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locking/atomic, arch/xtensa: Implement atomic_fetch_{add,sub,and,or,xor}() 

Implement FETCH-OP atomic primitives, these are very similar to the
existing OP-RETURN primitives we already have, except they return the
value of the atomic variable _before_ modification.

This is especially useful for irreversible operations -- such as
bitops (because it becomes impossible to reconstruct the state prior
to modification).

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Chris Zankel <chris@zankel.net>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Max Filippov <jcmvbkbc@gmail.com>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-arch@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Cc: linux-xtensa@linux-xtensa.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Peter Zijlstra 2016-04-18 01:16:03 +02:00 committed by Ingo Molnar
parent a8bcccaba1
commit 6dc25876cd
1 changed files with 50 additions and 4 deletions
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54
arch/xtensa/include/asm/atomic.h
View File

@ -98,6 +98,26 @@ static inline int atomic_##op##_return(int i, atomic_t * v) \
return result; \
}
#define ATOMIC_FETCH_OP(op) \
static inline int atomic_fetch_##op(int i, atomic_t * v) \
{ \
unsigned long tmp; \
int result; \
\
__asm__ __volatile__( \
"1: l32i %1, %3, 0\n" \
" wsr %1, scompare1\n" \
" " #op " %0, %1, %2\n" \
" s32c1i %0, %3, 0\n" \
" bne %0, %1, 1b\n" \
: "=&a" (result), "=&a" (tmp) \
: "a" (i), "a" (v) \
: "memory" \
); \
\
return result; \
}
#else /* XCHAL_HAVE_S32C1I */
#define ATOMIC_OP(op) \
@ -138,18 +158,44 @@ static inline int atomic_##op##_return(int i, atomic_t * v) \
return vval; \
}
#define ATOMIC_FETCH_OP(op) \
static inline int atomic_fetch_##op(int i, atomic_t * v) \
{ \
unsigned int tmp, vval; \
\
__asm__ __volatile__( \
" rsil a15,"__stringify(TOPLEVEL)"\n" \
" l32i %0, %3, 0\n" \
" " #op " %1, %0, %2\n" \
" s32i %1, %3, 0\n" \
" wsr a15, ps\n" \
" rsync\n" \
: "=&a" (vval), "=&a" (tmp) \
: "a" (i), "a" (v) \
: "a15", "memory" \
); \
\
return vval; \
}
#endif /* XCHAL_HAVE_S32C1I */
#define ATOMIC_OPS(op) ATOMIC_OP(op) ATOMIC_OP_RETURN(op)
#define ATOMIC_OPS(op) ATOMIC_OP(op) ATOMIC_FETCH_OP(op) ATOMIC_OP_RETURN(op)
ATOMIC_OPS(add)
ATOMIC_OPS(sub)
ATOMIC_OP(and)
ATOMIC_OP(or)
ATOMIC_OP(xor)
#undef ATOMIC_OPS
#define ATOMIC_OPS(op) ATOMIC_OP(op) ATOMIC_FETCH_OP(op)
#define atomic_fetch_or atomic_fetch_or
ATOMIC_OPS(and)
ATOMIC_OPS(or)
ATOMIC_OPS(xor)
#undef ATOMIC_OPS
#undef ATOMIC_FETCH_OP
#undef ATOMIC_OP_RETURN
#undef ATOMIC_OP