Fix deadlock caused by two-threaded property controls
Two threaded property controls were introduced in ag/21063815 to prevent
DOS for power controls. However, this causes deadlocks, so limit the
second thread to just sys.powerctl messages.
Bug: 273785601
Test: Boots, power messages work
Ignore-AOSP-First: Security fix
Change-Id: Ie27dc3b0cd9e2d28e94f2ad398c55ee27bc35835
diff --git a/init/property_service.cpp b/init/property_service.cpp
index 2d084db..4242912 100644
--- a/init/property_service.cpp
+++ b/init/property_service.cpp
@@ -117,7 +117,6 @@
static std::mutex accept_messages_lock;
static std::thread property_service_thread;
static std::thread property_service_for_system_thread;
-static std::mutex set_property_lock;
static std::unique_ptr<PersistWriteThread> persist_write_thread;
@@ -395,32 +394,37 @@
return {PROP_ERROR_INVALID_VALUE};
}
- auto lock = std::lock_guard{set_property_lock};
- prop_info* pi = (prop_info*)__system_property_find(name.c_str());
- if (pi != nullptr) {
- // ro.* properties are actually "write-once".
- if (StartsWith(name, "ro.")) {
- *error = "Read-only property was already set";
- return {PROP_ERROR_READ_ONLY_PROPERTY};
- }
-
- __system_property_update(pi, value.c_str(), valuelen);
+ if (name == "sys.powerctl") {
+ // No action here - NotifyPropertyChange will trigger the appropriate action, and since this
+ // can come to the second thread, we mustn't call out to the __system_property_* functions
+ // which support multiple readers but only one mutator.
} else {
- int rc = __system_property_add(name.c_str(), name.size(), value.c_str(), valuelen);
- if (rc < 0) {
- *error = "__system_property_add failed";
- return {PROP_ERROR_SET_FAILED};
- }
- }
+ prop_info* pi = (prop_info*)__system_property_find(name.c_str());
+ if (pi != nullptr) {
+ // ro.* properties are actually "write-once".
+ if (StartsWith(name, "ro.")) {
+ *error = "Read-only property was already set";
+ return {PROP_ERROR_READ_ONLY_PROPERTY};
+ }
- // Don't write properties to disk until after we have read all default
- // properties to prevent them from being overwritten by default values.
- if (socket && persistent_properties_loaded && StartsWith(name, "persist.")) {
- if (persist_write_thread) {
- persist_write_thread->Write(name, value, std::move(*socket));
- return {};
+ __system_property_update(pi, value.c_str(), valuelen);
+ } else {
+ int rc = __system_property_add(name.c_str(), name.size(), value.c_str(), valuelen);
+ if (rc < 0) {
+ *error = "__system_property_add failed";
+ return {PROP_ERROR_SET_FAILED};
+ }
}
- WritePersistentProperty(name, value);
+
+ // Don't write properties to disk until after we have read all default
+ // properties to prevent them from being overwritten by default values.
+ if (socket && persistent_properties_loaded && StartsWith(name, "persist.")) {
+ if (persist_write_thread) {
+ persist_write_thread->Write(name, value, std::move(*socket));
+ return {};
+ }
+ WritePersistentProperty(name, value);
+ }
}
NotifyPropertyChange(name, value);