+++ /dev/null
-/*
- * lttng-ust-comm.c
- *
- * Copyright (C) 2011 David Goulet <david.goulet@polymtl.ca>
- * Copyright (C) 2011 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
- *
- * This library is free software; you can redistribute it and/or
- * modify it under the terms of the GNU Lesser General Public
- * License as published by the Free Software Foundation; only
- * version 2.1 of the License.
- *
- * This library is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
- * Lesser General Public License for more details.
- *
- * You should have received a copy of the GNU Lesser General Public
- * License along with this library; if not, write to the Free Software
- * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
- */
-
-#define _LGPL_SOURCE
-#include <sys/types.h>
-#include <sys/socket.h>
-#include <sys/prctl.h>
-#include <sys/mman.h>
-#include <sys/stat.h>
-#include <sys/types.h>
-#include <sys/wait.h>
-#include <fcntl.h>
-#include <unistd.h>
-#include <errno.h>
-#include <pthread.h>
-#include <semaphore.h>
-#include <time.h>
-#include <assert.h>
-#include <signal.h>
-#include <urcu/uatomic.h>
-#include <urcu/futex.h>
-
-#include <lttng/ust-comm.h>
-#include <lttng/ust-events.h>
-#include <lttng/usterr-signal-safe.h>
-#include <lttng/ust-abi.h>
-#include <lttng/tracepoint.h>
-#include <lttng/tracepoint-internal.h>
-#include <lttng/ust.h>
-#include "ltt-tracer-core.h"
-
-/*
- * Has lttng ust comm constructor been called ?
- */
-static int initialized;
-
-/*
- * The ust_lock/ust_unlock lock is used as a communication thread mutex.
- * Held when handling a command, also held by fork() to deal with
- * removal of threads, and by exit path.
- */
-
-/* Should the ust comm thread quit ? */
-static int lttng_ust_comm_should_quit;
-
-/*
- * Wait for either of these before continuing to the main
- * program:
- * - the register_done message from sessiond daemon
- * (will let the sessiond daemon enable sessions before main
- * starts.)
- * - sessiond daemon is not reachable.
- * - timeout (ensuring applications are resilient to session
- * daemon problems).
- */
-static sem_t constructor_wait;
-/*
- * Doing this for both the global and local sessiond.
- */
-static int sem_count = { 2 };
-
-/*
- * Info about socket and associated listener thread.
- */
-struct sock_info {
- const char *name;
- pthread_t ust_listener; /* listener thread */
- int root_handle;
- int constructor_sem_posted;
- int allowed;
- int global;
-
- char sock_path[PATH_MAX];
- int socket;
-
- char wait_shm_path[PATH_MAX];
- char *wait_shm_mmap;
-};
-
-/* Socket from app (connect) to session daemon (listen) for communication */
-struct sock_info global_apps = {
- .name = "global",
- .global = 1,
-
- .root_handle = -1,
- .allowed = 1,
-
- .sock_path = DEFAULT_GLOBAL_APPS_UNIX_SOCK,
- .socket = -1,
-
- .wait_shm_path = DEFAULT_GLOBAL_APPS_WAIT_SHM_PATH,
-};
-
-/* TODO: allow global_apps_sock_path override */
-
-struct sock_info local_apps = {
- .name = "local",
- .global = 0,
- .root_handle = -1,
- .allowed = 0, /* Check setuid bit first */
-
- .socket = -1,
-};
-
-static int wait_poll_fallback;
-
-extern void ltt_ring_buffer_client_overwrite_init(void);
-extern void ltt_ring_buffer_client_discard_init(void);
-extern void ltt_ring_buffer_metadata_client_init(void);
-extern void ltt_ring_buffer_client_overwrite_exit(void);
-extern void ltt_ring_buffer_client_discard_exit(void);
-extern void ltt_ring_buffer_metadata_client_exit(void);
-
-static
-int setup_local_apps(void)
-{
- const char *home_dir;
- uid_t uid;
-
- uid = getuid();
- /*
- * Disallow per-user tracing for setuid binaries.
