--- /dev/null
+/*
+ * SPDX-License-Identifier: LGPL-2.1-only
+ *
+ * Copyright (C) 2011 David Goulet <david.goulet@polymtl.ca>
+ * Copyright (C) 2011 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
+ */
+
+#define _LGPL_SOURCE
+#include <stddef.h>
+#include <stdint.h>
+#include <sys/types.h>
+#include <sys/socket.h>
+#include <sys/mman.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <sys/wait.h>
+#include <dlfcn.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 <limits.h>
+#include <urcu/uatomic.h>
+#include "futex.h"
+#include <urcu/compiler.h>
+#include <lttng/urcu/urcu-ust.h>
+
+#include <lttng/ust-utils.h>
+#include <lttng/ust-events.h>
+#include <lttng/ust-abi.h>
+#include <lttng/ust-fork.h>
+#include <lttng/ust-error.h>
+#include <lttng/ust-ctl.h>
+#include <lttng/ust-libc-wrapper.h>
+#include <lttng/ust-thread.h>
+#include <lttng/ust-tracer.h>
+#include <urcu/tls-compat.h>
+#include <ust-comm.h>
+#include <ust-fd.h>
+#include <usterr-signal-safe.h>
+#include <ust-helper.h>
+#include "tracepoint-internal.h"
+#include "lttng-tracer-core.h"
+#include "compat.h"
+#include "../libringbuffer/rb-init.h"
+#include "lttng-ust-statedump.h"
+#include "clock.h"
+#include "../libringbuffer/getcpu.h"
+#include "getenv.h"
+#include "ust-events-internal.h"
+#include "context-internal.h"
+#include "ust-compat.h"
+#include "lttng-counter-client.h"
+#include "lttng-rb-clients.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.
+ *
+ * The UST lock is the centralized mutex across UST tracing control and
+ * probe registration.
+ *
+ * ust_exit_mutex must never nest in ust_mutex.
+ *
+ * ust_fork_mutex must never nest in ust_mutex.
+ *
+ * ust_mutex_nest is a per-thread nesting counter, allowing the perf
+ * counter lazy initialization called by events within the statedump,
+ * which traces while the ust_mutex is held.
+ *
+ * ust_lock nests within the dynamic loader lock (within glibc) because
+ * it is taken within the library constructor.
+ *
+ * The ust fd tracker lock nests within the ust_mutex.
+ */
+static pthread_mutex_t ust_mutex = PTHREAD_MUTEX_INITIALIZER;
+
+/* Allow nesting the ust_mutex within the same thread. */
+static DEFINE_URCU_TLS(int, ust_mutex_nest);
+
+/*
+ * ust_exit_mutex protects thread_active variable wrt thread exit. It
+ * cannot be done by ust_mutex because pthread_cancel(), which takes an
+ * internal libc lock, cannot nest within ust_mutex.
+ *
+ * It never nests within a ust_mutex.
+ */
+static pthread_mutex_t ust_exit_mutex = PTHREAD_MUTEX_INITIALIZER;
+
+/*
+ * ust_fork_mutex protects base address statedump tracing against forks. It
+ * prevents the dynamic loader lock to be taken (by base address statedump
+ * tracing) while a fork is happening, thus preventing deadlock issues with
+ * the dynamic loader lock.
+ */
+static pthread_mutex_t ust_fork_mutex = PTHREAD_MUTEX_INITIALIZER;
+
+/* Should the ust comm thread quit ? */
+static int lttng_ust_comm_should_quit;
+
+/*
+ * This variable can be tested by applications to check whether
+ * lttng-ust is loaded. They simply have to define their own
+ * "lttng_ust_loaded" weak symbol, and test it. It is set to 1 by the
+ * library constructor.
+ */
+int lttng_ust_loaded __attribute__((weak));
+
+/*
+ * Return 0 on success, -1 if should quit.
+ * The lock is taken in both cases.
+ * Signal-safe.
+ */
+int ust_lock(void)
+{
+ sigset_t sig_all_blocked, orig_mask;
+ int ret, oldstate;
+
+ ret = pthread_setcancelstate(PTHREAD_CANCEL_DISABLE, &oldstate);
+ if (ret) {
+ ERR("pthread_setcancelstate: %s", strerror(ret));
+ }
+ if (oldstate != PTHREAD_CANCEL_ENABLE) {
+ ERR("pthread_setcancelstate: unexpected oldstate");
+ }
+ sigfillset(&sig_all_blocked);
+ ret = pthread_sigmask(SIG_SETMASK, &sig_all_blocked, &orig_mask);
+ if (ret) {
+ ERR("pthread_sigmask: %s", strerror(ret));
+ }
+ if (!URCU_TLS(ust_mutex_nest)++)
+ pthread_mutex_lock(&ust_mutex);
+ ret = pthread_sigmask(SIG_SETMASK, &orig_mask, NULL);
+ if (ret) {
+ ERR("pthread_sigmask: %s", strerror(ret));
+ }
+ if (lttng_ust_comm_should_quit) {
+ return -1;
+ } else {
+ return 0;
+ }
+}
+
+/*
+ * ust_lock_nocheck() can be used in constructors/destructors, because
+ * they are already nested within the dynamic loader lock, and therefore
+ * have exclusive access against execution of liblttng-ust destructor.
+ * Signal-safe.
+ */
+void ust_lock_nocheck(void)
+{
+ sigset_t sig_all_blocked, orig_mask;
+ int ret, oldstate;
+
+ ret = pthread_setcancelstate(PTHREAD_CANCEL_DISABLE, &oldstate);
+ if (ret) {
+ ERR("pthread_setcancelstate: %s", strerror(ret));
+ }
+ if (oldstate != PTHREAD_CANCEL_ENABLE) {
+ ERR("pthread_setcancelstate: unexpected oldstate");
+ }
+ sigfillset(&sig_all_blocked);
+ ret = pthread_sigmask(SIG_SETMASK, &sig_all_blocked, &orig_mask);
+ if (ret) {
+ ERR("pthread_sigmask: %s", strerror(ret));
+ }
+ if (!URCU_TLS(ust_mutex_nest)++)
+ pthread_mutex_lock(&ust_mutex);
+ ret = pthread_sigmask(SIG_SETMASK, &orig_mask, NULL);
+ if (ret) {
+ ERR("pthread_sigmask: %s", strerror(ret));
+ }
+}
+
+/*
+ * Signal-safe.
+ */
+void ust_unlock(void)
+{
+ sigset_t sig_all_blocked, orig_mask;
+ int ret, oldstate;
+
+ sigfillset(&sig_all_blocked);
+ ret = pthread_sigmask(SIG_SETMASK, &sig_all_blocked, &orig_mask);
+ if (ret) {
+ ERR("pthread_sigmask: %s", strerror(ret));
+ }
+ if (!--URCU_TLS(ust_mutex_nest))
+ pthread_mutex_unlock(&ust_mutex);
+ ret = pthread_sigmask(SIG_SETMASK, &orig_mask, NULL);
+ if (ret) {
+ ERR("pthread_sigmask: %s", strerror(ret));
+ }
+ ret = pthread_setcancelstate(PTHREAD_CANCEL_ENABLE, &oldstate);
+ if (ret) {
+ ERR("pthread_setcancelstate: %s", strerror(ret));
+ }
+ if (oldstate != PTHREAD_CANCEL_DISABLE) {
+ ERR("pthread_setcancelstate: unexpected oldstate");
+ }
+}
+
+/*
+ * 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.
+ */
+enum {
+ sem_count_initial_value = 4,
+};
+
+static int sem_count = sem_count_initial_value;
+
+/*
+ * Counting nesting within lttng-ust. Used to ensure that calling fork()
+ * from liblttng-ust does not execute the pre/post fork handlers.
+ */
+static DEFINE_URCU_TLS(int, lttng_ust_nest_count);
+
+/*
+ * Info about socket and associated listener thread.
