Use inline assemblies for atomic_read/set(). This way there shouldn't
be any questions or subtle volatile semantics left.
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Let's make atomic_read() and atomic_set() behave like on all/most other
architectures. Generated code is identical with gcc 4.5.2.
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Drop support to compile the kernel with gcc versions older than 3.3.3.
This allows us to use the "Q" inline assembly contraint on some more
inline assemblies without duplicating a lot of complex code (e.g. __xchg
and __cmpxchg). The distinction for older gcc versions can be removed
which saves a few lines and simplifies the code.
Reviewed-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Git commit ea43546750 changed the
definition of atomic_t and atomic64_t for s390 by adding the volatile
modifier to the counter field. This has an unfortunate side effect
with newer versions of the gcc. The typeof operator now picks up the
volatile modifier from the expression. This causes the compiler to
think that it has to store the two temporary variable old_val and
new_val in the __CS_LOOP for the different atomic operations to the
stack as the variables are now volatile. Both stores are superfluous.
The hack to replace typeof(ptr->counter) with int in __CS_LOOP and
and long long in __CSG_LOOP avoids the two stores. A better solution
would be to drop the volatile from the counter field of the atomic_t
and atomic64_t definition. But that is a touchy subject ..
Cc: Matthew Wilcox <matthew@wil.cx>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Couple of coding style fixes, replace __inline__ with inline and
remove #ifdef __KERNEL_- since the header file isn't exported.
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Use compare double and swap to implement efficient atomic64 ops for 31 bit.
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Performance counters need 64 bit atomic operations.
To keep the patch small we use the simple generic atomic64_t implementation.
The native implementation follows with the next kernel.
Fixes this build bug:
In file included from kernel/sched.c:42:
include/linux/perf_counter.h:427: error: expected specifier-qualifier-list before 'atomic64_t'
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
The existing asm-generic/atomic.h only defines the
atomic_long type. This renames it to atomic-long.h
so we have a place to add a truly generic atomic.h
that can be used on all non-SMP systems.
Signed-off-by: Remis Lima Baima <remis.developer@googlemail.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Ingo Molnar <mingo@elte.hu>
The atomic_t type cannot currently be used in some header files because it
would create an include loop with asm/atomic.h. Move the type definition
to linux/types.h to break the loop.
Signed-off-by: Matthew Wilcox <willy@linux.intel.com>
Cc: Huang Ying <ying.huang@intel.com>
Cc: <linux-arch@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
