Introduce scsi_dh_attached_handler_name() to retrieve the name of the
scsi_dh that is attached to the scsi_device associated with the provided
request queue. Returns NULL if a scsi_dh is not attached.
Also, fix scsi_dh_{attach,detach} function header comments to document
@q rather than @sdev.
Signed-off-by: Mike Snitzer <snitzer@xxxxxxxxxx>
Tested-by: Babu Moger <babu.moger@xxxxxxxxxx>
Cc: Hannes Reinecke <hare@xxxxxxx>
Cc: Chandra Seetharaman <sekharan@xxxxxxxxxx>
---
drivers/scsi/device_handler/scsi_dh.c | 38 ++++++++++++++++++++++++++++++++--
include/scsi/scsi_dh.h | 6 +++++
2 files changed, 42 insertions(+), 2 deletions(-)
v4: fixed potential for returned string to be invalid (hch)
v3: fixed missing put_device that Babu pointed out
Index: linux-2.6/drivers/scsi/device_handler/scsi_dh.c
===================================================================
--- linux-2.6.orig/drivers/scsi/device_handler/scsi_dh.c
+++ linux-2.6/drivers/scsi/device_handler/scsi_dh.c
@@ -468,7 +468,8 @@ EXPORT_SYMBOL_GPL(scsi_dh_handler_exist)
/*
* scsi_dh_attach - Attach device handler
- * @sdev - sdev the handler should be attached to
+ * @q - Request queue that is associated with the scsi_device
+ * the handler should be attached to
* @name - name of the handler to attach
*/
int scsi_dh_attach(struct request_queue *q, const char *name)
@@ -498,7 +499,8 @@ EXPORT_SYMBOL_GPL(scsi_dh_attach);
/*
* scsi_dh_detach - Detach device handler
- * @sdev - sdev the handler should be detached from
+ * @q - Request queue that is associated with the scsi_device
+ * the handler should be detached from
*
* This function will detach the device handler only
* if the sdev is not part of the internal list, ie
@@ -527,6 +529,38 @@ void scsi_dh_detach(struct request_queue
}
EXPORT_SYMBOL_GPL(scsi_dh_detach);
+/*
+ * scsi_dh_attached_handler_name - Get attached device handler's name
+ * @q - Request queue that is associated with the scsi_device
+ * that may have a device handler attached
+ * @gfp - the GFP mask used in the kmalloc() call when allocating memory
+ *
+ * Returns name of attached handler, NULL if no handler is attached.
+ * Caller must take care to free the returned string.
+ */
+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);
+
+ if (!sdev)
+ return NULL;
+
+ if (sdev->scsi_dh_data)
+ handler_name = kstrdup(sdev->scsi_dh_data->scsi_dh->name, gfp);
+
+ put_device(&sdev->sdev_gendev);
+ return handler_name;
+}
+EXPORT_SYMBOL_GPL(scsi_dh_attached_handler_name);
+
static struct notifier_block scsi_dh_nb = {
.notifier_call = scsi_dh_notifier
};
Index: linux-2.6/include/scsi/scsi_dh.h
===================================================================
--- linux-2.6.orig/include/scsi/scsi_dh.h
+++ linux-2.6/include/scsi/scsi_dh.h
@@ -60,6 +60,7 @@ extern int scsi_dh_activate(struct reque
extern int scsi_dh_handler_exist(const char *);
extern int scsi_dh_attach(struct request_queue *, const char *);
extern void scsi_dh_detach(struct request_queue *);
+extern const char *scsi_dh_attached_handler_name(struct request_queue *, gfp_t);
extern int scsi_dh_set_params(struct request_queue *, const char *);
#else
static inline int scsi_dh_activate(struct request_queue *req,
@@ -80,6 +81,11 @@ static inline void scsi_dh_detach(struct
{
return;
}
+static inline const char *scsi_dh_attached_handler_name(struct request_queue *q,
+ gfp_t gfp)
+{
+ return NULL;
+}
static inline int scsi_dh_set_params(struct request_queue *req, const char *params)
{
return -SCSI_DH_NOSYS;
--
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