+ */
+struct sock_info {
+ const char *name;
+ pthread_t ust_listener; /* listener thread */
+ int root_handle;
+ int registration_done;
+ int allowed;
+ int global;
+ int thread_active;
+
+ char sock_path[PATH_MAX];
+ int socket;
+ int notify_socket;
+
+ char wait_shm_path[PATH_MAX];
+ char *wait_shm_mmap;
+ /* Keep track of lazy state dump not performed yet. */
+ int statedump_pending;
+ int initial_statedump_done;
+ /* Keep procname for statedump */
+ char procname[LTTNG_UST_ABI_PROCNAME_LEN];
+};
+
+/* Socket from app (connect) to session daemon (listen) for communication */
+struct sock_info global_apps = {
+ .name = "global",
+ .global = 1,
+
+ .root_handle = -1,
+ .registration_done = 0,
+ .allowed = 0,
+ .thread_active = 0,
+
+ .sock_path = LTTNG_DEFAULT_RUNDIR "/" LTTNG_UST_SOCK_FILENAME,
+ .socket = -1,
+ .notify_socket = -1,
+
+ .wait_shm_path = "/" LTTNG_UST_WAIT_FILENAME,
+
+ .statedump_pending = 0,
+ .initial_statedump_done = 0,
+ .procname[0] = '\0'
+};
+
+/* TODO: allow global_apps_sock_path override */
+
+struct sock_info local_apps = {
+ .name = "local",
+ .global = 0,
+ .root_handle = -1,
+ .registration_done = 0,
+ .allowed = 0, /* Check setuid bit first */
+ .thread_active = 0,
+
+ .socket = -1,
+ .notify_socket = -1,
+
+ .statedump_pending = 0,
+ .initial_statedump_done = 0,
+ .procname[0] = '\0'
+};
+
+static int wait_poll_fallback;
+
+static const char *cmd_name_mapping[] = {
+ [ LTTNG_UST_ABI_RELEASE ] = "Release",
+ [ LTTNG_UST_ABI_SESSION ] = "Create Session",
+ [ LTTNG_UST_ABI_TRACER_VERSION ] = "Get Tracer Version",
+
+ [ LTTNG_UST_ABI_TRACEPOINT_LIST ] = "Create Tracepoint List",
+ [ LTTNG_UST_ABI_WAIT_QUIESCENT ] = "Wait for Quiescent State",
+ [ LTTNG_UST_ABI_REGISTER_DONE ] = "Registration Done",
+ [ LTTNG_UST_ABI_TRACEPOINT_FIELD_LIST ] = "Create Tracepoint Field List",
+
+ [ LTTNG_UST_ABI_EVENT_NOTIFIER_GROUP_CREATE ] = "Create event notifier group",
+
+ /* Session FD commands */
+ [ LTTNG_UST_ABI_CHANNEL ] = "Create Channel",
+ [ LTTNG_UST_ABI_SESSION_START ] = "Start Session",
+ [ LTTNG_UST_ABI_SESSION_STOP ] = "Stop Session",
+
+ /* Channel FD commands */
+ [ LTTNG_UST_ABI_STREAM ] = "Create Stream",
+ [ LTTNG_UST_ABI_EVENT ] = "Create Event",
+
+ /* Event and Channel FD commands */
+ [ LTTNG_UST_ABI_CONTEXT ] = "Create Context",
+ [ LTTNG_UST_ABI_FLUSH_BUFFER ] = "Flush Buffer",
+
+ /* Event, Channel and Session commands */
+ [ LTTNG_UST_ABI_ENABLE ] = "Enable",
+ [ LTTNG_UST_ABI_DISABLE ] = "Disable",
+
+ /* Tracepoint list commands */
+ [ LTTNG_UST_ABI_TRACEPOINT_LIST_GET ] = "List Next Tracepoint",
+ [ LTTNG_UST_ABI_TRACEPOINT_FIELD_LIST_GET ] = "List Next Tracepoint Field",
+
+ /* Event FD commands */
+ [ LTTNG_UST_ABI_FILTER ] = "Create Filter",
+ [ LTTNG_UST_ABI_EXCLUSION ] = "Add exclusions to event",
+
+ /* Event notifier group commands */
+ [ LTTNG_UST_ABI_EVENT_NOTIFIER_CREATE ] = "Create event notifier",
+
+ /* Session and event notifier group commands */
+ [ LTTNG_UST_ABI_COUNTER ] = "Create Counter",
+
+ /* Counter commands */
+ [ LTTNG_UST_ABI_COUNTER_GLOBAL ] = "Create Counter Global",
+ [ LTTNG_UST_ABI_COUNTER_CPU ] = "Create Counter CPU",
+};
+
+static const char *str_timeout;
+static int got_timeout_env;
+
+static char *get_map_shm(struct sock_info *sock_info);
+
+ssize_t lttng_ust_read(int fd, void *buf, size_t len)
+{
+ ssize_t ret;
+ size_t copied = 0, to_copy = len;
+
+ do {
+ ret = read(fd, buf + copied, to_copy);
+ if (ret > 0) {
+ copied += ret;
+ to_copy -= ret;
+ }
+ } while ((ret > 0 && to_copy > 0)
+ || (ret < 0 && errno == EINTR));
+ if (ret > 0) {
+ ret = copied;
+ }
+ return ret;
+}
+/*
+ * Returns the HOME directory path. Caller MUST NOT free(3) the returned
+ * pointer.
+ */
+static
+const char *get_lttng_home_dir(void)
+{
+ const char *val;
+
+ val = (const char *) lttng_ust_getenv("LTTNG_HOME");
+ if (val != NULL) {
+ return val;
+ }
+ return (const char *) lttng_ust_getenv("HOME");
+}
+
+/*
+ * Force a read (imply TLS fixup for dlopen) of TLS variables.
+ */
+static
+void lttng_fixup_nest_count_tls(void)
+{
+ asm volatile ("" : : "m" (URCU_TLS(lttng_ust_nest_count)));
+}
+
+static
+void lttng_fixup_ust_mutex_nest_tls(void)
+{
+ asm volatile ("" : : "m" (URCU_TLS(ust_mutex_nest)));
+}
+
+/*
+ * Fixup lttng-ust urcu TLS.
+ */
+static
+void lttng_fixup_lttng_ust_urcu_tls(void)
+{
+ (void) lttng_ust_urcu_read_ongoing();
+}
+
+void lttng_ust_fixup_tls(void)
+{
+ lttng_fixup_lttng_ust_urcu_tls();
+ lttng_fixup_ringbuffer_tls();
+ lttng_fixup_vtid_tls();
+ lttng_fixup_nest_count_tls();
+ lttng_fixup_procname_tls();
+ lttng_fixup_ust_mutex_nest_tls();
+ lttng_ust_fixup_perf_counter_tls();
+ lttng_ust_fixup_fd_tracker_tls();
+ lttng_fixup_cgroup_ns_tls();
+ lttng_fixup_ipc_ns_tls();
+ lttng_fixup_net_ns_tls();
+ lttng_fixup_time_ns_tls();
+ lttng_fixup_uts_ns_tls();
+ lttng_ust_fixup_ring_buffer_client_discard_tls();
+ lttng_ust_fixup_ring_buffer_client_discard_rt_tls();
+ lttng_ust_fixup_ring_buffer_client_overwrite_tls();
+ lttng_ust_fixup_ring_buffer_client_overwrite_rt_tls();
+}
+
+/*
+ * LTTng-UST uses Global Dynamic model TLS variables rather than IE
+ * model because many versions of glibc don't preallocate a pool large
+ * enough for TLS variables IE model defined in other shared libraries,
+ * and causes issues when using LTTng-UST for Java tracing.
+ *
+ * Because of this use of Global Dynamic TLS variables, users wishing to
+ * trace from signal handlers need to explicitly trigger the lazy
+ * allocation of those variables for each thread before using them.
+ * This can be triggered by calling lttng_ust_init_thread().
+ */
+void lttng_ust_init_thread(void)
+{
+ /*
+ * Because those TLS variables are global dynamic, we need to
+ * ensure those are initialized before a signal handler nesting over
+ * this thread attempts to use them.
+ */
+ lttng_ust_fixup_tls();
+}
+
+int lttng_get_notify_socket(void *owner)
+{
+ struct sock_info *info = owner;
+
+ return info->notify_socket;
+}
+
+
+char* lttng_ust_sockinfo_get_procname(void *owner)
+{
+ struct sock_info *info = owner;
+
+ return info->procname;
+}
+
+static
+void print_cmd(int cmd, int handle)
+{
+ const char *cmd_name = "Unknown";
+
+ if (cmd >= 0 && cmd < LTTNG_ARRAY_SIZE(cmd_name_mapping)
+ && cmd_name_mapping[cmd]) {
+ cmd_name = cmd_name_mapping[cmd];
+ }
+ DBG("Message Received \"%s\" (%d), Handle \"%s\" (%d)",
+ cmd_name, cmd,
+ lttng_ust_obj_get_name(handle), handle);
+}
+
+static
+int setup_global_apps(void)
+{
+ int ret = 0;
+ assert(!global_apps.wait_shm_mmap);
+
+ global_apps.wait_shm_mmap = get_map_shm(&global_apps);
+ if (!global_apps.wait_shm_mmap) {
+ WARN("Unable to get map shm for global apps. Disabling LTTng-UST global tracing.");
+ global_apps.allowed = 0;
+ ret = -EIO;
+ goto error;
+ }
+
+ global_apps.allowed = 1;
+ lttng_pthread_getname_np(global_apps.procname, LTTNG_UST_ABI_PROCNAME_LEN);
+error:
+ return ret;
+}
+static
+int setup_local_apps(void)
+{
+ int ret = 0;
+ const char *home_dir;
+ uid_t uid;
+
+ assert(!local_apps.wait_shm_mmap);
+
+ uid = getuid();
+ /*
+ * Disallow per-user tracing for setuid binaries.
