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

Merge "liblog: remove Rwlocks for logd_socket and pmsg_fd" into rvc-dev am: 03ead14288

Browse source 
Change-Id: I77df9c4c1f4d5bbf34f4e96d42ebb9343ef446c5
This commit is contained in:
Tom Cherry 2020-04-29 17:48:38 +00:00 committed by Automerger Merge Worker
commit 178a714b88
7 changed files with 148 additions and 194 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

7
liblog/include/log/log.h
View file

@ -143,8 +143,11 @@ clockid_t android_log_clockid(void);
/*
* Release any logger resources (a new log write will immediately re-acquire)
*
* May be used to clean up File descriptors after a Fork, the resources are
* all O_CLOEXEC so wil self clean on exec().
* This is specifically meant to be used by Zygote to close open file descriptors after fork()
* and before specialization. O_CLOEXEC is used on file descriptors, so they will be closed upon
* exec() in normal use cases.
*
* Note that this is not safe to call from a multi-threaded program.
*/
void __android_log_close(void);

71
liblog/logd_writer.cpp
View file

@ -32,58 +32,53 @@
#include <time.h>
#include <unistd.h>
#include <shared_mutex>
#include <private/android_filesystem_config.h>
#include <private/android_logger.h>
#include "logger.h"
#include "rwlock.h"
#include "uio.h"
static int logd_socket;
static RwLock logd_socket_lock;
static void OpenSocketLocked() {
logd_socket = TEMP_FAILURE_RETRY(socket(PF_UNIX, SOCK_DGRAM | SOCK_CLOEXEC | SOCK_NONBLOCK, 0));
if (logd_socket <= 0) {
return;
}
static atomic_int logd_socket;
// Note that it is safe to call connect() multiple times on DGRAM Unix domain sockets, so this
// function is used to reconnect to logd without requiring a new socket.
static void LogdConnect() {
sockaddr_un un = {};
un.sun_family = AF_UNIX;
strcpy(un.sun_path, "/dev/socket/logdw");
if (TEMP_FAILURE_RETRY(
connect(logd_socket, reinterpret_cast<sockaddr*>(&un), sizeof(sockaddr_un))) < 0) {
close(logd_socket);
logd_socket = 0;
}
TEMP_FAILURE_RETRY(connect(logd_socket, reinterpret_cast<sockaddr*>(&un), sizeof(sockaddr_un)));
}
static void OpenSocket() {
auto lock = std::unique_lock{logd_socket_lock};
if (logd_socket > 0) {
// Someone raced us and opened the socket already.
// logd_socket should only be opened once. If we see that logd_socket is uninitialized, we create a
// new socket and attempt to exchange it into the atomic logd_socket. If the compare/exchange was
// successful, then that will be the socket used for the duration of the program, otherwise a
// different thread has already opened and written the socket to the atomic, so close the new socket
// and return.
static void GetSocket() {
if (logd_socket != 0) {
return;
}
OpenSocketLocked();
}
static void ResetSocket(int old_socket) {
auto lock = std::unique_lock{logd_socket_lock};
if (old_socket != logd_socket) {
// Someone raced us and reset the socket already.
int new_socket =
TEMP_FAILURE_RETRY(socket(PF_UNIX, SOCK_DGRAM | SOCK_CLOEXEC | SOCK_NONBLOCK, 0));
if (new_socket <= 0) {
return;
}
close(logd_socket);
logd_socket = 0;
OpenSocketLocked();
int uninitialized_value = 0;
if (!logd_socket.compare_exchange_strong(uninitialized_value, new_socket)) {
close(new_socket);
return;
}
LogdConnect();
}
// This is the one exception to the above. Zygote uses this to clean up open FD's after fork() and
// before specialization. It is single threaded at this point and therefore this function is
// explicitly not thread safe. It sets logd_socket to 0, so future logs will be safely initialized
// whenever they happen.
void LogdClose() {
auto lock = std::unique_lock{logd_socket_lock};
if (logd_socket > 0) {
close(logd_socket);
}
@ -99,12 +94,7 @@ int LogdWrite(log_id_t logId, struct timespec* ts, struct iovec* vec, size_t nr)
static atomic_int dropped;
static atomic_int droppedSecurity;
auto lock = std::shared_lock{logd_socket_lock};
if (logd_socket <= 0) {
lock.unlock();
OpenSocket();
lock.lock();
}
GetSocket();
if (logd_socket <= 0) {
return -EBADF;
@ -183,10 +173,7 @@ int LogdWrite(log_id_t logId, struct timespec* ts, struct iovec* vec, size_t nr)
// the connection, so we reset it and try again.
ret = TEMP_FAILURE_RETRY(writev(logd_socket, newVec, i));
if (ret < 0 && errno != EAGAIN) {
int old_socket = logd_socket;
lock.unlock();
ResetSocket(old_socket);
lock.lock();
LogdConnect();
ret = TEMP_FAILURE_RETRY(writev(logd_socket, newVec, i));
}