- */
- if (uid != geteuid()) {
- local_apps.allowed = 0;
- return 0;
- } else {
- local_apps.allowed = 1;
- }
- home_dir = (const char *) getenv("HOME");
- if (!home_dir)
- return -ENOENT;
- snprintf(local_apps.sock_path, PATH_MAX,
- DEFAULT_HOME_APPS_UNIX_SOCK, home_dir);
- snprintf(local_apps.wait_shm_path, PATH_MAX,
- DEFAULT_HOME_APPS_WAIT_SHM_PATH, uid);
- return 0;
-}
-
-static
-int register_app_to_sessiond(int socket)
-{
- ssize_t ret;
- int prctl_ret;
- struct {
- uint32_t major;
- uint32_t minor;
- pid_t pid;
- pid_t ppid;
- uid_t uid;
- gid_t gid;
- char name[16]; /* process name */
- } reg_msg;
-
- reg_msg.major = LTTNG_UST_COMM_VERSION_MAJOR;
- reg_msg.minor = LTTNG_UST_COMM_VERSION_MINOR;
- reg_msg.pid = getpid();
- reg_msg.ppid = getppid();
- reg_msg.uid = getuid();
- reg_msg.gid = getgid();
- prctl_ret = prctl(PR_GET_NAME, (unsigned long) reg_msg.name, 0, 0, 0);
- if (prctl_ret) {
- ERR("Error executing prctl");
- return -errno;
- }
-
- ret = ustcomm_send_unix_sock(socket, ®_msg, sizeof(reg_msg));
- if (ret >= 0 && ret != sizeof(reg_msg))
- return -EIO;
- return ret;
-}
-
-static
-int send_reply(int sock, struct ustcomm_ust_reply *lur)
-{
- ssize_t len;
-
- len = ustcomm_send_unix_sock(sock, lur, sizeof(*lur));
- switch (len) {
- case sizeof(*lur):
- DBG("message successfully sent");
- return 0;
- case -1:
- if (errno == ECONNRESET) {
- printf("remote end closed connection\n");
- return 0;
- }
- return -1;
- default:
- printf("incorrect message size: %zd\n", len);
- return -1;
- }
-}
-
-static
-int handle_register_done(struct sock_info *sock_info)
-{
- int ret;
-
- if (sock_info->constructor_sem_posted)
- return 0;
- sock_info->constructor_sem_posted = 1;
- if (uatomic_read(&sem_count) <= 0) {
- return 0;
- }
- ret = uatomic_add_return(&sem_count, -1);
- if (ret == 0) {
- ret = sem_post(&constructor_wait);
- assert(!ret);
- }
- return 0;
-}
-
-static
-int handle_message(struct sock_info *sock_info,
- int sock, struct ustcomm_ust_msg *lum)
-{
- int ret = 0;
- const struct lttng_ust_objd_ops *ops;
- struct ustcomm_ust_reply lur;
- int shm_fd, wait_fd;
-
- ust_lock();
-
- memset(&lur, 0, sizeof(lur));
-
- if (lttng_ust_comm_should_quit) {
- ret = -EPERM;
- goto end;
- }
-
- ops = objd_ops(lum->handle);
- if (!ops) {
- ret = -ENOENT;
- goto end;
- }
-
- switch (lum->cmd) {
- case LTTNG_UST_REGISTER_DONE:
- if (lum->handle == LTTNG_UST_ROOT_HANDLE)
- ret = handle_register_done(sock_info);
- else
- ret = -EINVAL;
- break;
- case LTTNG_UST_RELEASE:
- if (lum->handle == LTTNG_UST_ROOT_HANDLE)
- ret = -EPERM;
- else
- ret = lttng_ust_objd_unref(lum->handle);
- break;
- default:
- if (ops->cmd)
- ret = ops->cmd(lum->handle, lum->cmd,
- (unsigned long) &lum->u);
- else
- ret = -ENOSYS;
- break;
- }
-
-end:
- lur.handle = lum->handle;
- lur.cmd = lum->cmd;
- lur.ret_val = ret;
- if (ret >= 0) {
- lur.ret_code = USTCOMM_OK;
- } else {
- //lur.ret_code = USTCOMM_SESSION_FAIL;
- lur.ret_code = ret;
- }
- switch (lum->cmd) {
- case LTTNG_UST_STREAM:
- /*
- * Special-case reply to send stream info.
