On Thu, 2012-05-10 at 17:31 -0400, Mike Snitzer wrote:
> 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)
put_device() missing here.
> + 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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