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ALSA: 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@oracle.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
This commit is contained in:
Christine Spang 2013-03-04 17:02:59 -05:00 committed by Takashi Iwai
parent 8ba955cef3
commit d5702162f8
2 changed files with 13 additions and 23 deletions
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12
Documentation/DocBook/writing-an-alsa-driver.tmpl
View File

@ -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>

24
include/sound/core.h
View File

@ -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 */