On Thu, Feb 09, 2012 at 03:11:13PM +0100, Jan Kiszka wrote: > On 2012-02-09 13:07, Paul Brook wrote: > >>>> What about naming the problem instead: > >>>> > >>>> /* Comparison with IOCTL macros on 32-bit hosts requires unsigned. */ > >>> > >>> Just once, it would be nice to post something to this list and get a > >>> substantive comment _before_ the bitching about minutiae. > >>> > >>> Oh, and it's not just 32-bit hosts, it's anywhere sizeof(int)==4, > >>> which includes ppc64 amongst other 64-bit hosts. > >> > >> Then state "if int is 32 bits". The comment is unfortunately not helpful > >> without the commit log. > > > > Int is 32 bits on every host we're ever likey to care about, so clearly > > there's something else going on. > > Yep. So a better explanation could be "Required for comparison with > unsigned IOCTL macro values". This wasn't noticed so far as the original > code was never build on anything but IA32/64.
Right. The problem still exists on x86 and x86_64, but it occurs for
a different set of ioctls (IOC_READ instead of IOC_WRITE). I guess we
never did this sort of signed comparison on an IOC_WRITE ioctl number
(comparing ioctl numbers for equality isn't a particularly obvious
thing to do from userspace, after all).
--
David Gibson | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_
| _way_ _around_!
http://www.ozlabs.org/~dgibson
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