tequilaOS/platform_system_core
2
0
Fork 0
Code Issues Pull requests Projects Releases Packages Wiki Activity

init: handle property service callbacks asynchronously

Browse source 
A previous change moved property_service into its own thread, since
there was otherwise a deadlock whenever a process called by init would
try to set a property.  This new thread, however, would send a message
via a blocking socket to init for each property that it received,
since init may need to take action depending on which property it is.
Unfortunately, this means that the deadlock is still possible, the
only difference is the socket's buffer must be filled before init deadlocks.

There are possible partial solutions here: the socket's buffer may be
increased or property_service may only send messages for the
properties that init will take action on, however all of these
solutions still lead to eventual deadlock.  The only complete solution
is to handle these messages asynchronously.

This change, therefore, adds the following:
1) A lock for instructing init to reboot
2) A lock for waiting on properties
3) A lock for queueing new properties
4) A lock for any actions with ServiceList or any Services, enforced
   through thread annotations, particularly since this code was not
   designed with the intention of being multi-threaded.

Bug: 146877356
Bug: 148236233
Test: boot
Test: kill hwservicemanager without deadlock
Change-Id: I84108e54217866205a48c45e8b59355012c32ea8
This commit is contained in:
Tom Cherry 2020-01-29 14:09:24 -08:00
parent a2f9136b2c
commit 7205c62933
19 changed files with 479 additions and 193 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

2
init/Android.bp
View file

@ -28,6 +28,7 @@ init_common_sources = [
"rlimit_parser.cpp",
"service.cpp",
"service_list.cpp",
"service_lock.cpp",
"service_parser.cpp",
"service_utils.cpp",
"subcontext.cpp",
@ -81,6 +82,7 @@ cc_defaults {
"-Wextra",
"-Wno-unused-parameter",
"-Werror",
"-Wthread-safety",
"-DALLOW_FIRST_STAGE_CONSOLE=0",
"-DALLOW_LOCAL_PROP_OVERRIDE=0",
"-DALLOW_PERMISSIVE_SELINUX=0",

22
init/action_manager.cpp
View file

@ -41,10 +41,12 @@ void ActionManager::AddAction(std::unique_ptr<Action> action) {
}
void ActionManager::QueueEventTrigger(const std::string& trigger) {
auto lock = std::lock_guard{event_queue_lock_};
event_queue_.emplace(trigger);
}
void ActionManager::QueuePropertyChange(const std::string& name, const std::string& value) {
auto lock = std::lock_guard{event_queue_lock_};
event_queue_.emplace(std::make_pair(name, value));
}
@ -53,6 +55,7 @@ void ActionManager::QueueAllPropertyActions() {
}
void ActionManager::QueueBuiltinAction(BuiltinFunction func, const std::string& name) {
auto lock = std::lock_guard{event_queue_lock_};
auto action = std::make_unique<Action>(true, nullptr, "<Builtin Action>", 0, name,
std::map<std::string, std::string>{});
action->AddCommand(std::move(func), {name}, 0);
@ -62,15 +65,18 @@ void ActionManager::QueueBuiltinAction(BuiltinFunction func, const std::string&
}
void ActionManager::ExecuteOneCommand() {
// Loop through the event queue until we have an action to execute
while (current_executing_actions_.empty() && !event_queue_.empty()) {
for (const auto& action : actions_) {
if (std::visit([&action](const auto& event) { return action->CheckEvent(event); },
event_queue_.front())) {
current_executing_actions_.emplace(action.get());
{
auto lock = std::lock_guard{event_queue_lock_};
// Loop through the event queue until we have an action to execute
while (current_executing_actions_.empty() && !event_queue_.empty()) {
for (const auto& action : actions_) {
if (std::visit([&action](const auto& event) { return action->CheckEvent(event); },
event_queue_.front())) {
current_executing_actions_.emplace(action.get());
}
}
event_queue_.pop();
}
event_queue_.pop();
}
if (current_executing_actions_.empty()) {
@ -103,6 +109,7 @@ void ActionManager::ExecuteOneCommand() {
}
bool ActionManager::HasMoreCommands() const {
auto lock = std::lock_guard{event_queue_lock_};
return !current_executing_actions_.empty() || !event_queue_.empty();
}
@ -113,6 +120,7 @@ void ActionManager::DumpState() const {
}
void ActionManager::ClearQueue() {
auto lock = std::lock_guard{event_queue_lock_};
// We are shutting down so don't claim the oneshot builtin actions back
current_executing_actions_ = {};
event_queue_ = {};

7
init/action_manager.h
View file

@ -16,9 +16,12 @@
#pragma once
#include <mutex>
#include <string>
#include <vector>
#include <android-base/thread_annotations.h>
#include "action.h"
#include "builtins.h"
@ -48,7 +51,9 @@ class ActionManager {
void operator=(ActionManager const&) = delete;
std::vector<std::unique_ptr<Action>> actions_;
std::queue<std::variant<EventTrigger, PropertyChange, BuiltinAction>> event_queue_;
std::queue<std::variant<EventTrigger, PropertyChange, BuiltinAction>> event_queue_
GUARDED_BY(event_queue_lock_);
mutable std::mutex event_queue_lock_;
std::queue<const Action*> current_executing_actions_;
std::size_t current_command_;
};

