* [RFC PATCH] MIPS: cmpxchg64() and HAVE_VIRT_CPU_ACCOUNTING_GEN don't work for 32-bit SMP
@ 2017-10-04 2:46 Ben Hutchings
2017-11-13 18:19 ` James Hogan
0 siblings, 1 reply; 3+ messages in thread
From: Ben Hutchings @ 2017-10-04 2:46 UTC (permalink / raw)
To: Ralf Baechle; +Cc: linux-mips, Deng-Cheng Zhu
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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: 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>
---
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 cb7fcc4216fd..1e23f8455b7d 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
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^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [RFC PATCH] MIPS: cmpxchg64() and HAVE_VIRT_CPU_ACCOUNTING_GEN don't work for 32-bit SMP
@ 2017-11-13 18:19 ` James Hogan
0 siblings, 0 replies; 3+ messages in thread
From: James Hogan @ 2017-11-13 18:19 UTC (permalink / raw)
To: Ben Hutchings; +Cc: Ralf Baechle, linux-mips, Deng-Cheng Zhu
On Wed, Oct 04, 2017 at 03:46:14AM +0100, Ben Hutchings wrote:
> __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>
Thanks, looks reasonable to me
Applied
Cheers
James
> ---
> 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 cb7fcc4216fd..1e23f8455b7d 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
>
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [RFC PATCH] MIPS: cmpxchg64() and HAVE_VIRT_CPU_ACCOUNTING_GEN don't work for 32-bit SMP
@ 2017-11-13 18:19 ` James Hogan
0 siblings, 0 replies; 3+ messages in thread
From: James Hogan @ 2017-11-13 18:19 UTC (permalink / raw)
To: Ben Hutchings; +Cc: Ralf Baechle, linux-mips, Deng-Cheng Zhu
On Wed, Oct 04, 2017 at 03:46:14AM +0100, Ben Hutchings wrote:
> __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>
Thanks, looks reasonable to me
Applied
Cheers
James
> ---
> 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 cb7fcc4216fd..1e23f8455b7d 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
>
^ permalink raw reply [flat|nested] 3+ messages in thread
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2017-10-04 2:46 [RFC PATCH] MIPS: cmpxchg64() and HAVE_VIRT_CPU_ACCOUNTING_GEN don't work for 32-bit SMP Ben Hutchings
2017-11-13 18:19 ` James Hogan
2017-11-13 18:19 ` James Hogan
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