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xen: avoid type warning in xchg_xen_ulong

Message ID 20170529130125.307182-1-arnd@arndb.de
State Superseded
Headers show

Commit Message

Arnd Bergmann May 29, 2017, 1:01 p.m. UTC
The improved type-checking version of container_of() triggers a warning for
xchg_xen_ulong, pointing out that 'xen_ulong_t' is unsigned, but atomic64_t
contains a signed value:

drivers/xen/events/events_2l.c: In function 'evtchn_2l_handle_events':
arch/x86/include/asm/cmpxchg.h:87:21: error: 'pending_words' is used uninitialized in this function [-Werror=uninitialized]

This adds a cast to work around the warning

Cc: Ian Abbott <abbotti@mev.co.uk>
Fixes: 85323a991d40 ("xen: arm: mandate EABI and use generic atomic operations.")
Fixes: daa2ac80834d ("kernel.h: handle pointers to arrays better in container_of()")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

---
 arch/arm/include/asm/xen/events.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

-- 
2.9.0

Comments

Stefano Stabellini May 31, 2017, 12:05 a.m. UTC | #1
On Mon, 29 May 2017, Arnd Bergmann wrote:
> The improved type-checking version of container_of() triggers a warning for

> xchg_xen_ulong, pointing out that 'xen_ulong_t' is unsigned, but atomic64_t

> contains a signed value:

> 

> drivers/xen/events/events_2l.c: In function 'evtchn_2l_handle_events':

> arch/x86/include/asm/cmpxchg.h:87:21: error: 'pending_words' is used uninitialized in this function [-Werror=uninitialized]


I don't think this is the warning message you wanted to paste here?
Other than that, the patch is fine.


> This adds a cast to work around the warning

> 

> Cc: Ian Abbott <abbotti@mev.co.uk>

> Fixes: 85323a991d40 ("xen: arm: mandate EABI and use generic atomic operations.")

> Fixes: daa2ac80834d ("kernel.h: handle pointers to arrays better in container_of()")

> Signed-off-by: Arnd Bergmann <arnd@arndb.de>

> ---

>  arch/arm/include/asm/xen/events.h | 2 +-

>  1 file changed, 1 insertion(+), 1 deletion(-)

> 

> diff --git a/arch/arm/include/asm/xen/events.h b/arch/arm/include/asm/xen/events.h

> index 71e473d05fcc..620dc75362e5 100644

> --- a/arch/arm/include/asm/xen/events.h

> +++ b/arch/arm/include/asm/xen/events.h

> @@ -16,7 +16,7 @@ static inline int xen_irqs_disabled(struct pt_regs *regs)

>  	return raw_irqs_disabled_flags(regs->ARM_cpsr);

>  }

>  

> -#define xchg_xen_ulong(ptr, val) atomic64_xchg(container_of((ptr),	\

> +#define xchg_xen_ulong(ptr, val) atomic64_xchg(container_of((long long*)(ptr),\

>  							    atomic64_t,	\

>  							    counter), (val))
diff mbox

Patch

diff --git a/arch/arm/include/asm/xen/events.h b/arch/arm/include/asm/xen/events.h
index 71e473d05fcc..620dc75362e5 100644
--- a/arch/arm/include/asm/xen/events.h
+++ b/arch/arm/include/asm/xen/events.h
@@ -16,7 +16,7 @@  static inline int xen_irqs_disabled(struct pt_regs *regs)
 	return raw_irqs_disabled_flags(regs->ARM_cpsr);
 }
 
-#define xchg_xen_ulong(ptr, val) atomic64_xchg(container_of((ptr),	\
+#define xchg_xen_ulong(ptr, val) atomic64_xchg(container_of((long long*)(ptr),\
 							    atomic64_t,	\
 							    counter), (val))