Re: [PATCH] b43: Fix possible unaligned u32 access

["John W. Linville" <linville@tuxdriver.com>]

On Fri, Jun 05, 2009 at 07:29:07PM +0200, Michael Buesch wrote:
> On Friday 05 June 2009 14:25:03 John W. Linville wrote:
> > On Thu, Jun 04, 2009 at 11:18:33PM +0200, Michael Buesch wrote:
> > > From: Matthieu CASTET <castet.matthieu@free.fr>
> > > 
> > > Fix possible unaligned u32 access in b43_generate_plcp_hdr().
> > > Unaligned data is read/write with a u32 pointer instead of using the
> > > packed structure. Some versions of gcc ignore the "packed" attribute, if the
> > > structure element is accessed through a local pointer.
> > > 
> > > Signed-off-by: Matthieu CASTET <castet.matthieu@free.fr>
> > > Signed-off-by: Michael Buesch <mb@bu3sch.de>
> > 
> > That seems pretty brain-dead...can you cite a source for this
> > information?  The patch seems like a no-op...
> > 
> > John
> 
> struct foo {
> 	int data;
> } __attribute__((packed));
> 
> struct foo foo;
> int *d = &foo->data;
> foo->data = x;	/* Works for unaligned */
> *d = y;		/* Does not work for unaligned */

Why not?

-- 
John W. Linville		Someday the world will need a hero, and you
linville@tuxdriver.com			might be all we have.  Be ready.