[Mesa-dev] [PATCH] egl: Partially revert 23c86c74, fix eglMakeCurrent

[Tapani Pälli]

On 05/16/2017 08:10 PM, Chad Versace wrote:
> On Tue 16 May 2017, Tapani Pälli wrote:
>>
>>
>> On 05/16/2017 02:04 AM, Chad Versace wrote:
>>> Fixes regressions in Android CtsVerifier.apk on Intel Chrome OS devices
>>> due to incorrect error handling in eglMakeCurrent. See below on how to
>>> confirm the regression is fixed.
>>>
>>> This partially reverts
>>>
>>>       commit 23c86c74cc450a23848b85cfe914376caede1cdf
>>>       Author:  Chad Versace <chadversary at chromium.org>
>>>       Subject: egl: Emit error when EGLSurface is lost
>>>
>>> The bad commit added the error handling below. #2 and #3 were right,
>>> but #1 was wrong.
>>>
>>>       1. eglMakeCurrent emits EGL_BAD_CURRENT_SURFACE if the calling
>>>          thread has unflushed commands and either previous surface is no
>>>          longer valid.
>>>
>>>       2. eglMakeCurrent emits EGL_BAD_NATIVE_WINDOW if either new surface
>>>          is no longer valid.
>>>
>>>       3. eglSwapBuffers emits EGL_BAD_NATIVE_WINDOW if the swapped surface
>>>          is no longer valid.
>>>
>>> Whe I wrote the bad commit, I misunderstood the EGL spec language
>>> for #1. The correct behavior is, if I understand correctly now:
>>>
>>>       - Assume a bound EGLSurface is no longer valid.
>>>       - Assume the bound EGLContext has unflushed commands.
>>>       - The app calls eglMakeCurrent. The spec requires eglMakeCurrent to
>>>         implicitly flush. After flushing, eglMakeCurrent emits
>>>         EGL_BAD_CURRENT_SURFACE and does *not* alter the thread's
>>>         current bindings.
>>>       - If the app calls eglMakeCurrent again, and the app inserts no
>>>         commands into the GL command stream between the two eglMakeCurrent
>>>         calls, then this second eglMakeCurrent succeeds without emitting an
>>>         error.
>>>
>>> How to confirm this fixes the regression:
>>>
>>>       Download android-cts-verifier-7.1_r5-linux_x86-x86.zip from
>>>       source.android.com, unpack, and `adb install CtsVerifier.apk`.
>>>       Run test "Projection Cube". Click the Pass button (a
>>>       green checkmark). Then run test "Projection Widget". Confirm that
>>>       widgets are visible and that logcat does not complain about
>>>       eglMakeCurrent failure.
>>>
>>>       Then confirm there are no regressions in the cts-traded module that
>>>       commit 263243b1 fixed:
>>>
>>>           cts-tf > run cts --skip-preconditions --skip-device-info \
>>>                    -m CtsCameraTestCases \
>>>                    -t android.hardware.camera2.cts.RobustnessTest
>>>
>>>       Tested with Chrome OS board "reef".
>>
>> both tests passed on Android-IA with this patch ... but if I minimize
>> "Projection Widget" test it starts to bang EGL_BAD_NATIVE_WINDOW heavily. Is
>> this expected behavior?
> 
> I'm unsure. I haven't yet tried that experiment. I'll give it a try when
> I'm back at my desk.
> 
> Which EGL function is emitting EGL_BAD_NATIVE_WINDOW in logcat?
> eglMakeCurrent or eglSwapBuffers, or something else?

doh sorry, I actually meant 'Projection Cube' test, not the widget test. 
But yep, when tapping switcher button eglMakeCurrent starts to emit the 
error (likely the app just continues to submit frames even when it's 
'minimized'?). When switching back to app it cannot draw anymore as it 
keeps getting the error.

> What was the behavior before this patch? And before
> commit 23c86c74 (egl: Emit error when EGLSurface is lost)?

Without this patch (and before commit 23c86c74) I can minimize app to 
switcher and bring it back and it continues to draw.

Note that everything else seems to work just fine though (tested lots of 
GL apps) so is this just something specific what cts-verifier is doing 
or not handling properly?


>>> Cc: "17.1" <mesa-stable at lists.freedesktop.org>
>>> Cc: Tomasz Figa <tfiga at chromium.org>
>>> Cc: Nicolas Boichat <drinkcat at chromium.org>
>>> Cc: Emil Velikov <emil.velikov at collabora.com>
>>> Fixes: 23c86c74 (egl: Emit error when EGLSurface is lost)
>>> ---
>>>    src/egl/main/eglapi.c | 19 -------------------
>>>    1 file changed, 19 deletions(-)
>>>
>>> diff --git a/src/egl/main/eglapi.c b/src/egl/main/eglapi.c
>>> index aa0eb94666..9cea2f41ff 100644
>>> --- a/src/egl/main/eglapi.c
>>> +++ b/src/egl/main/eglapi.c
>>> @@ -828,25 +828,6 @@ eglMakeCurrent(EGLDisplay dpy, EGLSurface draw, EGLSurface read,
>>>             RETURN_EGL_ERROR(disp, EGL_BAD_MATCH, EGL_FALSE);
>>>       }
>>> -   _EGLThreadInfo *t =_eglGetCurrentThread();
>>> -   _EGLContext *old_ctx = t->CurrentContext;
>>> -   _EGLSurface *old_draw_surf = old_ctx ? old_ctx->DrawSurface : NULL;
>>> -   _EGLSurface *old_read_surf = old_ctx ? old_ctx->ReadSurface : NULL;
>>> -
>>> -   /* From the EGL 1.5 spec, Section 3.7.3 Binding Context and Drawables:
>>> -    *
>>> -    *    If the previous context of the calling thread has unflushed commands,
>>> -    *    and the previous surface is no longer valid, an
>>> -    *    EGL_BAD_CURRENT_SURFACE error is generated.
>>> -    *
>>> -    * It's difficult to check if the context has unflushed commands, but it's
>>> -    * easy to check if the surface is no longer valid.
>>> -    */
>>> -   if (old_draw_surf && old_draw_surf->Lost)
>>> -      RETURN_EGL_ERROR(disp, EGL_BAD_CURRENT_SURFACE, EGL_FALSE);
>>> -   if (old_read_surf && old_read_surf->Lost)
>>> -      RETURN_EGL_ERROR(disp, EGL_BAD_CURRENT_SURFACE, EGL_FALSE);
>>> -
>>>       /*    If a native window underlying either draw or read is no longer valid,
>>>        *    an EGL_BAD_NATIVE_WINDOW error is generated.
>>>        */
>>>
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