GPU process is terminated during debugging

https://bugs.webkit.org/show_bug.cgi?id=277731
rdar://133372529

Reviewed by Mike Wyrzykowski.

GPU process would not be debuggable due to WCP timing out a send or wait
to GPUP. This would cause following distinct problems
- WCP would ask UI to terminate GPUP
- Even if GPUP was not terminated, the WCP would already be in undefined
  state due to timing out a send or a wait.

Add a setting ChildProcessDebuggabilityEnabled which should be set when
the developer is intending to stop the GPU process in debugger.

The added implementation will set stream IPC connection timeout to
infinity. Later commits will modify other, less frequent normal IPC
sendSync and wait timeouts.

Run with:
  lldb -w -n GPU.Development -o c
  run-webkit-tests --internal-feature=ChildProcessDebuggabilityEnabled --no-timeout test.html

  run-minibrowser
  Set "Internal -> Child Process Debuggability" and restart

* Source/WTF/Scripts/GeneratePreferences.rb:
* Source/WTF/Scripts/Preferences/UnifiedWebPreferences.yaml:
* Source/WebKit/WebProcess/GPU/graphics/RemoteGraphicsContextGLProxy.cpp:
(WebKit::RemoteGraphicsContextGLProxy::create):
* Source/WebKit/WebProcess/GPU/graphics/RemoteRenderingBackendProxy.cpp:
(WebKit::RemoteRenderingBackendProxy::ensureGPUProcessConnection):
* Source/WebKit/WebProcess/GPU/graphics/WebGPU/RemoteGPUProxy.cpp:
(WebKit::RemoteGPUProxy::create):
* Source/WebKit/WebProcess/WebPage/WebPage.cpp:
(WebKit::WebPage::updatePreferences):
* Source/WebKit/WebProcess/WebProcess.cpp:
(WebKit::WebProcess::gpuProcessTimeoutDuration const):
(WebKit::WebProcess::setGPUProcessDebuggabilityEnabled):
* Source/WebKit/WebProcess/WebProcess.h:

Canonical link: https://commits.webkit.org/282280@main

Introduction.md

@@ -202,6 +202,10 @@ When debugging a debug build in LLDB, there are also a few functions that can be
     * showTreeForThis()
     * showNodePathForThis()
 
+Debugging child processes such as GPU process, "Child Process Debuggability" internal feature must be in use. For the test runner, you can
+specify `run-webkit-tests --internal-feature=ChildProcessDebuggabilityEnabled`. For MiniBrowser, set the Debug > Internal > Child Process Debuggability
+menu item and restart.
+
 ## Correctness Testing in WebKit
 
 WebKit is really big on test driven development, we have many types of tests.
@@ -1759,7 +1763,8 @@ You may want to specify OS_ACTIVITY_MODE environmental variable to “disable”
 in order to suppress all the system logging that happens during the debugging session.
 
 You may also want to specify `--no-timeout` option to prevent WebKitTestRunner or DumpRenderTree
-to stop the test after 30 seconds if you’re stepping through code.
+to stop the test after 30 seconds if you’re stepping through code. Specify additional
+`--internal-feature=ChildProcessDebuggabilityEnabled` when stepping through child process such as GPU process.
 
 Once this is done, you can run WebKitTestRunner or DumpRenderTree by going to Product > Perform Action > Run without Building.
 

Source/WTF/Scripts/Preferences/UnifiedWebPreferences.yaml

@@ -1707,6 +1707,21 @@ CaretBrowsingEnabled:
     WebCore:
       default: false
 
+ChildProcessDebuggabilityEnabled:
+  comment: Disables GPU process IPC timeouts
+  type: bool
+  status: internal
+  humanReadableName: "Child Process Debuggability"
+  humanReadableDescription: "Enable stopping child processes with a debugger"
+  exposed: [ WebKit ]
+  defaultValue:
+    WebKitLegacy:
+      default: false
+    WebKit:
+      default: false
+    WebCore:
+      default: false
+
 ClearSiteDataHTTPHeaderEnabled:
   type: bool
   status: stable

Source/WebKit/WebProcess/GPU/graphics/RemoteGraphicsContextGLProxy.cpp

@@ -81,10 +81,9 @@ RefPtr<RemoteGraphicsContextGLProxy> RemoteGraphicsContextGLProxy::create(const
 {
     constexpr unsigned defaultConnectionBufferSizeLog2 = 21;
     unsigned connectionBufferSizeLog2 = defaultConnectionBufferSizeLog2;
-    constexpr Seconds defaultTimeoutDuration = 30_s;
     if (attributes.failContextCreationForTesting == WebCore::GraphicsContextGLAttributes::SimulatedCreationFailure::IPCBufferOOM)
         connectionBufferSizeLog2 = 50; // Expect this to fail.
-    auto connectionPair = IPC::StreamClientConnection::create(connectionBufferSizeLog2, defaultTimeoutDuration);
+    auto connectionPair = IPC::StreamClientConnection::create(connectionBufferSizeLog2, WebProcess::singleton().gpuProcessTimeoutDuration());
     if (!connectionPair)
         return nullptr;
     auto [clientConnection, serverConnectionHandle] = WTFMove(*connectionPair);

