[Qemu-devel] [PATCH 1/4] iothread: wait until the glib context is acquired

[Marc-André Lureau]

Another thread may acquire the glib context (temporarily) before
g_main_context_push_thread_default().

This can happen with the following qemu_chr_fe_set_handlers()
modifications.

Unfortunately, g_main_context_wait() is deprecated in glib
2.58 (apparently it was a broken interface). Use a polling loop.

Signed-off-by: Marc-André Lureau <address@hidden>
---
 iothread.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/iothread.c b/iothread.c
index e615b7ae52..93cc3aa875 100644
--- a/iothread.c
+++ b/iothread.c
@@ -70,6 +70,11 @@ static void *iothread_run(void *opaque)
         if (iothread->running && atomic_read(&iothread->worker_context)) {
             GMainLoop *loop;
 
+            /* we may race with another thread acquiring the context */
+            while (!g_main_context_acquire(iothread->worker_context)) {
+                g_usleep(10000);
+            }
+
             g_main_context_push_thread_default(iothread->worker_context);
             iothread->main_loop =
                 g_main_loop_new(iothread->worker_context, TRUE);
@@ -80,6 +85,8 @@ static void *iothread_run(void *opaque)
             g_main_loop_unref(loop);
 
             g_main_context_pop_thread_default(iothread->worker_context);
+
+            g_main_context_release(iothread->worker_context);
         }
     }
 
-- 
2.21.0.rc1