+ */
+ if (uid != geteuid()) {
+ assert(local_apps.allowed == 0);
+ ret = 0;
+ goto end;
+ }
+ home_dir = get_lttng_home_dir();
+ if (!home_dir) {
+ WARN("HOME environment variable not set. Disabling LTTng-UST per-user tracing.");
+ assert(local_apps.allowed == 0);
+ ret = -ENOENT;
+ goto end;
+ }
+ local_apps.allowed = 1;
+ snprintf(local_apps.sock_path, PATH_MAX, "%s/%s/%s",
+ home_dir,
+ LTTNG_DEFAULT_HOME_RUNDIR,
+ LTTNG_UST_SOCK_FILENAME);
+ snprintf(local_apps.wait_shm_path, PATH_MAX, "/%s-%u",
+ LTTNG_UST_WAIT_FILENAME,
+ uid);
+
+ local_apps.wait_shm_mmap = get_map_shm(&local_apps);
+ if (!local_apps.wait_shm_mmap) {
+ WARN("Unable to get map shm for local apps. Disabling LTTng-UST per-user tracing.");
+ local_apps.allowed = 0;
+ ret = -EIO;
+ goto end;
+ }
+
+ lttng_pthread_getname_np(local_apps.procname, LTTNG_UST_ABI_PROCNAME_LEN);
+end:
+ return ret;
+}
+
+/*
+ * Get socket timeout, in ms.
+ * -1: wait forever. 0: don't wait. >0: timeout, in ms.
+ */
+static
+long get_timeout(void)
+{
+ long constructor_delay_ms = LTTNG_UST_DEFAULT_CONSTRUCTOR_TIMEOUT_MS;
+
+ if (!got_timeout_env) {
+ str_timeout = lttng_ust_getenv("LTTNG_UST_REGISTER_TIMEOUT");
+ got_timeout_env = 1;
+ }
+ if (str_timeout)
+ constructor_delay_ms = strtol(str_timeout, NULL, 10);
+ /* All negative values are considered as "-1". */
+ if (constructor_delay_ms < -1)
+ constructor_delay_ms = -1;
+ return constructor_delay_ms;
+}
+
+/* Timeout for notify socket send and recv. */
+static
+long get_notify_sock_timeout(void)
+{
+ return get_timeout();
+}
+
+/* Timeout for connecting to cmd and notify sockets. */
+static
+long get_connect_sock_timeout(void)
+{
+ return get_timeout();
+}
+
+/*
+ * Return values: -1: wait forever. 0: don't wait. 1: timeout wait.
+ */
+static
+int get_constructor_timeout(struct timespec *constructor_timeout)
+{
+ long constructor_delay_ms;
+ int ret;
+
+ constructor_delay_ms = get_timeout();
+
+ 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) {
+ /* Don't wait. */
+ return 0;
+ }
+ 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;
+ }
+ /* Timeout wait (constructor_delay_ms). */
+ return 1;
+}
+
+static
+void get_allow_blocking(void)
+{
+ const char *str_allow_blocking =
+ lttng_ust_getenv("LTTNG_UST_ALLOW_BLOCKING");
+
+ if (str_allow_blocking) {
+ DBG("%s environment variable is set",
+ "LTTNG_UST_ALLOW_BLOCKING");
+ lttng_ust_ringbuffer_set_allow_blocking();
+ }
+}
+
+static
+int register_to_sessiond(int socket, enum ustctl_socket_type type)
+{
+ return ustcomm_send_reg_msg(socket,
+ type,
+ CAA_BITS_PER_LONG,
+ lttng_ust_rb_alignof(uint8_t) * CHAR_BIT,
+ lttng_ust_rb_alignof(uint16_t) * CHAR_BIT,
+ lttng_ust_rb_alignof(uint32_t) * CHAR_BIT,
+ lttng_ust_rb_alignof(uint64_t) * CHAR_BIT,
+ lttng_ust_rb_alignof(unsigned long) * CHAR_BIT);
+}
+
+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;
+ default:
+ if (len == -ECONNRESET) {
+ DBG("remote end closed connection");
+ return 0;
+ }
+ if (len < 0)
+ return len;
+ DBG("incorrect message size: %zd", len);
+ return -EINVAL;
+ }
+}
+
+static
+void decrement_sem_count(unsigned int count)
+{
+ int ret;
+
+ assert(uatomic_read(&sem_count) >= count);
+
+ if (uatomic_read(&sem_count) <= 0) {
+ return;
+ }
+
+ ret = uatomic_add_return(&sem_count, -count);
+ if (ret == 0) {
+ ret = sem_post(&constructor_wait);
+ assert(!ret);
+ }
+}
+
+static
+int handle_register_done(struct sock_info *sock_info)
+{
+ if (sock_info->registration_done)
+ return 0;
+ sock_info->registration_done = 1;
+
+ decrement_sem_count(1);
+ if (!sock_info->statedump_pending) {
+ sock_info->initial_statedump_done = 1;
+ decrement_sem_count(1);
+ }
+
+ return 0;
+}
+
+static
+int handle_register_failed(struct sock_info *sock_info)
+{
+ if (sock_info->registration_done)
+ return 0;
+ sock_info->registration_done = 1;
+ sock_info->initial_statedump_done = 1;
+
+ decrement_sem_count(2);
+
+ return 0;
+}
+
+/*
+ * Only execute pending statedump after the constructor semaphore has
+ * been posted by the current listener thread. This means statedump will
+ * only be performed after the "registration done" command is received
+ * from this thread's session daemon.
+ *
+ * This ensures we don't run into deadlock issues with the dynamic
+ * loader mutex, which is held while the constructor is called and
+ * waiting on the constructor semaphore. All operations requiring this
+ * dynamic loader lock need to be postponed using this mechanism.
+ *
+ * In a scenario with two session daemons connected to the application,
+ * it is possible that the first listener thread which receives the
+ * registration done command issues its statedump while the dynamic
+ * loader lock is still held by the application constructor waiting on
+ * the semaphore. It will however be allowed to proceed when the
+ * second session daemon sends the registration done command to the
+ * second listener thread. This situation therefore does not produce
+ * a deadlock.
+ */
+static
+void handle_pending_statedump(struct sock_info *sock_info)
+{
+ if (sock_info->registration_done && sock_info->statedump_pending) {
+ sock_info->statedump_pending = 0;
+ pthread_mutex_lock(&ust_fork_mutex);
+ lttng_handle_pending_statedump(sock_info);
+ pthread_mutex_unlock(&ust_fork_mutex);
+
+ if (!sock_info->initial_statedump_done) {
+ sock_info->initial_statedump_done = 1;
+ decrement_sem_count(1);
+ }
+ }
+}
+
+static inline
+const char *bytecode_type_str(uint32_t cmd)
+{
+ switch (cmd) {
+ case LTTNG_UST_ABI_CAPTURE:
+ return "capture";
+ case LTTNG_UST_ABI_FILTER:
+ return "filter";
+ default:
+ abort();
+ }
+}
+
+static
+int handle_bytecode_recv(struct sock_info *sock_info,
+ int sock, struct ustcomm_ust_msg *lum)
+{
+ struct lttng_ust_bytecode_node *bytecode = NULL;
+ enum lttng_ust_bytecode_type type;
+ const struct lttng_ust_abi_objd_ops *ops;
+ uint32_t data_size, data_size_max, reloc_offset;
+ uint64_t seqnum;
+ ssize_t len;
+ int ret = 0;
+
+ switch (lum->cmd) {
+ case LTTNG_UST_ABI_FILTER:
+ type = LTTNG_UST_BYTECODE_TYPE_FILTER;
+ data_size = lum->u.filter.data_size;
+ data_size_max = LTTNG_UST_ABI_FILTER_BYTECODE_MAX_LEN;
+ reloc_offset = lum->u.filter.reloc_offset;
+ seqnum = lum->u.filter.seqnum;
+ break;
+ case LTTNG_UST_ABI_CAPTURE:
+ type = LTTNG_UST_BYTECODE_TYPE_CAPTURE;
+ data_size = lum->u.capture.data_size;
+ data_size_max = LTTNG_UST_ABI_CAPTURE_BYTECODE_MAX_LEN;
+ reloc_offset = lum->u.capture.reloc_offset;
+ seqnum = lum->u.capture.seqnum;
+ break;
+ default:
+ abort();
+ }
+
+ if (data_size > data_size_max) {
