| From | Greg Kroah-Hartman <> | Subject | [PATCH 4.14 023/193] MIPS: cmpxchg64() and HAVE_VIRT_CPU_ACCOUNTING_GEN dont work for 32-bit SMP | Date | Tue, 28 Nov 2017 11:24:30 +0100 |
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4.14-stable review patch. If anyone has any objections, please let me know.
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From: Ben Hutchings <ben@decadent.org.uk>
commit a3f143106596d739e7fbc4b84c96b1475247d876 upstream.
__cmpxchg64_local_generic() is atomic only w.r.t tasks and interrupts on the same CPU (that's what the 'local' means). We can't use it to implement cmpxchg64() in SMP configurations.
So, for 32-bit SMP configurations:
- Don't define cmpxchg64() - Don't enable HAVE_VIRT_CPU_ACCOUNTING_GEN, which requires it
Fixes: e2093c7b03c1 ("MIPS: Fall back to generic implementation of ...") Fixes: bb877e96bea1 ("MIPS: Add support for full dynticks CPU time accounting") Signed-off-by: Ben Hutchings <ben@decadent.org.uk> Cc: Ralf Baechle <ralf@linux-mips.org> Cc: Deng-Cheng Zhu <dengcheng.zhu@mips.com> Cc: linux-mips@linux-mips.org Patchwork: https://patchwork.linux-mips.org/patch/17413/ Signed-off-by: James Hogan <jhogan@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
--- arch/mips/Kconfig | 2 +- arch/mips/include/asm/cmpxchg.h | 2 ++ 2 files changed, 3 insertions(+), 1 deletion(-)
--- a/arch/mips/Kconfig +++ b/arch/mips/Kconfig @@ -65,7 +65,7 @@ config MIPS select HAVE_PERF_EVENTS select HAVE_REGS_AND_STACK_ACCESS_API select HAVE_SYSCALL_TRACEPOINTS - select HAVE_VIRT_CPU_ACCOUNTING_GEN + select HAVE_VIRT_CPU_ACCOUNTING_GEN if 64BIT || !SMP select IRQ_FORCED_THREADING select MODULES_USE_ELF_RELA if MODULES && 64BIT select MODULES_USE_ELF_REL if MODULES --- a/arch/mips/include/asm/cmpxchg.h +++ b/arch/mips/include/asm/cmpxchg.h @@ -204,8 +204,10 @@ static inline unsigned long __cmpxchg(vo #else #include <asm-generic/cmpxchg-local.h> #define cmpxchg64_local(ptr, o, n) __cmpxchg64_local_generic((ptr), (o), (n)) +#ifndef CONFIG_SMP #define cmpxchg64(ptr, o, n) cmpxchg64_local((ptr), (o), (n)) #endif +#endif #undef __scbeqz
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