[rtems commit] score: Fix atomic compare exchange

[Gedare Bloom]

Sebastian,
Does this need to go on 4.11 / ticket filed?

On Fri, Sep 25, 2015 at 3:51 PM, Sebastian Huber <sebh at rtems.org> wrote:
> Module:    rtems
> Branch:    master
> Commit:    1f7c5c88ca384baa312a0714c6e93174605418a7
> Changeset: http://git.rtems.org/rtems/commit/?id=1f7c5c88ca384baa312a0714c6e93174605418a7
>
> Author:    Sebastian Huber <sebastian.huber at embedded-brains.de>
> Date:      Fri Sep 25 21:31:00 2015 +0200
>
> score: Fix atomic compare exchange
>
> ---
>
>  cpukit/score/cpu/sparc/sparcv8-atomic.c         |  8 ++-
>  cpukit/score/include/rtems/score/cpustdatomic.h | 18 +++++--
>  testsuites/sptests/spatomic01/init.c            | 65 +++++++++++++++++++------
>  3 files changed, 70 insertions(+), 21 deletions(-)
>
> diff --git a/cpukit/score/cpu/sparc/sparcv8-atomic.c b/cpukit/score/cpu/sparc/sparcv8-atomic.c
> index b1c4f23..2b3bdbc 100644
> --- a/cpukit/score/cpu/sparc/sparcv8-atomic.c
> +++ b/cpukit/score/cpu/sparc/sparcv8-atomic.c
> @@ -1,5 +1,5 @@
>  /*
> - * Copyright (c) 2014 embedded brains GmbH.  All rights reserved.
> + * Copyright (c) 2014-2015 embedded brains GmbH.  All rights reserved.
>   *
>   *  embedded brains GmbH
>   *  Dornierstr. 4
> @@ -118,12 +118,16 @@ bool __atomic_compare_exchange_4(
>  {
>    bool equal;
>    ISR_Level level;
> +  uint32_t actual;
>
>    level = _SPARCV8_Acquire_the_one_lock();
>
> -  equal = *mem == *expected;
> +  actual = *mem;
> +  equal = ( actual == *expected );
>    if ( equal ) {
>      *mem = desired;
> +  } else {
> +    *expected = actual;
>    }
>
>    _SPARCV8_Release_the_one_lock( level );
> diff --git a/cpukit/score/include/rtems/score/cpustdatomic.h b/cpukit/score/include/rtems/score/cpustdatomic.h
> index 2696e3a..c66dd7e 100644
> --- a/cpukit/score/include/rtems/score/cpustdatomic.h
> +++ b/cpukit/score/include/rtems/score/cpustdatomic.h
> @@ -577,13 +577,17 @@ static inline bool _CPU_atomic_Compare_exchange_uint( CPU_atomic_Uint *obj, unsi
>  #else
>    bool success;
>    ISR_Level level;
> +  unsigned int actual;
>
>    (void) succ;
>    (void) fail;
>    _ISR_Disable( level );
> -  success = *obj == *expected;
> +  actual = *obj;
> +  success = ( actual == *expected );
>    if ( success ) {
>      *obj = desired;
> +  } else {
> +    *expected = actual;
>    }
>    _ISR_Enable( level );
>
> @@ -600,13 +604,17 @@ static inline bool _CPU_atomic_Compare_exchange_ulong( CPU_atomic_Ulong *obj, un
>  #else
>    bool success;
>    ISR_Level level;
> +  unsigned long actual;
>
>    (void) succ;
>    (void) fail;
>    _ISR_Disable( level );
> -  success = *obj == *expected;
> +  actual = *obj;
> +  success = ( actual == *expected );
>    if ( success ) {
>      *obj = desired;
> +  } else {
> +    *expected = actual;
>    }
>    _ISR_Enable( level );
>
> @@ -623,13 +631,17 @@ static inline bool _CPU_atomic_Compare_exchange_ptr( CPU_atomic_Pointer *obj, vo
>  #else
>    bool success;
>    ISR_Level level;
> +  uintptr_t actual;
>
>    (void) succ;
>    (void) fail;
>    _ISR_Disable( level );
