scsi_dh: add a common helper to get a scsi_device from a request_queue

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>
Signed-off-by: James Bottomley <JBottomley@Odin.com>

diff --git a/drivers/scsi/scsi_dh.c b/drivers/scsi/scsi_dh.c
index 33c1148ff3b54619cc8560f291e3339209c2e5e0..2e1db5738ae1a6da8532ddbf80e033fa6b8001fd 100644 (file)
--- a/drivers/scsi/scsi_dh.c
+++ b/drivers/scsi/scsi_dh.c
@@ -283,6 +283,20 @@ 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.
@@ -298,41 +312,37 @@ 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);
 
@@ -348,21 +358,15 @@ 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;
 }
@@ -376,23 +380,19 @@ 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)
@@ -419,22 +419,15 @@ 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;
 }