- * Use lum.u output.
- */
- lur.u.stream.memory_map_size = lum->u.stream.memory_map_size;
- shm_fd = lum->u.stream.shm_fd;
- wait_fd = lum->u.stream.wait_fd;
- break;
- case LTTNG_UST_METADATA:
- case LTTNG_UST_CHANNEL:
- lur.u.channel.memory_map_size = lum->u.channel.memory_map_size;
- shm_fd = lum->u.channel.shm_fd;
- wait_fd = lum->u.channel.wait_fd;
- break;
- case LTTNG_UST_VERSION:
- lur.u.version = lum->u.version;
- break;
- }
- ret = send_reply(sock, &lur);
- if (ret < 0) {
- perror("error sending reply");
- goto error;
- }
-
- if ((lum->cmd == LTTNG_UST_STREAM
- || lum->cmd == LTTNG_UST_CHANNEL
- || lum->cmd == LTTNG_UST_METADATA)
- && lur.ret_code == USTCOMM_OK) {
- /* we also need to send the file descriptors. */
- ret = ustcomm_send_fds_unix_sock(sock,
- &shm_fd, &shm_fd,
- 1, sizeof(int));
- if (ret < 0) {
- perror("send shm_fd");
- goto error;
- }
- ret = ustcomm_send_fds_unix_sock(sock,
- &wait_fd, &wait_fd,
- 1, sizeof(int));
- if (ret < 0) {
- perror("send wait_fd");
- goto error;
- }
- }
-error:
- ust_unlock();
- return ret;
-}
-
-static
-void cleanup_sock_info(struct sock_info *sock_info)
-{
- int ret;
-
- if (sock_info->socket != -1) {
- ret = close(sock_info->socket);
- if (ret) {
- ERR("Error closing apps socket");
- }
- sock_info->socket = -1;
- }
- if (sock_info->root_handle != -1) {
- ret = lttng_ust_objd_unref(sock_info->root_handle);
- if (ret) {
- ERR("Error unref root handle");
- }
- sock_info->root_handle = -1;
- }
- sock_info->constructor_sem_posted = 0;
- if (sock_info->wait_shm_mmap) {
- ret = munmap(sock_info->wait_shm_mmap, sysconf(_SC_PAGE_SIZE));
- if (ret) {
- ERR("Error unmapping wait shm");
- }
- sock_info->wait_shm_mmap = NULL;
- }
-}
-
-/*
- * Using fork to set umask in the child process (not multi-thread safe).
- * We deal with the shm_open vs ftruncate race (happening when the
- * sessiond owns the shm and does not let everybody modify it, to ensure
- * safety against shm_unlink) by simply letting the mmap fail and
- * retrying after a few seconds.
- * For global shm, everybody has rw access to it until the sessiond
- * starts.
- */
-static
-int get_wait_shm(struct sock_info *sock_info, size_t mmap_size)
-{
- int wait_shm_fd, ret;
- pid_t pid;
-
- /*
- * Try to open read-only.
- */
- wait_shm_fd = shm_open(sock_info->wait_shm_path, O_RDONLY, 0);
- if (wait_shm_fd >= 0) {
- goto end;
- } else if (wait_shm_fd < 0 && errno != ENOENT) {
- /*
- * Real-only open did not work, and it's not because the
- * entry was not present. It's a failure that prohibits
- * using shm.
- */
- ERR("Error opening shm %s", sock_info->wait_shm_path);
- goto end;
- }
- /*
- * If the open failed because the file did not exist, try
- * creating it ourself.
