Re: [PATCH 2/5] usb: gadget: mass_storage: Enforce contiguous LUN ids

[Michal Nazarewicz <mina86@mina86.com>]

On Mon, Jun 22 2015, Krzysztof Opasiak wrote:
> According to mass storage specification:
>
> "Logical Unit Numbers on the device shall be numbered contiguously
>  starting from LUN 0 to a maximum LUN of 15 (Fh)"
>
> So don't allow to bind ms function unless we have at least LUN0
> and LUNs ids are contiguous.
>
> Signed-off-by: Krzysztof Opasiak <k.opasiak@samsung.com>

Acked-by: Michal Nazarewicz <mina86@mina86.com>

but then again I think that we should let user space shoot themselves in
the foot if they want to, especially as letting them to that is less
code. ;)

> ---
>  drivers/usb/gadget/function/f_mass_storage.c |   29 ++++++++++++++++++++++++++
>  1 file changed, 29 insertions(+)
>
> diff --git a/drivers/usb/gadget/function/f_mass_storage.c b/drivers/usb/gadget/function/f_mass_storage.c
> index 2e8f37e..19b31d7 100644
> --- a/drivers/usb/gadget/function/f_mass_storage.c
> +++ b/drivers/usb/gadget/function/f_mass_storage.c
> @@ -3065,6 +3065,35 @@ static int fsg_bind(struct usb_configuration *c, struct usb_function *f)
>  	int			ret;
>  	struct fsg_opts		*opts;
>  
> +	/*
> +	 * Don't allow to bind if we don't have at least one LUN
> +	 * or LUNs ids are not contiguous.
> +	 */
> +	if (likely(common->luns)) {
> +		bool found_null = false;
> +
> +		for (i = 0; i < common->nluns; ++i) {
> +			if (!common->luns[i]) {
> +				found_null = true;
> +				continue;
> +			}
> +
> +			if (!found_null) {
> +				continue;
> +			} else {
> +				pr_err("LUN ids should be contiguous.\n");
> +				return -EINVAL;
> +			}
> +		}
> +
> +		if (i == 0 || !common->luns[i]) {
> +			pr_err("There should be at least one LUN.\n");
> +			return -EINVAL;
> +		}
> +	} else {
> +		return -EINVAL;
> +	}
> +
>  	opts = fsg_opts_from_func_inst(f->fi);
>  	if (!opts->no_configfs) {
>  		ret = fsg_common_set_cdev(fsg->common, c->cdev,
> -- 
> 1.7.9.5
>

-- 
Best regards,                                         _     _
.o. | Liege of Serenely Enlightened Majesty of      o' \,=./ `o
..o | Computer Science,  Michał “mina86” Nazarewicz    (o o)
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