15
init/builtins.cpp
View file

@ -151,6 +151,7 @@ static Result<void> reboot_into_recovery(const std::vector<std::string>& options
template <typename F>
static void ForEachServiceInClass(const std::string& classname, F function) {
auto lock = std::lock_guard{service_lock};
for (const auto& service : ServiceList::GetInstance()) {
if (service->classnames().count(classname)) std::invoke(function, service);
}
@ -162,6 +163,7 @@ static Result<void> do_class_start(const BuiltinArguments& args) {
return {};
// Starting a class does not start services which are explicitly disabled.
// They must be started individually.
auto lock = std::lock_guard{service_lock};
for (const auto& service : ServiceList::GetInstance()) {
if (service->classnames().count(args[1])) {
if (auto result = service->StartIfNotDisabled(); !result.ok()) {
@ -184,6 +186,7 @@ static Result<void> do_class_start_post_data(const BuiltinArguments& args) {
// stopped either.
return {};
}
auto lock = std::lock_guard{service_lock};
for (const auto& service : ServiceList::GetInstance()) {
if (service->classnames().count(args[1])) {
if (auto result = service->StartIfPostData(); !result.ok()) {
@ -234,6 +237,7 @@ static Result<void> do_domainname(const BuiltinArguments& args) {
}
static Result<void> do_enable(const BuiltinArguments& args) {
auto lock = std::lock_guard{service_lock};
Service* svc = ServiceList::GetInstance().FindService(args[1]);
if (!svc) return Error() << "Could not find service";
@ -245,6 +249,7 @@ static Result<void> do_enable(const BuiltinArguments& args) {
}
static Result<void> do_exec(const BuiltinArguments& args) {
auto lock = std::lock_guard{service_lock};
auto service = Service::MakeTemporaryOneshotService(args.args);
if (!service.ok()) {
return Error() << "Could not create exec service: " << service.error();
@ -258,6 +263,7 @@ static Result<void> do_exec(const BuiltinArguments& args) {
}
static Result<void> do_exec_background(const BuiltinArguments& args) {
auto lock = std::lock_guard{service_lock};
auto service = Service::MakeTemporaryOneshotService(args.args);
if (!service.ok()) {
return Error() << "Could not create exec background service: " << service.error();
@ -271,6 +277,7 @@ static Result<void> do_exec_background(const BuiltinArguments& args) {
}
static Result<void> do_exec_start(const BuiltinArguments& args) {
auto lock = std::lock_guard{service_lock};
Service* service = ServiceList::GetInstance().FindService(args[1]);
if (!service) {
return Error() << "Service not found";
@ -340,6 +347,7 @@ static Result<void> do_insmod(const BuiltinArguments& args) {
}
static Result<void> do_interface_restart(const BuiltinArguments& args) {
auto lock = std::lock_guard{service_lock};
Service* svc = ServiceList::GetInstance().FindInterface(args[1]);
if (!svc) return Error() << "interface " << args[1] << " not found";
svc->Restart();
@ -347,6 +355,7 @@ static Result<void> do_interface_restart(const BuiltinArguments& args) {
}
static Result<void> do_interface_start(const BuiltinArguments& args) {
auto lock = std::lock_guard{service_lock};
Service* svc = ServiceList::GetInstance().FindInterface(args[1]);
if (!svc) return Error() << "interface " << args[1] << " not found";
if (auto result = svc->Start(); !result.ok()) {
@ -356,6 +365,7 @@ static Result<void> do_interface_start(const BuiltinArguments& args) {
}
static Result<void> do_interface_stop(const BuiltinArguments& args) {
auto lock = std::lock_guard{service_lock};
Service* svc = ServiceList::GetInstance().FindInterface(args[1]);
if (!svc) return Error() << "interface " << args[1] << " not found";
svc->Stop();
@ -740,6 +750,7 @@ static Result<void> do_setrlimit(const BuiltinArguments& args) {
}
static Result<void> do_start(const BuiltinArguments& args) {
auto lock = std::lock_guard{service_lock};
Service* svc = ServiceList::GetInstance().FindService(args[1]);
if (!svc) return Error() << "service " << args[1] << " not found";
if (auto result = svc->Start(); !result.ok()) {
@ -749,6 +760,7 @@ static Result<void> do_start(const BuiltinArguments& args) {
}
static Result<void> do_stop(const BuiltinArguments& args) {
auto lock = std::lock_guard{service_lock};
Service* svc = ServiceList::GetInstance().FindService(args[1]);
if (!svc) return Error() << "service " << args[1] << " not found";
svc->Stop();
@ -756,6 +768,7 @@ static Result<void> do_stop(const BuiltinArguments& args) {
}
static Result<void> do_restart(const BuiltinArguments& args) {
auto lock = std::lock_guard{service_lock};
Service* svc = ServiceList::GetInstance().FindService(args[1]);
if (!svc) return Error() << "service " << args[1] << " not found";
svc->Restart();
@ -1111,6 +1124,7 @@ static Result<void> ExecWithFunctionOnFailure(const std::vector<std::string>& ar
function(StringPrintf("Exec service failed, status %d", siginfo.si_status));
}
});
auto lock = std::lock_guard{service_lock};
if (auto result = (*service)->ExecStart(); !result.ok()) {
function("ExecStart failed: " + result.error().message());
}
@ -1250,6 +1264,7 @@ static Result<void> parse_apex_configs() {
}
success &= parser.ParseConfigFile(c);
}
auto lock = std::lock_guard{service_lock};
ServiceList::GetInstance().MarkServicesUpdate();
if (success) {
return {};

