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MIPS: cmpxchg64() and HAVE_VIRT_CPU_ACCOUNTING_GEN don't work for 32-bit SMP

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__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: e2093c7b03 ("MIPS: Fall back to generic implementation of ...")
Fixes: bb877e96be ("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>
This commit is contained in:
Ben Hutchings 2017-10-04 03:46:14 +01:00 committed by James Hogan
parent 4dc4704c00
commit a3f1431065
2 changed files with 3 additions and 1 deletions
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2
arch/mips/Kconfig
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@ -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

2
arch/mips/include/asm/cmpxchg.h
View File

@ -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