* [PATCH] asm-generic: Fix 32 bit __generic_cmpxchg_local
@ 2024-01-04 9:40 Stuart Menefy
2024-01-05 22:25 ` Arnd Bergmann
0 siblings, 1 reply; 2+ messages in thread
From: Stuart Menefy @ 2024-01-04 9:40 UTC (permalink / raw)
To: Arnd Bergmann, linux-kernel; +Cc: linux-arch, David McKay
From: David McKay <david.mckay@codasip.com>
Commit 656e9007ef58 ("asm-generic: avoid __generic_cmpxchg_local
warnings") introduced a typo that means the code is incorrect for 32 bit
values. It will work fine for postive numbers, but will fail for
negative numbers on a system where longs are 64 bit.
Fixes: 656e9007ef58 ("asm-generic: avoid __generic_cmpxchg_local warnings")
Signed-off-by: David McKay <david.mckay@codasip.com>
Signed-off-by: Stuart Menefy <stuart.menefy@codasip.com>
---
include/asm-generic/cmpxchg-local.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/include/asm-generic/cmpxchg-local.h b/include/asm-generic/cmpxchg-local.h
index 3df9f59a544e..f27d66fdc00a 100644
--- a/include/asm-generic/cmpxchg-local.h
+++ b/include/asm-generic/cmpxchg-local.h
@@ -34,7 +34,7 @@ static inline unsigned long __generic_cmpxchg_local(volatile void *ptr,
*(u16 *)ptr = (new & 0xffffu);
break;
case 4: prev = *(u32 *)ptr;
- if (prev == (old & 0xffffffffffu))
+ if (prev == (old & 0xffffffffu))
*(u32 *)ptr = (new & 0xffffffffu);
break;
case 8: prev = *(u64 *)ptr;
--
2.39.3
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH] asm-generic: Fix 32 bit __generic_cmpxchg_local
2024-01-04 9:40 [PATCH] asm-generic: Fix 32 bit __generic_cmpxchg_local Stuart Menefy
@ 2024-01-05 22:25 ` Arnd Bergmann
0 siblings, 0 replies; 2+ messages in thread
From: Arnd Bergmann @ 2024-01-05 22:25 UTC (permalink / raw)
To: Stuart Menefy, linux-kernel; +Cc: Linux-Arch, David McKay
On Thu, Jan 4, 2024, at 10:40, Stuart Menefy wrote:
> From: David McKay <david.mckay@codasip.com>
>
> Commit 656e9007ef58 ("asm-generic: avoid __generic_cmpxchg_local
> warnings") introduced a typo that means the code is incorrect for 32 bit
> values. It will work fine for postive numbers, but will fail for
> negative numbers on a system where longs are 64 bit.
>
> Fixes: 656e9007ef58 ("asm-generic: avoid __generic_cmpxchg_local warnings")
> Signed-off-by: David McKay <david.mckay@codasip.com>
> Signed-off-by: Stuart Menefy <stuart.menefy@codasip.com>
Applied to the asm-generic tree, thanks a lot!
arnd
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