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Message-Id: <1362434579-7733-1-git-send-email-christine.spang@oracle.com>
Date: Mon, 4 Mar 2013 17:02:59 -0500
From: Christine Spang <christine.spang@...cle.com>
To: Jaroslav Kysela <perex@...ex.cz>, Takashi Iwai <tiwai@...e.de>
Cc: alsa-devel@...a-project.org, Jamie Iles <jamie.iles@...cle.com>,
Sasha Levin <sasha.levin@...cle.com>,
linux-kernel@...r.kernel.org,
Christine Spang <christine.spang@...cle.com>
Subject: [PATCH] Make snd_BUG_ON() always evaluate and return the conditional expression.
Having snd_BUG_ON() only evaluate its conditional when CONFIG_SND_DEBUG
is set leads to frequent bugs, since other similar macros in the kernel
have different behavior. Let's make snd_BUG_ON() act like those macros
so it will stop being accidentally misused.
Signed-off-by: Christine Spang <christine.spang@...cle.com>
---
Documentation/DocBook/writing-an-alsa-driver.tmpl | 12 +++++-------
include/sound/core.h | 24 ++++++++---------------
2 files changed, 13 insertions(+), 23 deletions(-)
diff --git a/Documentation/DocBook/writing-an-alsa-driver.tmpl b/Documentation/DocBook/writing-an-alsa-driver.tmpl
index bd6fee2..06741e9 100644
--- a/Documentation/DocBook/writing-an-alsa-driver.tmpl
+++ b/Documentation/DocBook/writing-an-alsa-driver.tmpl
@@ -6164,14 +6164,12 @@ struct _snd_pcm_runtime {
<para>
The macro takes an conditional expression to evaluate.
- When <constant>CONFIG_SND_DEBUG</constant>, is set, the
- expression is actually evaluated. If it's non-zero, it shows
- the warning message such as
+ When <constant>CONFIG_SND_DEBUG</constant>, is set, if the
+ expression is non-zero, it shows the warning message such as
<computeroutput>BUG? (xxx)</computeroutput>
- normally followed by stack trace. It returns the evaluated
- value.
- When no <constant>CONFIG_SND_DEBUG</constant> is set, this
- macro always returns zero.
+ normally followed by stack trace.
+
+ In both cases it returns the evaluated value.
</para>
</section>
diff --git a/include/sound/core.h b/include/sound/core.h
index 7cede2d..a63680b 100644
--- a/include/sound/core.h
+++ b/include/sound/core.h
@@ -379,18 +379,10 @@ void __snd_printk(unsigned int level, const char *file, int line,
* snd_BUG_ON - debugging check macro
* @cond: condition to evaluate
*
- * When CONFIG_SND_DEBUG is set, this macro evaluates the given condition,
- * and call WARN() and returns the value if it's non-zero.
- *
- * When CONFIG_SND_DEBUG is not set, this just returns zero, and the given
- * condition is ignored.
- *
- * NOTE: the argument won't be evaluated at all when CONFIG_SND_DEBUG=n.
- * Thus, don't put any statement that influences on the code behavior,
- * such as pre/post increment, to the argument of this macro.
- * If you want to evaluate and give a warning, use standard WARN_ON().
+ * Has the same behavior as WARN_ON when CONFIG_SND_DEBUG is set,
+ * otherwise just evaluates the conditional and returns the value.
*/
-#define snd_BUG_ON(cond) WARN((cond), "BUG? (%s)\n", __stringify(cond))
+#define snd_BUG_ON(cond) WARN_ON((cond))
#else /* !CONFIG_SND_DEBUG */
@@ -400,11 +392,11 @@ __printf(2, 3)
static inline void _snd_printd(int level, const char *format, ...) {}
#define snd_BUG() do { } while (0)
-static inline int __snd_bug_on(int cond)
-{
- return 0;
-}
-#define snd_BUG_ON(cond) __snd_bug_on(0 && (cond)) /* always false */
+
+#define snd_BUG_ON(condition) ({ \
+ int __ret_warn_on = !!(condition); \
+ unlikely(__ret_warn_on); \
+})
#endif /* CONFIG_SND_DEBUG */
--
1.8.2.rc0
--
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