linux-stable.git/arch/powerpc/include/asm/atomic.h, branch linux-3.5.y

Disintegrate asm/system.h for PowerPC

2012-03-28T17:30:02+00:00

Disintegrate asm/system.h for PowerPC.

Signed-off-by: David Howells 
Acked-by: Benjamin Herrenschmidt 
cc: linuxppc-dev@lists.ozlabs.org

powerpc/atomic: Implement atomic*_inc_not_zero

2012-03-07T06:06:08+00:00

Implement atomic_inc_not_zero and atomic64_inc_not_zero. At the
moment we use atomic*_add_unless which requires us to put 0 and
1 constants into registers. We can also avoid a subtract by
saving the original value in a second temporary.

This removes 3 instructions from fget:

- c0000000001b63c0:       39 00 00 00     li      r8,0
- c0000000001b63c4:       39 40 00 01     li      r10,1
...
- c0000000001b63e8:       7c 0a 00 50     subf    r0,r10,r0

Signed-off-by: Anton Blanchard 
Signed-off-by: Benjamin Herrenschmidt

powerpc: Fix atomic_xxx_return barrier semantics

2011-11-17T05:26:07+00:00

The Documentation/memory-barriers.txt document requires that atomic
operations that return a value act as a memory barrier both before
and after the actual atomic operation.

Our current implementation doesn't guarantee this. More specifically,
while a load following the isync can not be issued before stwcx. has
completed, that completion doesn't architecturally means that the
result of stwcx. is visible to other processors (or any previous stores
for that matter) (typically, the other processors L1 caches can still
hold the old value).

This has caused an actual crash in RCU torture testing on Power 7

This fixes it by changing those atomic ops to use new macros instead
of RELEASE/ACQUIRE barriers, called ATOMIC_ENTRY and ATMOIC_EXIT barriers,
which are then defined respectively to lwsync and sync.

I haven't had a chance to measure the performance impact (or rather
what I measured with kernel compiles is in the noise, I yet have to
find a more precise benchmark)

Signed-off-by: Benjamin Herrenschmidt 
Acked-by: Paul E. McKenney

atomic: cleanup asm-generic atomic*.h inclusion

2011-07-26T23:49:47+00:00

After changing all consumers of atomics to include , we
ran into some compile time errors due to this dependency chain:

linux/atomic.h
  -> asm/atomic.h
    -> asm-generic/atomic-long.h

where atomic-long.h could use funcs defined later in linux/atomic.h
without a prototype.  This patches moves the code that includes
asm-generic/atomic*.h to linux/atomic.h.

Archs that need  need to select
CONFIG_GENERIC_ATOMIC64 from now on (some of them used to include it
unconditionally).

Compile tested on i386 and x86_64 with allnoconfig.

Signed-off-by: Arun Sharma 
Cc: Eric Dumazet 
Cc: Ingo Molnar 
Cc: David Miller 
Acked-by: Mike Frysinger 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

atomic: move atomic_add_unless to generic code

2011-07-26T23:49:47+00:00

This is in preparation for more generic atomic primitives based on
__atomic_add_unless.

Signed-off-by: Arun Sharma 
Signed-off-by: Hans-Christian Egtvedt 
Reviewed-by: Eric Dumazet 
Cc: Ingo Molnar 
Cc: David Miller 
Acked-by: Mike Frysinger 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

atomic: use

2011-07-26T23:49:47+00:00

This allows us to move duplicated code in 
(atomic_inc_not_zero() for now) to 

Signed-off-by: Arun Sharma 
Reviewed-by: Eric Dumazet 
Cc: Ingo Molnar 
Cc: David Miller 
Cc: Eric Dumazet 
Acked-by: Mike Frysinger 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

powerpc: Rename LWSYNC_ON_SMP to PPC_RELEASE_BARRIER, ISYNC_ON_SMP to PPC_ACQUIRE_BARRIER

2010-02-17T03:03:15+00:00

For performance reasons we are about to change ISYNC_ON_SMP to sometimes be
lwsync. Now that the macro name doesn't make sense, change it and LWSYNC_ON_SMP
to better explain what the barriers are doing.

Signed-off-by: Anton Blanchard 
Signed-off-by: Benjamin Herrenschmidt

powerpc: Use generic atomic64_t implementation on 32-bit processors

2009-06-15T03:27:38+00:00

This makes 32-bit powerpc use the generic atomic64_t implementation.

Signed-off-by: Paul Mackerras 
Signed-off-by: Benjamin Herrenschmidt

asm-generic: rename atomic.h to atomic-long.h

2009-06-11T19:02:17+00:00

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 
Signed-off-by: Arnd Bergmann 
Acked-by: Ingo Molnar

atomic_t: unify all arch definitions

2009-01-06T23:59:10+00:00

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 
Cc: Huang Ying 
Cc: 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds