Messages in this thread Patch in this message | | | Date | Wed, 20 Apr 2011 07:39:25 +0200 | From | Willy Tarreau <> | Subject | Re: [Stable-review] [24/28] USB: xhci - fix unsafe macro definitions |
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On Wed, Apr 20, 2011 at 03:02:04AM +0100, Ben Hutchings wrote: > On Tue, 2011-04-19 at 13:31 -0700, Greg KH wrote: > > 2.6.32-longterm review patch. If anyone has any objections, please let us know. > > > > ------------------ > > > > From: Dmitry Torokhov <dtor@vmware.com> > > > > commit 5a6c2f3ff039154872ce597952f8b8900ea0d732 upstream. > > > > Macro arguments used in expressions need to be enclosed in parenthesis > > to avoid unpleasant surprises. > > Do you know of any specific uses of these macros where the missing > parentheses caused 'unpleasant surprises'?
In my opinion, this type of fix should be backported even if the current code does not appear to be at risk, otherwise a later fix in the kernel could cause a serious regression when backported to -stable. For instance, if we later have to backport this patch (cut'n'pasted) :
--- a/drivers/usb/host/xhci-mem.c +++ b/drivers/usb/host/xhci-mem.c @@ -1033,7 +1033,7 @@ static inline unsigned int xhci_get_endpoint_interval(struct usb_device *udev, default: BUG(); } - return EP_INTERVAL(interval); + return EP_INTERVAL(interval + 1); }
How can you guess that while works in mainline, it breaks -stable ?
As a user, I'd rather have known valid code in -stable and -longterm at the risk of an occasional *temporary* regression than longterm unexplainable regressions due to diverging code causing unexpected issues with backported fixes. Regards, Willy
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