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Better logging in libprocessgroup and make resources clean up themselves 

Bug: 36661364
Bug: 36701253
Bug: 37540956

Test: Reboot bullhead
Test: Start and stop services
Change-Id: I97b6e17a7350850db733bee9fc83bdd296d88c61
This commit is contained in:
Tom Cherry 2017-04-21 13:48:49 -07:00
parent 3d7ee068e0
commit 20514c4411
2 changed files with 103 additions and 83 deletions
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5
libprocessgroup/include/processgroup/processgroup.h
View File

@ -22,8 +22,13 @@
__BEGIN_DECLS
// Return 0 and removes the cgroup if there are no longer any processes in it.
// Returns -1 in the case of an error occurring or if there are processes still running
// even after retrying for up to 200ms.
int killProcessGroup(uid_t uid, int initialPid, int signal);
// Returns the same as killProcessGroup(), however it does not retry, which means
// that it only returns 0 in the case that the cgroup exists and it contains no processes.
int killProcessGroupOnce(uid_t uid, int initialPid, int signal);
int createProcessGroup(uid_t uid, int initialPid);

181
libprocessgroup/processgroup.cpp
View File

@ -34,6 +34,7 @@
#include <thread>
#include <android-base/logging.h>
#include <android-base/unique_fd.h>
#include <private/android_filesystem_config.h>
#include <processgroup/processgroup.h>
@ -64,12 +65,27 @@ using namespace std::chrono_literals;
std::once_flag init_path_flag;
struct ctx {
bool initialized;
int fd;
char buf[128];
char *buf_ptr;
size_t buf_len;
class ProcessGroup {
public:
ProcessGroup() : buf_ptr_(buf_), buf_len_(0) {}
bool Open(uid_t uid, int pid);
// Return positive number and sets *pid = next pid in process cgroup on success
// Returns 0 if there are no pids left in the process cgroup
// Returns -errno if an error was encountered
int GetOneAppProcess(pid_t* pid);
private:
// Returns positive number of bytes filled on success
// Returns 0 if there was nothing to read
// Returns -errno if an error was encountered
int RefillBuffer();
android::base::unique_fd fd_;
char buf_[128];
char* buf_ptr_;
size_t buf_len_;
};
static const char* getCgroupRootPath() {
@ -105,87 +121,67 @@ static int convertUidPidToPath(char *path, size_t size, uid_t uid, int pid)
pid);
}
static int initCtx(uid_t uid, int pid, struct ctx *ctx)
{
int ret;
bool ProcessGroup::Open(uid_t uid, int pid) {
char path[PROCESSGROUP_MAX_PATH_LEN] = {0};
convertUidPidToPath(path, sizeof(path), uid, pid);
strlcat(path, PROCESSGROUP_CGROUP_PROCS_FILE, sizeof(path));
int fd = open(path, O_RDONLY);
if (fd < 0) {
ret = -errno;
PLOG(WARNING) << "failed to open " << path;
return ret;
}
if (fd < 0) return false;
ctx->fd = fd;
ctx->buf_ptr = ctx->buf;
ctx->buf_len = 0;
ctx->initialized = true;
fd_.reset(fd);
LOG(VERBOSE) << "Initialized context for " << path;
return 0;
return true;
}
static int refillBuffer(struct ctx *ctx)
{
memmove(ctx->buf, ctx->buf_ptr, ctx->buf_len);
ctx->buf_ptr = ctx->buf;
int ProcessGroup::RefillBuffer() {
memmove(buf_, buf_ptr_, buf_len_);
buf_ptr_ = buf_;
ssize_t ret = read(ctx->fd, ctx->buf_ptr + ctx->buf_len,
sizeof(ctx->buf) - ctx->buf_len - 1);
ssize_t ret = read(fd_, buf_ptr_ + buf_len_, sizeof(buf_) - buf_len_ - 1);
if (ret < 0) {
return -errno;
} else if (ret == 0) {
return 0;
}
ctx->buf_len += ret;
ctx->buf[ctx->buf_len] = 0;
LOG(VERBOSE) << "Read " << ret << " to buffer: " << ctx->buf;
buf_len_ += ret;
buf_[buf_len_] = 0;
LOG(VERBOSE) << "Read " << ret << " to buffer: " << buf_;
assert(ctx->buf_len <= sizeof(ctx->buf));
