egl: add EGL_KHR_reusable_sync to egl_dri

This patch enables an EGL extension, EGL_KHR_reusable_sync.
This new extension basically provides a way for multiple APIs or
threads to be excuted synchronously via a "reusable sync"
primitive shared by those threads/API calls.

This was implemented based on the specification at

https://www.khronos.org/registry/egl/extensions/KHR/EGL_KHR_reusable_sync.txt

v2
- use thread functions defined in C11/threads.h instead of
  using direct pthread calls
- make the timeout set with reference to CLOCK_MONOTONIC
- cleaned up the way expiration time is calculated
- (bug fix) in dri2_client_wait_sync, case EGL_SYNC_CL_EVENT_KHR
  has been added.
- (bug fix) in dri2_destroy_sync, return from cond_broadcast
  call is now stored in 'err' intead of 'ret' to prevent 'ret'
  from being reset to 'EGL_FALSE' even in successful case
- corrected minor syntax problems

v3
- dri2_egl_unref_sync now became 'void' type. No more error check
  is needed for this function call as a result.
- (bug fix) resolved issue with duplicated unlocking of display in
  eglClientWaitSync when type of sync is "EGL_KHR_REUSABLE_SYNC"

Signed-off-by: Dongwon Kim <[email protected]>
Signed-off-by: Marek Olšák <[email protected]>

2 files changed, 18 insertions, 2 deletions

diff --git a/src/egl/main/eglapi.c b/src/egl/main/eglapi.c
index 8886759011a..64ffe92be43 100644
--- a/src/egl/main/eglapi.c
+++ b/src/egl/main/eglapi.c
@@ -1469,9 +1469,24 @@ eglClientWaitSync(EGLDisplay dpy, EGLSync sync, EGLint flags, EGLTime timeout)
    if (s->SyncStatus == EGL_SIGNALED_KHR)
       RETURN_EGL_EVAL(disp, EGL_CONDITION_SATISFIED_KHR);
 
+   /* if sync type is EGL_SYNC_REUSABLE_KHR, dpy should be
+    * unlocked here to allow other threads also to be able to
+    * go into waiting state.
+    */
+
+   if (s->Type == EGL_SYNC_REUSABLE_KHR)
+      _eglUnlockDisplay(dpy);
+
    ret = drv->API.ClientWaitSyncKHR(drv, disp, s, flags, timeout);
 
-   RETURN_EGL_EVAL(disp, ret);
+   /*
+    * 'disp' is already unlocked for reusable sync type,
+    * so passing 'NULL' to bypass unlocking display.
+    */
+   if (s->Type == EGL_SYNC_REUSABLE_KHR)
+      RETURN_EGL_EVAL(NULL, ret);
+   else
+      RETURN_EGL_EVAL(disp, ret);
 }
 
 
diff --git a/src/egl/main/eglsync.c b/src/egl/main/eglsync.c
index 999cb480c4b..33625e97ae3 100644
--- a/src/egl/main/eglsync.c
+++ b/src/egl/main/eglsync.c
@@ -152,7 +152,8 @@ _eglGetSyncAttrib(_EGLDriver *drv, _EGLDisplay *dpy, _EGLSync *sync,
       /* update the sync status */
       if (sync->SyncStatus != EGL_SIGNALED_KHR &&
           (sync->Type == EGL_SYNC_FENCE_KHR ||
-           sync->Type == EGL_SYNC_CL_EVENT_KHR))
+           sync->Type == EGL_SYNC_CL_EVENT_KHR ||
+	   sync->Type == EGL_SYNC_REUSABLE_KHR))
          drv->API.ClientWaitSyncKHR(drv, dpy, sync, 0, 0);
 
       *value = sync->SyncStatus;