From c792238027157d0fc6a80a8ea1b9d73443459d75 Mon Sep 17 00:00:00 2001 From: Ben Hutchings Date: Wed, 4 Oct 2017 03:46:14 +0100 Subject: [PATCH] MIPS: cmpxchg64() and HAVE_VIRT_CPU_ACCOUNTING_GEN don't work for 32-bit SMP 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 Cc: Ralf Baechle Cc: Deng-Cheng Zhu Cc: linux-mips@linux-mips.org Patchwork: https://patchwork.linux-mips.org/patch/17413/ Signed-off-by: James Hogan Signed-off-by: Greg Kroah-Hartman --- arch/mips/Kconfig | 2 +- arch/mips/include/asm/cmpxchg.h | 2 ++ 2 files changed, 3 insertions(+), 1 deletion(-) diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig index 5d3284d20678..c3d798b44030 100644 --- 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 diff --git a/arch/mips/include/asm/cmpxchg.h b/arch/mips/include/asm/cmpxchg.h index 7e25c5cc353a..89e9fb7976fe 100644 --- a/arch/mips/include/asm/cmpxchg.h +++ b/arch/mips/include/asm/cmpxchg.h @@ -204,8 +204,10 @@ static inline unsigned long __cmpxchg(volatile void *ptr, unsigned long old, #else #include #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 -- 2.20.1