Messages in this thread | | | Date | Wed, 25 Sep 2013 16:35:14 +0200 | From | Andrzej Pietrasiewicz <> | Subject | Re: [PATCH] Remove VLAIS usage from gadget code - alternate patch |
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Hi Mark,
Nice to hear from you again; on Saturday LOT's dreamliner was not grounded and I have safely returned home ;)
Please see my comments inline.
W dniu 24.09.2013 19:56, charlebm@gmail.com pisze: > From: Mark Charlebois <charlebm@gmail.com> > > > --- linux.orig/drivers/usb/gadget/f_fs.c > +++ linux/drivers/usb/gadget/f_fs.c > @@ -30,6 +30,21 @@ > > #define FUNCTIONFS_MAGIC 0xa647361 /* Chosen by a honest dice roll ;) */ > > +/* Variable Length Array Macros **********************************************/ > +#define vla_struct(structname) size_t structname##__##next = 0 > +#define vla_struct_size(structname) structname##__##next > + > +#define vla_item(structname, type, name, n) \ > + type * structname##_##name; \ > + size_t structname##_##name##__##offset = \ > + (structname##__##next + __alignof__(type) - 1) & \ > + ~(__alignof__(type) - 1); \ > + size_t structname##_##name##__##sz = n * sizeof(type); \
most likely this shoud read:
+ size_t structname##_##name##__##sz = (n) * sizeof(type); \
otherwise vla_item(....., lang_count + 1); will expand to:
size_t d_stringtabs__sz = lang_count + \ 1 * sizeof(struct usb_gadget_strings *);
> + structname##__##next = structname##_##name##__##offset + \ > + structname##_##name##__##sz; > + > +#define vla_ptr(ptr,structname,name) structname##_##name = \ > + (__typeof__(structname##_##name))&ptr[structname##_##name##__##offset]
<snip>
> unsigned i = 0; > + vla_struct(d); > + vla_item(d, struct usb_gadget_strings *, stringtabs, > + lang_count + 1);
Can you somehow avoid mixing code and declarations? The last thing in the expansion of this vla_item(.......) is an assignment, and
> + vla_item(d, struct usb_gadget_strings, stringtab, lang_count);
the first thing in expansion of the next vla_item(.......) is a declaration. GCC most likely will complain (issue a warning).
One solution I can think of here (a bit hackish) is to use a braced group as an expression: define vla_item() in such a way that first it declares e.g. d_stringtabs__offset, then d_stringtabs__sz, and then
struct usb_gadget_strings **d_stringtabs = ({d__next = d_stringtabs__offset + d_stringtabs__sz; NULL;});
I am not a fan of this kind of style, but can't think of any better way now. And I don't know what Clang thinks of it :O
Thanks,
AP
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