36
liblog/pmsg_writer.cpp
View file

@ -23,30 +23,36 @@
#include <sys/types.h>
#include <time.h>
#include <shared_mutex>
#include <log/log_properties.h>
#include <private/android_logger.h>
#include "logger.h"
#include "rwlock.h"
#include "uio.h"
static int pmsg_fd;
static RwLock pmsg_fd_lock;
static atomic_int pmsg_fd;
static void PmsgOpen() {
auto lock = std::unique_lock{pmsg_fd_lock};
if (pmsg_fd > 0) {
// Someone raced us and opened the socket already.
// pmsg_fd should only beopened once. If we see that pmsg_fd is uninitialized, we open "/dev/pmsg0"
// then attempt to compare/exchange it into pmsg_fd. If the compare/exchange was successful, then
// that will be the fd used for the duration of the program, otherwise a different thread has
// already opened and written the fd to the atomic, so close the new fd and return.
static void GetPmsgFd() {
if (pmsg_fd != 0) {
return;
}
pmsg_fd = TEMP_FAILURE_RETRY(open("/dev/pmsg0", O_WRONLY | O_CLOEXEC));
int new_fd = TEMP_FAILURE_RETRY(open("/dev/pmsg0", O_WRONLY | O_CLOEXEC));
if (new_fd <= 0) {
return;
}
int uninitialized_value = 0;
if (!pmsg_fd.compare_exchange_strong(uninitialized_value, new_fd)) {
close(new_fd);
return;
}
}
void PmsgClose() {
auto lock = std::unique_lock{pmsg_fd_lock};
if (pmsg_fd > 0) {
close(pmsg_fd);
}
@ -77,13 +83,7 @@ int PmsgWrite(log_id_t logId, struct timespec* ts, struct iovec* vec, size_t nr)
}
}
auto lock = std::shared_lock{pmsg_fd_lock};
if (pmsg_fd <= 0) {
lock.unlock();
PmsgOpen();
lock.lock();
}
GetPmsgFd();
if (pmsg_fd <= 0) {
return -EBADF;

39
liblog/rwlock.h
View file

@ -1,39 +0,0 @@
/*
* Copyright (C) 2019 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 <pthread.h>
// As of the end of Dec 2019, std::shared_mutex is *not* simply a pthread_rwlock, but rather a
// combination of std::mutex and std::condition variable, which is obviously less efficient. This
// immitates what std::shared_mutex should be doing and is compatible with std::shared_lock and
// std::unique_lock.
class RwLock {
public:
RwLock() {}
~RwLock() {}
void lock() { pthread_rwlock_wrlock(&rwlock_); }
void unlock() { pthread_rwlock_unlock(&rwlock_); }
void lock_shared() { pthread_rwlock_rdlock(&rwlock_); }
void unlock_shared() { pthread_rwlock_unlock(&rwlock_); }
private:
pthread_rwlock_t rwlock_ = PTHREAD_RWLOCK_INITIALIZER;
};

3
liblog/tests/Android.bp
View file

@ -63,8 +63,8 @@ cc_defaults {
"log_system_test.cpp",
"log_time_test.cpp",
"log_wrap_test.cpp",
"logd_writer_test.cpp",
"logprint_test.cpp",
"rwlock_test.cpp",
],
shared_libs: [
"libcutils",
@ -108,7 +108,6 @@ cc_test_host {
"liblog_host_test.cpp",
"liblog_default_tag.cpp",
"liblog_global_state.cpp",
"rwlock_test.cpp",
],
isolated: true,
}