280
init/init.cpp
View file

@ -33,7 +33,9 @@
#include <functional>
#include <map>
#include <memory>
#include <mutex>
#include <optional>
#include <thread>
#include <vector>
#include <android-base/chrono_utils.h>
@ -95,15 +97,148 @@ static int property_triggers_enabled = 0;
static int signal_fd = -1;
static int property_fd = -1;
static std::unique_ptr<Timer> waiting_for_prop(nullptr);
static std::string wait_prop_name;
static std::string wait_prop_value;
static std::string shutdown_command;
static bool do_shutdown = false;
static std::unique_ptr<Subcontext> subcontext;
// Init epolls various FDs to wait for various inputs. It previously waited on property changes
// with a blocking socket that contained the information related to the change, however, it was easy
// to fill that socket and deadlock the system. Now we use locks to handle the property changes
// directly in the property thread, however we still must wake the epoll to inform init that there
// is a change to process, so we use this FD. It is non-blocking, since we do not care how many
// times WakeEpoll() is called, only that the epoll will wake.
static int wake_epoll_fd = -1;
static void InstallInitNotifier(Epoll* epoll) {
int sockets[2];
if (socketpair(AF_UNIX, SOCK_STREAM | SOCK_CLOEXEC | SOCK_NONBLOCK, 0, sockets) != 0) {
PLOG(FATAL) << "Failed to socketpair() between property_service and init";
}
int epoll_fd = sockets[0];
wake_epoll_fd = sockets[1];
auto drain_socket = [epoll_fd] {
char buf[512];
while (read(epoll_fd, buf, sizeof(buf)) > 0) {
}
};
if (auto result = epoll->RegisterHandler(epoll_fd, drain_socket); !result) {
LOG(FATAL) << result.error();
}
}
static void WakeEpoll() {
constexpr char value[] = "1";
write(wake_epoll_fd, value, sizeof(value));
}
static class PropWaiterState {
public:
bool StartWaiting(const char* name, const char* value) {
auto lock = std::lock_guard{lock_};
if (waiting_for_prop_) {
return false;
}
if (GetProperty(name, "") != value) {
// Current property value is not equal to expected value
wait_prop_name_ = name;
wait_prop_value_ = value;
waiting_for_prop_.reset(new Timer());
} else {
LOG(INFO) << "start_waiting_for_property(\"" << name << "\", \"" << value
<< "\"): already set";
}
return true;
}
void ResetWaitForProp() {
auto lock = std::lock_guard{lock_};
ResetWaitForPropLocked();
}
void CheckAndResetWait(const std::string& name, const std::string& value) {
auto lock = std::lock_guard{lock_};
// We always record how long init waited for ueventd to tell us cold boot finished.
// If we aren't waiting on this property, it means that ueventd finished before we even
// started to wait.
if (name == kColdBootDoneProp) {
auto time_waited = waiting_for_prop_ ? waiting_for_prop_->duration().count() : 0;
std::thread([time_waited] {
SetProperty("ro.boottime.init.cold_boot_wait", std::to_string(time_waited));
}).detach();
}
if (waiting_for_prop_) {
if (wait_prop_name_ == name && wait_prop_value_ == value) {
LOG(INFO) << "Wait for property '" << wait_prop_name_ << "=" << wait_prop_value_
<< "' took " << *waiting_for_prop_;
ResetWaitForPropLocked();
WakeEpoll();
}
}
}
// This is not thread safe because it releases the lock when it returns, so the waiting state
// may change. However, we only use this function to prevent running commands in the main
// thread loop when we are waiting, so we do not care about false positives; only false
// negatives. StartWaiting() and this function are always called from the same thread, so false
// negatives are not possible and therefore we're okay.
bool MightBeWaiting() {
auto lock = std::lock_guard{lock_};
return static_cast<bool>(waiting_for_prop_);
}
private:
void ResetWaitForPropLocked() {
wait_prop_name_.clear();
wait_prop_value_.clear();
waiting_for_prop_.reset();
}
std::mutex lock_;
std::unique_ptr<Timer> waiting_for_prop_{nullptr};
std::string wait_prop_name_;
std::string wait_prop_value_;
} prop_waiter_state;
bool start_waiting_for_property(const char* name, const char* value) {
return prop_waiter_state.StartWaiting(name, value);
}
void ResetWaitForProp() {
prop_waiter_state.ResetWaitForProp();
}
static class ShutdownState {
public:
void TriggerShutdown(const std::string& command) {
// We can't call HandlePowerctlMessage() directly in this function,
// because it modifies the contents of the action queue, which can cause the action queue
// to get into a bad state if this function is called from a command being executed by the
// action queue. Instead we set this flag and ensure that shutdown happens before the next
// command is run in the main init loop.
auto lock = std::lock_guard{shutdown_command_lock_};
shutdown_command_ = command;
do_shutdown_ = true;
WakeEpoll();
}
std::optional<std::string> CheckShutdown() {
auto lock = std::lock_guard{shutdown_command_lock_};
if (do_shutdown_ && !IsShuttingDown()) {
do_shutdown_ = false;
return shutdown_command_;
}
return {};
}
private:
std::mutex shutdown_command_lock_;
std::string shutdown_command_;
bool do_shutdown_ = false;
} shutdown_state;
void DumpState() {
auto lock = std::lock_guard{service_lock};
ServiceList::GetInstance().DumpState();
ActionManager::GetInstance().DumpState();
}
@ -156,40 +291,7 @@ static void LoadBootScripts(ActionManager& action_manager, ServiceList& service_
}
}
bool start_waiting_for_property(const char *name, const char *value)
{
if (waiting_for_prop) {
return false;
}
if (GetProperty(name, "") != value) {
// Current property value is not equal to expected value
wait_prop_name = name;
wait_prop_value = value;
waiting_for_prop.reset(new Timer());
} else {
LOG(INFO) << "start_waiting_for_property(\""
<< name << "\", \"" << value << "\"): already set";
}
return true;
}
void ResetWaitForProp() {
wait_prop_name.clear();
wait_prop_value.clear();
waiting_for_prop.reset();
}
static void TriggerShutdown(const std::string& command) {
// We can't call HandlePowerctlMessage() directly in this function,
// because it modifies the contents of the action queue, which can cause the action queue
// to get into a bad state if this function is called from a command being executed by the
// action queue. Instead we set this flag and ensure that shutdown happens before the next
// command is run in the main init loop.
shutdown_command = command;
do_shutdown = true;
}
void property_changed(const std::string& name, const std::string& value) {
void PropertyChanged(const std::string& name, const std::string& value) {
// If the property is sys.powerctl, we bypass the event queue and immediately handle it.
// This is to ensure that init will always and immediately shutdown/reboot, regardless of
// if there are other pending events to process or if init is waiting on an exec service or
@ -197,30 +299,20 @@ void property_changed(const std::string& name, const std::string& value) {
// In non-thermal-shutdown case, 'shutdown' trigger will be fired to let device specific
// commands to be executed.
if (name == "sys.powerctl") {
TriggerShutdown(value);
trigger_shutdown(value);
}
if (property_triggers_enabled) ActionManager::GetInstance().QueuePropertyChange(name, value);
// We always record how long init waited for ueventd to tell us cold boot finished.
// If we aren't waiting on this property, it means that ueventd finished before we even started
