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

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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>
This commit is contained in:
Christoph Hellwig 2014-02-20 14:20:55 -08:00 committed by James Bottomley
parent 21a05df547
commit 0479633686
5 changed files with 33 additions and 30 deletions
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37
drivers/scsi/scsi.c
View File

@ -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);

6
drivers/scsi/scsi_error.c
View File

@ -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;
}

14
drivers/scsi/scsi_lib.c
View File

@ -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 @@ int scsi_init_io(struct scsi_cmnd *cmd, gfp_t gfp_mask)
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) {
cmd = scsi_get_command(sdev, GFP_ATOMIC);
if (unlikely(!cmd))
/* 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)) {
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;

3
drivers/scsi/scsi_tgt_lib.c
View File

@ -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);

3
include/scsi/scsi_cmnd.h
View File

@ -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,