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From bc2d0d8c41541bfea6fc2974bb4722c096211d9e Mon Sep 17 00:00:00 2001
From: Kamil Rytarowski <n54@gmx.com>
Date: Thu, 13 Feb 2020 16:23:21 +0100
Subject: [PATCH] mutex: Switch the POSIX backend to PTHREAD_MUTEX_RECURSIVE
The code for recursive mutexes triggered Undefined Behavior
and crash as pthread_equal(3) was not used in a portable way.
On the first call of mutex_lock() pthread_equal() was called with
a pthread_t of value -1 which is invalid.
Passing a non valid thread ID to pthread_equal is undefined.
Switch the backend to native interface for POSIX recursive
mutexes with PTHREAD_MUTEX_RECURSIVE and simplify the code.
Detected on NetBSD/amd64 9.99.46.
Signed-off-by: Marvin Scholz <epirat07@gmail.com>
---
src/util/mutex.c | 47 +++++++++--------------------------------------
1 file changed, 9 insertions(+), 38 deletions(-)
diff --git a/src/util/mutex.c b/src/util/mutex.c
index c32bb5fd..b3fee526 100644
--- a/src/util/mutex.c
+++ b/src/util/mutex.c
@@ -68,18 +68,16 @@ static int _mutex_destroy(MUTEX_IMPL *p)
#elif defined(HAVE_PTHREAD_H)
-typedef struct {
- int lock_count;
- pthread_t owner;
- pthread_mutex_t mutex;
-} MUTEX_IMPL;
+typedef pthread_mutex_t MUTEX_IMPL;
static int _mutex_init(MUTEX_IMPL *p)
{
- p->owner = (pthread_t)-1;
- p->lock_count = 0;
+ pthread_mutexattr_t attr;
- if (pthread_mutex_init(&p->mutex, NULL)) {
+ pthread_mutexattr_init(&attr);
+ pthread_mutexattr_settype(&attr, PTHREAD_MUTEX_RECURSIVE);
+
+ if (pthread_mutex_init(p, &attr)) {
BD_DEBUG(DBG_BLURAY|DBG_CRIT, "pthread_mutex_init() failed !\n");
return -1;
}
@@ -89,40 +87,17 @@ static int _mutex_init(MUTEX_IMPL *p)
static int _mutex_lock(MUTEX_IMPL *p)
{
- if (pthread_equal(p->owner, pthread_self())) {
- /* recursive lock */
- p->lock_count++;
- return 0;
- }
-
- if (pthread_mutex_lock(&p->mutex)) {
+ if (pthread_mutex_lock(p)) {
BD_DEBUG(DBG_BLURAY|DBG_CRIT, "pthread_mutex_lock() failed !\n");
return -1;
}
- p->owner = pthread_self();
- p->lock_count = 1;
-
return 0;
}
static int _mutex_unlock(MUTEX_IMPL *p)
{
- if (!pthread_equal(p->owner, pthread_self())) {
- BD_DEBUG(DBG_BLURAY|DBG_CRIT, "bd_mutex_unlock(): not owner !\n");
- return -1;
- }
-
- p->lock_count--;
- if (p->lock_count > 0) {
- return 0;
- }
-
- /* unlock */
-
- p->owner = (pthread_t)-1;
-
- if (pthread_mutex_unlock(&p->mutex)) {
+ if (pthread_mutex_unlock(p)) {
BD_DEBUG(DBG_BLURAY|DBG_CRIT, "pthread_mutex_unlock() failed !\n");
return -1;
}
@@ -132,10 +107,7 @@ static int _mutex_unlock(MUTEX_IMPL *p)
static int _mutex_destroy(MUTEX_IMPL *p)
{
- _mutex_lock(p);
- _mutex_unlock(p);
-
- if (pthread_mutex_destroy(&p->mutex)) {
+ if (pthread_mutex_destroy(p)) {
BD_DEBUG(DBG_BLURAY|DBG_CRIT, "pthread_mutex_destroy() failed !\n");
return -1;
}
@@ -193,4 +165,3 @@ int bd_mutex_destroy(BD_MUTEX *p)
X_FREE(p->impl);
return 0;
}
-
--
2.24.1
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