- */
- pid = fork();
- if (pid > 0) {
- int status;
-
- /*
- * Parent: wait for child to return, in which case the
- * shared memory map will have been created.
- */
- pid = wait(&status);
- if (!WIFEXITED(status) || WEXITSTATUS(status) != 0) {
- wait_shm_fd = -1;
- goto end;
- }
- /*
- * Try to open read-only again after creation.
- */
- wait_shm_fd = shm_open(sock_info->wait_shm_path, O_RDONLY, 0);
- if (wait_shm_fd < 0) {
- /*
- * Real-only open did not work. It's a failure
- * that prohibits using shm.
- */
- ERR("Error opening shm %s", sock_info->wait_shm_path);
- goto end;
- }
- goto end;
- } else if (pid == 0) {
- int create_mode;
-
- /* Child */
- create_mode = S_IRUSR | S_IWUSR | S_IRGRP;
- if (sock_info->global)
- create_mode |= S_IROTH | S_IWGRP | S_IWOTH;
- /*
- * We're alone in a child process, so we can modify the
- * process-wide umask.
- */
- umask(~create_mode);
- /*
- * Try creating shm (or get rw access).
- * We don't do an exclusive open, because we allow other
- * processes to create+ftruncate it concurrently.
- */
- wait_shm_fd = shm_open(sock_info->wait_shm_path,
- O_RDWR | O_CREAT, create_mode);
- if (wait_shm_fd >= 0) {
- ret = ftruncate(wait_shm_fd, mmap_size);
- if (ret) {
- PERROR("ftruncate");
- exit(EXIT_FAILURE);
- }
- exit(EXIT_SUCCESS);
- }
- /*
- * For local shm, we need to have rw access to accept
- * opening it: this means the local sessiond will be
- * able to wake us up. For global shm, we open it even
- * if rw access is not granted, because the root.root
- * sessiond will be able to override all rights and wake
- * us up.
- */
- if (!sock_info->global && errno != EACCES) {
- ERR("Error opening shm %s", sock_info->wait_shm_path);
- exit(EXIT_FAILURE);
- }
- /*
- * The shm exists, but we cannot open it RW. Report
- * success.
- */
- exit(EXIT_SUCCESS);
- } else {
- return -1;
- }
-end:
- if (wait_shm_fd >= 0 && !sock_info->global) {
- struct stat statbuf;
-
- /*
- * Ensure that our user is the owner of the shm file for
- * local shm. If we do not own the file, it means our
- * sessiond will not have access to wake us up (there is
- * probably a rogue process trying to fake our
- * sessiond). Fallback to polling method in this case.
- */
- ret = fstat(wait_shm_fd, &statbuf);
- if (ret) {
- PERROR("fstat");
- goto error_close;
- }
- if (statbuf.st_uid != getuid())
- goto error_close;
- }
- return wait_shm_fd;
-
-error_close:
- ret = close(wait_shm_fd);
- if (ret) {
- PERROR("Error closing fd");
- }
- return -1;
-}
-
-static
-char *get_map_shm(struct sock_info *sock_info)
-{
- size_t mmap_size = sysconf(_SC_PAGE_SIZE);
- int wait_shm_fd, ret;
- char *wait_shm_mmap;
-
- wait_shm_fd = get_wait_shm(sock_info, mmap_size);
- if (wait_shm_fd < 0) {
- goto error;
- }
- wait_shm_mmap = mmap(NULL, mmap_size, PROT_READ,
- MAP_SHARED, wait_shm_fd, 0);
- /* close shm fd immediately after taking the mmap reference */
- ret = close(wait_shm_fd);
- if (ret) {
- PERROR("Error closing fd");
- }
- if (wait_shm_mmap == MAP_FAILED) {
- DBG("mmap error (can be caused by race with sessiond). Fallback to poll mode.");
- goto error;
- }
- return wait_shm_mmap;
-
-error:
- return NULL;
