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

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
...@@ -13,4 +13,10 @@ ...@@ -13,4 +13,10 @@
#define __must_check __attribute__((warn_unused_result)) #define __must_check __attribute__((warn_unused_result))
#endif #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)) #define __always_inline inline __attribute__((always_inline))
...@@ -16,3 +16,9 @@ ...@@ -16,3 +16,9 @@
#define __must_check __attribute__((warn_unused_result)) #define __must_check __attribute__((warn_unused_result))
#define __compiler_offsetof(a,b) __builtin_offsetof(a,b) #define __compiler_offsetof(a,b) __builtin_offsetof(a,b)
#define __always_inline inline __attribute__((always_inline)) #define __always_inline inline __attribute__((always_inline))
/*
* A trick to suppress uninitialized variable warning without generating any
* code
*/
#define uninitialized_var(x) x = x
...@@ -22,3 +22,5 @@ ...@@ -22,3 +22,5 @@
(typeof(ptr)) (__ptr + (off)); }) (typeof(ptr)) (__ptr + (off)); })
#endif #endif
#define uninitialized_var(x) x
...@@ -1455,7 +1455,7 @@ static int apply_to_pte_range(struct mm_struct *mm, pmd_t *pmd, ...@@ -1455,7 +1455,7 @@ static int apply_to_pte_range(struct mm_struct *mm, pmd_t *pmd,
pte_t *pte; pte_t *pte;
int err; int err;
struct page *pmd_page; struct page *pmd_page;
spinlock_t *ptl = ptl; /* Suppress gcc warning */ spinlock_t *uninitialized_var(ptl);
pte = (mm == &init_mm) ? pte = (mm == &init_mm) ?
pte_alloc_kernel(pmd, addr) : pte_alloc_kernel(pmd, addr) :
......
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