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Commit a3f14310 authored by Ben Hutchings's avatar Ben Hutchings Committed by James Hogan
Browse files

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: e2093c7b ("MIPS: Fall back to generic implementation of ...")
Fixes: bb877e96 ("MIPS: Add support for full dynticks CPU time accounting")
Signed-off-by: default avatarBen 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: default avatarJames Hogan <jhogan@kernel.org>
parent 4dc4704c

arch/mips/Kconfig

+1 −1
Original line number Diff line number Diff line
@@ -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

arch/mips/include/asm/cmpxchg.h

+2 −0
Original line number Diff line number Diff line
@@ -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