glib-compat.h: add new thread API emulation on top of pre-2.31 API

Thread API changed in glib-2.31 significantly.  Before that version,
conditionals and mutexes were only allocated dynamically, using
_new()/_free() interface.  in 2.31 and up, they're allocated statically
as regular variables, and old interface is deprecated.

(Note: glib docs says the new interface is available since version
2.32, but it was actually introduced in version 2.31).

Create the new interface using old primitives, by providing non-opaque
definitions of the base types (GCond and GMutex) using GOnces.

Replace #ifdeffery around GCond and GMutex in trace/simple.c and
coroutine-gthread.c too because it does not work anymore with the new
glib-compat.h.

Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
[Use GOnce to support lazy initialization; introduce CompatGMutex
 and CompatGCond.  - Paolo]
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

1 files changed, 8 insertions, 21 deletions

diff --git a/coroutine-gthread.c b/coroutine-gthread.c
index a61efe01dc..6bd6d6b22f 100644
--- a/coroutine-gthread.c
+++ b/coroutine-gthread.c
@@ -30,20 +30,14 @@ typedef struct {
     CoroutineAction action;
 } CoroutineGThread;
 
-static GStaticMutex coroutine_lock = G_STATIC_MUTEX_INIT;
+static CompatGMutex coroutine_lock;
+static CompatGCond coroutine_cond;
 
 /* GLib 2.31 and beyond deprecated various parts of the thread API,
  * but the new interfaces are not available in older GLib versions
  * so we have to cope with both.
  */
 #if GLIB_CHECK_VERSION(2, 31, 0)
-/* Default zero-initialisation is sufficient for 2.31+ GCond */
-static GCond the_coroutine_cond;
-static GCond *coroutine_cond = &the_coroutine_cond;
-static inline void init_coroutine_cond(void)
-{
-}
-
 /* Awkwardly, the GPrivate API doesn't provide a way to update the
  * GDestroyNotify handler for the coroutine key dynamically. So instead
  * we track whether or not the CoroutineGThread should be freed on
@@ -84,11 +78,6 @@ static inline GThread *create_thread(GThreadFunc func, gpointer data)
 #else
 
 /* Handle older GLib versions */
-static GCond *coroutine_cond;
-static inline void init_coroutine_cond(void)
-{
-    coroutine_cond = g_cond_new();
-}
 
 static GStaticPrivate coroutine_key = G_STATIC_PRIVATE_INIT;
 
@@ -120,22 +109,20 @@ static void __attribute__((constructor)) coroutine_init(void)
         g_thread_init(NULL);
     }
 #endif
-
-    init_coroutine_cond();
 }
 
 static void coroutine_wait_runnable_locked(CoroutineGThread *co)
 {
     while (!co->runnable) {
-        g_cond_wait(coroutine_cond, g_static_mutex_get_mutex(&coroutine_lock));
+        g_cond_wait(&coroutine_cond, &coroutine_lock);
     }
 }
 
 static void coroutine_wait_runnable(CoroutineGThread *co)
 {
-    g_static_mutex_lock(&coroutine_lock);
+    g_mutex_lock(&coroutine_lock);
     coroutine_wait_runnable_locked(co);
-    g_static_mutex_unlock(&coroutine_lock);
+    g_mutex_unlock(&coroutine_lock);
 }
 
 static gpointer coroutine_thread(gpointer opaque)
@@ -177,17 +164,17 @@ CoroutineAction qemu_coroutine_switch(Coroutine *from_,
     CoroutineGThread *from = DO_UPCAST(CoroutineGThread, base, from_);
     CoroutineGThread *to = DO_UPCAST(CoroutineGThread, base, to_);
 
-    g_static_mutex_lock(&coroutine_lock);
+    g_mutex_lock(&coroutine_lock);
     from->runnable = false;
     from->action = action;
     to->runnable = true;
     to->action = action;
-    g_cond_broadcast(coroutine_cond);
+    g_cond_broadcast(&coroutine_cond);
 
     if (action != COROUTINE_TERMINATE) {
         coroutine_wait_runnable_locked(from);
     }
-    g_static_mutex_unlock(&coroutine_lock);
+    g_mutex_unlock(&coroutine_lock);
     return from->action;
 }