[PATCH wayland] client: Fix double locking bug

Ander Conselvan de Oliveira ander.conselvan.de.oliveira at intel.com
Thu Oct 11 04:55:59 PDT 2012

The function wl_proxy_create_for_id() would try to acquire the display
lock, but the only call path leading to it would call it with the lock
already acquired.

This patch removes the attempt to acquire the lock and makes the
function static. It was exported before because client had to create
proxy's manually when the server sent a new object id, but since commit
9de9e39f [1] this is no longer necessary.

[1] commit 9de9e39f87adfce1ea9755e394928756254c0ba2
    Author: Kristian Høgsberg <krh at bitplanet.net>
    Date:   Thu Jun 28 22:01:58 2012 -0400

        Allocate client proxy automatically for new objects

v2: Change the right function. Previous patch changed wl_proxy_create()
    instead of wl_proxy_create_for_id().
 src/wayland-client.c |    5 ++---
 src/wayland-client.h |    3 ---
 2 files changed, 2 insertions(+), 6 deletions(-)

diff --git a/src/wayland-client.c b/src/wayland-client.c
index c007f4c..625cd76 100644
--- a/src/wayland-client.c
+++ b/src/wayland-client.c
@@ -141,7 +141,8 @@ wl_proxy_create(struct wl_proxy *factory, const struct wl_interface *interface)
 	return proxy;
-WL_EXPORT struct wl_proxy *
+/* The caller should hold the display lock */
+static struct wl_proxy *
 wl_proxy_create_for_id(struct wl_proxy *factory,
 		       uint32_t id, const struct wl_interface *interface)
@@ -159,9 +160,7 @@ wl_proxy_create_for_id(struct wl_proxy *factory,
 	proxy->queue = factory->queue;
 	proxy->id_deleted = 0;
-	pthread_mutex_lock(&display->mutex);
 	wl_map_insert_at(&display->objects, id, proxy);
-	pthread_mutex_unlock(&display->mutex);
 	return proxy;
diff --git a/src/wayland-client.h b/src/wayland-client.h
index f064010..cb1be9c 100644
--- a/src/wayland-client.h
+++ b/src/wayland-client.h
@@ -39,9 +39,6 @@ void wl_event_queue_destroy(struct wl_event_queue *queue);
 void wl_proxy_marshal(struct wl_proxy *p, uint32_t opcode, ...);
 struct wl_proxy *wl_proxy_create(struct wl_proxy *factory,
 				 const struct wl_interface *interface);
-struct wl_proxy *wl_proxy_create_for_id(struct wl_proxy *factory,
-					uint32_t id,
-					const struct wl_interface *interface);
 void wl_proxy_destroy(struct wl_proxy *proxy);
 int wl_proxy_add_listener(struct wl_proxy *proxy,

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