commit aadc62d761cfda80a5aedab7643767292a7fcca9
author Leon Scroggins III <scroggo@google.com> Fri Mar 03 11:07:50 2023 -0500
committer Leon Scroggins III <scroggo@google.com> Fri Mar 03 14:24:28 2023 -0500
tree 5208e32a17f8d325c1730450b99c31fc22b9fea1
parent 1af0fb6ed00132a4f9c8f45eae420a7f552cd37a

Fix subtle bug in disableHardwareVsync

I54a1304a3428968134cc707b24d5b325927c31df introduced a bug in
disableHardwareVsync. If you pass false for `disallow`, it can switch
from the `Disallowed` state to the `Disabled` state, which is not
intended. Correct this by leaving the state unchanged if it's already
`Disallowed`.

Add tests. DisableDoesNotMakeAllowed catches the failure. While we're at
it, add a test that verifies that it disallows when it's intended to,
versions of the existing tests calling disableHardwareVsync that
pass true for `disallow`, and a test verifying that disable leaves it
allowed when passing `false`.

Bug: 241286146
Test: VsyncScheduleTest
Change-Id: I0036ba97b28bef64f9bae7c1c93f3c31e8733f48

services/surfaceflinger/tests/unittests/VsyncScheduleTest.cpp

diff --git a/services/surfaceflinger/tests/unittests/VsyncScheduleTest.cpp b/services/surfaceflinger/tests/unittests/VsyncScheduleTest.cpp
index adf0804..4010fa6 100644
--- a/services/surfaceflinger/tests/unittests/VsyncScheduleTest.cpp
+++ b/services/surfaceflinger/tests/unittests/VsyncScheduleTest.cpp
@@ -86,6 +86,12 @@
     mVsyncSchedule->disableHardwareVsync(mCallback, false /* disallow */);
 }
 
+TEST_F(VsyncScheduleTest, DisableDoesNothingWhenDisallowed2) {
+    EXPECT_CALL(mCallback, setVsyncEnabled(_, _)).Times(0);
+
+    mVsyncSchedule->disableHardwareVsync(mCallback, true /* disallow */);
+}
+
 TEST_F(VsyncScheduleTest, MakeAllowed) {
     ASSERT_TRUE(mVsyncSchedule->isHardwareVsyncAllowed(true /* makeAllowed */));
 }
@@ -97,6 +103,13 @@
     mVsyncSchedule->disableHardwareVsync(mCallback, false /* disallow */);
 }
 
+TEST_F(VsyncScheduleTest, DisableDoesNothingWhenDisabled2) {
+    ASSERT_TRUE(mVsyncSchedule->isHardwareVsyncAllowed(true /* makeAllowed */));
+    EXPECT_CALL(mCallback, setVsyncEnabled(_, _)).Times(0);
+
+    mVsyncSchedule->disableHardwareVsync(mCallback, true /* disallow */);
+}
+
 TEST_F(VsyncScheduleTest, EnableWorksWhenDisabled) {
     ASSERT_TRUE(mVsyncSchedule->isHardwareVsyncAllowed(true /* makeAllowed */));
     EXPECT_CALL(mCallback, setVsyncEnabled(DEFAULT_DISPLAY_ID, true));
@@ -129,6 +142,16 @@
     mVsyncSchedule->disableHardwareVsync(mCallback, false /* disallow */);
 }
 
+TEST_F(VsyncScheduleTest, EnableDisable2) {
+    ASSERT_TRUE(mVsyncSchedule->isHardwareVsyncAllowed(true /* makeAllowed */));
+    EXPECT_CALL(mCallback, setVsyncEnabled(DEFAULT_DISPLAY_ID, true));
+
+    mVsyncSchedule->enableHardwareVsync(mCallback);
+
+    EXPECT_CALL(mCallback, setVsyncEnabled(DEFAULT_DISPLAY_ID, false));
+    mVsyncSchedule->disableHardwareVsync(mCallback, true /* disallow */);
+}
+
 TEST_F(VsyncScheduleTest, StartPeriodTransition) {
     // Note: startPeriodTransition is only called when hardware vsyncs are
     // allowed.
@@ -225,5 +248,23 @@
     ASSERT_FALSE(mVsyncSchedule->getPendingHardwareVsyncState());
 }
 
+TEST_F(VsyncScheduleTest, DisableDoesNotMakeAllowed) {
+    ASSERT_FALSE(mVsyncSchedule->isHardwareVsyncAllowed(false /* makeAllowed */));
+    mVsyncSchedule->disableHardwareVsync(mCallback, false /* disallow */);
+    ASSERT_FALSE(mVsyncSchedule->isHardwareVsyncAllowed(false /* makeAllowed */));
+}
+
+TEST_F(VsyncScheduleTest, DisallowMakesNotAllowed) {
+    ASSERT_TRUE(mVsyncSchedule->isHardwareVsyncAllowed(true /* makeAllowed */));
+    mVsyncSchedule->disableHardwareVsync(mCallback, true /* disallow */);
+    ASSERT_FALSE(mVsyncSchedule->isHardwareVsyncAllowed(false /* makeAllowed */));
+}
+
+TEST_F(VsyncScheduleTest, StillAllowedAfterDisable) {
+    ASSERT_TRUE(mVsyncSchedule->isHardwareVsyncAllowed(true /* makeAllowed */));
+    mVsyncSchedule->disableHardwareVsync(mCallback, false /* disallow */);
+    ASSERT_TRUE(mVsyncSchedule->isHardwareVsyncAllowed(false /* makeAllowed */));
+}
+
 } // namespace
 } // namespace android