+ ERR("Bytecode %s data size is too large: %u bytes",
+ bytecode_type_str(lum->cmd), data_size);
+ ret = -EINVAL;
+ goto end;
+ }
+
+ if (reloc_offset > data_size) {
+ ERR("Bytecode %s reloc offset %u is not within data",
+ bytecode_type_str(lum->cmd), reloc_offset);
+ ret = -EINVAL;
+ goto end;
+ }
+
+ /* Allocate the structure AND the `data[]` field. */
+ bytecode = zmalloc(sizeof(*bytecode) + data_size);
+ if (!bytecode) {
+ ret = -ENOMEM;
+ goto end;
+ }
+
+ bytecode->bc.len = data_size;
+ bytecode->bc.reloc_offset = reloc_offset;
+ bytecode->bc.seqnum = seqnum;
+ bytecode->type = type;
+
+ len = ustcomm_recv_unix_sock(sock, bytecode->bc.data, bytecode->bc.len);
+ switch (len) {
+ case 0: /* orderly shutdown */
+ ret = 0;
+ goto end;
+ default:
+ if (len == bytecode->bc.len) {
+ DBG("Bytecode %s data received",
+ bytecode_type_str(lum->cmd));
+ break;
+ } else if (len < 0) {
+ DBG("Receive failed from lttng-sessiond with errno %d",
+ (int) -len);
+ if (len == -ECONNRESET) {
+ ERR("%s remote end closed connection",
+ sock_info->name);
+ ret = len;
+ goto end;
+ }
+ ret = len;
+ goto end;
+ } else {
+ DBG("Incorrect %s bytecode data message size: %zd",
+ bytecode_type_str(lum->cmd), len);
+ ret = -EINVAL;
+ goto end;
+ }
+ }
+
+ ops = lttng_ust_abi_objd_ops(lum->handle);
+ if (!ops) {
+ ret = -ENOENT;
+ goto end;
+ }
+
+ if (ops->cmd)
+ ret = ops->cmd(lum->handle, lum->cmd,
+ (unsigned long) &bytecode,
+ NULL, sock_info);
+ else
+ ret = -ENOSYS;
+
+end:
+ free(bytecode);
+ return ret;
+}
+
+static
+int handle_message(struct sock_info *sock_info,
+ int sock, struct ustcomm_ust_msg *lum)
+{
+ int ret = 0;
+ const struct lttng_ust_abi_objd_ops *ops;
+ struct ustcomm_ust_reply lur;
+ union lttng_ust_abi_args args;
+ char ctxstr[LTTNG_UST_ABI_SYM_NAME_LEN]; /* App context string. */
+ ssize_t len;
+
+ memset(&lur, 0, sizeof(lur));
+
+ if (ust_lock()) {
+ ret = -LTTNG_UST_ERR_EXITING;
+ goto error;
+ }
+
+ ops = lttng_ust_abi_objd_ops(lum->handle);
+ if (!ops) {
+ ret = -ENOENT;
+ goto error;
+ }
+
+ switch (lum->cmd) {
+ case LTTNG_UST_ABI_REGISTER_DONE:
+ if (lum->handle == LTTNG_UST_ABI_ROOT_HANDLE)
+ ret = handle_register_done(sock_info);
+ else
+ ret = -EINVAL;
+ break;
+ case LTTNG_UST_ABI_RELEASE:
+ if (lum->handle == LTTNG_UST_ABI_ROOT_HANDLE)
+ ret = -EPERM;
+ else
+ ret = lttng_ust_abi_objd_unref(lum->handle, 1);
+ break;
+ case LTTNG_UST_ABI_CAPTURE:
+ case LTTNG_UST_ABI_FILTER:
+ ret = handle_bytecode_recv(sock_info, sock, lum);
+ if (ret)
+ goto error;
+ break;
+ case LTTNG_UST_ABI_EXCLUSION:
+ {
+ /* Receive exclusion names */
+ struct lttng_ust_excluder_node *node;
+ unsigned int count;
+
+ count = lum->u.exclusion.count;
+ if (count == 0) {
+ /* There are no names to read */
+ ret = 0;
+ goto error;
+ }
+ node = zmalloc(sizeof(*node) +
+ count * LTTNG_UST_ABI_SYM_NAME_LEN);
+ if (!node) {
+ ret = -ENOMEM;
+ goto error;
+ }
+ node->excluder.count = count;
+ len = ustcomm_recv_unix_sock(sock, node->excluder.names,
+ count * LTTNG_UST_ABI_SYM_NAME_LEN);
+ switch (len) {
+ case 0: /* orderly shutdown */
+ ret = 0;
+ free(node);
+ goto error;
+ default:
+ if (len == count * LTTNG_UST_ABI_SYM_NAME_LEN) {
+ DBG("Exclusion data received");
+ break;
+ } else if (len < 0) {
+ DBG("Receive failed from lttng-sessiond with errno %d", (int) -len);
+ if (len == -ECONNRESET) {
+ ERR("%s remote end closed connection", sock_info->name);
+ ret = len;
+ free(node);
+ goto error;
+ }
+ ret = len;
+ free(node);
+ goto error;
+ } else {
+ DBG("Incorrect exclusion data message size: %zd", len);
+ ret = -EINVAL;
+ free(node);
+ goto error;
+ }
+ }
+ if (ops->cmd)
+ ret = ops->cmd(lum->handle, lum->cmd,
+ (unsigned long) &node,
+ &args, sock_info);
+ else
+ ret = -ENOSYS;
+ free(node);
+ break;
+ }
+ case LTTNG_UST_ABI_EVENT_NOTIFIER_GROUP_CREATE:
+ {
+ int event_notifier_notif_fd, close_ret;
+
+ len = ustcomm_recv_event_notifier_notif_fd_from_sessiond(sock,
+ &event_notifier_notif_fd);
+ switch (len) {
+ case 0: /* orderly shutdown */
+ ret = 0;
+ goto error;
+ case 1:
+ break;
+ default:
+ if (len < 0) {
+ DBG("Receive failed from lttng-sessiond with errno %d",
+ (int) -len);
+ if (len == -ECONNRESET) {
+ ERR("%s remote end closed connection",
+ sock_info->name);
+ ret = len;
+ goto error;
+ }
+ ret = len;
+ goto error;
+ } else {
+ DBG("Incorrect event notifier fd message size: %zd",
+ len);
+ ret = -EINVAL;
+ goto error;
+ }
+ }
+ args.event_notifier_handle.event_notifier_notif_fd =
+ event_notifier_notif_fd;
+ if (ops->cmd)
+ ret = ops->cmd(lum->handle, lum->cmd,
+ (unsigned long) &lum->u,
+ &args, sock_info);
+ else
+ ret = -ENOSYS;
+ if (args.event_notifier_handle.event_notifier_notif_fd >= 0) {
+ lttng_ust_lock_fd_tracker();
+ close_ret = close(args.event_notifier_handle.event_notifier_notif_fd);
+ lttng_ust_unlock_fd_tracker();
+ if (close_ret)
+ PERROR("close");
+ }
+ break;
+ }
+ case LTTNG_UST_ABI_CHANNEL:
+ {
+ void *chan_data;
+ int wakeup_fd;
+
+ len = ustcomm_recv_channel_from_sessiond(sock,
+ &chan_data, lum->u.channel.len,
+ &wakeup_fd);
+ switch (len) {
+ case 0: /* orderly shutdown */
+ ret = 0;
+ goto error;
+ default:
+ if (len == lum->u.channel.len) {
+ DBG("channel data received");
+ break;
+ } else if (len < 0) {
+ DBG("Receive failed from lttng-sessiond with errno %d", (int) -len);
+ if (len == -ECONNRESET) {
+ ERR("%s remote end closed connection", sock_info->name);
+ ret = len;
+ goto error;
+ }
+ ret = len;
+ goto error;
+ } else {
+ DBG("incorrect channel data message size: %zd", len);
+ ret = -EINVAL;
+ goto error;
+ }
+ }
+ args.channel.chan_data = chan_data;
+ args.channel.wakeup_fd = wakeup_fd;
+ if (ops->cmd)
+ ret = ops->cmd(lum->handle, lum->cmd,
+ (unsigned long) &lum->u,
+ &args, sock_info);
+ else
+ ret = -ENOSYS;
+ if (args.channel.wakeup_fd >= 0) {
+ int close_ret;
+
+ lttng_ust_lock_fd_tracker();
+ close_ret = close(args.channel.wakeup_fd);
+ lttng_ust_unlock_fd_tracker();
+ args.channel.wakeup_fd = -1;
+ if (close_ret)
+ PERROR("close");
+ }
+ free(args.channel.chan_data);
+ break;
+ }
+ case LTTNG_UST_ABI_STREAM:
+ {
+ int close_ret;
+
+ /* Receive shm_fd, wakeup_fd */
+ ret = ustcomm_recv_stream_from_sessiond(sock,
+ NULL,
+ &args.stream.shm_fd,
+ &args.stream.wakeup_fd);
+ if (ret) {
+ goto error;
+ }
+
+ if (ops->cmd)
+ ret = ops->cmd(lum->handle, lum->cmd,
+ (unsigned long) &lum->u,
+ &args, sock_info);
+ else
+ ret = -ENOSYS;
+ if (args.stream.shm_fd >= 0) {
+ lttng_ust_lock_fd_tracker();
+ close_ret = close(args.stream.shm_fd);
+ lttng_ust_unlock_fd_tracker();
+ args.stream.shm_fd = -1;
