alignment faults in 3.6

Russell King - ARM Linux [off-list ref] writes:

On Fri, Oct 12, 2012 at 08:11:42AM +0000, Arnd Bergmann wrote:

quoted

On Thursday 11 October 2012, M?ns Rullg?rd wrote:

quoted

quoted

But, the IP header is expected to be aligned.

Everything tells the compiler the struct is perfectly aligned.  When the
buggy driver passes a misaligned pointer, bad things happen.

Would it be appropriate to add a WARN_ON_ONCE() in the alignment fault path
then?

I think that's an excellent idea.

quoted

If all alignment faults in the kernel are caused by broken drivers,
that would at least give us some hope of finding those drivers while
at the same time not causing much overhead in the case where we need
to do the fixup in the meantime.

No.  It is my understanding that various IP option processing can also
cause the alignment fault handler to be invoked, even when the packet is
properly aligned, and then there's jffs2/mtd which also relies upon
alignment faults being fixed up.

As far as I'm concerned, this is all hearsay, and I've only ever heard
it from you.  Why can't you let those who care fix these bugs instead?

-- 
M?ns Rullg?rd
mans at mansr.com