diff options
Diffstat (limited to 'import-layers/yocto-poky/meta/recipes-core/glibc/glibc/0006-Fix-atomic_fetch_xor_release.patch')
| -rw-r--r-- | import-layers/yocto-poky/meta/recipes-core/glibc/glibc/0006-Fix-atomic_fetch_xor_release.patch | 81 |
1 files changed, 81 insertions, 0 deletions
diff --git a/import-layers/yocto-poky/meta/recipes-core/glibc/glibc/0006-Fix-atomic_fetch_xor_release.patch b/import-layers/yocto-poky/meta/recipes-core/glibc/glibc/0006-Fix-atomic_fetch_xor_release.patch new file mode 100644 index 000000000..7616efa18 --- /dev/null +++ b/import-layers/yocto-poky/meta/recipes-core/glibc/glibc/0006-Fix-atomic_fetch_xor_release.patch @@ -0,0 +1,81 @@ +From b671f20cc160238b62894d032a55baf85867106e Mon Sep 17 00:00:00 2001 +From: Catalin Enache <catalin.enache@windriver.com> +Date: Fri, 30 Jun 2017 19:12:43 +0300 +Subject: [PATCH 6/6] Fix atomic_fetch_xor_release. + +No code uses atomic_fetch_xor_release except for the upcoming +conditional variable rewrite. Therefore there is no user +visible bug here. The use of atomic_compare_and_exchange_bool_rel +is removed (since it doesn't exist anymore), and is replaced +by atomic_compare_exchange_weak_release. + +We use weak_release because it provides better performance in +the loop (the weak semantic) and because the xor is release MO +(the release semantic). We don't reload expected in the loop +because atomic_compare_and_exchange_weak_release does this for +us as part of the CAS failure. + +It is otherwise a fairly plain conversion that fixes building +the new condvar for 32-bit x86. Passes all regression tests +for x86. + +Upstream-Status: Backport + +Author: Carlos O'Donell <carlos@systemhalted.org> +Signed-off-by: Catalin Enache <catalin.enache@windriver.com> +--- + ChangeLog | 6 ++++++ + include/atomic.h | 19 +++++++++++-------- + 2 files changed, 17 insertions(+), 8 deletions(-) + +diff --git a/ChangeLog b/ChangeLog +index 44c518b..893262d 100644 +--- a/ChangeLog ++++ b/ChangeLog +@@ -1,3 +1,9 @@ ++2016-10-26 Carlos O'Donell <carlos@redhat.com> ++ ++ * include/atomic.h ++ [USE_COMPILER_ATOMIC_BUILTINS && !atomic_fetch_xor_release] ++ (atomic_fetch_xor_release): Use atomic_compare_exchange_weak_release. ++ + 2017-04-04 Adhemerval Zanella <adhemerval.zanella@linaro.org> + + * nptl/pthreadP.h (USE_REQUEUE_PI): Remove ununsed macro. +diff --git a/include/atomic.h b/include/atomic.h +index 5a8e7e7..c8b4664 100644 +--- a/include/atomic.h ++++ b/include/atomic.h +@@ -777,18 +777,21 @@ void __atomic_link_error (void); + # endif + + # ifndef atomic_fetch_xor_release ++/* Failing the atomic_compare_exchange_weak_release reloads the value in ++ __atg104_expected, so we need only do the XOR again and retry. */ + # define atomic_fetch_xor_release(mem, operand) \ +- ({ __typeof (*(mem)) __atg104_old; \ +- __typeof (mem) __atg104_memp = (mem); \ ++ ({ __typeof (mem) __atg104_memp = (mem); \ ++ __typeof (*(mem)) __atg104_expected = (*__atg104_memp); \ ++ __typeof (*(mem)) __atg104_desired; \ + __typeof (*(mem)) __atg104_op = (operand); \ + \ + do \ +- __atg104_old = (*__atg104_memp); \ +- while (__builtin_expect \ +- (atomic_compare_and_exchange_bool_rel ( \ +- __atg104_memp, __atg104_old ^ __atg104_op, __atg104_old), 0));\ +- \ +- __atg104_old; }) ++ __atg104_desired = __atg104_expected ^ __atg104_op; \ ++ while (__glibc_unlikely \ ++ (atomic_compare_exchange_weak_release ( \ ++ __atg104_memp, &__atg104_expected, __atg104_desired) \ ++ == 0)); \ ++ __atg104_expected; }) + #endif + + #endif /* !USE_ATOMIC_COMPILER_BUILTINS */ +-- +2.10.2 + |
