_device *sdev = cmd->device;
        unsigned long flags;
 
        /* serious error if the command hasn't come from a device list */
@@ -357,7 +344,7 @@ void scsi_put_command(struct scsi_cmnd *cmd)
 
        cancel_delayed_work(&cmd->abort_work);
 
-       __scsi_put_command(cmd->device->host, cmd, &sdev->sdev_gendev);
+       __scsi_put_command(cmd->device->host, cmd);
 }
 EXPORT_SYMBOL(scsi_put_command);
 

diff --git a/drivers/scsi/scsi_error.c b/drivers/scsi/scsi_error.c
index 78b004da288518e2a2d9279eca7d32c2fe9bbc42..771c16bfdbac4be2fac180459ff5711407c98a01 100644 (file)
--- a/drivers/scsi/scsi_error.c
+++ b/drivers/scsi/scsi_error.c
@@ -2288,6 +2288,11 @@ scsi_reset_provider(struct scsi_device *dev, int flag)
        if (scsi_autopm_get_host(shost) < 0)
                return FAILED;
 
+       if (!get_device(&dev->sdev_gendev)) {
+               rtn = FAILED;
+               goto out_put_autopm_host;
+       }
+
        scmd = scsi_get_command(dev, GFP_KERNEL);
        blk_rq_init(NULL, &req);
        scmd->request = &req;
@@ -2345,6 +2350,7 @@ scsi_reset_provider(struct scsi_device *dev, int flag)
        scsi_run_host_queues(shost);
 
        scsi_next_command(scmd);
+out_put_autopm_host:
        scsi_autopm_put_host(shost);
        return rtn;
 }

diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
index 492071ca45d1c5b12381c7d3c852a1e5838eaacd..007e979fa4372e4fb345193e058554275732efbf 100644 (file)
--- a/drivers/scsi/scsi_lib.c
+++ b/drivers/scsi/scsi_lib.c
@@ -95,6 +95,7 @@ static void scsi_unprep_request(struct request *req)
        req->special = NULL;
 
        scsi_put_command(cmd);
+       put_device(&cmd->device->sdev_gendev);
 }
 
 /**
@@ -529,6 +530,7 @@ void scsi_next_command(struct scsi_cmnd *cmd)
        get_device(&sdev->sdev_gendev);
 
        scsi_put_command(cmd);
+       put_device(&sdev->sdev_gendev);
        scsi_run_queue(q);
 
        /* ok to remove device now */
@@ -1123,6 +1125,7 @@ err_exit:
        scsi_release_buffers(cmd);
        cmd->request->special = NULL;
        scsi_put_command(cmd);
+       put_device(&cmd->device->sdev_gendev);
        return error;
 }
 EXPORT_SYMBOL(scsi_init_io);
@@ -1133,9 +1136,15 @@ static struct scsi_cmnd *scsi_get_cmd_from_req(struct scsi_device *sdev,
        struct scsi_cmnd *cmd;
 
        if (!req->special) {
+               /* Bail if we can't get a reference to the device */
+               if (!get_device(&sdev->sdev_gendev))
+                       return NULL;
+
                cmd = scsi_get_command(sdev, GFP_ATOMIC);
-               if (unlikely(!cmd))
+               if (unlikely(!cmd)) {
+                       put_device(&sdev->sdev_gendev);
                        return NULL;
+               }
                req->special = cmd;
        } else {
                cmd = req->special;
@@ -1298,6 +1307,7 @@ int scsi_prep_return(struct request_queue *q, struct request *req, int ret)
                        struct scsi_cmnd *cmd = req->special;
                        scsi_release_buffers(cmd);
                        scsi_put_command(cmd);
+                       put_device(&cmd->device->sdev_gendev);
                        req->special = NULL;
                }
                break;

diff --git a/drivers/scsi/scsi_tgt_lib.c b/drivers/scsi/scsi_tgt_lib.c
index 84a1fdf67864cc4e0169b78d57687509c403a907..e51add05fb8dbdc848206b2d6c86a50d0f6ef80b 100644 (file)
--- a/drivers/scsi/scsi_tgt_lib.c
+++ b/drivers/scsi/scsi_tgt_lib.c
@@ -155,7 +155,8 @@ void scsi_host_put_command(struct Scsi_Host *shost, struct scsi_cmnd *cmd)
        __blk_put_request(q, rq);
        spin_unlock_irqrestore(q->queue_lock, flags);
 
-       __scsi_put_command(shost, cmd, &shost->shost_gendev);
+       __scsi_put_command(shost, cmd);
+       put_device(&shost->shost_gendev);
 }
 EXPORT_SYMBOL_GPL(scsi_host_put_command);
 

diff --git a/include/scsi/scsi_cmnd.h b/include/scsi/scsi_cmnd.h
index 91558a1f97f4817685dbc18665e1aaf98cf8afae..414edf9b12720ce09c176d89eb622d4383b9407a 100644 (file)
--- a/include/scsi/scsi_cmnd.h
+++ b/include/scsi/scsi_cmnd.h
@@ -142,8 +142,7 @@ static inline struct scsi_driver *scsi_cmd_to_driver(struct scsi_cmnd *cmd)
 extern struct scsi_cmnd *scsi_get_command(struct scsi_device *, gfp_t);
 extern struct scsi_cmnd *__scsi_get_command(struct Scsi_Host *, gfp_t);
 extern void scsi_put_command(struct scsi_cmnd *);
-extern void __scsi_put_command(struct Scsi_Host *, struct scsi_cmnd *,
-                              struct device *);
+extern void __scsi_put_command(struct Scsi_Host *, struct scsi_cmnd *);
 extern void scsi_finish_command(struct scsi_cmnd *cmd);
 
 extern void *scsi_kmap_atomic_sg(struct scatterlist *sg, int sg_count,