linux-kernel - Re: [PATCH v2] usb: gadget: f

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Date:	Tue, 07 Oct 2014 12:07:41 +0200
From:	Michal Nazarewicz <mina86@...a86.com>
To:	Robert Baldyga <r.baldyga@...sung.com>, balbi@...com
Cc:	gregkh@...uxfoundation.org, linux-usb@...r.kernel.org,
	linux-kernel@...r.kernel.org, andrzej.p@...sung.com,
	k.opasiak@...sung.com, Robert Baldyga <r.baldyga@...sung.com>
Subject: Re: [PATCH v2] usb: gadget: f_fs: add "zombie" mode

On Tue, Oct 07 2014, Robert Baldyga <r.baldyga@...sung.com> wrote:
> @@ -1411,8 +1425,17 @@ static void ffs_data_closed(struct ffs_data *ffs)
>  	ENTER();
>  
>  	if (atomic_dec_and_test(&ffs->opened)) {
> -		ffs->state = FFS_CLOSING;
> -		ffs_data_reset(ffs);
> +		if (ffs->zombie_mode) {
> +			ffs->state = FFS_ZOMBIE;
> +			if (ffs->epfiles)
> +				ffs_epfiles_delete(ffs->epfiles,
> +						   ffs->eps_count);

This looks suspicious.  Why isn't it:

+			if (ffs->epfiles) {
+				ffs_epfiles_destroy(ffs->epfiles,
+						   ffs->eps_count);
+				ffs->epfiles = NULL;
+			}

If ffs->epfiles is not NULLed, call to ffs_data_reset in ffs_data_open
will call ffs_epfiles_destroy which we don't want, do we?

> +			if (ffs->setup_state == FFS_SETUP_PENDING)
> +				__ffs_ep0_stall(ffs);
> +		} else {
> +			ffs->state = FFS_CLOSING;
> +			ffs_data_reset(ffs);
> +		}
>  	}
>  
>  	ffs_data_put(ffs);

> @@ -93,6 +93,26 @@ enum ffs_state {
>  	FFS_ACTIVE,
>  
>  	/*
> +	 * Function is visible to host, but it's not functional. All
> +	 * setup requests are stalled and another transfers are refused.

“and transfers on other endpoints are refused.”

> +	 * All epfiles, excepting ep0, are deleted so there is no way

s/excepting/except/

> +	 * to perform any operations on them.
> +	 *
> +	 * This state is set after closing all functionfs files, when
> +	 * mount parameter "zombie=1" has been set. Function will remain
> +	 * in zombie state until filesystem will be umounted or ep0 will

s/will be umounted/is unmounted/
s/ep0 will be/ep0 is/

> +	 * be opened again. In the second case functionfs state will be
> +	 * reseted, and it will be ready for descriptors and strings

s/reseted/reset/

> +	 * writing.
> +	 *
> +	 * This is useful only when functionfs is composed to gadget
> +	 * with another function which can perform some critical
> +	 * operations, and it's strongly desired to have this operations
> +	 * completed, even after functionfs files closure.
> +	 */
> +	FFS_ZOMBIE,
> +
> +	/*
>  	 * All endpoints have been closed.  This state is also set if
>  	 * we encounter an unrecoverable error.  The only
>  	 * unrecoverable error is situation when after reading strings

-- 
Best regards,                                         _     _
.o. | Liege of Serenely Enlightened Majesty of      o' \,=./ `o
..o | Computer Science,  Michał “mina86” Nazarewicz    (o o)
ooo +--<mpn@...gle.com>--<xmpp:mina86@...ber.org>--ooO--(_)--Ooo--
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