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Commit 5ef03460 authored by Takashi Iwai's avatar Takashi Iwai Committed by Jaroslav Kysela
Browse files

ALSA: Introduce snd_BUG_ON() macro 



Introduced snd_BUG_ON() macro as a replacement of snd_assert() macro.
snd_assert() is pretty ugly as it has the control flow in its argument.
OTOH, snd_BUG_ON() behaves like a normal conditional, thus it's much
easier to read the flow.

Signed-off-by: default avatarTakashi Iwai <tiwai@suse.de>
Signed-off-by: default avatarJaroslav Kysela <perex@perex.cz>
parent 3caf8c08

Documentation/sound/alsa/DocBook/writing-an-alsa-driver.tmpl

+41 −0
Original line number Diff line number Diff line
@@ -6173,6 +6173,47 @@ struct _snd_pcm_runtime { 
	 When no debug flag is set, this macro is ignored. 

      </para>

    </section>



    <section id="useful-functions-snd-bug-on">

      <title><function>snd_BUG_ON()</function></title>

      <para>

        <function>snd_BUG_ON()</function> macro is similar with

	<function>WARN_ON()</function> macro. For example,  



        <informalexample>

          <programlisting>

<![CDATA[

  snd_BUG_ON(!pointer);

]]>

          </programlisting>

        </informalexample>



	or it can be used as the condition,

        <informalexample>

          <programlisting>

<![CDATA[

  if (snd_BUG_ON(non_zero_is_bug))

          return -EINVAL;

]]>

          </programlisting>

        </informalexample>



      </para>



      <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

	<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.

      </para>



    </section>



  </chapter>

include/sound/core.h

+4 −0
Original line number Diff line number Diff line
@@ -28,6 +28,7 @@ 
#include <linux/rwsem.h>		/* struct rw_semaphore */

#include <linux/pm.h>			/* pm_message_t */

#include <linux/device.h>

#include <linux/stringify.h>



/* number of supported soundcards */

#ifdef CONFIG_SND_DYNAMIC_MINORS
@@ -405,11 +406,14 @@ void snd_verbose_printd(const char *file, int line, const char *format, ...) 
	dump_stack();				\

} while (0)



#define snd_BUG_ON(cond)	WARN((cond), "BUG? (%s)\n", __stringify(cond))



#else /* !CONFIG_SND_DEBUG */



#define snd_printd(fmt, args...)	/* nothing */

#define snd_assert(expr, args...)	(void)(expr)

#define snd_BUG()			/* nothing */

#define snd_BUG_ON(cond)	({/*(void)(cond);*/ 0;})  /* always false */



#endif /* CONFIG_SND_DEBUG */