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authorDave Airlie <airlied@gmail.com>2011-01-25 08:41:58 +1000
committerDave Airlie <airlied@gmail.com>2011-01-25 08:41:58 +1000
commitabb72c828878a2c69b2cfb33ac30007c8ecd735e (patch)
treea95ace4f34d86d55b3307bd53354d335e9f23563 /include/linux/kernel.h
parent58bbf018a70c562437eeae121a5d021ba7fe56a5 (diff)
parent8e934dbf264418afe4d1dff34ce074ecc14280db (diff)
Merge branch 'drm-intel-fixes-2' of ssh://master.kernel.org/pub/scm/linux/kernel/git/ickle/drm-intel into drm-fixes
* 'drm-intel-fixes-2' of ssh://master.kernel.org/pub/scm/linux/kernel/git/ickle/drm-intel: (30 commits) drm/i915: Prevent uninitialised reads during error state capture drm/i915: Use consistent mappings for OpRegion between ACPI and i915 drm/i915: Handle the no-interrupts case for UMS by polling drm/i915: Disable high-precision vblank timestamping for UMS drm/i915: Increase the amount of defense before computing vblank timestamps drm/i915,agp/intel: Do not clear stolen entries Remove MAYBE_BUILD_BUG_ON BUILD_BUG_ON: make it handle more cases module: fix missing semicolons in MODULE macro usage param: add null statement to compiled-in module params module: fix linker error for MODULE_VERSION when !MODULE and CONFIG_SYSFS=n module: show version information for built-in modules in sysfs selinux: return -ENOMEM when memory allocation fails tpm: fix panic caused by "tpm: Autodetect itpm devices" TPM: Long default timeout fix trusted keys: Fix a memory leak in trusted_update(). keys: add trusted and encrypted maintainers encrypted-keys: rename encrypted_defined files to encrypted trusted-keys: rename trusted_defined files to trusted drm/i915: Recognise non-VGA display devices ...
Diffstat (limited to 'include/linux/kernel.h')
-rw-r--r--include/linux/kernel.h32
1 files changed, 26 insertions, 6 deletions
diff --git a/include/linux/kernel.h b/include/linux/kernel.h
index d07d8057e440..e2f4d6af2125 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__)