commit 76cbf5bedb9670837fb0d4a3efed9828018dd567
author Dominik Laskowski <domlaskowski@google.com> Mon Aug 26 10:02:40 2024 -0400
committer Dominik Laskowski <domlaskowski@google.com> Tue Nov 12 16:36:41 2024 -0500
tree ca613e3a273b59770c14372daba9e75586fba195
parent 225c2c825e2a8f18ea98f077db72d25715ae62f4

SF: Remove flag check for modesetting lock

Ie15de10d16eefeb65289574b120d2ef4cc09d6c0, which restored mStateLock for
modesetting to fix races that led to crashes and broken scheduling, was
flagged to the rolled-out connected_display flag, such that the feature
could be rolled back if needed. Now that the fix has soaked, remove the
race-prone code path that is no longer taken.

Bug: 255635711
Flag: EXEMPT removing connected_display
Test: Build
Change-Id: Ib535e92906fb2d8be2bc70b9af29805a00d40e90

services/surfaceflinger/SurfaceFlinger.cpp

diff --git a/services/surfaceflinger/SurfaceFlinger.cpp b/services/surfaceflinger/SurfaceFlinger.cpp
index 0d03a6c..7d89b78 100644
--- a/services/surfaceflinger/SurfaceFlinger.cpp
+++ b/services/surfaceflinger/SurfaceFlinger.cpp
@@ -1418,8 +1418,6 @@
     return future.get();
 }
 
-// TODO: b/241285876 - Restore thread safety analysis once mStateLock below is unconditional.
-[[clang::no_thread_safety_analysis]]
 void SurfaceFlinger::finalizeDisplayModeChange(PhysicalDisplayId displayId) {
     SFTRACE_NAME(ftl::Concat(__func__, ' ', displayId.value).c_str());
 
@@ -1435,8 +1433,6 @@
     if (const auto oldResolution =
                 mDisplayModeController.getActiveMode(displayId).modePtr->getResolution();
         oldResolution != activeMode.modePtr->getResolution()) {
-        ConditionalLock lock(mStateLock, !FlagManager::getInstance().connected_display());
-
         auto& state = mCurrentState.displays.editValueFor(getPhysicalDisplayTokenLocked(displayId));
         // We need to generate new sequenceId in order to recreate the display (and this
         // way the framebuffer).
@@ -2597,7 +2593,7 @@
     }
 
     {
-        ConditionalLock lock(mStateLock, FlagManager::getInstance().connected_display());
+        Mutex::Autolock lock(mStateLock);
 
         for (const auto [displayId, _] : frameTargets) {
             if (mDisplayModeController.isModeSetPending(displayId)) {
@@ -2700,13 +2696,6 @@
         mScheduler->chooseRefreshRateForContent(&mLayerHierarchyBuilder.getHierarchy(),
                                                 updateAttachedChoreographer);
 
-        if (FlagManager::getInstance().connected_display()) {
-            initiateDisplayModeChanges();
-        }
-    }
-
-    if (!FlagManager::getInstance().connected_display()) {
-        ftl::FakeGuard guard(mStateLock);
         initiateDisplayModeChanges();
     }