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authorLinus Torvalds <torvalds@linux-foundation.org>2011-01-24 19:58:39 +1000
committerLinus Torvalds <torvalds@linux-foundation.org>2011-01-24 19:58:39 +1000
commitd315777b32a4696feb86f2a0c9e9f39c94683649 (patch)
treef21c24d85cde6ad453c4d9485f5de49357336f81 /include
parent5a05a6d7a51bcc47c5c6f0ed68e433f9a01afd89 (diff)
parent1765e3a4933ea0870fabd755feffc5473c4363ce (diff)
Merge branch 'BUG_ON' of git://git.kernel.org/pub/scm/linux/kernel/git/rusty/linux-2.6-for-linus
* 'BUG_ON' of git://git.kernel.org/pub/scm/linux/kernel/git/rusty/linux-2.6-for-linus: Remove MAYBE_BUILD_BUG_ON BUILD_BUG_ON: make it handle more cases
Diffstat (limited to 'include')
-rw-r--r--include/linux/gfp.h2
-rw-r--r--include/linux/kernel.h32
-rw-r--r--include/linux/kmemcheck.h2
-rw-r--r--include/linux/virtio_config.h5
4 files changed, 32 insertions, 9 deletions
diff --git a/include/linux/gfp.h b/include/linux/gfp.h
index a3b148a9187..0b84c61607e 100644
--- a/include/linux/gfp.h
+++ b/include/linux/gfp.h
@@ -249,7 +249,7 @@ static inline enum zone_type gfp_zone(gfp_t flags)
((1 << ZONES_SHIFT) - 1);
if (__builtin_constant_p(bit))
- MAYBE_BUILD_BUG_ON((GFP_ZONE_BAD >> bit) & 1);
+ BUILD_BUG_ON((GFP_ZONE_BAD >> bit) & 1);
else {
#ifdef CONFIG_DEBUG_VM
BUG_ON((GFP_ZONE_BAD >> bit) & 1);
diff --git a/include/linux/kernel.h b/include/linux/kernel.h
index d07d8057e44..e2f4d6af212 100644
--- a/include/linux/kernel.h
+++ b/include/linux/kernel.h
@@ -575,12 +575,6 @@ struct sysinfo {
char _f[20-2*sizeof(long)-sizeof(int)]; /* Padding: libc5 uses this.. */
};
-/* Force a compilation error if condition is true */
-#define BUILD_BUG_ON(condition) ((void)BUILD_BUG_ON_ZERO(condition))
-
-/* Force a compilation error if condition is constant and true */
-#define MAYBE_BUILD_BUG_ON(cond) ((void)sizeof(char[1 - 2 * !!(cond)]))
-
/* Force a compilation error if a constant expression is not a power of 2 */
#define BUILD_BUG_ON_NOT_POWER_OF_2(n) \
BUILD_BUG_ON((n) == 0 || (((n) & ((n) - 1)) != 0))
@@ -592,6 +586,32 @@ struct sysinfo {
#define BUILD_BUG_ON_ZERO(e) (sizeof(struct { int:-!!(e); }))
#define BUILD_BUG_ON_NULL(e) ((void *)sizeof(struct { int:-!!(e); }))
+/**
+ * BUILD_BUG_ON - break compile if a condition is true.
+ * @cond: the condition which the compiler should know is false.
+ *
+ * If you have some code which relies on certain constants being equal, or
+ * other compile-time-evaluated condition, you should use BUILD_BUG_ON to
+ * detect if someone changes it.
+ *
+ * The implementation uses gcc's reluctance to create a negative array, but
+ * gcc (as of 4.4) only emits that error for obvious cases (eg. not arguments
+ * to inline functions). So as a fallback we use the optimizer; if it can't
+ * prove the condition is false, it will cause a link error on the undefined
+ * "__build_bug_on_failed". This error message can be harder to track down
+ * though, hence the two different methods.
+ */
+#ifndef __OPTIMIZE__
+#define BUILD_BUG_ON(condition) ((void)sizeof(char[1 - 2*!!(condition)]))
+#else
+extern int __build_bug_on_failed;
+#define BUILD_BUG_ON(condition) \
+ do { \
+ ((void)sizeof(char[1 - 2*!!(condition)])); \
+ if (condition) __build_bug_on_failed = 1; \
+ } while(0)
+#endif
+
/* Trap pasters of __FUNCTION__ at compile-time */
#define __FUNCTION__ (__func__)
diff --git a/include/linux/kmemcheck.h b/include/linux/kmemcheck.h
index 08d7dc4ddf4..39f8453239f 100644
--- a/include/linux/kmemcheck.h
+++ b/include/linux/kmemcheck.h
@@ -76,7 +76,7 @@ bool kmemcheck_is_obj_initialized(unsigned long addr, size_t size);
\
_n = (long) &((ptr)->name##_end) \
- (long) &((ptr)->name##_begin); \
- MAYBE_BUILD_BUG_ON(_n < 0); \
+ BUILD_BUG_ON(_n < 0); \
\
kmemcheck_mark_initialized(&((ptr)->name##_begin), _n); \
} while (0)
diff --git a/include/linux/virtio_config.h b/include/linux/virtio_config.h
index 0093dd7c1d6..800617b4ddd 100644
--- a/include/linux/virtio_config.h
+++ b/include/linux/virtio_config.h
@@ -109,7 +109,10 @@ static inline bool virtio_has_feature(const struct virtio_device *vdev,
unsigned int fbit)
{
/* Did you forget to fix assumptions on max features? */
- MAYBE_BUILD_BUG_ON(fbit >= 32);
+ if (__builtin_constant_p(fbit))
+ BUILD_BUG_ON(fbit >= 32);
+ else
+ BUG_ON(fbit >= 32);
if (fbit < VIRTIO_TRANSPORT_F_START)
virtio_check_driver_offered_feature(vdev, fbit);