-}
-
-static
-void wait_for_sessiond(struct sock_info *sock_info)
-{
- int ret;
-
- ust_lock();
- if (lttng_ust_comm_should_quit) {
- goto quit;
- }
- if (wait_poll_fallback) {
- goto error;
- }
- if (!sock_info->wait_shm_mmap) {
- sock_info->wait_shm_mmap = get_map_shm(sock_info);
- if (!sock_info->wait_shm_mmap)
- goto error;
- }
- ust_unlock();
-
- DBG("Waiting for %s apps sessiond", sock_info->name);
- /* Wait for futex wakeup */
- if (uatomic_read((int32_t *) sock_info->wait_shm_mmap) == 0) {
- ret = futex_async((int32_t *) sock_info->wait_shm_mmap,
- FUTEX_WAIT, 0, NULL, NULL, 0);
- if (ret < 0) {
- if (errno == EFAULT) {
- wait_poll_fallback = 1;
- WARN(
-"Linux kernels 2.6.33 to 3.0 (with the exception of stable versions) "
-"do not support FUTEX_WAKE on read-only memory mappings correctly. "
-"Please upgrade your kernel "
-"(fix is commit 9ea71503a8ed9184d2d0b8ccc4d269d05f7940ae in Linux kernel "
-"mainline). LTTng-UST will use polling mode fallback.");
- }
- PERROR("futex");
- }
- }
- return;
-
-quit:
- ust_unlock();
- return;
-
-error:
- ust_unlock();
- return;
-}
-
-/*
- * This thread does not allocate any resource, except within
- * handle_message, within mutex protection. This mutex protects against
- * fork and exit.
- * The other moment it allocates resources is at socket connexion, which
- * is also protected by the mutex.
- */
-static
-void *ust_listener_thread(void *arg)
-{
- struct sock_info *sock_info = arg;
- int sock, ret, prev_connect_failed = 0, has_waited = 0;
-
- /* Restart trying to connect to the session daemon */
-restart:
- if (prev_connect_failed) {
- /* Wait for sessiond availability with pipe */
- wait_for_sessiond(sock_info);
- if (has_waited) {
- has_waited = 0;
- /*
- * Sleep for 5 seconds before retrying after a
- * sequence of failure / wait / failure. This
- * deals with a killed or broken session daemon.
- */
- sleep(5);
- }
- has_waited = 1;
- prev_connect_failed = 0;
- }
- ust_lock();
-
- if (lttng_ust_comm_should_quit) {
- ust_unlock();
- goto quit;
- }
-
- if (sock_info->socket != -1) {
- ret = close(sock_info->socket);
- if (ret) {
- ERR("Error closing %s apps socket", sock_info->name);
- }
- sock_info->socket = -1;
- }
-
- /* Register */
- ret = ustcomm_connect_unix_sock(sock_info->sock_path);
- if (ret < 0) {
- ERR("Error connecting to %s apps socket", sock_info->name);
- prev_connect_failed = 1;
- /*
- * If we cannot find the sessiond daemon, don't delay
- * constructor execution.
- */
- ret = handle_register_done(sock_info);
- assert(!ret);
- ust_unlock();
- goto restart;
- }
-
- sock_info->socket = sock = ret;
-
- /*
- * Create only one root handle per listener thread for the whole
- * process lifetime.
- */
- if (sock_info->root_handle == -1) {
- ret = lttng_abi_create_root_handle();
- if (ret < 0) {
- ERR("Error creating root handle");
- ust_unlock();
- goto quit;
- }
- sock_info->root_handle = ret;
- }
-
- ret = register_app_to_sessiond(sock);
- if (ret < 0) {
- ERR("Error registering to %s apps socket", sock_info->name);
- prev_connect_failed = 1;
- /*
- * If we cannot register to the sessiond daemon, don't
- * delay constructor execution.