assert(buf_len_ <= sizeof(buf_));
return ret;
}
static pid_t getOneAppProcess(uid_t uid, int appProcessPid, struct ctx *ctx)
{
if (!ctx->initialized) {
int ret = initCtx(uid, appProcessPid, ctx);
if (ret < 0) {
return ret;
}
}
int ProcessGroup::GetOneAppProcess(pid_t* out_pid) {
*out_pid = 0;
char *eptr;
while ((eptr = (char *)memchr(ctx->buf_ptr, '\n', ctx->buf_len)) == NULL) {
int ret = refillBuffer(ctx);
if (ret == 0) {
return -ERANGE;
}
if (ret < 0) {
return ret;
}
char* eptr;
while ((eptr = static_cast<char*>(memchr(buf_ptr_, '\n', buf_len_))) == nullptr) {
int ret = RefillBuffer();
if (ret <= 0) return ret;
}
*eptr = '\0';
char *pid_eptr = NULL;
char* pid_eptr = nullptr;
errno = 0;
long pid = strtol(ctx->buf_ptr, &pid_eptr, 10);
long pid = strtol(buf_ptr_, &pid_eptr, 10);
if (errno != 0) {
return -errno;
}
if (pid_eptr != eptr) {
return -EINVAL;
errno = EINVAL;
return -errno;
}
ctx->buf_len -= (eptr - ctx->buf_ptr) + 1;
ctx->buf_ptr = eptr + 1;
buf_len_ -= (eptr - buf_ptr_) + 1;
buf_ptr_ = eptr + 1;
return (pid_t)pid;
*out_pid = static_cast<pid_t>(pid);
return 1;
}
static int removeProcessGroup(uid_t uid, int pid)
@ -219,8 +215,8 @@ static void removeUidProcessGroups(const char *uid_path)
}
snprintf(path, sizeof(path), "%s/%s", uid_path, dir->d_name);
LOG(VERBOSE) << "removing " << path;
if (rmdir(path) == -1) PLOG(WARNING) << "failed to remove " << path;
LOG(VERBOSE) << "Removing " << path;
if (rmdir(path) == -1) PLOG(WARNING) << "Failed to remove " << path;
}
}
}
@ -231,7 +227,7 @@ void removeAllProcessGroups()
const char* cgroup_root_path = getCgroupRootPath();
std::unique_ptr<DIR, decltype(&closedir)> root(opendir(cgroup_root_path), closedir);
if (root == NULL) {
PLOG(ERROR) << "failed to open " << cgroup_root_path;
PLOG(ERROR) << "Failed to open " << cgroup_root_path;
} else {
dirent* dir;
while ((dir = readdir(root.get())) != nullptr) {
@ -246,20 +242,26 @@ void removeAllProcessGroups()
snprintf(path, sizeof(path), "%s/%s", cgroup_root_path, dir->d_name);
removeUidProcessGroups(path);
LOG(VERBOSE) << "removing " << path;
if (rmdir(path) == -1) PLOG(WARNING) << "failed to remove " << path;
LOG(VERBOSE) << "Removing " << path;
if (rmdir(path) == -1) PLOG(WARNING) << "Failed to remove " << path;
}
}
}
// Returns number of processes killed on success
// Returns 0 if there are no processes in the process cgroup left to kill
// Returns -errno on error
static int doKillProcessGroupOnce(uid_t uid, int initialPid, int signal) {
int processes = 0;
struct ctx ctx;
ProcessGroup process_group;
if (!process_group.Open(uid, initialPid)) {
PLOG(WARNING) << "Failed to open process cgroup uid " << uid << " pid " << initialPid;
return -errno;
}
int ret;
pid_t pid;
ctx.initialized = false;
while ((pid = getOneAppProcess(uid, initialPid, &ctx)) >= 0) {
int processes = 0;
while ((ret = process_group.GetOneAppProcess(&pid)) > 0 && pid >= 0) {
processes++;
if (pid == 0) {
// Should never happen... but if it does, trying to kill this
@ -267,55 +269,68 @@ static int doKillProcessGroupOnce(uid_t uid, int initialPid, int signal) {
LOG(WARNING) << "Yikes, we've been told to kill pid 0! How about we don't do that?";
continue;
}
LOG(VERBOSE) << "Killing pid " << pid << " in uid " << uid
<< " as part of process group " << initialPid;
LOG(VERBOSE) << "Killing pid " << pid << " in uid " << uid << " as part of process cgroup "
<< initialPid;
if (kill(pid, signal) == -1) {
PLOG(WARNING) << "kill(" << pid << ", " << signal << ") failed";
}
}
if (ctx.initialized) {
close(ctx.fd);
}
return processes;