+ if (close_ret)
+ PERROR("close");
+ }
+ if (args.stream.wakeup_fd >= 0) {
+ lttng_ust_lock_fd_tracker();
+ close_ret = close(args.stream.wakeup_fd);
+ lttng_ust_unlock_fd_tracker();
+ args.stream.wakeup_fd = -1;
+ if (close_ret)
+ PERROR("close");
+ }
+ break;
+ }
+ case LTTNG_UST_ABI_CONTEXT:
+ switch (lum->u.context.ctx) {
+ case LTTNG_UST_ABI_CONTEXT_APP_CONTEXT:
+ {
+ char *p;
+ size_t ctxlen, recvlen;
+
+ ctxlen = strlen("$app.") + lum->u.context.u.app_ctx.provider_name_len - 1
+ + strlen(":") + lum->u.context.u.app_ctx.ctx_name_len;
+ if (ctxlen >= LTTNG_UST_ABI_SYM_NAME_LEN) {
+ ERR("Application context string length size is too large: %zu bytes",
+ ctxlen);
+ ret = -EINVAL;
+ goto error;
+ }
+ strcpy(ctxstr, "$app.");
+ p = &ctxstr[strlen("$app.")];
+ recvlen = ctxlen - strlen("$app.");
+ len = ustcomm_recv_unix_sock(sock, p, recvlen);
+ switch (len) {
+ case 0: /* orderly shutdown */
+ ret = 0;
+ goto error;
+ default:
+ if (len == recvlen) {
+ DBG("app context data received");
+ break;
+ } else if (len < 0) {
+ DBG("Receive failed from lttng-sessiond with errno %d", (int) -len);
+ if (len == -ECONNRESET) {
+ ERR("%s remote end closed connection", sock_info->name);
+ ret = len;
+ goto error;
+ }
+ ret = len;
+ goto error;
+ } else {
+ DBG("incorrect app context data message size: %zd", len);
+ ret = -EINVAL;
+ goto error;
+ }
+ }
+ /* Put : between provider and ctxname. */
+ p[lum->u.context.u.app_ctx.provider_name_len - 1] = ':';
+ args.app_context.ctxname = ctxstr;
+ break;
+ }
+ default:
+ break;
+ }
+ if (ops->cmd) {
+ ret = ops->cmd(lum->handle, lum->cmd,
+ (unsigned long) &lum->u,
+ &args, sock_info);
+ } else {
+ ret = -ENOSYS;
+ }
+ break;
+ case LTTNG_UST_ABI_COUNTER:
+ {
+ void *counter_data;
+
+ len = ustcomm_recv_counter_from_sessiond(sock,
+ &counter_data, lum->u.counter.len);
+ switch (len) {
+ case 0: /* orderly shutdown */
+ ret = 0;
+ goto error;
+ default:
+ if (len == lum->u.counter.len) {
+ DBG("counter data received");
+ break;
+ } else if (len < 0) {
+ DBG("Receive failed from lttng-sessiond with errno %d", (int) -len);
+ if (len == -ECONNRESET) {
+ ERR("%s remote end closed connection", sock_info->name);
+ ret = len;
+ goto error;
+ }
+ ret = len;
+ goto error;
+ } else {
+ DBG("incorrect counter data message size: %zd", len);
+ ret = -EINVAL;
+ goto error;
+ }
+ }
+ args.counter.counter_data = counter_data;
+ if (ops->cmd)
+ ret = ops->cmd(lum->handle, lum->cmd,
+ (unsigned long) &lum->u,
+ &args, sock_info);
+ else
+ ret = -ENOSYS;
+ free(args.counter.counter_data);
+ break;
+ }
+ case LTTNG_UST_ABI_COUNTER_GLOBAL:
+ {
+ /* Receive shm_fd */
+ ret = ustcomm_recv_counter_shm_from_sessiond(sock,
+ &args.counter_shm.shm_fd);
+ if (ret) {
+ goto error;
+ }
+
+ if (ops->cmd)
+ ret = ops->cmd(lum->handle, lum->cmd,
+ (unsigned long) &lum->u,
+ &args, sock_info);
+ else
+ ret = -ENOSYS;
+ if (args.counter_shm.shm_fd >= 0) {
+ int close_ret;
+
+ lttng_ust_lock_fd_tracker();
+ close_ret = close(args.counter_shm.shm_fd);
+ lttng_ust_unlock_fd_tracker();
+ args.counter_shm.shm_fd = -1;
+ if (close_ret)
+ PERROR("close");
+ }
+ break;
+ }
+ case LTTNG_UST_ABI_COUNTER_CPU:
+ {
+ /* Receive shm_fd */
+ ret = ustcomm_recv_counter_shm_from_sessiond(sock,
+ &args.counter_shm.shm_fd);
+ if (ret) {
+ goto error;
+ }
+
+ if (ops->cmd)
+ ret = ops->cmd(lum->handle, lum->cmd,
+ (unsigned long) &lum->u,
+ &args, sock_info);
+ else
+ ret = -ENOSYS;
+ if (args.counter_shm.shm_fd >= 0) {
+ int close_ret;
+
+ lttng_ust_lock_fd_tracker();
+ close_ret = close(args.counter_shm.shm_fd);
+ lttng_ust_unlock_fd_tracker();
+ args.counter_shm.shm_fd = -1;
+ if (close_ret)
+ PERROR("close");
+ }
+ break;
+ }
+ case LTTNG_UST_ABI_EVENT_NOTIFIER_CREATE:
+ {
+ /* Receive struct lttng_ust_event_notifier */
+ struct lttng_ust_abi_event_notifier event_notifier;
+
+ if (sizeof(event_notifier) != lum->u.event_notifier.len) {
+ DBG("incorrect event notifier data message size: %u", lum->u.event_notifier.len);
+ ret = -EINVAL;
+ goto error;
+ }
+ len = ustcomm_recv_unix_sock(sock, &event_notifier, sizeof(event_notifier));
+ switch (len) {
+ case 0: /* orderly shutdown */
+ ret = 0;
+ goto error;
+ default:
+ if (len == sizeof(event_notifier)) {
+ DBG("event notifier data received");
+ break;
+ } else if (len < 0) {
+ DBG("Receive failed from lttng-sessiond with errno %d", (int) -len);
+ if (len == -ECONNRESET) {
+ ERR("%s remote end closed connection", sock_info->name);
+ ret = len;
+ goto error;
+ }
+ ret = len;
+ goto error;
+ } else {
+ DBG("incorrect event notifier data message size: %zd", len);
+ ret = -EINVAL;
+ goto error;
+ }
+ }
+ if (ops->cmd)
+ ret = ops->cmd(lum->handle, lum->cmd,
+ (unsigned long) &event_notifier,
+ &args, sock_info);
+ else
+ ret = -ENOSYS;
+ break;
+ }
+
+ default:
+ if (ops->cmd)
+ ret = ops->cmd(lum->handle, lum->cmd,
+ (unsigned long) &lum->u,
+ &args, sock_info);
+ else
+ ret = -ENOSYS;
+ break;
+ }
+
+ lur.handle = lum->handle;
+ lur.cmd = lum->cmd;
+ lur.ret_val = ret;
+ if (ret >= 0) {
+ lur.ret_code = LTTNG_UST_OK;
+ } else {
+ /*
+ * Use -LTTNG_UST_ERR as wildcard for UST internal
+ * error that are not caused by the transport, except if
+ * we already have a more precise error message to
+ * report.
+ */
+ if (ret > -LTTNG_UST_ERR) {
+ /* Translate code to UST error. */
+ switch (ret) {
+ case -EEXIST:
+ lur.ret_code = -LTTNG_UST_ERR_EXIST;
+ break;
+ case -EINVAL:
+ lur.ret_code = -LTTNG_UST_ERR_INVAL;
+ break;
+ case -ENOENT:
+ lur.ret_code = -LTTNG_UST_ERR_NOENT;
+ break;
+ case -EPERM:
+ lur.ret_code = -LTTNG_UST_ERR_PERM;
+ break;
+ case -ENOSYS:
+ lur.ret_code = -LTTNG_UST_ERR_NOSYS;
+ break;
+ default:
+ lur.ret_code = -LTTNG_UST_ERR;
+ break;
+ }
+ } else {
+ lur.ret_code = ret;
+ }
+ }
+ if (ret >= 0) {
+ switch (lum->cmd) {
+ case LTTNG_UST_ABI_TRACER_VERSION:
+ lur.u.version = lum->u.version;
+ break;
+ case LTTNG_UST_ABI_TRACEPOINT_LIST_GET:
+ memcpy(&lur.u.tracepoint, &lum->u.tracepoint, sizeof(lur.u.tracepoint));
+ break;
+ }
+ }
+ DBG("Return value: %d", lur.ret_val);
+
+ ust_unlock();
+
+ /*
+ * Performed delayed statedump operations outside of the UST
+ * lock. We need to take the dynamic loader lock before we take
+ * the UST lock internally within handle_pending_statedump().
+ */
+ handle_pending_statedump(sock_info);
+
+ if (ust_lock()) {
+ ret = -LTTNG_UST_ERR_EXITING;
+ goto error;
+ }
+
+ ret = send_reply(sock, &lur);
+ if (ret < 0) {
+ DBG("error sending reply");
+ goto error;
+ }
+
+ /*
+ * LTTNG_UST_TRACEPOINT_FIELD_LIST_GET needs to send the field
+ * after the reply.
