From: Steven Rostedt Both WARN_ON() and WARN_ON_SMP() should be able to be used in an if statement. if (WARN_ON_SMP(foo)) { ... } Because WARN_ON_SMP() is defined as a do { } while (0) on UP, it can not be used this way. Convert it to the same form that WARN_ON() is, even when CONFIG_SMP is off. Signed-off-by: Steven Rostedt --- include/asm-generic/bug.h | 28 +++++++++++++++++++++++++++- 1 files changed, 27 insertions(+), 1 deletions(-) diff --git a/include/asm-generic/bug.h b/include/asm-generic/bug.h index c2c9ba0..f2d2faf 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 -- 1.7.2.3 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/