posix_types.h: Cleanup stale __NFDBITS and related definitions

Recently, glibc made a change to suppress sign-conversion warnings in
FD_SET (glibc commit ceb9e56b3d1).  This uncovered an issue with the
kernel's definition of __NFDBITS if applications #include
<linux/types.h> after including <sys/select.h>.  A build failure would
be seen when passing the -Werror=sign-compare and -D_FORTIFY_SOURCE=2
flags to gcc.

It was suggested that the kernel should either match the glibc
definition of __NFDBITS or remove that entirely.  The current in-kernel
uses of __NFDBITS can be replaced with BITS_PER_LONG, and there are no
uses of the related __FDELT and __FDMASK defines.  Given that, we'll
continue the cleanup that was started with commit 8b3d1cda4f5f
("posix_types: Remove fd_set macros") and drop the remaining unused
macros.

Additionally, linux/time.h has similar macros defined that expand to
nothing so we'll remove those at the same time.

Reported-by: Jeff Law <law@redhat.com>
Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
CC: <stable@vger.kernel.org>
Signed-off-by: Josh Boyer <jwboyer@redhat.com>
[ .. and fix up whitespace as per akpm ]
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 3 insertions, 15 deletions

diff --git a/include/linux/posix_types.h b/include/linux/posix_types.h
index f04c98cf44f3..988f76e636e3 100644
--- a/include/linux/posix_types.h
+++ b/include/linux/posix_types.h
@@ -15,26 +15,14 @@
  */
 
 /*
- * Those macros may have been defined in <gnu/types.h>. But we always
- * use the ones here. 
+ * This macro may have been defined in <gnu/types.h>. But we always
+ * use the one here.
  */
-#undef __NFDBITS
-#define __NFDBITS	(8 * sizeof(unsigned long))
-
 #undef __FD_SETSIZE
 #define __FD_SETSIZE	1024
 
-#undef __FDSET_LONGS
-#define __FDSET_LONGS	(__FD_SETSIZE/__NFDBITS)
-
-#undef __FDELT
-#define	__FDELT(d)	((d) / __NFDBITS)
-
-#undef __FDMASK
-#define	__FDMASK(d)	(1UL << ((d) % __NFDBITS))
-
 typedef struct {
-	unsigned long fds_bits [__FDSET_LONGS];
+	unsigned long fds_bits[__FD_SETSIZE / (8 * sizeof(long))];
 } __kernel_fd_set;
 
 /* Type of a signal handler.  */