Re: [patch] s390: missing ifdef in bitops.h

[Martin Schwidefsky <schwidefsky@de.ibm.com>]

On Tue, 2006-06-13 at 22:43 +0200, Arnd Bergmann wrote:
> Am Tuesday 13 June 2006 22:33 schrieb Arnd Bergmann:
> > Erm, I don't think the kernel even uses those definitions, the only reason
> > to keep them is old user space.
> 
> Sorry, misinformation on my side. The kernel uses the FD_foo versions,
> not the __FD_foo ones, so I did not find them at first.
> 
> It's only used in fs/open.c though, and I wonder if that could just
> use the bitops versions directly, as these are more likely to be
> optimized well for a given architecture.

Using set_bit and clear_bit is actually overkill since they use compare
and swap to do an atomic update. That is not needed for __FD_foo. How
about the attached patch ?

-- 
blue skies,
  Martin.

Martin Schwidefsky
Linux for zSeries Development & Services
IBM Deutschland Entwicklung GmbH

"Reality continues to ruin my life." - Calvin.

--

From: Martin Schwidefsky <schwidefsky@de.ibm.com>

[S390] __FD_foo definitions.

Make the definitions of __FD_SET, __FD_CLR and __FD_ISSET independent
from asm/bitops.h and remove the macro magic that tests for __GLIBC__.
Use simple C inline functions instead of set_bit, clear_bit and test_bit.

Spotted by David Woodhouse <dwmw2@infradead.org>

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
---

 include/asm-s390/posix_types.h |   42 ++++++++++++++++++++++++++---------------
 1 files changed, 27 insertions(+), 15 deletions(-)

diff -urpN linux-2.6/include/asm-s390/posix_types.h linux-2.6-patched/include/asm-s390/posix_types.h
--- linux-2.6/include/asm-s390/posix_types.h	2006-03-20 06:53:29.000000000 +0100
+++ linux-2.6-patched/include/asm-s390/posix_types.h	2006-06-14 12:37:54.000000000 +0200
@@ -76,24 +76,36 @@ typedef struct {
 } __kernel_fsid_t;
 
 
-#if defined(__KERNEL__) || !defined(__GLIBC__) || (__GLIBC__ < 2)
+#ifdef __KERNEL__
 
-#ifndef _S390_BITOPS_H
-#include <asm/bitops.h>
-#endif
-
-#undef  __FD_SET
-#define __FD_SET(fd,fdsetp)  set_bit((fd),(fdsetp)->fds_bits)
-
-#undef  __FD_CLR
-#define __FD_CLR(fd,fdsetp)  clear_bit((fd),(fdsetp)->fds_bits)
-
-#undef  __FD_ISSET
-#define __FD_ISSET(fd,fdsetp)  test_bit((fd),(fdsetp)->fds_bits)
+#undef __FD_SET
+static inline void __FD_SET(unsigned long fd, __kernel_fd_set *fdsetp)
+{
+	unsigned long _tmp = fd / __NFDBITS;
+	unsigned long _rem = fd % __NFDBITS;
+	fdsetp->fds_bits[_tmp] |= (1UL<<_rem);
+}
+
+#undef __FD_CLR
+static inline void __FD_CLR(unsigned long fd, __kernel_fd_set *fdsetp)
+{
+	unsigned long _tmp = fd / __NFDBITS;
+	unsigned long _rem = fd % __NFDBITS;
+	fdsetp->fds_bits[_tmp] &= ~(1UL<<_rem);
+}
+
+#undef __FD_ISSET
+static inline int __FD_ISSET(unsigned long fd, const __kernel_fd_set *fdsetp)
+{
+	unsigned long _tmp = fd / __NFDBITS;
+	unsigned long _rem = fd % __NFDBITS;
+	return (fdsetp->fds_bits[_tmp] & (1UL<<_rem)) != 0;
+}
 
 #undef  __FD_ZERO
-#define __FD_ZERO(fdsetp) (memset ((fdsetp), 0, sizeof(*(fd_set *)(fdsetp))))
+#define __FD_ZERO(fdsetp) \
+	((void) memset ((__ptr_t) (fdsetp), 0, sizeof (__kernel_fd_set)))
 
-#endif     /* defined(__KERNEL__) || !defined(__GLIBC__) || (__GLIBC__ < 2)*/
+#endif     /* __KERNEL__ */
 
 #endif