+ */
+ if (lur.ret_code == LTTNG_UST_OK) {
+ switch (lum->cmd) {
+ case LTTNG_UST_ABI_TRACEPOINT_FIELD_LIST_GET:
+ len = ustcomm_send_unix_sock(sock,
+ &args.field_list.entry,
+ sizeof(args.field_list.entry));
+ if (len < 0) {
+ ret = len;
+ goto error;
+ }
+ if (len != sizeof(args.field_list.entry)) {
+ ret = -EINVAL;
+ goto error;
+ }
+ }
+ }
+
+error:
+ ust_unlock();
+
+ return ret;
+}
+
+static
+void cleanup_sock_info(struct sock_info *sock_info, int exiting)
+{
+ int ret;
+
+ if (sock_info->root_handle != -1) {
+ ret = lttng_ust_abi_objd_unref(sock_info->root_handle, 1);
+ if (ret) {
+ ERR("Error unref root handle");
+ }
+ sock_info->root_handle = -1;
+ }
+ sock_info->registration_done = 0;
+ sock_info->initial_statedump_done = 0;
+
+ /*
+ * wait_shm_mmap, socket and notify socket are used by listener
+ * threads outside of the ust lock, so we cannot tear them down
+ * ourselves, because we cannot join on these threads. Leave
+ * responsibility of cleaning up these resources to the OS
+ * process exit.
+ */
+ if (exiting)
+ return;
+
+ if (sock_info->socket != -1) {
+ ret = ustcomm_close_unix_sock(sock_info->socket);
+ if (ret) {
+ ERR("Error closing ust cmd socket");
+ }
+ sock_info->socket = -1;
+ }
+ if (sock_info->notify_socket != -1) {
+ ret = ustcomm_close_unix_sock(sock_info->notify_socket);
+ if (ret) {
+ ERR("Error closing ust notify socket");
+ }
+ sock_info->notify_socket = -1;
+ }
+ if (sock_info->wait_shm_mmap) {
+ long page_size;
+
+ page_size = LTTNG_UST_PAGE_SIZE;
+ if (page_size <= 0) {
+ if (!page_size) {
+ errno = EINVAL;
+ }
+ PERROR("Error in sysconf(_SC_PAGE_SIZE)");
+ } else {
+ ret = munmap(sock_info->wait_shm_mmap, 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) {
+ int32_t tmp_read;
+ ssize_t len;
+ size_t bytes_read = 0;
+
+ /*
+ * Try to read the fd. If unable to do so, try opening
+ * it in write mode.
+ */
+ do {
+ len = read(wait_shm_fd,
+ &((char *) &tmp_read)[bytes_read],
+ sizeof(tmp_read) - bytes_read);
+ if (len > 0) {
+ bytes_read += len;
+ }
+ } while ((len < 0 && errno == EINTR)
+ || (len > 0 && bytes_read < sizeof(tmp_read)));
+ if (bytes_read != sizeof(tmp_read)) {
+ ret = close(wait_shm_fd);
+ if (ret) {
+ ERR("close wait_shm_fd");
+ }
+ goto open_write;
+ }
+ 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;
+ }
+
+open_write:
+ /*
+ * If the open failed because the file did not exist, or because
+ * the file was not truncated yet, try creating it ourself.
+ */
+ URCU_TLS(lttng_ust_nest_count)++;
+ pid = fork();
+ URCU_TLS(lttng_ust_nest_count)--;
+ 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 (pid < 0 || !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)
+{
+ long page_size;
+ int wait_shm_fd, ret;
+ char *wait_shm_mmap;
+
+ page_size = sysconf(_SC_PAGE_SIZE);
+ if (page_size <= 0) {
+ if (!page_size) {
+ errno = EINVAL;
+ }
+ PERROR("Error in sysconf(_SC_PAGE_SIZE)");
+ goto error;
+ }
+
+ lttng_ust_lock_fd_tracker();
+ wait_shm_fd = get_wait_shm(sock_info, page_size);
+ if (wait_shm_fd < 0) {
+ lttng_ust_unlock_fd_tracker();
+ goto error;
+ }
+
+ ret = lttng_ust_add_fd_to_tracker(wait_shm_fd);
+ if (ret < 0) {
+ ret = close(wait_shm_fd);
+ if (!ret) {
+ PERROR("Error closing fd");
+ }
+ lttng_ust_unlock_fd_tracker();
+ goto error;
+ }
+
+ wait_shm_fd = ret;
+ lttng_ust_unlock_fd_tracker();
+
+ wait_shm_mmap = mmap(NULL, page_size, PROT_READ,
+ MAP_SHARED, wait_shm_fd, 0);
+
+ /* close shm fd immediately after taking the mmap reference */
+ lttng_ust_lock_fd_tracker();
+ ret = close(wait_shm_fd);
+ if (!ret) {
+ lttng_ust_delete_fd_from_tracker(wait_shm_fd);
+ } else {
+ PERROR("Error closing fd");
+ }
+ lttng_ust_unlock_fd_tracker();
+
+ 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)
+{
+ /* Use ust_lock to check if we should quit. */
+ if (ust_lock()) {
+ goto quit;
+ }
+ if (wait_poll_fallback) {
+ goto error;
+ }
+ ust_unlock();
+
+ assert(sock_info->wait_shm_mmap);
+
+ DBG("Waiting for %s apps sessiond", sock_info->name);
+ /* Wait for futex wakeup */
+ if (uatomic_read((int32_t *) sock_info->wait_shm_mmap))
+ goto end_wait;
+
+ while (lttng_ust_futex_async((int32_t *) sock_info->wait_shm_mmap,
+ FUTEX_WAIT, 0, NULL, NULL, 0)) {
+ switch (errno) {
+ case EWOULDBLOCK:
+ /* Value already changed. */
+ goto end_wait;
+ case EINTR:
+ /* Retry if interrupted by signal. */
+ break; /* Get out of switch. */
+ case EFAULT:
+ wait_poll_fallback = 1;
+ DBG(
+"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.");
+ if (ust_err_debug_enabled())
+ PERROR("futex");
+ goto end_wait;
+ }
+ }
+end_wait:
+ 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 connection, 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, fd;
+ long timeout;
+
+ lttng_ust_fixup_tls();
+ /*
+ * If available, add '-ust' to the end of this thread's
+ * process name
+ */
+ ret = lttng_ust_setustprocname();
+ if (ret) {
+ ERR("Unable to set UST process name");
+ }
+
+ /* 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);
+ } else {
+ has_waited = 1;
+ }
+ prev_connect_failed = 0;
+ }
+
+ if (ust_lock()) {
+ goto quit;
+ }
+
+ if (sock_info->socket != -1) {
+ /* FD tracker is updated by ustcomm_close_unix_sock() */
+ ret = ustcomm_close_unix_sock(sock_info->socket);
+ if (ret) {
+ ERR("Error closing %s ust cmd socket",
+ sock_info->name);
+ }
+ sock_info->socket = -1;
+ }
+ if (sock_info->notify_socket != -1) {
+ /* FD tracker is updated by ustcomm_close_unix_sock() */
+ ret = ustcomm_close_unix_sock(sock_info->notify_socket);
+ if (ret) {
+ ERR("Error closing %s ust notify socket",
+ sock_info->name);
+ }
+ sock_info->notify_socket = -1;
+ }
+
+
+ /*
+ * Register. We need to perform both connect and sending
+ * registration message before doing the next connect otherwise
+ * we may reach unix socket connect queue max limits and block
+ * on the 2nd connect while the session daemon is awaiting the
+ * first connect registration message.
+ */
+ /* Connect cmd socket */
+ lttng_ust_lock_fd_tracker();
+ ret = ustcomm_connect_unix_sock(sock_info->sock_path,
+ get_connect_sock_timeout());
+ if (ret < 0) {
+ lttng_ust_unlock_fd_tracker();
+ DBG("Info: sessiond not accepting connections 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_failed(sock_info);
+ assert(!ret);
+ ust_unlock();
+ goto restart;
+ }
+ fd = ret;
+ ret = lttng_ust_add_fd_to_tracker(fd);
+ if (ret < 0) {
+ ret = close(fd);
+ if (ret) {
+ PERROR("close on sock_info->socket");
+ }
+ ret = -1;
+ lttng_ust_unlock_fd_tracker();
+ ust_unlock();
+ goto quit;
+ }
+
+ sock_info->socket = ret;
+ lttng_ust_unlock_fd_tracker();
+
+ ust_unlock();
+ /*
+ * Unlock/relock ust lock because connect is blocking (with
+ * timeout). Don't delay constructors on the ust lock for too
+ * long.
+ */
+ if (ust_lock()) {
+ goto quit;
+ }
+
+ /*
+ * Create only one root handle per listener thread for the whole
+ * process lifetime, so we ensure we get ID which is statically
+ * assigned to the root handle.
+ */
+ if (sock_info->root_handle == -1) {
+ ret = lttng_abi_create_root_handle();
+ if (ret < 0) {
+ ERR("Error creating root handle");
+ goto quit;
+ }
+ sock_info->root_handle = ret;
+ }
+
+ ret = register_to_sessiond(sock_info->socket, USTCTL_SOCKET_CMD);
+ if (ret < 0) {
+ ERR("Error registering to %s ust cmd socket",
+ sock_info->name);
+ prev_connect_failed = 1;
+ /*
+ * If we cannot register to the sessiond daemon, don't
+ * delay constructor execution.
