On Wed, Oct 23 2013, Andrzej Pietrasiewicz wrote:
> USB function's configfs config group is created in a generic way in
> usb/gadget/configfs.c:function_make(), which in turn delegates actual
> allocation and setup of the USB function instance to a particular
> implementation, e.g. in f_acm.c. The said implementation does its job
> in a parameter-less function e.g. acm_alloc_instance(), which results
> in creating an unnamed config group, whose name is set later in
> function_make(). function_make() creates the name by parsing a string
> of the form:
>
> <function name>.<instance name>
>
> which comes from userspace as a parameter to mkdir invocation.
>
> Up to now only <function name> has been used, while <instance name>
> has been ignored. This patch adds a set_inst_name() operation to
> struct usb_function_instance which allows passing the <instance name>
> from function_make() so that it is not ignored. It is entirely up to the
> implementor of set_inst_name() what to do with the <instance name>.
>
> In a typical case, the struct usb_function_instance is embedded in a
> larger struct which is retrieved in set_inst_name() with container_of(),
> and the larger struct contains a field to store the <instance name>.
>
> Signed-off-by: Andrzej Pietrasiewicz <andrzej.p@xxxxxxxxxxx>
> Signed-off-by: Kyungmin Park <kyungmin.park@xxxxxxxxxxx>
Acked-by: Michal Nazarewicz <mina86@xxxxxxxxxx>
> ---
> drivers/usb/gadget/configfs.c | 7 +++++++
> include/linux/usb/composite.h | 2 ++
> 2 files changed, 9 insertions(+), 0 deletions(-)
>
> diff --git a/drivers/usb/gadget/configfs.c b/drivers/usb/gadget/configfs.c
> index 2588511..d6c8ab4 100644
> --- a/drivers/usb/gadget/configfs.c
> +++ b/drivers/usb/gadget/configfs.c
> @@ -564,6 +564,13 @@ static struct config_group *function_make(
> usb_put_function_instance(fi);
> return ERR_PTR(ret);
> }
> + if (fi->set_inst_name) {
> + ret = fi->set_inst_name(fi, instance_name);
> + if (ret) {
> + usb_put_function_instance(fi);
> + return ERR_PTR(ret);
> + }
> + }
>
> gi = container_of(group, struct gadget_info, functions_group);
>
> diff --git a/include/linux/usb/composite.h b/include/linux/usb/composite.h
> index 5e61589..dba63f5 100644
> --- a/include/linux/usb/composite.h
> +++ b/include/linux/usb/composite.h
> @@ -468,6 +468,8 @@ struct usb_function_instance {
> struct config_group group;
> struct list_head cfs_list;
> struct usb_function_driver *fd;
> + int (*set_inst_name)(struct usb_function_instance *inst,
> + const char *name);
> void (*free_func_inst)(struct usb_function_instance *inst);
> };
>
> --
> 1.7.0.4
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