Watchdog: break timeout loop via system fatal crash

Request system fatal crash via SysRq when a watchdog timeout loop is
detected. This escapes automatically the device hanging symptom and also
preserves context of system server in memory snapshot.

More details and background: go/break-sys-watchdog-loop

Bug: 141948707
Test: Insert 'sleep_forever()' to block BinderThreadMonitor to reproduce
      watchdog timeout.
Change-Id: I3ae4b33b0d7811764c61663ac3718311b55fd048

4 files changed, 93 insertions, 0 deletions

diff --git a/core/sysprop/Android.bp b/core/sysprop/Android.bp
index 7f20a0ba6642..237ede2006ea 100644
--- a/core/sysprop/Android.bp
+++ b/core/sysprop/Android.bp
@@ -19,3 +19,11 @@ sysprop_library {
     api_packages: ["android.sysprop"],
     vendor_available: false,
 }
+
+sysprop_library {
+    name: "com.android.sysprop.watchdog",
+    srcs: ["WatchdogProperties.sysprop"],
+    property_owner: "Platform",
+    api_packages: ["android.sysprop"],
+    vendor_available: false,
+}
diff --git a/core/sysprop/WatchdogProperties.sysprop b/core/sysprop/WatchdogProperties.sysprop
new file mode 100644
index 000000000000..1bcc773a9a5d
--- /dev/null
+++ b/core/sysprop/WatchdogProperties.sysprop
@@ -0,0 +1,45 @@
+# Copyright (C) 2020 The Android Open Source Project
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+module: "android.sysprop.WatchdogProperties"
+owner: Platform
+
+# To escape the watchdog timeout loop, fatal reboot the system when
+# watchdog timed out 'fatal_count' times in 'fatal_window_second'
+# seconds, if both values are not 0. Default value of both is 0.
+prop {
+    api_name: "fatal_count"
+    type: Integer
+    prop_name: "framework_watchdog.fatal_count"
+    scope: Internal
+    access: Readonly
+}
+
+prop {
+    api_name: "fatal_window_second"
+    type: Integer
+    prop_name: "framework_watchdog.fatal_window.second"
+    scope: Internal
+    access: Readonly
+}
+
+# The fatal counting can be disabled by setting property
+# 'is_fatal_ignore' to true.
+prop {
+    api_name: "is_fatal_ignore"
+    type: Boolean
+    prop_name: "persist.debug.framework_watchdog.fatal_ignore"
+    scope: Internal
+    access: Readonly
+}
diff --git a/core/sysprop/api/com.android.sysprop.watchdog-current.txt b/core/sysprop/api/com.android.sysprop.watchdog-current.txt
new file mode 100644
index 000000000000..d901aef945c9
--- /dev/null
+++ b/core/sysprop/api/com.android.sysprop.watchdog-current.txt
@@ -0,0 +1,20 @@
+props {
+  module: "android.sysprop.WatchdogProperties"
+  prop {
+    api_name: "fatal_count"
+    type: Integer
+    scope: Internal
+    prop_name: "framework_watchdog.fatal_count"
+  }
+  prop {
+    api_name: "fatal_window_second"
+    type: Integer
+    scope: Internal
+    prop_name: "framework_watchdog.fatal_window.second"
+  }
+  prop {
+    api_name: "is_fatal_ignore"
+    scope: Internal
+    prop_name: "persist.debug.framework_watchdog.fatal_ignore"
+  }
+}
diff --git a/core/sysprop/api/com.android.sysprop.watchdog-latest.txt b/core/sysprop/api/com.android.sysprop.watchdog-latest.txt
new file mode 100644
index 000000000000..d901aef945c9
--- /dev/null
+++ b/core/sysprop/api/com.android.sysprop.watchdog-latest.txt
@@ -0,0 +1,20 @@
+props {
+  module: "android.sysprop.WatchdogProperties"
+  prop {
+    api_name: "fatal_count"
+    type: Integer
+    scope: Internal
+    prop_name: "framework_watchdog.fatal_count"
+  }
+  prop {
+    api_name: "fatal_window_second"
+    type: Integer
+    scope: Internal
+    prop_name: "framework_watchdog.fatal_window.second"
+  }
+  prop {
+    api_name: "is_fatal_ignore"
+    scope: Internal
+    prop_name: "persist.debug.framework_watchdog.fatal_ignore"
+  }
+}