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Commit 8ded2bbc authored by Josh Boyer's avatar Josh Boyer Committed by Linus Torvalds
Browse files

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 8b3d1cda
("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: default avatarJeff Law <law@redhat.com>
Suggested-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
CC: <stable@vger.kernel.org>
Signed-off-by: default avatarJosh Boyer <jwboyer@redhat.com>
[ .. and fix up whitespace as per akpm ]
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 4cb38750

arch/mips/kernel/kspd.c

+1 −1
Original line number Diff line number Diff line
@@ -323,7 +323,7 @@ static void sp_cleanup(void) 
	fdt = files_fdtable(files);

	for (;;) {

		unsigned long set;

		i = j * __NFDBITS;

		i = j * BITS_PER_LONG;

		if (i >= fdt->max_fds)

			break;

		set = fdt->open_fds[j++];

fs/exec.c

+1 −1
Original line number Diff line number Diff line
@@ -1020,7 +1020,7 @@ static void flush_old_files(struct files_struct * files) 
		unsigned long set, i;



		j++;

		i = j * __NFDBITS;

		i = j * BITS_PER_LONG;

		fdt = files_fdtable(files);

		if (i >= fdt->max_fds)

			break;

fs/select.c

+5 −5
Original line number Diff line number Diff line
@@ -345,8 +345,8 @@ static int max_select_fd(unsigned long n, fd_set_bits *fds) 
	struct fdtable *fdt;



	/* handle last in-complete long-word first */

	set = ~(~0UL << (n & (__NFDBITS-1)));

	n /= __NFDBITS;

	set = ~(~0UL << (n & (BITS_PER_LONG-1)));

	n /= BITS_PER_LONG;

	fdt = files_fdtable(current->files);

	open_fds = fdt->open_fds + n;

	max = 0;
@@ -373,7 +373,7 @@ static int max_select_fd(unsigned long n, fd_set_bits *fds) 
			max++;

			set >>= 1;

		} while (set);

		max += n * __NFDBITS;

		max += n * BITS_PER_LONG;

	}



	return max;
@@ -435,11 +435,11 @@ int do_select(int n, fd_set_bits *fds, struct timespec *end_time) 
			in = *inp++; out = *outp++; ex = *exp++;

			all_bits = in | out | ex;

			if (all_bits == 0) {

				i += __NFDBITS;

				i += BITS_PER_LONG;

				continue;

			}



			for (j = 0; j < __NFDBITS; ++j, ++i, bit <<= 1) {

			for (j = 0; j < BITS_PER_LONG; ++j, ++i, bit <<= 1) {

				int fput_needed;

				if (i >= n)

					break;

include/linux/posix_types.h

+3 −15
Original line number Diff line number Diff line
@@ -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.  */

include/linux/time.h

+0 −8
Original line number Diff line number Diff line
@@ -257,14 +257,6 @@ static __always_inline void timespec_add_ns(struct timespec *a, u64 ns) 


#endif /* __KERNEL__ */



#define NFDBITS			__NFDBITS



#define FD_SETSIZE		__FD_SETSIZE

#define FD_SET(fd,fdsetp)	__FD_SET(fd,fdsetp)

#define FD_CLR(fd,fdsetp)	__FD_CLR(fd,fdsetp)

#define FD_ISSET(fd,fdsetp)	__FD_ISSET(fd,fdsetp)

#define FD_ZERO(fdsetp)		__FD_ZERO(fdsetp)



/*

 * Names of the interval timers, and structure

 * defining a timer setting: