The patch below does not apply to the 4.9-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
From a3f143106596d739e7fbc4b84c96b1475247d876 Mon Sep 17 00:00:00 2001
From: Ben Hutchings ben@decadent.org.uk 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
__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 Cc: stable@vger.kernel.org # 4.1+ Patchwork: https://patchwork.linux-mips.org/patch/17413/ Signed-off-by: James Hogan jhogan@kernel.org
diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig index 43411118dd4f..b09b644cd57c 100644 --- a/arch/mips/Kconfig +++ b/arch/mips/Kconfig @@ -64,7 +64,7 @@ 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 903f3bf48419..ae2b4583b486 100644 --- a/arch/mips/include/asm/cmpxchg.h +++ b/arch/mips/include/asm/cmpxchg.h @@ -202,8 +202,10 @@ static inline unsigned long __cmpxchg(volatile void *ptr, unsigned long old, #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