// to wait.
if (name == kColdBootDoneProp) {
auto time_waited = waiting_for_prop ? waiting_for_prop->duration().count() : 0;
SetProperty("ro.boottime.init.cold_boot_wait", std::to_string(time_waited));
if (property_triggers_enabled) {
ActionManager::GetInstance().QueuePropertyChange(name, value);
WakeEpoll();
}
if (waiting_for_prop) {
if (wait_prop_name == name && wait_prop_value == value) {
LOG(INFO) << "Wait for property '" << wait_prop_name << "=" << wait_prop_value
<< "' took " << *waiting_for_prop;
ResetWaitForProp();
}
}
prop_waiter_state.CheckAndResetWait(name, value);
}
static std::optional<boot_clock::time_point> HandleProcessActions() {
std::optional<boot_clock::time_point> next_process_action_time;
auto lock = std::lock_guard{service_lock};
for (const auto& s : ServiceList::GetInstance()) {
if ((s->flags() & SVC_RUNNING) && s->timeout_period()) {
auto timeout_time = s->time_started() + *s->timeout_period();
@ -249,7 +341,7 @@ static std::optional<boot_clock::time_point> HandleProcessActions() {
return next_process_action_time;
}
static Result<void> DoControlStart(Service* service) {
static Result<void> DoControlStart(Service* service) REQUIRES(service_lock) {
return service->Start();
}
@ -258,7 +350,7 @@ static Result<void> DoControlStop(Service* service) {
return {};
}
static Result<void> DoControlRestart(Service* service) {
static Result<void> DoControlRestart(Service* service) REQUIRES(service_lock) {
service->Restart();
return {};
}
@ -292,7 +384,7 @@ static const std::map<std::string, ControlMessageFunction>& get_control_message_
return control_message_functions;
}
bool HandleControlMessage(const std::string& msg, const std::string& name, pid_t pid) {
bool HandleControlMessage(const std::string& msg, const std::string& name, pid_t from_pid) {
const auto& map = get_control_message_map();
const auto it = map.find(msg);
@ -301,7 +393,7 @@ bool HandleControlMessage(const std::string& msg, const std::string& name, pid_t
return false;
}
std::string cmdline_path = StringPrintf("proc/%d/cmdline", pid);
std::string cmdline_path = StringPrintf("proc/%d/cmdline", from_pid);
std::string process_cmdline;
if (ReadFileToString(cmdline_path, &process_cmdline)) {
std::replace(process_cmdline.begin(), process_cmdline.end(), '\0', ' ');
@ -312,6 +404,8 @@ bool HandleControlMessage(const std::string& msg, const std::string& name, pid_t
const ControlMessageFunction& function = it->second;
auto lock = std::lock_guard{service_lock};
Service* svc = nullptr;
switch (function.target) {
@ -329,23 +423,24 @@ bool HandleControlMessage(const std::string& msg, const std::string& name, pid_t
if (svc == nullptr) {
LOG(ERROR) << "Control message: Could not find '" << name << "' for ctl." << msg
<< " from pid: " << pid << " (" << process_cmdline << ")";
<< " from pid: " << from_pid << " (" << process_cmdline << ")";
return false;
}
if (auto result = function.action(svc); !result.ok()) {
LOG(ERROR) << "Control message: Could not ctl." << msg << " for '" << name
<< "' from pid: " << pid << " (" << process_cmdline << "): " << result.error();
<< "' from pid: " << from_pid << " (" << process_cmdline
<< "): " << result.error();
return false;
}
LOG(INFO) << "Control message: Processed ctl." << msg << " for '" << name
<< "' from pid: " << pid << " (" << process_cmdline << ")";
<< "' from pid: " << from_pid << " (" << process_cmdline << ")";
return true;
}
static Result<void> wait_for_coldboot_done_action(const BuiltinArguments& args) {
if (!start_waiting_for_property(kColdBootDoneProp, "true")) {
if (!prop_waiter_state.StartWaiting(kColdBootDoneProp, "true")) {
LOG(FATAL) << "Could not wait for '" << kColdBootDoneProp << "'";
}
@ -493,6 +588,7 @@ void HandleKeychord(const std::vector<int>& keycodes) {
}
auto found = false;
auto lock = std::lock_guard{service_lock};
for (const auto& service : ServiceList::GetInstance()) {
auto svc = service.get();
if (svc->keycodes() == keycodes) {
@ -579,44 +675,6 @@ void SendStartSendingMessagesMessage() {
}
}
static void HandlePropertyFd() {
auto message = ReadMessage(property_fd);
if (!message.ok()) {
LOG(ERROR) << "Could not read message from property service: " << message.error();
return;
}
auto property_message = PropertyMessage{};
if (!property_message.ParseFromString(*message)) {
LOG(ERROR) << "Could not parse message from property service";
return;
}
switch (property_message.msg_case()) {
case PropertyMessage::kControlMessage: {
auto& control_message = property_message.control_message();
bool success = HandleControlMessage(control_message.msg(), control_message.name(),
control_message.pid());
uint32_t response = success ? PROP_SUCCESS : PROP_ERROR_HANDLE_CONTROL_MESSAGE;
if (control_message.has_fd()) {
int fd = control_message.fd();
TEMP_FAILURE_RETRY(send(fd, &response, sizeof(response), 0));
close(fd);
}
break;
}
case PropertyMessage::kChangedMessage: {
auto& changed_message = property_message.changed_message();
property_changed(changed_message.name(), changed_message.value());
break;
}
default:
LOG(ERROR) << "Unknown message type from property service: "
<< property_message.msg_case();
}
}
int SecondStageMain(int argc, char** argv) {
if (REBOOT_BOOTLOADER_ON_PANIC) {
InstallRebootSignalHandlers();
@ -624,7 +682,7 @@ int SecondStageMain(int argc, char** argv) {
boot_clock::time_point start_time = boot_clock::now();
trigger_shutdown = TriggerShutdown;
trigger_shutdown = [](const std::string& command) { shutdown_state.TriggerShutdown(command); };
SetStdioToDevNull(argv);
InitKernelLogging(argv);
@ -684,11 +742,8 @@ int SecondStageMain(int argc, char** argv) {
}
InstallSignalFdHandler(&epoll);
InstallInitNotifier(&epoll);
StartPropertyService(&property_fd);
if (auto result = epoll.RegisterHandler(property_fd, HandlePropertyFd); !result.ok()) {
LOG(FATAL) << "Could not register epoll handler for property fd: " << result.error();
}
// Make the time that init stages started available for bootstat to log.
RecordStageBoottimes(start_time);
@ -742,6 +797,7 @@ int SecondStageMain(int argc, char** argv) {
Keychords keychords;
am.QueueBuiltinAction(
[&epoll, &keychords](const BuiltinArguments& args) -> Result<void> {
auto lock = std::lock_guard{service_lock};
for (const auto& svc : ServiceList::GetInstance()) {
keychords.Register(svc->keycodes());
}
@ -772,12 +828,12 @@ int SecondStageMain(int argc, char** argv) {
// By default, sleep until something happens.
auto epoll_timeout = std::optional<std::chrono::milliseconds>{};
if (do_shutdown && !IsShuttingDown()) {
do_shutdown = false;
HandlePowerctlMessage(shutdown_command);
auto shutdown_command = shutdown_state.CheckShutdown();
if (shutdown_command) {
HandlePowerctlMessage(*shutdown_command);
}
if (!(waiting_for_prop || Service::is_exec_service_running())) {
if (!(prop_waiter_state.MightBeWaiting() || Service::is_exec_service_running())) {
am.ExecuteOneCommand();
}
if (!IsShuttingDown()) {
@ -791,7 +847,7 @@ int SecondStageMain(int argc, char** argv) {
}
}
if (!(waiting_for_prop || Service::is_exec_service_running())) {
if (!(prop_waiter_state.MightBeWaiting() || Service::is_exec_service_running())) {
// If there's more work to do, wake up again immediately.
if (am.HasMoreCommands()) epoll_timeout = 0ms;
}

