config: convert R/W lock to mutex

The lock is no longer taken for reading ever, so it is equivalent to a
mutex. In fact, the lock is only needed to prevent concurrent writes
to the same config_item_t::value.

src/config/configuration.h

@@ -63,7 +63,7 @@ bool config_PrintHelp (vlc_object_t *);
 int config_SortConfig (void);
 void config_UnsortConfig (void);
 
-extern vlc_rwlock_t config_lock;
+extern vlc_mutex_t config_lock;
 extern _Atomic bool config_dirty;
 
 bool config_IsSafe (const char *);

src/config/core.c

@@ -39,7 +39,7 @@
 #include "modules/modules.h"
 #include "misc/rcu.h"
 
-vlc_rwlock_t config_lock = VLC_STATIC_RWLOCK;
+vlc_mutex_t config_lock = VLC_STATIC_MUTEX;
 atomic_bool config_dirty = ATOMIC_VAR_INIT(false);
 
 static inline char *strdupnull (const char *src)
@@ -139,9 +139,9 @@ int vlc_param_SetString(struct vlc_param *param, const char *value)
 
 void config_PutPsz(const char *psz_name, const char *psz_value)
 {
-    vlc_rwlock_wrlock (&config_lock);
+    vlc_mutex_lock(&config_lock);
     vlc_param_SetString(vlc_param_Find(psz_name), psz_value);
-    vlc_rwlock_unlock (&config_lock);
+    vlc_mutex_unlock(&config_lock);
     atomic_store_explicit(&config_dirty, true, memory_order_release);
 }
 
@@ -160,9 +160,9 @@ void config_PutInt(const char *name, int64_t i_value)
         i_value = p_config->max.i;
 
     atomic_store_explicit(&param->value.i, i_value, memory_order_relaxed);
-    vlc_rwlock_wrlock (&config_lock);
+    vlc_mutex_lock(&config_lock);
     p_config->value.i = i_value;
-    vlc_rwlock_unlock (&config_lock);
+    vlc_mutex_unlock(&config_lock);
     atomic_store_explicit(&config_dirty, true, memory_order_release);
 }
 
@@ -184,9 +184,9 @@ void config_PutFloat(const char *name, float f_value)
         f_value = p_config->max.f;
 
     atomic_store_explicit(&param->value.f, f_value, memory_order_relaxed);
-    vlc_rwlock_wrlock (&config_lock);
+    vlc_mutex_lock(&config_lock);
     p_config->value.f = f_value;
-    vlc_rwlock_unlock (&config_lock);
+    vlc_mutex_unlock(&config_lock);
     atomic_store_explicit(&config_dirty, true, memory_order_release);
 }
 
@@ -492,7 +492,7 @@ void config_Free(struct vlc_param *tab, size_t confsize)
 
 void config_ResetAll(void)
 {
-    vlc_rwlock_wrlock (&config_lock);
+    vlc_mutex_lock(&config_lock);
     for (vlc_plugin_t *p = vlc_plugins; p != NULL; p = p->next)
     {
         for (size_t i = 0; i < p->conf.size; i++ )
@@ -518,6 +518,6 @@ void config_ResetAll(void)
                 vlc_param_SetString(param, p_config->orig.psz);
         }
     }
-    vlc_rwlock_unlock (&config_lock);
+    vlc_mutex_lock(&config_lock);
     atomic_store_explicit(&config_dirty, true, memory_order_release);
 }

src/config/file.c

@@ -186,7 +186,7 @@ int config_LoadConfigFile( vlc_object_t *p_this )
     locale_t loc = newlocale (LC_NUMERIC_MASK, "C", NULL);
     locale_t baseloc = uselocale (loc);
 
-    vlc_rwlock_wrlock (&config_lock);
+    vlc_mutex_lock(&config_lock);
     while ((linelen = getline (&line, &bufsize, file)) != -1)
     {
         line[linelen - 1] = '\0'; /* trim newline */
@@ -257,7 +257,7 @@ int config_LoadConfigFile( vlc_object_t *p_this )
                 break;
         }
     }
-    vlc_rwlock_unlock (&config_lock);
+    vlc_mutex_unlock(&config_lock);
     free (line);
 
     if (ferror (file))