From: Joonbum Ko <joonbum.ko@samsung.com>
Date: Fri, 2 Dec 2022 07:17:32 +0000 (+0900)
Subject: utils_gthread: Prevent deadlock caused by wait_idle
X-Git-Tag: accepted/tizen/unified/20230116.060903~6
X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=cb176af61a52c48c85cce74af397eaedcf65848d;p=platform%2Fcore%2Fuifw%2Flibtpl-egl.git

utils_gthread: Prevent deadlock caused by wait_idle

 Deadlock situation: Multi-threaded and multi surfaces for each thread

                        T2: call pause_in_idle()->wait_idle()
                            cond_wait() until idle signaled
 T1: call wait_idle()
     wait for lock idle_mutex
                        T2: _thread_idle_cb unlock idle_mutex,
                           set is_idle to TPL_TRUE
                           and wait to lock pause_mutex
 T1: change is_idle to TPL_FALSE
     cond_wait()
                        T2: cannot exit from while loop
                           still cond_wait()

 - is_idle changing should be set TPL_FALSE after cond_wait finished

Change-Id: I44292e486a1b9f686ec28bc0ae10ddedf94a48e3
Signed-off-by: Joonbum Ko <joonbum.ko@samsung.com>
---

diff --git a/src/tpl_utils_gthread.c b/src/tpl_utils_gthread.c
index 208d881..bdc1109 100644
--- a/src/tpl_utils_gthread.c
+++ b/src/tpl_utils_gthread.c
@@ -475,7 +475,7 @@ _thread_idle_cb(gpointer data)
 
 	g_mutex_lock(&gthread->idle_mutex);
 	gthread->is_idle = TPL_TRUE;
-	g_cond_signal(&gthread->idle_cond);
+	g_cond_broadcast(&gthread->idle_cond);
 	g_mutex_unlock(&gthread->idle_mutex);
 
 	/* If the caller thread of tpl_gthread_wait_idle locked the pause_mutex,
@@ -498,7 +498,10 @@ tpl_gthread_wait_idle(tpl_gthread *gthread)
 	TPL_DEBUG("[WAIT IDLE] BEGIN");
 
 	g_mutex_lock(&gthread->idle_mutex);
-	gthread->is_idle = TPL_FALSE;
+	if (gthread->is_idle) {
+		g_mutex_unlock(&gthread->idle_mutex);
+		return;
+	}
 
 	idle_source = g_idle_source_new();
 	if (idle_source == NULL) {
@@ -517,8 +520,7 @@ tpl_gthread_wait_idle(tpl_gthread *gthread)
 	/* 200ms timeout */
 	end_time = g_get_monotonic_time() +
 				(200 * G_TIME_SPAN_MILLISECOND);
-
-	while (!gthread->is_idle) {
+	do {
 		ret = g_cond_wait_until(&gthread->idle_cond,
 								&gthread->idle_mutex,
 								end_time);
@@ -526,7 +528,10 @@ tpl_gthread_wait_idle(tpl_gthread *gthread)
 			TPL_ERR("wait_idle timeout!");
 			break;
 		}
-	}
+	} while (!gthread->is_idle);
+
+	gthread->is_idle = TPL_FALSE;
+
 	g_mutex_unlock(&gthread->idle_mutex);
 
 	TPL_DEBUG("[WAIT IDLE] END");