3
init/init.h
View file

@ -41,6 +41,9 @@ void SendLoadPersistentPropertiesMessage();
void SendStopSendingMessagesMessage();
void SendStartSendingMessagesMessage();
void PropertyChanged(const std::string& name, const std::string& value);
bool HandleControlMessage(const std::string& msg, const std::string& name, pid_t from_pid);
int SecondStageMain(int argc, char** argv);
} // namespace init

1
init/init_test.cpp
View file

@ -167,6 +167,7 @@ service A something
ServiceList service_list;
TestInitText(init_script, BuiltinFunctionMap(), {}, &service_list);
auto lock = std::lock_guard{service_lock};
ASSERT_EQ(1, std::distance(service_list.begin(), service_list.end()));
auto service = service_list.begin()->get();

3
init/lmkd_service.cpp
View file

@ -79,7 +79,8 @@ static bool UnregisterProcess(pid_t pid) {
}
static void RegisterServices(pid_t exclude_pid) {
for (const auto& service : ServiceList::GetInstance().services()) {
auto lock = std::lock_guard{service_lock};
for (const auto& service : ServiceList::GetInstance()) {
auto svc = service.get();
if (svc->oom_score_adjust() != DEFAULT_OOM_SCORE_ADJUST) {
// skip if process is excluded or not yet forked (pid==0)

11
init/mount_namespace.cpp
View file

@ -29,6 +29,7 @@
#include <android-base/unique_fd.h>
#include <apex_manifest.pb.h>
#include "property_service.h"
#include "util.h"
namespace android {
@ -290,6 +291,14 @@ bool SwitchToDefaultMountNamespace() {
return true;
}
if (default_ns_id != GetMountNamespaceId()) {
// The property service thread and its descendent threads must be in the correct mount
// namespace to call Service::Start(), however setns() only operates on a single thread and
// fails when secondary threads attempt to join the same mount namespace. Therefore, we
// must join the property service thread and its descendents before the setns() call. Those
// threads are then started again after the setns() call, and they'll be in the proper
// namespace.
PausePropertyService();
if (setns(default_ns_fd.get(), CLONE_NEWNS) == -1) {
PLOG(ERROR) << "Failed to switch back to the default mount namespace.";
return false;
@ -299,6 +308,8 @@ bool SwitchToDefaultMountNamespace() {
LOG(ERROR) << result.error();
return false;
}
ResumePropertyService();
}
LOG(INFO) << "Switched to default mount namespace";

