lkml.org 
[lkml]   [2011]   [Mar]   [17]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
Date
From
Subject[PATCH 1/2 v2] WARN_ON_SMP(): Allow use in if statements on UP
From: Steven Rostedt <srostedt@redhat.com>

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 <rostedt@goodmis.org>
---
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



\
 
 \ /
  Last update: 2011-03-17 23:01    [W:0.078 / U:0.264 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site