> -  success = *obj == (uintptr_t) *expected;
> +  actual = *obj;
> +  success = ( actual == (uintptr_t) *expected );
>    if ( success ) {
>      *obj = (uintptr_t) desired;
> +  } else {
> +    *expected = (void *) actual;
>    }
>    _ISR_Enable( level );
>
> diff --git a/testsuites/sptests/spatomic01/init.c b/testsuites/sptests/spatomic01/init.c
> index fbfd071..b90ffd0 100644
> --- a/testsuites/sptests/spatomic01/init.c
> +++ b/testsuites/sptests/spatomic01/init.c
> @@ -1,5 +1,5 @@
>  /*
> - * Copyright (c) 2013-2014 embedded brains GmbH.  All rights reserved.
> + * Copyright (c) 2013-2015 embedded brains GmbH.  All rights reserved.
>   *
>   *  embedded brains GmbH
>   *  Dornierstr. 4
> @@ -189,24 +189,57 @@ static void test_simple_atomic_exchange_body(test_context *ctx)
>
>  static void test_simple_atomic_compare_exchange_body(test_context *ctx)
>  {
> -  unsigned int ia = 8, ib = 4;
> -  unsigned int ic;
> -  unsigned long a = 2, b = 1;
> -  unsigned long c;
> +  unsigned int ei;
> +  unsigned int vi;
> +  unsigned long el;
> +  unsigned long vl;
> +  bool success;
>
>    puts("=== atomic simple compare exchange test case ===");
>
> -  _Atomic_Store_uint(&ctx->atomic_int_value, ia, ATOMIC_ORDER_RELAXED);
> -  _Atomic_Compare_exchange_uint(&ctx->atomic_int_value, &ia, ib,
> -    ATOMIC_ORDER_RELAXED, ATOMIC_ORDER_RELAXED);
> -  ic = _Atomic_Load_uint(&ctx->atomic_int_value, ATOMIC_ORDER_RELAXED);
> -  rtems_test_assert(ic == ib);
> -
> -  _Atomic_Store_ulong(&ctx->atomic_value, a, ATOMIC_ORDER_RELAXED);
> -  _Atomic_Compare_exchange_ulong(&ctx->atomic_value, &a, b,
> -    ATOMIC_ORDER_RELAXED, ATOMIC_ORDER_RELAXED);
> -  c = _Atomic_Load_ulong(&ctx->atomic_value, ATOMIC_ORDER_RELAXED);
> -  rtems_test_assert(c == b);
> +  _Atomic_Store_uint(&ctx->atomic_int_value, 1, ATOMIC_ORDER_RELAXED);
> +  ei = 2;
> +  success = _Atomic_Compare_exchange_uint(
> +    &ctx->atomic_int_value,
> +    &ei,
> +    3,
> +    ATOMIC_ORDER_RELAXED,
> +    ATOMIC_ORDER_RELAXED
> +  );
> +  rtems_test_assert(!success);
> +  rtems_test_assert(ei == 1);
> +  success = _Atomic_Compare_exchange_uint(
> +    &ctx->atomic_int_value,
> +    &ei,
> +    3,
> +    ATOMIC_ORDER_RELAXED,
> +    ATOMIC_ORDER_RELAXED
> +  );
> +  rtems_test_assert(success);
> +  vi = _Atomic_Load_uint(&ctx->atomic_int_value, ATOMIC_ORDER_RELAXED);
> +  rtems_test_assert(vi == 3);
> +
> +  _Atomic_Store_ulong(&ctx->atomic_value, 10, ATOMIC_ORDER_RELAXED);
> +  el = 11;
> +  success = _Atomic_Compare_exchange_ulong(
> +    &ctx->atomic_value,
> +    &el,
> +    12,
> +    ATOMIC_ORDER_RELAXED,
> +    ATOMIC_ORDER_RELAXED
> +  );
> +  rtems_test_assert(!success);
> +  rtems_test_assert(el == 10);
> +  success = _Atomic_Compare_exchange_ulong(
> +    &ctx->atomic_value,
> +    &el,
> +    12,
> +    ATOMIC_ORDER_RELAXED,
> +    ATOMIC_ORDER_RELAXED
> +  );
> +  rtems_test_assert(success);
> +  vl = _Atomic_Load_ulong(&ctx->atomic_value, ATOMIC_ORDER_RELAXED);
> +  rtems_test_assert(vl == 12);
>  }
>
>  static const simple_test_body simple_test_bodies[] = {
>
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