return ret >= 0 ? processes : ret;
}
static int killProcessGroup(uid_t uid, int initialPid, int signal, int retry) {
static int killProcessGroup(uid_t uid, int initialPid, int signal, int retries) {
std::chrono::steady_clock::time_point start = std::chrono::steady_clock::now();
int retry = retries;
int processes;
while ((processes = doKillProcessGroupOnce(uid, initialPid, signal)) > 0) {
LOG(VERBOSE) << "killed " << processes << " processes for processgroup " << initialPid;
LOG(VERBOSE) << "Killed " << processes << " processes for processgroup " << initialPid;
if (retry > 0) {
std::this_thread::sleep_for(5ms);
--retry;
} else {
LOG(ERROR) << "failed to kill " << processes << " processes for processgroup "
<< initialPid;
break;
}
}
std::chrono::steady_clock::time_point end = std::chrono::steady_clock::now();
if (processes < 0) {
PLOG(ERROR) << "Error encountered killing process cgroup uid " << uid << " pid "
<< initialPid;
return -1;
}
std::chrono::steady_clock::time_point end = std::chrono::steady_clock::now();
auto ms = std::chrono::duration_cast<std::chrono::milliseconds>(end - start).count();
LOG(VERBOSE) << "Killed process group uid " << uid << " pid " << initialPid << " in "
<< static_cast<int>(ms) << "ms, " << processes << " procs remain";
// We only calculate the number of 'processes' when killing the processes.
// In the retries == 0 case, we only kill the processes once and therefore
// will not have waited then recalculated how many processes are remaining
// after the first signals have been sent.
// Logging anything regarding the number of 'processes' here does not make sense.
if (processes == 0) {
if (retries > 0) {
LOG(INFO) << "Successfully killed process cgroup uid " << uid << " pid " << initialPid
<< " in " << static_cast<int>(ms) << "ms";
}
return removeProcessGroup(uid, initialPid);
} else {
if (retries > 0) {
LOG(ERROR) << "Failed to kill process cgroup uid " << uid << " pid " << initialPid
<< " in " << static_cast<int>(ms) << "ms, " << processes
<< " processes remain";
}
return -1;
}
}
int killProcessGroup(uid_t uid, int initialPid, int signal) {
return killProcessGroup(uid, initialPid, signal, 40 /*maxRetry*/);
return killProcessGroup(uid, initialPid, signal, 40 /*retries*/);
}
int killProcessGroupOnce(uid_t uid, int initialPid, int signal) {
return killProcessGroup(uid, initialPid, signal, 0 /*maxRetry*/);
return killProcessGroup(uid, initialPid, signal, 0 /*retries*/);
}
static bool mkdirAndChown(const char *path, mode_t mode, uid_t uid, gid_t gid)
@ -341,14 +356,14 @@ int createProcessGroup(uid_t uid, int initialPid)
convertUidToPath(path, sizeof(path), uid);
if (!mkdirAndChown(path, 0750, AID_SYSTEM, AID_SYSTEM)) {
PLOG(ERROR) << "failed to make and chown " << path;
PLOG(ERROR) << "Failed to make and chown " << path;
return -errno;
}
convertUidPidToPath(path, sizeof(path), uid, initialPid);
if (!mkdirAndChown(path, 0750, AID_SYSTEM, AID_SYSTEM)) {
PLOG(ERROR) << "failed to make and chown " << path;
PLOG(ERROR) << "Failed to make and chown " << path;
return -errno;
}
@ -357,7 +372,7 @@ int createProcessGroup(uid_t uid, int initialPid)
int fd = open(path, O_WRONLY);
if (fd == -1) {
int ret = -errno;
PLOG(ERROR) << "failed to open " << path;
PLOG(ERROR) << "Failed to open " << path;
return ret;
}
@ -367,7 +382,7 @@ int createProcessGroup(uid_t uid, int initialPid)
int ret = 0;
if (write(fd, pid, len) < 0) {
ret = -errno;
PLOG(ERROR) << "failed to write '" << pid << "' to " << path;
PLOG(ERROR) << "Failed to write '" << pid << "' to " << path;
}
close(fd);