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Commit 94909914 authored by Borislav Petkov's avatar Borislav Petkov Committed by Linus Torvalds
Browse files

Add unitialized_var() macro for suppressing gcc warnings 



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: default avatarBorislav Petkov <bbpetkov@yahoo.de>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent a8127717

include/linux/compiler-gcc3.h

+6 −0
Original line number Diff line number Diff line
@@ -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))

include/linux/compiler-gcc4.h

+6 −0
Original line number Diff line number Diff line
@@ -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

include/linux/compiler-intel.h

+2 −0
Original line number Diff line number Diff line
@@ -22,3 +22,5 @@ 
    (typeof(ptr)) (__ptr + (off)); })



#endif



#define uninitialized_var(x) x

mm/memory.c

+1 −1
Original line number Diff line number Diff line
@@ -1455,7 +1455,7 @@ static int apply_to_pte_range(struct mm_struct *mm, pmd_t *pmd, 
	pte_t *pte;

	int err;

	struct page *pmd_page;

	spinlock_t *ptl = ptl;		/* Suppress gcc warning */

	spinlock_t *uninitialized_var(ptl);



	pte = (mm == &init_mm) ?

		pte_alloc_kernel(pmd, addr) :