This is a note to let you know that I've just added the patch titled
MIPS: cmpxchg64() and HAVE_VIRT_CPU_ACCOUNTING_GEN don't work for 32-bit SMP
to the 4.14-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
mips-cmpxchg64-and-have_virt_cpu_accounting_gen-don-t-work-for-32-bit-smp.patch
and it can be found in the queue-4.14 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From a3f143106596d739e7fbc4b84c96b1475247d876 Mon Sep 17 00:00:00 2001
From: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
Date: Wed, 4 Oct 2017 03:46:14 +0100
Subject: MIPS: cmpxchg64() and HAVE_VIRT_CPU_ACCOUNTING_GEN don't work for 32-bit SMP
From: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
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@xxxxxxxxxxxxxxx>
Cc: Ralf Baechle <ralf@xxxxxxxxxxxxxx>
Cc: Deng-Cheng Zhu <dengcheng.zhu@xxxxxxxx>
Cc: linux-mips@xxxxxxxxxxxxxx
Patchwork: https://patchwork.linux-mips.org/patch/17413/
Signed-off-by: James Hogan <jhogan@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
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
Patches currently in stable-queue which might be from ben@xxxxxxxxxxxxxxx are
queue-4.14/mips-cmpxchg64-and-have_virt_cpu_accounting_gen-don-t-work-for-32-bit-smp.patch