+ */
+ ret = handle_register_failed(sock_info);
+ assert(!ret);
+ ust_unlock();
+ goto restart;
+ }
+
+ ust_unlock();
+ /*
+ * Unlock/relock ust lock because connect is blocking (with
+ * timeout). Don't delay constructors on the ust lock for too
+ * long.
+ */
+ if (ust_lock()) {
+ goto quit;
+ }
+
+ /* Connect notify socket */
+ lttng_ust_lock_fd_tracker();
+ ret = ustcomm_connect_unix_sock(sock_info->sock_path,
+ get_connect_sock_timeout());
+ if (ret < 0) {
+ lttng_ust_unlock_fd_tracker();
+ DBG("Info: sessiond not accepting connections 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_failed(sock_info);
+ assert(!ret);
+ ust_unlock();
+ goto restart;
+ }
+
+ fd = ret;
+ ret = lttng_ust_add_fd_to_tracker(fd);
+ if (ret < 0) {
+ ret = close(fd);
+ if (ret) {
+ PERROR("close on sock_info->notify_socket");
+ }
+ ret = -1;
+ lttng_ust_unlock_fd_tracker();
+ ust_unlock();
+ goto quit;
+ }
+
+ sock_info->notify_socket = ret;
+ lttng_ust_unlock_fd_tracker();
+
+ ust_unlock();
+ /*
+ * Unlock/relock ust lock because connect is blocking (with
+ * timeout). Don't delay constructors on the ust lock for too
+ * long.
+ */
+ if (ust_lock()) {
+ goto quit;
+ }
+
+ timeout = get_notify_sock_timeout();
+ if (timeout >= 0) {
+ /*
+ * Give at least 10ms to sessiond to reply to
+ * notifications.
+ */
+ if (timeout < 10)
+ timeout = 10;
+ ret = ustcomm_setsockopt_rcv_timeout(sock_info->notify_socket,
+ timeout);
+ if (ret < 0) {
+ WARN("Error setting socket receive timeout");
+ }
+ ret = ustcomm_setsockopt_snd_timeout(sock_info->notify_socket,
+ timeout);
+ if (ret < 0) {
+ WARN("Error setting socket send timeout");
+ }
+ } else if (timeout < -1) {
+ WARN("Unsupported timeout value %ld", timeout);
+ }
+
+ ret = register_to_sessiond(sock_info->notify_socket,
+ USTCTL_SOCKET_NOTIFY);
+ if (ret < 0) {
+ ERR("Error registering to %s ust notify socket",
+ sock_info->name);
+ prev_connect_failed = 1;
+ /*
+ * If we cannot register to the sessiond daemon, don't
+ * delay constructor execution.
+ */
+ ret = handle_register_failed(sock_info);
+ assert(!ret);
+ ust_unlock();
+ goto restart;
+ }
+ sock = sock_info->socket;
+
+ 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 lttng-sessiond has performed an orderly shutdown", sock_info->name);
+ if (ust_lock()) {
+ goto quit;
+ }
+ /*
+ * Either sessiond has shutdown or refused us by closing the socket.
+ * In either case, we don't want to delay construction execution,
+ * and we need to wait before retry.
+ */
+ prev_connect_failed = 1;
+ /*
+ * If we cannot register to the sessiond daemon, don't
+ * delay constructor execution.
+ */
+ ret = handle_register_failed(sock_info);
+ assert(!ret);
+ ust_unlock();
+ goto end;
+ case sizeof(lum):
+ print_cmd(lum.cmd, lum.handle);
+ ret = handle_message(sock_info, sock, &lum);
+ if (ret) {
+ ERR("Error handling message for %s socket",
+ sock_info->name);
+ /*
+ * Close socket if protocol error is
+ * detected.
+ */
+ goto end;
+ }
+ continue;
+ default:
+ if (len < 0) {
+ DBG("Receive failed from lttng-sessiond with errno %d", (int) -len);
+ } else {
+ DBG("incorrect message size (%s socket): %zd", sock_info->name, len);
+ }
+ if (len == -ECONNRESET) {
+ DBG("%s remote end closed connection", sock_info->name);
+ goto end;
+ }
+ goto end;
+ }
+
+ }
+end:
+ if (ust_lock()) {
+ goto quit;
+ }
+ /* Cleanup socket handles before trying to reconnect */
+ lttng_ust_abi_objd_table_owner_cleanup(sock_info);
+ ust_unlock();
+ goto restart; /* try to reconnect */
+
+quit:
+ ust_unlock();
+
+ pthread_mutex_lock(&ust_exit_mutex);
+ sock_info->thread_active = 0;
+ pthread_mutex_unlock(&ust_exit_mutex);
+ return NULL;
+}
+
+/*
+ * Weak symbol to call when the ust malloc wrapper is not loaded.
+ */
+__attribute__((weak))
+void lttng_ust_libc_wrapper_malloc_init(void)
+{
+}
+
+/*
+ * sessiond monitoring thread: monitor presence of global and per-user
+ * sessiond by polling the application common named pipe.
+ */
+static
+void lttng_ust_init(void)
+ __attribute__((constructor));
+static
+void lttng_ust_init(void)
+{
+ struct timespec constructor_timeout;
+ sigset_t sig_all_blocked, orig_parent_mask;
+ pthread_attr_t thread_attr;
+ int timeout_mode;
+ int ret;
+ void *handle;
+
+ if (uatomic_xchg(&initialized, 1) == 1)
+ return;
+
+ /*
+ * Fixup interdependency between TLS fixup mutex (which happens
+ * to be the dynamic linker mutex) and ust_lock, taken within
+ * the ust lock.
+ */
+ lttng_ust_fixup_tls();
+
+ lttng_ust_loaded = 1;
+
+ /*
+ * We need to ensure that the liblttng-ust library is not unloaded to avoid
+ * the unloading of code used by the ust_listener_threads as we can not
+ * reliably know when they exited. To do that, manually load
+ * liblttng-ust.so to increment the dynamic loader's internal refcount for
+ * this library so it never becomes zero, thus never gets unloaded from the
+ * address space of the process. Since we are already running in the
+ * constructor of the LTTNG_UST_LIB_SONAME library, calling dlopen will
+ * simply increment the refcount and no additionnal work is needed by the
+ * dynamic loader as the shared library is already loaded in the address
+ * space. As a safe guard, we use the RTLD_NODELETE flag to prevent
+ * unloading of the UST library if its refcount becomes zero (which should
+ * never happen). Do the return value check but discard the handle at the
+ * end of the function as it's not needed.
+ */
+ handle = dlopen(LTTNG_UST_LIB_SONAME, RTLD_LAZY | RTLD_NODELETE);
+ if (!handle) {
+ ERR("dlopen of liblttng-ust shared library (%s).", LTTNG_UST_LIB_SONAME);
+ }
+
+ /*
+ * 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).
+ */
+ ust_err_init();
+ lttng_ust_getenv_init(); /* Needs ust_err_init() to be completed. */
+ lttng_ust_tp_init();
+ lttng_ust_init_fd_tracker();
+ lttng_ust_clock_init();
+ lttng_ust_getcpu_init();
+ lttng_ust_statedump_init();
+ lttng_ust_ring_buffer_clients_init();
+ lttng_ust_counter_clients_init();
+ lttng_perf_counter_init();
+ /*
+ * Invoke ust malloc wrapper init before starting other threads.
+ */
+ lttng_ust_libc_wrapper_malloc_init();
+
+ timeout_mode = get_constructor_timeout(&constructor_timeout);
+
+ get_allow_blocking();
+
+ ret = sem_init(&constructor_wait, 0, 0);
+ if (ret) {
+ PERROR("sem_init");
+ }
+
+ ret = setup_global_apps();
+ if (ret) {
+ assert(global_apps.allowed == 0);
+ DBG("global apps setup returned %d", ret);
+ }
+
+ ret = setup_local_apps();
+ if (ret) {
+ assert(local_apps.allowed == 0);
+ DBG("local apps setup returned %d", ret);
+ }
+
+ /* A new thread created by pthread_create inherits the signal mask
+ * from the parent. To avoid any signal being received by the
+ * listener thread, we block all signals temporarily in the parent,
+ * while we create the listener thread.
