On Fri, 2017-05-05 at 21:47 +0200, Arnd Bergmann wrote:
> From: Andre Przywara <andre.przywara@xxxxxxx>
>
> Commit 2427963027aea8d649b69a6956979cc875edfcf3 upstream.
>
> Commit 8053871d0f7f ("smp: Fix smp_call_function_single_async()
> locking") introduced a call to smp_load_acquire() with a u16 argument,
But the other commit hasn't been backported to 3.16. Should it be? Or
is there some other reason we need this one?
Ben.
> but we only cared about u32 and u64 types in that function so far.
> This resulted in a compiler warning fortunately, pointing at an
> uninitialized use. Due to the implementation structure the compiler
> misses that bug in the smp_store_release(), though.
> Add the u16 and u8 variants using ldarh/stlrh and ldarb/stlrb,
> respectively. Together with the compiletime_assert_atomic_type() check
> this should cover all cases now.
>
> Acked-by: Will Deacon <will.deacon@xxxxxxx>
> Signed-off-by: Andre Przywara <andre.przywara@xxxxxxx>
> Signed-off-by: Will Deacon <will.deacon@xxxxxxx>
> Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx>
> ---
> arch/arm64/include/asm/barrier.h | 16 ++++++++++++++++
> 1 file changed, 16 insertions(+)
>
> diff --git a/arch/arm64/include/asm/barrier.h b/arch/arm64/include/asm/barrier.h
> index 6389d60574d9..45548e19c673 100644
> --- a/arch/arm64/include/asm/barrier.h
> +++ b/arch/arm64/include/asm/barrier.h
> @@ -62,6 +62,14 @@ do { \
> do { \
> compiletime_assert_atomic_type(*p); \
> switch (sizeof(*p)) { \
> + case 1: \
> + asm volatile ("stlrb %w1, %0" \
> + : "=Q" (*p) : "r" (v) : "memory"); \
> + break; \
> + case 2: \
> + asm volatile ("stlrh %w1, %0" \
> + : "=Q" (*p) : "r" (v) : "memory"); \
> + break; \
> case 4: \
> asm volatile ("stlr %w1, %0" \
> : "=Q" (*p) : "r" (v) : "memory"); \
> @@ -78,6 +86,14 @@ do { \
> typeof(*p) ___p1; \
> compiletime_assert_atomic_type(*p); \
> switch (sizeof(*p)) { \
> + case 1: \
> + asm volatile ("ldarb %w0, %1" \
> + : "=r" (___p1) : "Q" (*p) : "memory"); \
> + break; \
> + case 2: \
> + asm volatile ("ldarh %w0, %1" \
> + : "=r" (___p1) : "Q" (*p) : "memory"); \
> + break; \
> case 4: \
> asm volatile ("ldar %w0, %1" \
> : "=r" (___p1) : "Q" (*p) : "memory"); \
--
Ben Hutchings
It is a miracle that curiosity survives formal education. - Albert
Einstein
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