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authorBorislav Petkov <bbpetkov@yahoo.de>2007-05-06 14:49:17 -0700
committerLinus Torvalds <torvalds@woody.linux-foundation.org>2007-05-07 12:12:52 -0700
commit9490991482a2091a828d997adbc088e24c310a4d (patch)
treedcdd9febee63e82cd792250a8a4c4dd8e6aab4be
parenta8127717cb24be7b8827a8d9e0ddbfde6b392146 (diff)
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: Borislav Petkov <bbpetkov@yahoo.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--include/linux/compiler-gcc3.h6
-rw-r--r--include/linux/compiler-gcc4.h6
-rw-r--r--include/linux/compiler-intel.h2
-rw-r--r--mm/memory.c2
4 files changed, 15 insertions, 1 deletions
diff --git a/include/linux/compiler-gcc3.h b/include/linux/compiler-gcc3.h
index 1698b845761..ecd621fd27d 100644
--- a/include/linux/compiler-gcc3.h
+++ b/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 --git a/include/linux/compiler-gcc4.h b/include/linux/compiler-gcc4.h
index 6f5cc6f0e7a..fd0cc7c4a63 100644
--- a/include/linux/compiler-gcc4.h
+++ b/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 --git a/include/linux/compiler-intel.h b/include/linux/compiler-intel.h
index 1d1c3ceaff4..a436eea4391 100644
--- a/include/linux/compiler-intel.h
+++ b/include/linux/compiler-intel.h
@@ -22,3 +22,5 @@
(typeof(ptr)) (__ptr + (off)); })
#endif
+
+#define uninitialized_var(x) x
diff --git a/mm/memory.c b/mm/memory.c
index c252aae544e..1d647ab0ee7 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -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) :