Re: [PATCH 13/13] atomics/treewide: make test ops optional

[Mark Rutland]

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@xxxxxxx>
> Cc: Boqun Feng <boqun.feng@xxxxxxxxx>
> Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
> Cc: Will Deacon <will.deacon@xxxxxxx>
> ---
>  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