linux-kernel - [PATCH 1/2] ALSA: pcm: use "do {} while (0)" for empty macro

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Message-Id: <20170518133610.1914235-1-arnd@arndb.de>
Date:   Thu, 18 May 2017 15:35:54 +0200
From:   Arnd Bergmann <arnd@...db.de>
To:     Takashi Iwai <tiwai@...e.com>
Cc:     Arnd Bergmann <arnd@...db.de>, Jaroslav Kysela <perex@...ex.cz>,
        alsa-devel@...a-project.org, linux-kernel@...r.kernel.org
Subject: [PATCH 1/2] ALSA: pcm: use "do {} while (0)" for empty macro

Recent compilers produce a harmless warning for the new pcm_call_notify()
macro when CONFIG_SND_PCM_OSS is disabled:

sound/core/pcm.c: In function 'snd_pcm_free':
sound/core/pcm.c:905:37: error: suggest braces around empty body in an 'if' statement [-Werror=empty-body]

This turns the empty macro into a 'do {} while (0)' statement to avoid
the warning.

Fixes: 58f30d650c7f ("ALSA: pcm: Build pcm notifier code conditionally")
Signed-off-by: Arnd Bergmann <arnd@...db.de>
---
 sound/core/pcm.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/sound/core/pcm.c b/sound/core/pcm.c
index 24acbfb5c531..d30dba0ee688 100644
--- a/sound/core/pcm.c
+++ b/sound/core/pcm.c
@@ -894,7 +894,7 @@ static void snd_pcm_free_stream(struct snd_pcm_str * pstr)
 			_notify->call(pcm);				\
 	} while (0)
 #else
-#define pcm_call_notify(pcm, call) /* NOP */
+#define pcm_call_notify(pcm, call) do {} while (0)
 #endif
 
 static int snd_pcm_free(struct snd_pcm *pcm)
-- 
2.9.0