Messages in this thread Patch in this message | | | Date | Sun, 29 Apr 2007 02:24:40 -0700 | From | Andrew Morton <> | Subject | Re: [PATCH] mm/memory.c: remove warning from an uninitialized spinlock. was: Re: 2.6.21-rc7-mm2 |
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On Sun, 29 Apr 2007 08:50:49 +0200 Borislav Petkov <bbpetkov@yahoo.de> wrote:
> Introduce a macro for suppressing gcc from generating a warning about a probable > unitialized state of a variable.
I ended up doing the below.
It's better to make this a per-compiler-version thing: later versions of gcc might need different tricks, or might provide __attribute__((stfu)) or whatever.
Plus I don't know if the x=x trick is needed on the intel compiler, nor if it even works, so I left ICC alone.
From: Borislav Petkov <bbpetkov@yahoo.de>
Introduce a macro for suppressing gcc from generating a warning about a probable uninitialized state of a variable.
Example:
- spinlock_t *ptl; + spinlock_t *uninitialized_var(ptl);
Not a happy solution, but those warnings are obnoxious.
- Using the usual pointlessly-set-it-to-zero approach wastes several bytes of text.
- Using a macro means we can (hopefully) do something else if gcc changes cause the `x = x' hack to stop working
- Using a macro means that people who are worried about hiding true bugs can easily turn it off.
Signed-off-by: Borislav Petkov <bbpetkov@yahoo.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> ---
include/linux/compiler-gcc3.h | 6 ++++++ include/linux/compiler-gcc4.h | 6 ++++++ include/linux/compiler-intel.h | 2 ++ 3 files changed, 14 insertions(+)
diff -puN include/linux/compiler-gcc3.h~add-unitialized_var-macro-for-suppressing-gcc-warnings include/linux/compiler-gcc3.h --- a/include/linux/compiler-gcc3.h~add-unitialized_var-macro-for-suppressing-gcc-warnings +++ a/include/linux/compiler-gcc3.h @@ -13,4 +13,10 @@ #define __must_check __attribute__((warn_unused_result)) #endif +/* + * A trick to suppress uninitialized variable warning without generating any + * code + */ +#define uninitialized_var(x) x = x + #define __always_inline inline __attribute__((always_inline)) diff -puN include/linux/compiler-gcc4.h~add-unitialized_var-macro-for-suppressing-gcc-warnings include/linux/compiler-gcc4.h --- a/include/linux/compiler-gcc4.h~add-unitialized_var-macro-for-suppressing-gcc-warnings +++ a/include/linux/compiler-gcc4.h @@ -16,3 +16,9 @@ #define __must_check __attribute__((warn_unused_result)) #define __compiler_offsetof(a,b) __builtin_offsetof(a,b) #define __always_inline inline __attribute__((always_inline)) + +/* + * A trick to suppress uninitialized variable warning without generating any + * code + */ +#define uninitialized_var(x) x = x diff -puN include/linux/compiler-intel.h~add-unitialized_var-macro-for-suppressing-gcc-warnings include/linux/compiler-intel.h --- a/include/linux/compiler-intel.h~add-unitialized_var-macro-for-suppressing-gcc-warnings +++ a/include/linux/compiler-intel.h @@ -22,3 +22,5 @@ (typeof(ptr)) (__ptr + (off)); }) #endif + +#define uninitialized_var(x) x _ - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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