204
init/property_service.cpp
View file

@ -92,8 +92,10 @@ namespace init {
static bool persistent_properties_loaded = false;
static int property_set_fd = -1;
static int from_init_socket = -1;
static int init_socket = -1;
static bool accept_messages = false;
static std::thread property_service_thread;
static PropertyInfoAreaFile property_info_area;
@ -147,17 +149,6 @@ static bool CheckMacPerms(const std::string& name, const char* target_context,
return has_access;
}
static void SendPropertyChanged(const std::string& name, const std::string& value) {
auto property_msg = PropertyMessage{};
auto* changed_message = property_msg.mutable_changed_message();
changed_message->set_name(name);
changed_message->set_value(value);
if (auto result = SendMessage(init_socket, property_msg); !result.ok()) {
LOG(ERROR) << "Failed to send property changed message: " << result.error();
}
}
static uint32_t PropertySet(const std::string& name, const std::string& value, std::string* error) {
size_t valuelen = value.size();
@ -196,47 +187,137 @@ static uint32_t PropertySet(const std::string& name, const std::string& value, s
// If init hasn't started its main loop, then it won't be handling property changed messages
// anyway, so there's no need to try to send them.
if (accept_messages) {
SendPropertyChanged(name, value);
PropertyChanged(name, value);
}
return PROP_SUCCESS;
}
class AsyncRestorecon {
template <typename T>
class SingleThreadExecutor {
public:
void TriggerRestorecon(const std::string& path) {
auto guard = std::lock_guard{mutex_};
paths_.emplace(path);
virtual ~SingleThreadExecutor() {}
if (!thread_started_) {
thread_started_ = true;
std::thread{&AsyncRestorecon::ThreadFunction, this}.detach();
template <typename F = T>
void Run(F&& item) {
auto guard = std::lock_guard{mutex_};
items_.emplace(std::forward<F>(item));
if (thread_state_ == ThreadState::kRunning || thread_state_ == ThreadState::kStopped) {
return;
}
if (thread_state_ == ThreadState::kPendingJoin) {
thread_.join();
}
StartThread();
}
void StopAndJoin() {
auto lock = std::unique_lock{mutex_};
if (thread_state_ == ThreadState::kPendingJoin) {
thread_.join();
} else if (thread_state_ == ThreadState::kRunning) {
thread_state_ = ThreadState::kStopped;
lock.unlock();
thread_.join();
lock.lock();
}
thread_state_ = ThreadState::kStopped;
}
void Restart() {
auto guard = std::lock_guard{mutex_};
if (items_.empty()) {
thread_state_ = ThreadState::kNotStarted;
} else {
StartThread();
}
}
void MaybeJoin() {
auto guard = std::lock_guard{mutex_};
if (thread_state_ == ThreadState::kPendingJoin) {
thread_.join();
thread_state_ = ThreadState::kNotStarted;
}
}
private:
virtual void Execute(T&& item) = 0;
void StartThread() {
thread_state_ = ThreadState::kRunning;
auto thread = std::thread{&SingleThreadExecutor::ThreadFunction, this};
std::swap(thread_, thread);
}
void ThreadFunction() {
auto lock = std::unique_lock{mutex_};
while (!paths_.empty()) {
auto path = paths_.front();
paths_.pop();
while (!items_.empty()) {
auto item = items_.front();
items_.pop();
lock.unlock();
if (selinux_android_restorecon(path.c_str(), SELINUX_ANDROID_RESTORECON_RECURSE) != 0) {
LOG(ERROR) << "Asynchronous restorecon of '" << path << "' failed'";
}
android::base::SetProperty(kRestoreconProperty, path);
Execute(std::move(item));
lock.lock();
}
thread_started_ = false;
if (thread_state_ != ThreadState::kStopped) {
thread_state_ = ThreadState::kPendingJoin;
}
}
std::mutex mutex_;
std::queue<std::string> paths_;
bool thread_started_ = false;
std::queue<T> items_;
enum class ThreadState {
kNotStarted, // Initial state when starting the program or when restarting with no items to
// process.
kRunning, // The thread is running and is in a state that it will process new items if
// are run.
kPendingJoin, // The thread has run to completion and is pending join(). A new thread must
// be launched for new items to be processed.
kStopped, // This executor has stopped and will not process more items until Restart() is
// called. Currently pending items will be processed and the thread will be
// joined.
};
ThreadState thread_state_ = ThreadState::kNotStarted;
std::thread thread_;
};
class RestoreconThread : public SingleThreadExecutor<std::string> {
virtual void Execute(std::string&& path) override {
if (selinux_android_restorecon(path.c_str(), SELINUX_ANDROID_RESTORECON_RECURSE) != 0) {
LOG(ERROR) << "Asynchronous restorecon of '" << path << "' failed'";
}
android::base::SetProperty(kRestoreconProperty, path);
}
};
struct ControlMessageInfo {
std::string message;
std::string name;
pid_t pid;
int fd;
};
class ControlMessageThread : public SingleThreadExecutor<ControlMessageInfo> {
virtual void Execute(ControlMessageInfo&& info) override {
bool success = HandleControlMessage(info.message, info.name, info.pid);
uint32_t response = success ? PROP_SUCCESS : PROP_ERROR_HANDLE_CONTROL_MESSAGE;
if (info.fd != -1) {
TEMP_FAILURE_RETRY(send(info.fd, &response, sizeof(response), 0));
close(info.fd);
}
}
};
static RestoreconThread restorecon_thread;
static ControlMessageThread control_message_thread;
class SocketConnection {
public:
SocketConnection(int socket, const ucred& cred) : socket_(socket), cred_(cred) {}
@ -378,29 +459,17 @@ static uint32_t SendControlMessage(const std::string& msg, const std::string& na
return PROP_ERROR_HANDLE_CONTROL_MESSAGE;
}
auto property_msg = PropertyMessage{};
auto* control_message = property_msg.mutable_control_message();
control_message->set_msg(msg);
control_message->set_name(name);
control_message->set_pid(pid);
// We must release the fd before sending it to init, otherwise there will be a race with init.
// If init calls close() before Release(), then fdsan will see the wrong tag and abort().
// We must release the fd before spawning the thread, otherwise there will be a race with the
// thread. If the thread calls close() before this function calls Release(), then fdsan will see
// the wrong tag and abort().
int fd = -1;
if (socket != nullptr && SelinuxGetVendorAndroidVersion() > __ANDROID_API_Q__) {
fd = socket->Release();
control_message->set_fd(fd);
}
if (auto result = SendMessage(init_socket, property_msg); !result.ok()) {
// We've already released the fd above, so if we fail to send the message to init, we need
// to manually free it here.
if (fd != -1) {
close(fd);
}
*error = "Failed to send control message: " + result.error().message();
return PROP_ERROR_HANDLE_CONTROL_MESSAGE;
}
// Handling a control message likely calls SetProperty, which we must synchronously handle,
// therefore we must fork a thread to handle it.
control_message_thread.Run({msg, name, pid, fd});
return PROP_SUCCESS;
}
@ -502,8 +571,7 @@ uint32_t HandlePropertySet(const std::string& name, const std::string& value,
// We use a thread to do this restorecon operation to prevent holding up init, as it may take
// a long time to complete.
if (name == kRestoreconProperty && cr.pid != 1 && !value.empty()) {
static AsyncRestorecon async_restorecon;
async_restorecon.TriggerRestorecon(value);
restorecon_thread.Run(value);
return PROP_SUCCESS;
}
@ -1082,6 +1150,8 @@ void PropertyInit() {
PropertyLoadBootDefaults();
}
static bool pause_property_service = false;
static void HandleInitSocket() {
auto message = ReadMessage(init_socket);
if (!message.ok()) {
@ -1116,6 +1186,10 @@ static void HandleInitSocket() {
accept_messages = true;
break;
}
case InitMessage::kPausePropertyService: {
pause_property_service = true;
break;
}
default:
LOG(ERROR) << "Unknown message type from init: " << init_message.msg_case();
}
@ -1136,7 +1210,7 @@ static void PropertyServiceThread() {
LOG(FATAL) << result.error();
}
while (true) {
while (!pause_property_service) {
auto pending_functions = epoll.Wait(std::nullopt);
if (!pending_functions.ok()) {
LOG(ERROR) << pending_functions.error();
@ -1145,9 +1219,34 @@ static void PropertyServiceThread() {
(*function)();
}
}
control_message_thread.MaybeJoin();
restorecon_thread.MaybeJoin();
}
}
void SendStopPropertyServiceMessage() {
auto init_message = InitMessage{};
init_message.set_pause_property_service(true);
if (auto result = SendMessage(from_init_socket, init_message); !result.ok()) {
LOG(ERROR) << "Failed to send stop property service message: " << result.error();
}
}
void PausePropertyService() {
control_message_thread.StopAndJoin();
restorecon_thread.StopAndJoin();
SendStopPropertyServiceMessage();
property_service_thread.join();
}
void ResumePropertyService() {
pause_property_service = false;
auto new_thread = std::thread{PropertyServiceThread};
property_service_thread.swap(new_thread);
restorecon_thread.Restart();
control_message_thread.Restart();
}
void StartPropertyService(int* epoll_socket) {
InitPropertySet("ro.property_service.version", "2");
@ -1155,7 +1254,7 @@ void StartPropertyService(int* epoll_socket) {
if (socketpair(AF_UNIX, SOCK_SEQPACKET | SOCK_CLOEXEC, 0, sockets) != 0) {
PLOG(FATAL) << "Failed to socketpair() between property_service and init";
}
*epoll_socket = sockets[0];
*epoll_socket = from_init_socket = sockets[0];
init_socket = sockets[1];
accept_messages = true;
@ -1169,7 +1268,8 @@ void StartPropertyService(int* epoll_socket) {
listen(property_set_fd, 8);
std::thread{PropertyServiceThread}.detach();
auto new_thread = std::thread{PropertyServiceThread};
property_service_thread.swap(new_thread);
}
} // namespace init