- */
- ret = handle_register_done(sock_info);
- assert(!ret);
- ust_unlock();
- goto restart;
- }
- ust_unlock();
-
- for (;;) {
- ssize_t len;
- struct ustcomm_ust_msg lum;
-
- len = ustcomm_recv_unix_sock(sock, &lum, sizeof(lum));
- switch (len) {
- case 0: /* orderly shutdown */
- DBG("%s ltt-sessiond has performed an orderly shutdown\n", sock_info->name);
- goto end;
- case sizeof(lum):
- DBG("message received\n");
- ret = handle_message(sock_info, sock, &lum);
- if (ret < 0) {
- ERR("Error handling message for %s socket", sock_info->name);
- }
- continue;
- case -1:
- if (errno == ECONNRESET) {
- ERR("%s remote end closed connection\n", sock_info->name);
- goto end;
- }
- goto end;
- default:
- ERR("incorrect message size (%s socket): %zd\n", sock_info->name, len);
- continue;
- }
-
- }
-end:
- goto restart; /* try to reconnect */
-quit:
- return NULL;
-}
-
-/*
- * Return values: -1: don't wait. 0: wait forever. 1: timeout wait.
- */
-static
-int get_timeout(struct timespec *constructor_timeout)
-{
- long constructor_delay_ms = LTTNG_UST_DEFAULT_CONSTRUCTOR_TIMEOUT_MS;
- char *str_delay;
- int ret;
-
- str_delay = getenv("UST_REGISTER_TIMEOUT");
- if (str_delay) {
- constructor_delay_ms = strtol(str_delay, NULL, 10);
- }
-
- switch (constructor_delay_ms) {
- case -1:/* fall-through */
- case 0:
- return constructor_delay_ms;
- default:
- break;
- }
-
- /*
- * If we are unable to find the current time, don't wait.
- */
- ret = clock_gettime(CLOCK_REALTIME, constructor_timeout);
- if (ret) {
- return -1;
- }
- constructor_timeout->tv_sec += constructor_delay_ms / 1000UL;
- constructor_timeout->tv_nsec +=
- (constructor_delay_ms % 1000UL) * 1000000UL;
- if (constructor_timeout->tv_nsec >= 1000000000UL) {
- constructor_timeout->tv_sec++;
- constructor_timeout->tv_nsec -= 1000000000UL;
- }
- return 1;
-}
-
-/*
- * sessiond monitoring thread: monitor presence of global and per-user
- * sessiond by polling the application common named pipe.
- */
-/* TODO */
-
-void __attribute__((constructor)) lttng_ust_init(void)
-{
- struct timespec constructor_timeout;
- int timeout_mode;
- int ret;
-
- if (uatomic_xchg(&initialized, 1) == 1)
- return;
-
- /*
- * We want precise control over the order in which we construct
- * our sub-libraries vs starting to receive commands from
- * sessiond (otherwise leading to errors when trying to create
- * sessiond before the init functions are completed).
- */
- init_usterr();
- init_tracepoint();
- ltt_ring_buffer_metadata_client_init();
- ltt_ring_buffer_client_overwrite_init();
- ltt_ring_buffer_client_discard_init();
-
- timeout_mode = get_timeout(&constructor_timeout);
-
- ret = sem_init(&constructor_wait, 0, 0);
- assert(!ret);
-
- ret = setup_local_apps();
- if (ret) {
- ERR("Error setting up to local apps");
- }
- ret = pthread_create(&local_apps.ust_listener, NULL,
- ust_listener_thread, &local_apps);
-
- if (local_apps.allowed) {
- ret = pthread_create(&global_apps.ust_listener, NULL,
- ust_listener_thread, &global_apps);
- } else {
- handle_register_done(&local_apps);
- }
-
- switch (timeout_mode) {
- case 1: /* timeout wait */
- do {
- ret = sem_timedwait(&constructor_wait,
- &constructor_timeout);
- } while (ret < 0 && errno == EINTR);
- if (ret < 0 && errno == ETIMEDOUT) {
- ERR("Timed out waiting for ltt-sessiond");
- } else {
- assert(!ret);
- }
- break;
- case -1:/* wait forever */
- do {
- ret = sem_wait(&constructor_wait);
- } while (ret < 0 && errno == EINTR);
- assert(!ret);
- break;
- case 0: /* no timeout */
- break;
- }
-}
-
-static
-void lttng_ust_cleanup(int exiting)
-{
- cleanup_sock_info(&global_apps);
- if (local_apps.allowed) {
- cleanup_sock_info(&local_apps);
- }
- lttng_ust_abi_exit();
- lttng_ust_events_exit();
- ltt_ring_buffer_client_discard_exit();
- ltt_ring_buffer_client_overwrite_exit();
- ltt_ring_buffer_metadata_client_exit();
- exit_tracepoint();
- if (!exiting) {
- /* Reinitialize values for fork */
- sem_count = 2;
- lttng_ust_comm_should_quit = 0;
- initialized = 0;
- }
-}
-
-void __attribute__((destructor)) lttng_ust_exit(void)
-{
- int ret;
-
- /*
- * Using pthread_cancel here because:
- * A) we don't want to hang application teardown.
