Add unitialized_var() macro for suppressing gcc warnings (94909914) · Commits · 戴 / test

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> Signed-off-by:

Linus Torvalds <torvalds@linux-foundation.org>

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) :

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