[PATCH 7/8] scsi_dh: add a common helper to get a scsi_device from a request_queue

Christoph Hellwig
2015-05-10T18:42:38Z

And cleanup the various messy opencoded versions of this. Note that this
moves the sdev_state checks outside the queue_lock coverage, but as
we don't hold the lock over the activation they are only advisory anyway.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Reviewed-by: Hannes Reinecke <hare@suse.de>
---
drivers/scsi/scsi_dh.c | 99 +++++++++++++++++++++++---------------------------
1 file changed, 46 insertions(+), 53 deletions(-)

diff --git a/drivers/scsi/scsi_dh.c b/drivers/scsi/scsi_dh.c
index f0b100e..8cae1c9 100644
--- a/drivers/scsi/scsi_dh.c
+++ b/drivers/scsi/scsi_dh.c
@@ -281,6 +281,20 @@ int scsi_unregister_device_handler(struct scsi_device_handler *scsi_dh)
}
EXPORT_SYMBOL_GPL(scsi_unregister_device_handler);

+static struct scsi_device *get_sdev_from_queue(struct request_queue *q)
+{
+ struct scsi_device *sdev;
+ unsigned long flags;
+
+ spin_lock_irqsave(q->queue_lock, flags);
+ sdev = q->queuedata;
+ if (!sdev || !get_device(&sdev->sdev_gendev))
+ sdev = NULL;
+ spin_unlock_irqrestore(q->queue_lock, flags);
+
+ return sdev;
+}
+
/*
* scsi_dh_activate - activate the path associated with the scsi_device
* corresponding to the given request queue.
@@ -296,41 +310,37 @@ EXPORT_SYMBOL_GPL(scsi_unregister_device_handler);
*/
int scsi_dh_activate(struct request_queue *q, activate_complete fn, void *data)
{
- int err = 0;
- unsigned long flags;
struct scsi_device *sdev;
- struct device *dev = NULL;
+ int err = SCSI_DH_NOSYS;

- spin_lock_irqsave(q->queue_lock, flags);
- sdev = q->queuedata;
+ sdev = get_sdev_from_queue(q);
if (!sdev) {
- spin_unlock_irqrestore(q->queue_lock, flags);
- err = SCSI_DH_NOSYS;
if (fn)
fn(data, err);
return err;
}

- dev = get_device(&sdev->sdev_gendev);
- if (!sdev->handler || !dev ||
- sdev->sdev_state == SDEV_CANCEL ||
+ if (!sdev->handler)
+ goto out_fn;
+ if (sdev->sdev_state == SDEV_CANCEL ||
sdev->sdev_state == SDEV_DEL)
- err = SCSI_DH_NOSYS;
- if (sdev->sdev_state == SDEV_OFFLINE)
- err = SCSI_DH_DEV_OFFLINED;
- spin_unlock_irqrestore(q->queue_lock, flags);
+ goto out_fn;

- if (err) {
- if (fn)
- fn(data, err);
- goto out;
- }
+ err = SCSI_DH_DEV_OFFLINED;
+ if (sdev->sdev_state == SDEV_OFFLINE)
+ goto out_fn;

if (sdev->handler->activate)
err = sdev->handler->activate(sdev, fn, data);
-out:
- put_device(dev);
+
+out_put_device:
+ put_device(&sdev->sdev_gendev);
return err;
+
+out_fn:
+ if (fn)
+ fn(data, err);
+ goto out_put_device;
}
EXPORT_SYMBOL_GPL(scsi_dh_activate);

@@ -346,21 +356,15 @@ EXPORT_SYMBOL_GPL(scsi_dh_activate);
*/
int scsi_dh_set_params(struct request_queue *q, const char *params)
{
- int err = -SCSI_DH_NOSYS;
- unsigned long flags;
struct scsi_device *sdev;
+ int err = -SCSI_DH_NOSYS;

- spin_lock_irqsave(q->queue_lock, flags);
- sdev = q->queuedata;
- if (sdev->handler &&
- sdev->handler->set_params &&
- get_device(&sdev->sdev_gendev))
- err = 0;
- spin_unlock_irqrestore(q->queue_lock, flags);
-
- if (err)
+ sdev = get_sdev_from_queue(q);
+ if (!sdev)
return err;
- err = sdev->handler->set_params(sdev, params);
+
+ if (sdev->handler && sdev->handler->set_params)
+ err = sdev->handler->set_params(sdev, params);
put_device(&sdev->sdev_gendev);
return err;
}
@@ -374,23 +378,19 @@ EXPORT_SYMBOL_GPL(scsi_dh_set_params);
*/
int scsi_dh_attach(struct request_queue *q, const char *name)
{
- unsigned long flags;
struct scsi_device *sdev;
struct scsi_device_handler *scsi_dh;
int err = 0;

- scsi_dh = scsi_dh_lookup(name);
- if (!scsi_dh)
- return -EINVAL;
-
- spin_lock_irqsave(q->queue_lock, flags);
- sdev = q->queuedata;
- if (!sdev || !get_device(&sdev->sdev_gendev))
- err = -ENODEV;
- spin_unlock_irqrestore(q->queue_lock, flags);
+ sdev = get_sdev_from_queue(q);
+ if (!sdev)
+ return -ENODEV;

- if (err)
- return err;
+ scsi_dh = scsi_dh_lookup(name);
+ if (!scsi_dh) {
+ err = -EINVAL;
+ goto out_put_device;
+ }

if (sdev->handler) {
if (sdev->handler != scsi_dh)
@@ -417,22 +417,15 @@ EXPORT_SYMBOL_GPL(scsi_dh_attach);
*/
const char *scsi_dh_attached_handler_name(struct request_queue *q, gfp_t gfp)
{
- unsigned long flags;
struct scsi_device *sdev;
const char *handler_name = NULL;

- spin_lock_irqsave(q->queue_lock, flags);
- sdev = q->queuedata;
- if (!sdev || !get_device(&sdev->sdev_gendev))
- sdev = NULL;
- spin_unlock_irqrestore(q->queue_lock, flags);
-
+ sdev = get_sdev_from_queue(q);
if (!sdev)
return NULL;

if (sdev->handler)
handler_name = kstrdup(sdev->handler->name, gfp);
-
put_device(&sdev->sdev_gendev);
return handler_name;
}
--
1.9.1