2
init/property_service.h
View file

@ -31,6 +31,8 @@ bool CanReadProperty(const std::string& source_context, const std::string& name)
void PropertyInit();
void StartPropertyService(int* epoll_socket);
void ResumePropertyService();
void PausePropertyService();
} // namespace init
} // namespace android

1
init/property_service.proto
View file

@ -41,5 +41,6 @@ message InitMessage {
bool load_persistent_properties = 1;
bool stop_sending_messages = 2;
bool start_sending_messages = 3;
bool pause_property_service = 4;
};
}

8
init/reboot.cpp
View file

@ -85,7 +85,7 @@ static bool shutting_down = false;
static const std::set<std::string> kDebuggingServices{"tombstoned", "logd", "adbd", "console"};
static std::vector<Service*> GetDebuggingServices(bool only_post_data) {
static std::vector<Service*> GetDebuggingServices(bool only_post_data) REQUIRES(service_lock) {
std::vector<Service*> ret;
ret.reserve(kDebuggingServices.size());
for (const auto& s : ServiceList::GetInstance()) {
@ -179,7 +179,7 @@ class MountEntry {
};
// Turn off backlight while we are performing power down cleanup activities.
static void TurnOffBacklight() {
static void TurnOffBacklight() REQUIRES(service_lock) {
Service* service = ServiceList::GetInstance().FindService("blank_screen");
if (service == nullptr) {
LOG(WARNING) << "cannot find blank_screen in TurnOffBacklight";
@ -587,6 +587,7 @@ static void DoReboot(unsigned int cmd, const std::string& reason, const std::str
// Start reboot monitor thread
sem_post(&reboot_semaphore);
auto lock = std::lock_guard{service_lock};
// watchdogd is a vendor specific component but should be alive to complete shutdown safely.
const std::set<std::string> to_starts{"watchdogd"};
std::vector<Service*> stop_first;
@ -706,6 +707,7 @@ static void EnterShutdown() {
// Skip wait for prop if it is in progress
ResetWaitForProp();
// Clear EXEC flag if there is one pending
auto lock = std::lock_guard{service_lock};
for (const auto& s : ServiceList::GetInstance()) {
s->UnSetExec();
}
@ -749,6 +751,7 @@ static Result<void> DoUserspaceReboot() {
return Error() << "Failed to set sys.init.userspace_reboot.in_progress property";
}
EnterShutdown();
auto lock = std::lock_guard{service_lock};
if (!SetProperty("sys.powerctl", "")) {
return Error() << "Failed to reset sys.powerctl property";
}
@ -907,6 +910,7 @@ void HandlePowerctlMessage(const std::string& command) {
run_fsck = true;
} else if (cmd_params[1] == "thermal") {
// Turn off sources of heat immediately.
auto lock = std::lock_guard{service_lock};
TurnOffBacklight();
// run_fsck is false to avoid delay
cmd = ANDROID_RB_THERMOFF;

