Protect context switches with a lock in the router

router/alc.c

@@ -420,16 +420,21 @@ ALC_API ALCboolean ALC_APIENTRY alcMakeContextCurrent(ALCcontext *context)
 {
     ALint idx = -1;
 
+    almtx_lock(&ContextSwitchLock);
     if(context)
     {
         idx = LookupPtrIntMapKey(&ContextIfaceMap, context);
         if(idx < 0)
         {
             ATOMIC_STORE_SEQ(&LastError, ALC_INVALID_CONTEXT);
+            almtx_unlock(&ContextSwitchLock);
             return ALC_FALSE;
         }
         if(!DriverList[idx].alcMakeContextCurrent(context))
+        {
+            almtx_unlock(&ContextSwitchLock);
             return ALC_FALSE;
+        }
     }
 
     /* Unset the context from the old driver if it's different from the new
@@ -446,6 +451,7 @@ ALC_API ALCboolean ALC_APIENTRY alcMakeContextCurrent(ALCcontext *context)
         if(oldiface && oldiface != &DriverList[idx])
             oldiface->alcMakeContextCurrent(NULL);
     }
+    almtx_unlock(&ContextSwitchLock);
 
     return ALC_TRUE;
 }

router/router.c

@@ -16,6 +16,7 @@ int DriverListSize = 0;
 static int DriverListSizeMax = 0;
 
 almtx_t EnumerationLock;
+almtx_t ContextSwitchLock;
 
 static void LoadDriverList(void);
 
@@ -29,6 +30,7 @@ BOOL APIENTRY DllMain(HINSTANCE UNUSED(module), DWORD reason, void* UNUSED(reser
         case DLL_PROCESS_ATTACH:
             LoadDriverList();
             almtx_init(&EnumerationLock, almtx_recursive);
+            almtx_init(&ContextSwitchLock, almtx_plain);
             break;
 
         case DLL_THREAD_ATTACH:
@@ -37,6 +39,7 @@ BOOL APIENTRY DllMain(HINSTANCE UNUSED(module), DWORD reason, void* UNUSED(reser
 
         case DLL_PROCESS_DETACH:
             ReleaseALC();
+            almtx_destroy(&ContextSwitchLock);
             almtx_destroy(&EnumerationLock);
             for(i = 0;i < DriverListSize;i++)
             {

router/router.h

@@ -152,6 +152,7 @@ ALint LookupPtrIntMapKey(PtrIntMap *map, ALvoid *key);
 
 
 extern almtx_t EnumerationLock;
+extern almtx_t ContextSwitchLock;
 
 void ReleaseALC(void);