On Thu, 15 May 2008, Bryan Wu wrote:

quoted text
> >>>> What is supposed to make all these changes a good idea?
> >>>>
> >>> Since buf might not be 4-byte aligned.
> >>
> >> It is. Please analyze the code before you use these access methods.
> >>
> > You are right. buf has been 4-byte aligned since 2.6.19. My patch was
> > written two years ago. Sorry for the noise I caused.
> >
> 
> I has keeping this patch for a long time.  Jie fixed this patch at
> 2006/09/20 in our svn:
> http://blackfin.uclinux.org/git/?p=readonly-mirrors/linux-kernel.git;a=commit;h=cb3da1...
> http://blackfin.uclinux.org/git/?p=readonly-mirrors/linux-kernel.git;a=commit;h=255929...
> 
> And a similar patch from David Miller was accept in ohci-hub.c
> http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commitdiff;h=92164c...
> 
> Also because of the same issue, which was fixed by:
> http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commitdiff;h=54bee6...
> 
> If other functions not only rh_call_control() call this hub_control()
> pointer and the buf is not 4-byte aligned,
> this bug will fire again without the unaligned API. This patch is
> safer for the caller, although not efficient.

But the hub_control routines are almost never called by anything 
other than rh_call_control().  The only exception is in ehci_hub.c, and 
there the buf pointer is NULL.

So I don't see any need for this patch.

On the other hand, Jie could make a bunch of useful changes to
drivers/usb/gadget/file_storage.c, which has its own private routines
for unaligned little-endian access.

Alan Stern

--
unsubscribe notice
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/