+ */
+ sigfillset(&sig_all_blocked);
+ ret = pthread_sigmask(SIG_SETMASK, &sig_all_blocked, &orig_parent_mask);
+ if (ret) {
+ ERR("pthread_sigmask: %s", strerror(ret));
+ }
+
+ ret = pthread_attr_init(&thread_attr);
+ if (ret) {
+ ERR("pthread_attr_init: %s", strerror(ret));
+ }
+ ret = pthread_attr_setdetachstate(&thread_attr, PTHREAD_CREATE_DETACHED);
+ if (ret) {
+ ERR("pthread_attr_setdetachstate: %s", strerror(ret));
+ }
+
+ if (global_apps.allowed) {
+ pthread_mutex_lock(&ust_exit_mutex);
+ ret = pthread_create(&global_apps.ust_listener, &thread_attr,
+ ust_listener_thread, &global_apps);
+ if (ret) {
+ ERR("pthread_create global: %s", strerror(ret));
+ }
+ global_apps.thread_active = 1;
+ pthread_mutex_unlock(&ust_exit_mutex);
+ } else {
+ handle_register_done(&global_apps);
+ }
+
+ if (local_apps.allowed) {
+ pthread_mutex_lock(&ust_exit_mutex);
+ ret = pthread_create(&local_apps.ust_listener, &thread_attr,
+ ust_listener_thread, &local_apps);
+ if (ret) {
+ ERR("pthread_create local: %s", strerror(ret));
+ }
+ local_apps.thread_active = 1;
+ pthread_mutex_unlock(&ust_exit_mutex);
+ } else {
+ handle_register_done(&local_apps);
+ }
+ ret = pthread_attr_destroy(&thread_attr);
+ if (ret) {
+ ERR("pthread_attr_destroy: %s", strerror(ret));
+ }
+
+ /* Restore original signal mask in parent */
+ ret = pthread_sigmask(SIG_SETMASK, &orig_parent_mask, NULL);
+ if (ret) {
+ ERR("pthread_sigmask: %s", strerror(ret));
+ }
+
+ switch (timeout_mode) {
+ case 1: /* timeout wait */
+ do {
+ ret = sem_timedwait(&constructor_wait,
+ &constructor_timeout);
+ } while (ret < 0 && errno == EINTR);
+ if (ret < 0) {
+ switch (errno) {
+ case ETIMEDOUT:
+ ERR("Timed out waiting for lttng-sessiond");
+ break;
+ case EINVAL:
+ PERROR("sem_timedwait");
+ break;
+ default:
+ ERR("Unexpected error \"%s\" returned by sem_timedwait",
+ strerror(errno));
+ }
+ }
+ break;
+ case -1:/* wait forever */
+ do {
+ ret = sem_wait(&constructor_wait);
+ } while (ret < 0 && errno == EINTR);
+ if (ret < 0) {
+ switch (errno) {
+ case EINVAL:
+ PERROR("sem_wait");
+ break;
+ default:
+ ERR("Unexpected error \"%s\" returned by sem_wait",
+ strerror(errno));
+ }
+ }
+ break;
+ case 0: /* no timeout */
+ break;
+ }
+}
+
+static
+void lttng_ust_cleanup(int exiting)
+{
+ cleanup_sock_info(&global_apps, exiting);
+ cleanup_sock_info(&local_apps, exiting);
+ local_apps.allowed = 0;
+ global_apps.allowed = 0;
+ /*
+ * The teardown in this function all affect data structures
+ * accessed under the UST lock by the listener thread. This
+ * lock, along with the lttng_ust_comm_should_quit flag, ensure
+ * that none of these threads are accessing this data at this
+ * point.
+ */
+ lttng_ust_abi_exit();
+ lttng_ust_abi_events_exit();
+ lttng_perf_counter_exit();
+ lttng_ust_ring_buffer_clients_exit();
+ lttng_ust_counter_clients_exit();
+ lttng_ust_statedump_destroy();
+ lttng_ust_tp_exit();
+ if (!exiting) {
+ /* Reinitialize values for fork */
+ sem_count = sem_count_initial_value;
+ lttng_ust_comm_should_quit = 0;
+ initialized = 0;
+ }
+}
+
+static
+void lttng_ust_exit(void)
+ __attribute__((destructor));
+static
+void 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_nocheck();
+ lttng_ust_comm_should_quit = 1;
+ ust_unlock();
+
+ pthread_mutex_lock(&ust_exit_mutex);
+ /* cancel threads */
+ if (global_apps.thread_active) {
+ ret = pthread_cancel(global_apps.ust_listener);
+ if (ret) {
+ ERR("Error cancelling global ust listener thread: %s",
+ strerror(ret));
+ } else {
+ global_apps.thread_active = 0;
+ }
+ }
+ if (local_apps.thread_active) {
+ ret = pthread_cancel(local_apps.ust_listener);
+ if (ret) {
+ ERR("Error cancelling local ust listener thread: %s",
+ strerror(ret));
+ } else {
+ local_apps.thread_active = 0;
+ }
+ }
+ pthread_mutex_unlock(&ust_exit_mutex);
+
+ /*
+ * Do NOT join threads: use of sys_futex makes it impossible to
+ * join the threads without using async-cancel, but async-cancel
+ * is delivered by a signal, which could hit the target thread
+ * anywhere in its code path, including while the ust_lock() is
+ * held, causing a deadlock for the other thread. Let the OS
+ * cleanup the threads if there are stalled in a syscall.
+ */
+ lttng_ust_cleanup(1);
+}
+
+static
+void ust_context_ns_reset(void)
+{
+ lttng_context_pid_ns_reset();
+ lttng_context_cgroup_ns_reset();
+ lttng_context_ipc_ns_reset();
+ lttng_context_mnt_ns_reset();
+ lttng_context_net_ns_reset();
+ lttng_context_user_ns_reset();
+ lttng_context_time_ns_reset();
+ lttng_context_uts_ns_reset();
+}
+
+static
+void ust_context_vuids_reset(void)
+{
+ lttng_context_vuid_reset();
+ lttng_context_veuid_reset();
+ lttng_context_vsuid_reset();
+}
+
+static
+void ust_context_vgids_reset(void)
+{
+ lttng_context_vgid_reset();
+ lttng_context_vegid_reset();
+ lttng_context_vsgid_reset();
+}
+
+/*
+ * 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 lttng_ust_before_fork(sigset_t *save_sigset)
+{
+ /*
+ * 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;
+
+ /* Fixup lttng-ust TLS. */
+ lttng_ust_fixup_tls();
+
+ if (URCU_TLS(lttng_ust_nest_count))
+ return;
+ /* Disable signals */
+ sigfillset(&all_sigs);
+ ret = sigprocmask(SIG_BLOCK, &all_sigs, save_sigset);
+ if (ret == -1) {
+ PERROR("sigprocmask");
+ }
+
+ pthread_mutex_lock(&ust_fork_mutex);
+
+ ust_lock_nocheck();
+ lttng_ust_urcu_before_fork();
+ lttng_ust_lock_fd_tracker();
+ lttng_perf_lock();
+}
+
+static void ust_after_fork_common(sigset_t *restore_sigset)
+{
+ int ret;
+
+ DBG("process %d", getpid());
+ lttng_perf_unlock();
+ lttng_ust_unlock_fd_tracker();
+ ust_unlock();
+
+ pthread_mutex_unlock(&ust_fork_mutex);
+
+ /* Restore signals */
+ ret = sigprocmask(SIG_SETMASK, restore_sigset, NULL);
+ if (ret == -1) {
+ PERROR("sigprocmask");
+ }
+}
+
+void lttng_ust_after_fork_parent(sigset_t *restore_sigset)
+{
+ if (URCU_TLS(lttng_ust_nest_count))
+ return;
+ DBG("process %d", getpid());
+ lttng_ust_urcu_after_fork_parent();
+ /* Release mutexes and reenable signals */
+ ust_after_fork_common(restore_sigset);
+}
+
+/*
+ * 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 lttng_ust_after_fork_child(sigset_t *restore_sigset)
+{
+ if (URCU_TLS(lttng_ust_nest_count))
+ return;
+ lttng_context_vpid_reset();
+ lttng_context_vtid_reset();
+ lttng_ust_context_procname_reset();
+ ust_context_ns_reset();
+ ust_context_vuids_reset();
+ ust_context_vgids_reset();
+ DBG("process %d", getpid());
+ /* Release urcu mutexes */
+ lttng_ust_urcu_after_fork_child();
+ lttng_ust_cleanup(0);
+ /* Release mutexes and reenable signals */
+ ust_after_fork_common(restore_sigset);
+ lttng_ust_init();
+}
+
+void lttng_ust_after_setns(void)
+{
+ ust_context_ns_reset();
+ ust_context_vuids_reset();
+ ust_context_vgids_reset();
+}
+
+void lttng_ust_after_unshare(void)
+{
+ ust_context_ns_reset();
+ ust_context_vuids_reset();
+ ust_context_vgids_reset();
+}
+
+void lttng_ust_after_setuid(void)
+{
+ ust_context_vuids_reset();
+}
+
+void lttng_ust_after_seteuid(void)
+{
+ ust_context_vuids_reset();
+}
+
+void lttng_ust_after_setreuid(void)
+{
+ ust_context_vuids_reset();
+}
+
+void lttng_ust_after_setresuid(void)
+{
+ ust_context_vuids_reset();
+}
+
+void lttng_ust_after_setgid(void)
+{
+ ust_context_vgids_reset();
+}
+
+void lttng_ust_after_setegid(void)
+{
+ ust_context_vgids_reset();
+}
+
+void lttng_ust_after_setregid(void)
+{
+ ust_context_vgids_reset();
+}
+
+void lttng_ust_after_setresgid(void)
+{
+ ust_context_vgids_reset();
+}
+
+void lttng_ust_sockinfo_session_enabled(void *owner)
+{
+ struct sock_info *sock_info = owner;
+ sock_info->statedump_pending = 1;
+}
projects / lttng-ust.git / blobdiff