On Tue, Jul 24, 2012 at 11:46:25AM -0700, Linus Torvalds wrote: > On Tue, Jul 24, 2012 at 11:32 AM, Josh Boyer <[email protected]> wrote: > > Recent glibc made a change to suppress sign-conversion warnings from FD_SET > > (glibc commit ceb9e56b3d1). That patch solved the particular error it was > > aiming to, however applications that #include <linux/types.h> after > > including <sys/select.h> can now hit a build failure if -Werror=sign-compare > > and -D_FORTIFY_SOURCE=2 is passed to gcc. This can be seen when building > > this trivial application against a recent enough glibc: > > Looking more at this, I now hate it for *another* reason. > > Making __NFDBITS be a signed value turns __FDELT() and __FDMASK() into > potentially pure and utter crap. Doing signed divisions (or modulus) > is a disaster - suddenly it's not just a bit shift any more. > > Guys, the glibc people really seem to not have thought their change > through. Or maybe they fixed their __FDELT/__FDMASK at the same time?
Jeff can probably answer this better than I can, so likely best to wait for him. FWIW, the definitions of __FD_ELT/__FD_MASK in glibc are: #define __FD_ELT(d) ((d) / __NFDBITS) #define __FD_MASK(d) ((__fd_mask) 1 << ((d) % __NFDBITS)) where __fd_mask is 'typdef long int'. __NFDBITS was changed to int type with glibc commit eb0b6cb6e in 2009, and __FDELT/__FDMASK were basically renamed with glibc commit e529793b508 in 2011. josh -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
