Am 03.12.2014 um 23:30 schrieb Christian Borntraeger: > As discussed on LKML http://marc.info/?i=54611D86.4040306%40de.ibm.com > ACCESS_ONCE might fail with specific compiler for non-scalar accesses. > > Here is a set of patches to tackle that problem. > > The first patch introduce READ_ONCE and ASSIGN_ONCE. If the data structure > is larger than the machine word size memcpy is used and a warning is emitted. > The next patches fix up all in-tree users of ACCESS_ONCE on non-scalar types. > The last patch forces ACCESS_ONCE to work only on scalar types. > > I have cross-compiled the resulting kernel with defconfig and gcc 4.9 for > microblaze, m68k, alpha, s390,x86_64, i686, sparc, sparc64, mips, > ia64, arm and arm64. > > Runtime tested on s390x and x86_64. I have also verified that ASSIGN_ONCE works > as expected with some test changes as there are no user in this patch series. > > Linus, ok for the next merge window? > > Christian Borntraeger (9): > kernel: Provide READ_ONCE and ASSIGN_ONCE > mm: replace ACCESS_ONCE with READ_ONCE or barriers > x86/spinlock: Replace ACCESS_ONCE with READ_ONCE > x86/gup: Replace ACCESS_ONCE with READ_ONCE > mips/gup: Replace ACCESS_ONCE with READ_ONCE > arm64/spinlock: Replace ACCESS_ONCE READ_ONCE > arm/spinlock: Replace ACCESS_ONCE with READ_ONCE > s390/kvm: REPLACE ACCESS_ONCE with READ_ONCE > kernel: tighten rules for ACCESS ONCE > > arch/arm/include/asm/spinlock.h | 4 +-- > arch/arm64/include/asm/spinlock.h | 4 +-- > arch/mips/mm/gup.c | 2 +- > arch/s390/kvm/gaccess.c | 14 ++++---- > arch/x86/include/asm/spinlock.h | 8 ++--- > arch/x86/mm/gup.c | 2 +- > include/linux/compiler.h | 74 ++++++++++++++++++++++++++++++++++++++- > mm/gup.c | 2 +- > mm/memory.c | 2 +- > mm/rmap.c | 3 +- > 10 files changed, 95 insertions(+), 20 deletions(-) > FWIW, the code is on git://git.kernel.org/pub/scm/linux/kernel/git/borntraeger/linux.git linux-next and git://git.kernel.org/pub/scm/linux/kernel/git/borntraeger/linux.git ACCESS_ONCE I rebased the queue against rc3 + the initial patch that triggered the whole discussion. Christian -- To unsubscribe from this list: send the line "unsubscribe linux-arch" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