95
liblog/tests/logd_writer_test.cpp Normal file
View file

@ -0,0 +1,95 @@
/*
* 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 <sys/un.h>
#include <unistd.h>
#include <android-base/file.h>
#include <android-base/stringprintf.h>
#include <android-base/unique_fd.h>
#include <gtest/gtest.h>
using android::base::StringPrintf;
using android::base::unique_fd;
// logd_writer takes advantage of the fact that connect() can be called multiple times for a DGRAM
// socket. This tests for that behavior.
TEST(liblog, multi_connect_dgram_socket) {
#ifdef __ANDROID__
auto temp_dir = TemporaryDir();
auto socket_path = StringPrintf("%s/test_socket", temp_dir.path);
unique_fd server_socket;
auto open_server_socket = [&] {
server_socket.reset(TEMP_FAILURE_RETRY(socket(AF_UNIX, SOCK_DGRAM | SOCK_CLOEXEC, 0)));
ASSERT_TRUE(server_socket.ok());
sockaddr_un server_sockaddr = {};
server_sockaddr.sun_family = AF_UNIX;
strlcpy(server_sockaddr.sun_path, socket_path.c_str(), sizeof(server_sockaddr.sun_path));
ASSERT_EQ(0,
TEMP_FAILURE_RETRY(bind(server_socket, reinterpret_cast<sockaddr*>(&server_sockaddr),
sizeof(server_sockaddr))));
};
// Open the server socket.
open_server_socket();
// Open the client socket.
auto client_socket =
unique_fd{TEMP_FAILURE_RETRY(socket(AF_UNIX, SOCK_DGRAM | SOCK_NONBLOCK | SOCK_CLOEXEC, 0))};
ASSERT_TRUE(client_socket.ok());
sockaddr_un client_sockaddr = {};
client_sockaddr.sun_family = AF_UNIX;
strlcpy(client_sockaddr.sun_path, socket_path.c_str(), sizeof(client_sockaddr.sun_path));
ASSERT_EQ(0,
TEMP_FAILURE_RETRY(connect(client_socket, reinterpret_cast<sockaddr*>(&client_sockaddr),
sizeof(client_sockaddr))));
// Ensure that communication works.
constexpr static char kSmoke[] = "smoke test";
ssize_t smoke_len = sizeof(kSmoke);
ASSERT_EQ(smoke_len, TEMP_FAILURE_RETRY(write(client_socket, kSmoke, sizeof(kSmoke))));
char read_buf[512];
ASSERT_EQ(smoke_len, TEMP_FAILURE_RETRY(read(server_socket, read_buf, sizeof(read_buf))));
ASSERT_STREQ(kSmoke, read_buf);
// Close the server socket.
server_socket.reset();
ASSERT_EQ(0, unlink(socket_path.c_str())) << strerror(errno);
// Ensure that write() from the client returns an error since the server is closed.
ASSERT_EQ(-1, TEMP_FAILURE_RETRY(write(client_socket, kSmoke, sizeof(kSmoke))));
ASSERT_EQ(errno, ECONNREFUSED) << strerror(errno);
// Open the server socket again.
open_server_socket();
// Reconnect the same client socket.
ASSERT_EQ(0,
TEMP_FAILURE_RETRY(connect(client_socket, reinterpret_cast<sockaddr*>(&client_sockaddr),
sizeof(client_sockaddr))))
<< strerror(errno);
// Ensure that communication works.
ASSERT_EQ(smoke_len, TEMP_FAILURE_RETRY(write(client_socket, kSmoke, sizeof(kSmoke))));
ASSERT_EQ(smoke_len, TEMP_FAILURE_RETRY(read(server_socket, read_buf, sizeof(read_buf))));
ASSERT_STREQ(kSmoke, read_buf);
#else
GTEST_LOG_(INFO) << "This test does nothing.\n";
#endif
}

91
liblog/tests/rwlock_test.cpp
View file

@ -1,91 +0,0 @@
/*
* Copyright (C) 2019 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 "../rwlock.h"
#include <chrono>
#include <shared_mutex>
#include <thread>
#include <gtest/gtest.h>
using namespace std::literals;
TEST(rwlock, reader_then_reader_lock) {
RwLock lock;
bool thread_ran = false;
auto read_guard = std::shared_lock{lock};
auto reader_thread = std::thread([&] {
auto read_guard = std::shared_lock{lock};
thread_ran = true;
});
auto end_time = std::chrono::steady_clock::now() + 1s;
while (std::chrono::steady_clock::now() < end_time) {
if (thread_ran) {
break;
}
}
EXPECT_EQ(true, thread_ran);
// Unlock the lock in case something went wrong, to ensure that we can still join() the thread.
read_guard.unlock();
reader_thread.join();
}
template <template <typename> typename L1, template <typename> typename L2>
void TestBlockingLocks() {
RwLock lock;
bool thread_ran = false;
auto read_guard = L1{lock};
auto reader_thread = std::thread([&] {
auto read_guard = L2{lock};
thread_ran = true;
});
auto end_time = std::chrono::steady_clock::now() + 1s;
while (std::chrono::steady_clock::now() < end_time) {
if (thread_ran) {
break;
}
}
EXPECT_EQ(false, thread_ran);
read_guard.unlock();
reader_thread.join();
EXPECT_EQ(true, thread_ran);
}
TEST(rwlock, reader_then_writer_lock) {
TestBlockingLocks<std::shared_lock, std::unique_lock>();
}
TEST(rwlock, writer_then_reader_lock) {
TestBlockingLocks<std::unique_lock, std::shared_lock>();
}
TEST(rwlock, writer_then_writer_lock) {
TestBlockingLocks<std::unique_lock, std::unique_lock>();
}