Source/WebKit/WebProcess/GPU/graphics/RemoteRenderingBackendProxy.cpp

@@ -102,8 +102,8 @@ void RemoteRenderingBackendProxy::ensureGPUProcessConnection()
 {
     if (m_connection)
         return;
-    static constexpr auto connectionBufferSizeLog2 = 21;
-    auto connectionPair = IPC::StreamClientConnection::create(connectionBufferSizeLog2, defaultTimeout);
+    constexpr unsigned connectionBufferSizeLog2 = 21u;
+    auto connectionPair = IPC::StreamClientConnection::create(connectionBufferSizeLog2, WebProcess::singleton().gpuProcessTimeoutDuration());
     if (!connectionPair)
         CRASH();
     auto [streamConnection, serverHandle] = WTFMove(*connectionPair);

Source/WebKit/WebProcess/GPU/graphics/WebGPU/RemoteGPUProxy.cpp

@@ -57,8 +57,7 @@ RefPtr<RemoteGPUProxy> RemoteGPUProxy::create(WebGPU::ConvertToBackingContext& c
 RefPtr<RemoteGPUProxy> RemoteGPUProxy::create(WebGPU::ConvertToBackingContext& convertToBackingContext, RemoteRenderingBackendProxy& renderingBackend, SerialFunctionDispatcher& dispatcher)
 {
     constexpr size_t connectionBufferSizeLog2 = 21;
-    constexpr Seconds defaultTimeoutDuration = 30_s;
-    auto connectionPair = IPC::StreamClientConnection::create(connectionBufferSizeLog2, defaultTimeoutDuration);
+    auto connectionPair = IPC::StreamClientConnection::create(connectionBufferSizeLog2, WebProcess::singleton().gpuProcessTimeoutDuration());
     if (!connectionPair)
         return nullptr;
     auto [clientConnection, serverConnectionHandle] = WTFMove(*connectionPair);

Source/WebKit/WebProcess/WebPage/WebPage.cpp

@@ -4701,6 +4701,8 @@ void WebPage::updatePreferences(const WebPreferencesStore& store)
     if (m_drawingArea)
         m_drawingArea->updatePreferences(store);
 
+    WebProcess::singleton().setChildProcessDebuggabilityEnabled(store.getBoolValueForKey(WebPreferencesKey::childProcessDebuggabilityEnabledKey()));
+
 #if ENABLE(GPU_PROCESS)
     static_cast<WebMediaStrategy&>(platformStrategies()->mediaStrategy()).setUseGPUProcess(m_shouldPlayMediaInGPUProcess);
 #if ENABLE(VIDEO)

Source/WebKit/WebProcess/WebProcess.cpp

@@ -1377,6 +1377,12 @@ GPUProcessConnection& WebProcess::ensureGPUProcessConnection()
     return *m_gpuProcessConnection;
 }
 
+Seconds WebProcess::gpuProcessTimeoutDuration() const
+{
+    constexpr Seconds defaultTimeoutDuration = 15_s;
+    return m_childProcessDebuggabilityEnabled ? Seconds::infinity() : defaultTimeoutDuration;
+}
+
 void WebProcess::gpuProcessConnectionClosed()
 {
     ASSERT(m_gpuProcessConnection);
@@ -2212,6 +2218,11 @@ void WebProcess::updateDomainsWithStorageAccessQuirks(HashSet<WebCore::Registrab
         m_domainsWithStorageAccessQuirks.add(domain);
 }
 
+void WebProcess::setChildProcessDebuggabilityEnabled(bool childProcessDebuggabilityEnabled)
+{
+    m_childProcessDebuggabilityEnabled = childProcessDebuggabilityEnabled;
+}
+
 #if ENABLE(GPU_PROCESS)
 void WebProcess::setUseGPUProcessForCanvasRendering(bool useGPUProcessForCanvasRendering)
 {

Source/WebKit/WebProcess/WebProcess.h

@@ -248,6 +248,8 @@ class WebProcess : public AuxiliaryProcess
 #if ENABLE(GPU_PROCESS)
     GPUProcessConnection& ensureGPUProcessConnection();
     GPUProcessConnection* existingGPUProcessConnection() { return m_gpuProcessConnection.get(); }
+    // Returns timeout duration for GPU process connections. Thread-safe.
+    Seconds gpuProcessTimeoutDuration() const;
     void gpuProcessConnectionClosed();
     void gpuProcessConnectionDidBecomeUnresponsive();
 
@@ -383,6 +385,8 @@ class WebProcess : public AuxiliaryProcess
     void updatePageScreenProperties();
 #endif
 
+    void setChildProcessDebuggabilityEnabled(bool);
+
 #if ENABLE(GPU_PROCESS)
     void setUseGPUProcessForCanvasRendering(bool);
     void setUseGPUProcessForDOMRendering(bool);
@@ -805,6 +809,8 @@ class WebProcess : public AuxiliaryProcess
     RetainPtr<NSMutableDictionary> m_accessibilityRemoteFrameTokenCache;
 #endif
 
+    bool m_childProcessDebuggabilityEnabled { false };
+
 #if ENABLE(GPU_PROCESS)
     bool m_useGPUProcessForCanvasRendering { false };
     bool m_useGPUProcessForDOMRendering { false };