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authorLinus Torvalds <torvalds@linux-foundation.org>2011-03-25 17:52:22 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2011-03-25 17:52:22 -0700
commit94df491c4a01b39d81279a68386158eb02656712 (patch)
treeba431d9d74f11a7117883df54908ea39e4ef7c5c /include/asm-generic
parent26ff6801f751cd47e44c2e9507ec08b447f2d2b9 (diff)
parent29096202176ceaa5016a17ea2dd1aea19a4e90e2 (diff)
Merge branch 'core-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip
* 'core-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: futex: Fix WARN_ON() test for UP WARN_ON_SMP(): Allow use in if() statements on UP x86, dumpstack: Use %pB format specifier for stack trace vsprintf: Introduce %pB format specifier lockdep: Remove unused 'factor' variable from lockdep_stats_show()
Diffstat (limited to 'include/asm-generic')
-rw-r--r--include/asm-generic/bug.h28
1 files changed, 27 insertions, 1 deletions
diff --git a/include/asm-generic/bug.h b/include/asm-generic/bug.h
index c2c9ba032d46..f2d2faf4d9ae 100644
--- a/include/asm-generic/bug.h
+++ b/include/asm-generic/bug.h
@@ -165,10 +165,36 @@ extern void warn_slowpath_null(const char *file, const int line);
#define WARN_ON_RATELIMIT(condition, state) \
WARN_ON((condition) && __ratelimit(state))
+/*
+ * WARN_ON_SMP() is for cases that the warning is either
+ * meaningless for !SMP or may even cause failures.
+ * This is usually used for cases that we have
+ * WARN_ON(!spin_is_locked(&lock)) checks, as spin_is_locked()
+ * returns 0 for uniprocessor settings.
+ * It can also be used with values that are only defined
+ * on SMP:
+ *
+ * struct foo {
+ * [...]
+ * #ifdef CONFIG_SMP
+ * int bar;
+ * #endif
+ * };
+ *
+ * void func(struct foo *zoot)
+ * {
+ * WARN_ON_SMP(!zoot->bar);
+ *
+ * For CONFIG_SMP, WARN_ON_SMP() should act the same as WARN_ON(),
+ * and should be a nop and return false for uniprocessor.
+ *
+ * if (WARN_ON_SMP(x)) returns true only when CONFIG_SMP is set
+ * and x is true.
+ */
#ifdef CONFIG_SMP
# define WARN_ON_SMP(x) WARN_ON(x)
#else
-# define WARN_ON_SMP(x) do { } while (0)
+# define WARN_ON_SMP(x) ({0;})
#endif
#endif