Re: [PATCH] USB: Removing the use of VLAIS from the gadget driver

[Behan Webster]

On 09/23/13 16:24, Felipe Balbi wrote:
> Hi,
>
> On Thu, Aug 01, 2013 at 09:35:44PM -0400, behanw@xxxxxxxxxxxxxxxxxx wrote:
> > From: Behan Webster <behanw@xxxxxxxxxxxxxxxxxx>
> >
> > The use of variable length arrays in structs (VLAIS) in the Linux Kernel code
> > precludes the use of compilers which don't implement VLAIS (for instance the
> > Clang compiler). This patch removes the use of VLAIS in the gadget driver.
> >
> > Signed-off-by: Mark Charlebois <charlebm@xxxxxxxxx>
> > Signed-off-by: Behan Webster <behanw@xxxxxxxxxxxxxxxxxx>
> > ---
> >   drivers/usb/gadget/f_fs.c | 128 +++++++++++++++++++++++++++-------------------
> >   1 file changed, 76 insertions(+), 52 deletions(-)
> >
> > diff --git a/drivers/usb/gadget/f_fs.c b/drivers/usb/gadget/f_fs.c
> > index f394f29..4b872c4 100644
> > --- a/drivers/usb/gadget/f_fs.c
> > +++ b/drivers/usb/gadget/f_fs.c
> > @@ -30,7 +30,6 @@
> >   
> >   #define FUNCTIONFS_MAGIC	0xa647361 /* Chosen by a honest dice roll ;) */
> >   
> > -
> >   /* Debugging ****************************************************************/
> >   
> >   #ifdef VERBOSE_DEBUG
> > @@ -214,6 +213,8 @@ struct ffs_data {
> >   	/* ids in stringtabs are set in functionfs_bind() */
> >   	const void			*raw_strings;
> >   	struct usb_gadget_strings	**stringtabs;
> > +	struct usb_gadget_strings	*stringtab;
> > +	struct usb_string		*strings;
> >   
> >   	/*
> >   	 * File system's super block, write once when file system is
> > @@ -263,7 +264,10 @@ struct ffs_function {
> >   
> >   	struct ffs_ep			*eps;
> >   	u8				eps_revmap[16];
> > +	struct usb_descriptor_header	**fs_descs;
> > +	struct usb_descriptor_header	**hs_descs;
> >   	short				*interfaces_nums;
> > +	char				*raw_descs;
> >   
> >   	struct usb_function		function;
> >   };
> > @@ -1345,6 +1349,8 @@ static void ffs_data_clear(struct ffs_data *ffs)
> >   	kfree(ffs->raw_descs);
> >   	kfree(ffs->raw_strings);
> >   	kfree(ffs->stringtabs);
> > +	kfree(ffs->stringtab);
> > +	kfree(ffs->strings);
> >   }
> >   
> >   static void ffs_data_reset(struct ffs_data *ffs)
> > @@ -1357,6 +1363,8 @@ static void ffs_data_reset(struct ffs_data *ffs)
> >   	ffs->raw_descs = NULL;
> >   	ffs->raw_strings = NULL;
> >   	ffs->stringtabs = NULL;
> > +	ffs->stringtab = NULL;
> > +	ffs->strings = NULL;
> >   
> >   	ffs->raw_descs_length = 0;
> >   	ffs->raw_fs_descs_length = 0;
> > @@ -1528,12 +1536,10 @@ static void ffs_func_free(struct ffs_function *func)
> >   	ffs_data_put(func->ffs);
> >   
> >   	kfree(func->eps);
> > -	/*
> > -	 * eps and interfaces_nums are allocated in the same chunk so
> > -	 * only one free is required.  Descriptors are also allocated
> > -	 * in the same chunk.
> > -	 */
> > -
> > +	kfree(func->fs_descs);
> > +	kfree(func->hs_descs);
> > +	kfree(func->interfaces_nums);
> > +	kfree(func->raw_descs);
> >   	kfree(func);
> >   }
> >   
> > @@ -1907,33 +1913,35 @@ static int __ffs_data_got_strings(struct ffs_data *ffs,
> >   		return 0;
> >   	}
> >   
> > -	/* Allocate everything in one chunk so there's less maintenance. */
> >   	{
> > -		struct {
> > -			struct usb_gadget_strings *stringtabs[lang_count + 1];
> > -			struct usb_gadget_strings stringtab[lang_count];
> > -			struct usb_string strings[lang_count*(needed_count+1)];
> > -		} *d;
> >   		unsigned i = 0;
> > -
> > -		d = kmalloc(sizeof *d, GFP_KERNEL);
> > -		if (unlikely(!d)) {
> > +		usb_gadget_strings **stringtabs = NULL;
> > +		usb_gadget_strings *stringtab = NULL;
> > +		usb_string *strings = NULL;
> did you compile this patch ?
Appologies. The patch as posted has a bug which was fixed after sending 
it to the list.

Andrzej Pietrasiewicz <andrzej.p@xxxxxxxxxxx> has the fixed one. Will 
send the fixed one to the list too.

Behan

--
Behan Webster
behanw@xxxxxxxxxxxxxxxxxx

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