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Message-ID: <20180529091047.kg3et36pxzwohhat@lakrids.cambridge.arm.com>
Date: Tue, 29 May 2018 10:11:19 +0100
From: Mark Rutland <mark.rutland@....com>
To: linux-kernel@...r.kernel.org, Peter Zijlstra <peterz@...radead.org>
Cc: Boqun Feng <boqun.feng@...il.com>,
Will Deacon <will.deacon@....com>
Subject: Re: [PATCH 13/13] atomics/treewide: make test ops optional
On Wed, May 23, 2018 at 02:35:33PM +0100, Mark Rutland wrote:
> Some of the atomics return the result of a test applied after the atomic
> operation, and almost all architectures implement these as trivial
> wrappers around the underlying atomic. Specifically:
>
> * <atomic>_inc_and_test(v) is (<atomic>_inc_return(v) == 0)
>
> * <atomic>_dec_and_test(v) is (<atomic>_dec_return(v) == 0)
>
> * <atomic>_sub_and_test(i, v) is (<atomic>_sub_return(i, v) == 0)
>
> * <atomic>_add_negative(i, v) is (<atomic>_add_return(i, v) < 0)
>
> Rather than have these definitions duplicated in all architectures, with
> minor inconsistencies in formatting and documentation, let's make these
> operations optional, with default fallbacks as above. Implementations
> must now provide a preprocessor symbol.
>
> The instrumented atomics are updated accordingly.
>
> Both x86 and m68k have custom implementations, which are left as-is,
> given preprocessor symbols to avoid being overridden.
>
> There should be no functional change as a result of this patch.
>
> Signed-off-by: Mark Rutland <mark.rutland@....com>
> Cc: Boqun Feng <boqun.feng@...il.com>
> Cc: Peter Zijlstra <peterz@...radead.org>
> Cc: Will Deacon <will.deacon@....com>
> ---
> arch/alpha/include/asm/atomic.h | 12 ---
> arch/arc/include/asm/atomic.h | 10 ---
> arch/arm/include/asm/atomic.h | 9 ---
> arch/arm64/include/asm/atomic.h | 8 --
> arch/h8300/include/asm/atomic.h | 5 --
> arch/hexagon/include/asm/atomic.h | 5 --
> arch/ia64/include/asm/atomic.h | 23 ------
> arch/m68k/include/asm/atomic.h | 4 +
> arch/mips/include/asm/atomic.h | 84 --------------------
> arch/parisc/include/asm/atomic.h | 22 ------
> arch/powerpc/include/asm/atomic.h | 30 --------
> arch/s390/include/asm/atomic.h | 8 --
> arch/sh/include/asm/atomic.h | 4 -
> arch/sparc/include/asm/atomic_32.h | 15 ----
> arch/sparc/include/asm/atomic_64.h | 20 -----
> arch/x86/include/asm/atomic.h | 4 +
> arch/x86/include/asm/atomic64_32.h | 54 -------------
> arch/x86/include/asm/atomic64_64.h | 4 +
> arch/xtensa/include/asm/atomic.h | 42 ----------
> include/asm-generic/atomic-instrumented.h | 24 ++++++
> include/asm-generic/atomic.h | 9 ---
> include/asm-generic/atomic64.h | 4 -
> include/linux/atomic.h | 124 ++++++++++++++++++++++++++++++
> 23 files changed, 160 insertions(+), 364 deletions(-)
I missed the risvc bits, since those are generated and don't have
preprocessor symbols.
Peter, does your ack still stand if I fold in the below?
Thanks,
Mark.
---->8----
diff --git a/arch/riscv/include/asm/atomic.h b/arch/riscv/include/asm/atomic.h
index d959bbaaad41..68eef0a805ca 100644
--- a/arch/riscv/include/asm/atomic.h
+++ b/arch/riscv/include/asm/atomic.h
@@ -209,36 +209,6 @@ ATOMIC_OPS(xor, xor, i)
#undef ATOMIC_FETCH_OP
#undef ATOMIC_OP_RETURN
-/*
- * The extra atomic operations that are constructed from one of the core
- * AMO-based operations above (aside from sub, which is easier to fit above).
- * These are required to perform a full barrier, but they're OK this way
- * because atomic_*_return is also required to perform a full barrier.
- *
- */
-#define ATOMIC_OP(op, func_op, comp_op, I, c_type, prefix) \
-static __always_inline \
-bool atomic##prefix##_##op(c_type i, atomic##prefix##_t *v) \
-{ \
- return atomic##prefix##_##func_op##_return(i, v) comp_op I; \
-}
-
-#ifdef CONFIG_GENERIC_ATOMIC64
-#define ATOMIC_OPS(op, func_op, comp_op, I) \
- ATOMIC_OP(op, func_op, comp_op, I, int, )
-#else
-#define ATOMIC_OPS(op, func_op, comp_op, I) \
- ATOMIC_OP(op, func_op, comp_op, I, int, ) \
- ATOMIC_OP(op, func_op, comp_op, I, long, 64)
-#endif
-
-ATOMIC_OPS(add_and_test, add, ==, 0)
-ATOMIC_OPS(sub_and_test, sub, ==, 0)
-ATOMIC_OPS(add_negative, add, <, 0)
-
-#undef ATOMIC_OP
-#undef ATOMIC_OPS
-
#define ATOMIC_OP(op, func_op, I, c_type, prefix) \
static __always_inline \
void atomic##prefix##_##op(atomic##prefix##_t *v) \
@@ -315,22 +285,6 @@ ATOMIC_OPS(dec, add, +, -1)
#undef ATOMIC_FETCH_OP
#undef ATOMIC_OP_RETURN
-#define ATOMIC_OP(op, func_op, comp_op, I, prefix) \
-static __always_inline \
-bool atomic##prefix##_##op(atomic##prefix##_t *v) \
-{ \
- return atomic##prefix##_##func_op##_return(v) comp_op I; \
-}
-
-ATOMIC_OP(inc_and_test, inc, ==, 0, )
-ATOMIC_OP(dec_and_test, dec, ==, 0, )
-#ifndef CONFIG_GENERIC_ATOMIC64
-ATOMIC_OP(inc_and_test, inc, ==, 0, 64)
-ATOMIC_OP(dec_and_test, dec, ==, 0, 64)
-#endif
-
-#undef ATOMIC_OP
-
/* This is required to provide a full barrier on success. */
static __always_inline int atomic_fetch_add_unless(atomic_t *v, int a, int u)
{
--
2.11.0
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