- * B) the thread is not allocating any resource.
- */
-
- /*
- * Require the communication thread to quit. Synchronize with
- * mutexes to ensure it is not in a mutex critical section when
- * pthread_cancel is later called.
- */
- ust_lock();
- lttng_ust_comm_should_quit = 1;
- ust_unlock();
-
- ret = pthread_cancel(global_apps.ust_listener);
- if (ret) {
- ERR("Error cancelling global ust listener thread");
- }
- if (local_apps.allowed) {
- ret = pthread_cancel(local_apps.ust_listener);
- if (ret) {
- ERR("Error cancelling local ust listener thread");
- }
- }
- lttng_ust_cleanup(1);
-}
-
-/*
- * We exclude the worker threads across fork and clone (except
- * CLONE_VM), because these system calls only keep the forking thread
- * running in the child. Therefore, we don't want to call fork or clone
- * in the middle of an tracepoint or ust tracing state modification.
- * Holding this mutex protects these structures across fork and clone.
- */
-void ust_before_fork(ust_fork_info_t *fork_info)
-{
- /*
- * Disable signals. This is to avoid that the child intervenes
- * before it is properly setup for tracing. It is safer to
- * disable all signals, because then we know we are not breaking
- * anything by restoring the original mask.
- */
- sigset_t all_sigs;
- int ret;
-
- /* Disable signals */
- sigfillset(&all_sigs);
- ret = sigprocmask(SIG_BLOCK, &all_sigs, &fork_info->orig_sigs);
- if (ret == -1) {
- PERROR("sigprocmask");
- }
- ust_lock();
- rcu_bp_before_fork();
-}
-
-static void ust_after_fork_common(ust_fork_info_t *fork_info)
-{
- int ret;
-
- DBG("process %d", getpid());
- ust_unlock();
- /* Restore signals */
- ret = sigprocmask(SIG_SETMASK, &fork_info->orig_sigs, NULL);
- if (ret == -1) {
- PERROR("sigprocmask");
- }
-}
-
-void ust_after_fork_parent(ust_fork_info_t *fork_info)
-{
- DBG("process %d", getpid());
- rcu_bp_after_fork_parent();
- /* Release mutexes and reenable signals */
- ust_after_fork_common(fork_info);
-}
-
-/*
- * After fork, in the child, we need to cleanup all the leftover state,
- * except the worker thread which already magically disappeared thanks
- * to the weird Linux fork semantics. After tyding up, we call
- * lttng_ust_init() again to start over as a new PID.
- *
- * This is meant for forks() that have tracing in the child between the
- * fork and following exec call (if there is any).
- */
-void ust_after_fork_child(ust_fork_info_t *fork_info)
-{
- DBG("process %d", getpid());
- /* Release urcu mutexes */
- rcu_bp_after_fork_child();
- lttng_ust_cleanup(0);
- lttng_context_vtid_reset();
- /* Release mutexes and reenable signals */
- ust_after_fork_common(fork_info);
- lttng_ust_init();
-}
projects / ust.git / blobdiff