14
init/service.h
View file

@ -27,12 +27,14 @@
#include <vector>
#include <android-base/chrono_utils.h>
#include <android-base/thread_annotations.h>
#include <cutils/iosched_policy.h>
#include "action.h"
#include "capabilities.h"
#include "keyword_map.h"
#include "parser.h"
#include "service_lock.h"
#include "service_utils.h"
#include "subcontext.h"
@ -77,17 +79,17 @@ class Service {
bool IsRunning() { return (flags_ & SVC_RUNNING) != 0; }
bool IsEnabled() { return (flags_ & SVC_DISABLED) == 0; }
Result<void> ExecStart();
Result<void> Start();
Result<void> StartIfNotDisabled();
Result<void> StartIfPostData();
Result<void> Enable();
Result<void> ExecStart() REQUIRES(service_lock);
Result<void> Start() REQUIRES(service_lock);
Result<void> StartIfNotDisabled() REQUIRES(service_lock);
Result<void> StartIfPostData() REQUIRES(service_lock);
Result<void> Enable() REQUIRES(service_lock);
void Reset();
void ResetIfPostData();
void Stop();
void Terminate();
void Timeout();
void Restart();
void Restart() REQUIRES(service_lock);
void Reap(const siginfo_t& siginfo);
void DumpState() const;
void SetShutdownCritical() { flags_ |= SVC_SHUTDOWN_CRITICAL; }

30
init/service_list.h
View file

@ -17,9 +17,13 @@
#pragma once
#include <memory>
#include <mutex>
#include <vector>
#include <android-base/thread_annotations.h>
#include "service.h"
#include "service_lock.h"
namespace android {
namespace init {
@ -32,16 +36,16 @@ class ServiceList {
ServiceList();
size_t CheckAllCommands();
void AddService(std::unique_ptr<Service> service);
void RemoveService(const Service& svc);
void AddService(std::unique_ptr<Service> service) REQUIRES(service_lock);
void RemoveService(const Service& svc) REQUIRES(service_lock);
template <class UnaryPredicate>
void RemoveServiceIf(UnaryPredicate predicate) {
void RemoveServiceIf(UnaryPredicate predicate) REQUIRES(service_lock) {
services_.erase(std::remove_if(services_.begin(), services_.end(), predicate),
services_.end());
}
template <typename T, typename F = decltype(&Service::name)>
Service* FindService(T value, F function = &Service::name) const {
Service* FindService(T value, F function = &Service::name) const REQUIRES(service_lock) {
auto svc = std::find_if(services_.begin(), services_.end(),
[&function, &value](const std::unique_ptr<Service>& s) {
return std::invoke(function, s) == value;
@ -52,7 +56,7 @@ class ServiceList {
return nullptr;
}
Service* FindInterface(const std::string& interface_name) {
Service* FindInterface(const std::string& interface_name) REQUIRES(service_lock) {
for (const auto& svc : services_) {
if (svc->interfaces().count(interface_name) > 0) {
return svc.get();
@ -62,18 +66,20 @@ class ServiceList {
return nullptr;
}
void DumpState() const;
void DumpState() const REQUIRES(service_lock);
auto begin() const { return services_.begin(); }
auto end() const { return services_.end(); }
const std::vector<std::unique_ptr<Service>>& services() const { return services_; }
const std::vector<Service*> services_in_shutdown_order() const;
auto begin() const REQUIRES(service_lock) { return services_.begin(); }
auto end() const REQUIRES(service_lock) { return services_.end(); }
const std::vector<std::unique_ptr<Service>>& services() const REQUIRES(service_lock) {
return services_;
}
const std::vector<Service*> services_in_shutdown_order() const REQUIRES(service_lock);
void MarkPostData();
bool IsPostData();
void MarkServicesUpdate();
void MarkServicesUpdate() REQUIRES(service_lock);
bool IsServicesUpdated() const { return services_update_finished_; }
void DelayService(const Service& service);
void DelayService(const Service& service) REQUIRES(service_lock);
private:
std::vector<std::unique_ptr<Service>> services_;

25
init/service_lock.cpp Normal file
View file

@ -0,0 +1,25 @@
/*
* 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.
*/
#include "service_lock.h"
namespace android {
namespace init {
RecursiveMutex service_lock;
} // namespace init
} // namespace android

40
init/service_lock.h Normal file
View file

@ -0,0 +1,40 @@
/*
* 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.
*/
#pragma once
#include <mutex>
#include <android-base/thread_annotations.h>
namespace android {
namespace init {
// This class exists to add thread annotations, since they're absent from std::recursive_mutex.
class CAPABILITY("mutex") RecursiveMutex {
public:
void lock() ACQUIRE() { mutex_.lock(); }
void unlock() RELEASE() { mutex_.unlock(); }
private:
std::recursive_mutex mutex_;
};
extern RecursiveMutex service_lock;
} // namespace init
} // namespace android

2
init/service_parser.cpp
View file

@ -168,6 +168,7 @@ Result<void> ServiceParser::ParseInterface(std::vector<std::string>&& args) {
const std::string fullname = interface_name + "/" + instance_name;
auto lock = std::lock_guard{service_lock};
for (const auto& svc : *service_list_) {
if (svc->interfaces().count(fullname) > 0) {
return Error() << "Interface '" << fullname << "' redefined in " << service_->name()
@ -598,6 +599,7 @@ Result<void> ServiceParser::EndSection() {
}
}
auto lock = std::lock_guard{service_lock};
Service* old_service = service_list_->FindService(service_->name());
if (old_service) {
if (!service_->is_override()) {

2
init/sigchld_handler.cpp
View file

@ -64,6 +64,8 @@ static pid_t ReapOneProcess() {
std::string wait_string;
Service* service = nullptr;
auto lock = std::lock_guard{service_lock};
if (SubcontextChildReap(pid)) {
name = "Subcontext";
} else {