[PATCH 2/2] alsa-utils: pcmjob.c: use portable way to initialize recursive mutex

[PATCH 2/2] alsa-utils: pcmjob.c: use portable way to initialize recursive mutex

[John Spencer]

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attaching the patch, as i currently have problems with git-send-email.

thanks,
--JS

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From faed06fd4a3b97ee7f4b46c60e3a828e47845d0e Mon Sep 17 00:00:00 2001
From: John Spencer <maillist-alsa@barfooze.de>
Date: Fri, 8 Nov 2013 13:59:41 +0100
Subject: [PATCH] pcmjob.c: use portable way to initialize recursive mutex

PTHREAD_RECURSIVE_MUTEX_INITIALIZER_NP is not in POSIX, as _NP
(non-portable) suggests.

exposing such a symbol in musl libc would lock in the ABI for all
times and makes it impossible to do future changes to the under-
lying struct without hideous symbol versioning hacks.

use the portable way instead: pthread_once was designed for such
cases.

Signed-off-by: John Spencer <maillist-alsa@barfooze.de>
Tested-by: John Spencer <maillist-alsa@barfooze.de>
---
 alsaloop/pcmjob.c | 15 +++++++++++++--
 1 file changed, 13 insertions(+), 2 deletions(-)

diff --git a/alsaloop/pcmjob.c b/alsaloop/pcmjob.c
index 139b6fd..f32180c 100644
--- a/alsaloop/pcmjob.c
+++ b/alsaloop/pcmjob.c
@@ -62,11 +62,22 @@ static const char *src_types[] = {
 };
 #endif
 
-static pthread_mutex_t pcm_open_mutex =
-                                PTHREAD_RECURSIVE_MUTEX_INITIALIZER_NP;
+static pthread_once_t pcm_open_mutex_once = PTHREAD_ONCE_INIT;
+static pthread_mutex_t pcm_open_mutex;
+
+static void pcm_open_init_mutex(void)
+{
+	pthread_mutexattr_t attr;
+
+	pthread_mutexattr_init(&attr);
+	pthread_mutexattr_settype(&attr, PTHREAD_MUTEX_RECURSIVE);
+	pthread_mutex_init(&pcm_open_mutex, &attr);
+	pthread_mutexattr_destroy(&attr);
+}
 
 static inline void pcm_open_lock(void)
 {
+	pthread_once(&pcm_open_mutex_once, pcm_open_init_mutex);
 	if (workarounds & WORKAROUND_SERIALOPEN)
 	        pthread_mutex_lock(&pcm_open_mutex);
 }
-- 
1.8.4


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Re: [PATCH 2/2] alsa-utils: pcmjob.c: use portable way to initialize recursive mutex

[Jaroslav Kysela]

Date 8.11.2013 14:03, John Spencer wrote:
> attaching the patch, as i currently have problems with git-send-email.

Applied to our repo. Thanks.

					Jaroslav

-- 
Jaroslav Kysela <perex@perex.cz>
Linux Kernel Sound Maintainer
ALSA Project; Red Hat, Inc.