[vlc-devel] [RFC] vdpau/instance: create the vdp/device under lock

[Steve Lhomme]

There's no reason to unlock before creating more than 1 instance and then
destroying the extra ones. No matter what we'll still return only after
an instance has been created (or failed to be created). Concurrent calls
for the same display name will only create one instance.
---
 modules/hw/vdpau/instance.c | 21 ++++++---------------
 1 file changed, 6 insertions(+), 15 deletions(-)

diff --git a/modules/hw/vdpau/instance.c b/modules/hw/vdpau/instance.c
index 4a6d27fe5f0..862e63e0e21 100644
--- a/modules/hw/vdpau/instance.c
+++ b/modules/hw/vdpau/instance.c
@@ -129,7 +129,7 @@ static pthread_mutex_t lock = PTHREAD_MUTEX_INITIALIZER;
 VdpStatus vdp_get_x11(const char *display_name, int snum,
                       vdp_t **restrict vdpp, VdpDevice *restrict devicep)
 {
-    vdp_instance_t *vi, *vi2;
+    vdp_instance_t *vi;
 
     if (display_name == NULL)
     {
@@ -140,29 +140,20 @@ VdpStatus vdp_get_x11(const char *display_name, int snum,
 
     pthread_mutex_lock(&lock);
     vi = vdp_instance_lookup(display_name, snum);
-    pthread_mutex_unlock(&lock);
     if (vi != NULL)
         goto found;
 
     vi = vdp_instance_create(display_name, snum);
     if (vi == NULL)
-        return VDP_STATUS_ERROR;
-
-    pthread_mutex_lock(&lock);
-    vi2 = vdp_instance_lookup(display_name, snum);
-    if (unlikely(vi2 != NULL))
-    {   /* Another thread created the instance (race condition corner case) */
-        pthread_mutex_unlock(&lock);
-        vdp_instance_destroy(vi);
-        vi = vi2;
-    }
-    else
     {
-        vi->next = list;
-        list = vi;
         pthread_mutex_unlock(&lock);
+        return VDP_STATUS_ERROR;
     }
+
+    vi->next = list;
+    list = vi;
 found:
+    pthread_mutex_unlock(&lock);
     *vdpp = vi->vdp;
     *devicep = vi->device;
     return VDP_STATUS_OK;
-- 
2.17.1