X-Git-Url: http://git.liburcu.org/?a=blobdiff_plain;f=liblttng-ust%2Flttng-ust-comm.c;h=9d0c010d502079a164e453cb67778f3a547cc2d1;hb=HEAD;hp=ace63bb8ec015c8701f10a13238e3cc4e7da2832;hpb=28515902a0c1d721e1a92c4a25f20574e0e4f24a;p=lttng-ust.git diff --git a/liblttng-ust/lttng-ust-comm.c b/liblttng-ust/lttng-ust-comm.c deleted file mode 100644 index ace63bb8..00000000 --- a/liblttng-ust/lttng-ust-comm.c +++ /dev/null @@ -1,1723 +0,0 @@ -/* - * lttng-ust-comm.c - * - * Copyright (C) 2011 David Goulet - * Copyright (C) 2011 Mathieu Desnoyers - * - * 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 -#define _GNU_SOURCE -#include -#include -#include -#include -#include -#include -#include -#include -#include -#include -#include -#include -#include -#include -#include -#include -#include - -#include -#include -#include -#include -#include -#include -#include -#include -#include -#include "tracepoint-internal.h" -#include "lttng-tracer-core.h" -#include "compat.h" -#include "../libringbuffer/tlsfixup.h" -#include "lttng-ust-baddr.h" -#include "clock.h" -#include "../libringbuffer/getcpu.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. - */ -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; - -/* - * 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; - - 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; - - 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; - - 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)); - } -} - -/* - * 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 }; - -/* - * 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 constructor_sem_posted; - 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; -}; - -/* Socket from app (connect) to session daemon (listen) for communication */ -struct sock_info global_apps = { - .name = "global", - .global = 1, - - .root_handle = -1, - .allowed = 1, - .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, -}; - -/* 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 */ - .thread_active = 0, - - .socket = -1, - .notify_socket = -1, - - .statedump_pending = 0, -}; - -static int wait_poll_fallback; - -static const char *cmd_name_mapping[] = { - [ LTTNG_UST_RELEASE ] = "Release", - [ LTTNG_UST_SESSION ] = "Create Session", - [ LTTNG_UST_TRACER_VERSION ] = "Get Tracer Version", - - [ LTTNG_UST_TRACEPOINT_LIST ] = "Create Tracepoint List", - [ LTTNG_UST_WAIT_QUIESCENT ] = "Wait for Quiescent State", - [ LTTNG_UST_REGISTER_DONE ] = "Registration Done", - [ LTTNG_UST_TRACEPOINT_FIELD_LIST ] = "Create Tracepoint Field List", - - /* Session FD commands */ - [ LTTNG_UST_CHANNEL ] = "Create Channel", - [ LTTNG_UST_SESSION_START ] = "Start Session", - [ LTTNG_UST_SESSION_STOP ] = "Stop Session", - - /* Channel FD commands */ - [ LTTNG_UST_STREAM ] = "Create Stream", - [ LTTNG_UST_EVENT ] = "Create Event", - - /* Event and Channel FD commands */ - [ LTTNG_UST_CONTEXT ] = "Create Context", - [ LTTNG_UST_FLUSH_BUFFER ] = "Flush Buffer", - - /* Event, Channel and Session commands */ - [ LTTNG_UST_ENABLE ] = "Enable", - [ LTTNG_UST_DISABLE ] = "Disable", - - /* Tracepoint list commands */ - [ LTTNG_UST_TRACEPOINT_LIST_GET ] = "List Next Tracepoint", - [ LTTNG_UST_TRACEPOINT_FIELD_LIST_GET ] = "List Next Tracepoint Field", - - /* Event FD commands */ - [ LTTNG_UST_FILTER ] = "Create Filter", - [ LTTNG_UST_EXCLUSION ] = "Add exclusions to event", -}; - -static const char *str_timeout; -static int got_timeout_env; - -extern void lttng_ring_buffer_client_overwrite_init(void); -extern void lttng_ring_buffer_client_overwrite_rt_init(void); -extern void lttng_ring_buffer_client_discard_init(void); -extern void lttng_ring_buffer_client_discard_rt_init(void); -extern void lttng_ring_buffer_metadata_client_init(void); -extern void lttng_ring_buffer_client_overwrite_exit(void); -extern void lttng_ring_buffer_client_overwrite_rt_exit(void); -extern void lttng_ring_buffer_client_discard_exit(void); -extern void lttng_ring_buffer_client_discard_rt_exit(void); -extern void lttng_ring_buffer_metadata_client_exit(void); - -/* - * 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 *) getenv("LTTNG_HOME"); - if (val != NULL) { - return val; - } - return (const char *) 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 urcu bp TLS. - */ -static -void lttng_fixup_urcu_bp_tls(void) -{ - rcu_read_lock(); - rcu_read_unlock(); -} - -int lttng_get_notify_socket(void *owner) -{ - struct sock_info *info = owner; - - return info->notify_socket; -} - -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_local_apps(void) -{ - const char *home_dir; - uid_t uid; - - uid = getuid(); - /* - * Disallow per-user tracing for setuid binaries. - */ - if (uid != geteuid()) { - assert(local_apps.allowed == 0); - return 0; - } - 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); - return -ENOENT; - } - 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); - return 0; -} - -/* - * Get notify_sock 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 = getenv("LTTNG_UST_REGISTER_TIMEOUT"); - got_timeout_env = 1; - } - if (str_timeout) - constructor_delay_ms = strtol(str_timeout, NULL, 10); - return constructor_delay_ms; -} - -static -long get_notify_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 -int register_to_sessiond(int socket, enum ustctl_socket_type type) -{ - return ustcomm_send_reg_msg(socket, - type, - CAA_BITS_PER_LONG, - lttng_alignof(uint8_t) * CHAR_BIT, - lttng_alignof(uint16_t) * CHAR_BIT, - lttng_alignof(uint32_t) * CHAR_BIT, - lttng_alignof(uint64_t) * CHAR_BIT, - lttng_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 -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; -} - -/* - * Only execute pending statedump after the constructor semaphore has - * been posted by each listener thread. This means statedump will only - * be performed after the "registration done" command is received from - * each session daemon the application is connected to. - * - * 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. - */ -static -void handle_pending_statedump(struct sock_info *sock_info) -{ - int ctor_passed = sock_info->constructor_sem_posted; - - if (ctor_passed && 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); - } -} - -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; - union ust_args args; - ssize_t len; - - memset(&lur, 0, sizeof(lur)); - - if (ust_lock()) { - ret = -LTTNG_UST_ERR_EXITING; - 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, 1); - break; - case LTTNG_UST_FILTER: - { - /* Receive filter data */ - struct lttng_ust_filter_bytecode_node *bytecode; - - if (lum->u.filter.data_size > FILTER_BYTECODE_MAX_LEN) { - ERR("Filter data size is too large: %u bytes", - lum->u.filter.data_size); - ret = -EINVAL; - goto error; - } - - if (lum->u.filter.reloc_offset > lum->u.filter.data_size) { - ERR("Filter reloc offset %u is not within data", - lum->u.filter.reloc_offset); - ret = -EINVAL; - goto error; - } - - bytecode = zmalloc(sizeof(*bytecode) + lum->u.filter.data_size); - if (!bytecode) { - ret = -ENOMEM; - goto error; - } - len = ustcomm_recv_unix_sock(sock, bytecode->bc.data, - lum->u.filter.data_size); - switch (len) { - case 0: /* orderly shutdown */ - ret = 0; - free(bytecode); - goto error; - default: - if (len == lum->u.filter.data_size) { - DBG("filter 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(bytecode); - goto error; - } - ret = len; - free(bytecode); - goto end; - } else { - DBG("incorrect filter data message size: %zd", len); - ret = -EINVAL; - free(bytecode); - goto end; - } - } - bytecode->bc.len = lum->u.filter.data_size; - bytecode->bc.reloc_offset = lum->u.filter.reloc_offset; - bytecode->bc.seqnum = lum->u.filter.seqnum; - if (ops->cmd) { - ret = ops->cmd(lum->handle, lum->cmd, - (unsigned long) bytecode, - &args, sock_info); - if (ret) { - free(bytecode); - } - /* don't free bytecode if everything went fine. */ - } else { - ret = -ENOSYS; - free(bytecode); - } - break; - } - case LTTNG_UST_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_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_SYM_NAME_LEN); - switch (len) { - case 0: /* orderly shutdown */ - ret = 0; - free(node); - goto error; - default: - if (len == count * LTTNG_UST_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 end; - } else { - DBG("Incorrect exclusion data message size: %zd", len); - ret = -EINVAL; - free(node); - goto end; - } - } - if (ops->cmd) { - ret = ops->cmd(lum->handle, lum->cmd, - (unsigned long) node, - &args, sock_info); - if (ret) { - free(node); - } - /* Don't free exclusion data if everything went fine. */ - } else { - ret = -ENOSYS; - free(node); - } - break; - } - case LTTNG_UST_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 end; - } else { - DBG("incorrect channel data message size: %zd", len); - ret = -EINVAL; - goto end; - } - } - 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; - break; - } - case LTTNG_UST_STREAM: - { - /* Receive shm_fd, wakeup_fd */ - ret = ustcomm_recv_stream_from_sessiond(sock, - &lum->u.stream.len, - &args.stream.shm_fd, - &args.stream.wakeup_fd); - if (ret) { - goto end; - } - if (ops->cmd) - ret = ops->cmd(lum->handle, lum->cmd, - (unsigned long) &lum->u, - &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; - } - -end: - 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_TRACER_VERSION: - lur.u.version = lum->u.version; - break; - case LTTNG_UST_TRACEPOINT_LIST_GET: - memcpy(&lur.u.tracepoint, &lum->u.tracepoint, sizeof(lur.u.tracepoint)); - break; - } - } - DBG("Return value: %d", lur.ret_val); - 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_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(); - - /* - * 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); - - 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_objd_unref(sock_info->root_handle, 1); - if (ret) { - ERR("Error unref root handle"); - } - sock_info->root_handle = -1; - } - sock_info->constructor_sem_posted = 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 = sysconf(_SC_PAGE_SIZE); - if (page_size > 0) { - 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) { - goto error; - } - - wait_shm_fd = get_wait_shm(sock_info, page_size); - if (wait_shm_fd < 0) { - goto error; - } - wait_shm_mmap = mmap(NULL, page_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; - - if (ust_lock()) { - 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; - 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_debug()) - 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 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; - long timeout; - - /* 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; - } - - if (sock_info->socket != -1) { - 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) { - 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 */ - ret = ustcomm_connect_unix_sock(sock_info->sock_path); - if (ret < 0) { - DBG("Info: sessiond not accepting connections to %s apps socket", sock_info->name); - prev_connect_failed = 1; - - if (ust_lock()) { - goto quit; - } - - /* - * 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 = ret; - - 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_done(sock_info); - assert(!ret); - ust_unlock(); - goto restart; - } - - ust_unlock(); - - /* Connect notify socket */ - ret = ustcomm_connect_unix_sock(sock_info->sock_path); - if (ret < 0) { - DBG("Info: sessiond not accepting connections to %s apps socket", sock_info->name); - prev_connect_failed = 1; - - if (ust_lock()) { - goto quit; - } - - /* - * 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->notify_socket = ret; - - 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); - } - - if (ust_lock()) { - goto quit; - } - - 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_done(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_done(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); - } - 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_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_malloc_wrapper_init(void) -{ -} - -/* - * sessiond monitoring thread: monitor presence of global and per-user - * sessiond by polling the application common named pipe. - */ -void __attribute__((constructor)) 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; - - 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_fixup_urcu_bp_tls(); - lttng_fixup_ringbuffer_tls(); - lttng_fixup_vtid_tls(); - lttng_fixup_nest_count_tls(); - lttng_fixup_procname_tls(); - lttng_fixup_ust_mutex_nest_tls(); - - /* - * 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(); - lttng_ust_clock_init(); - lttng_ust_getcpu_init(); - lttng_ust_baddr_statedump_init(); - lttng_ring_buffer_metadata_client_init(); - lttng_ring_buffer_client_overwrite_init(); - lttng_ring_buffer_client_overwrite_rt_init(); - lttng_ring_buffer_client_discard_init(); - lttng_ring_buffer_client_discard_rt_init(); - lttng_perf_counter_init(); - lttng_context_init(); - /* - * Invoke ust malloc wrapper init before starting other threads. - */ - lttng_ust_malloc_wrapper_init(); - - timeout_mode = get_constructor_timeout(&constructor_timeout); - - ret = sem_init(&constructor_wait, 0, 0); - assert(!ret); - - ret = setup_local_apps(); - if (ret) { - 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)); - } - - 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); - - 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 && errno == ETIMEDOUT) { - ERR("Timed out waiting for lttng-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, exiting); - if (local_apps.allowed) { - cleanup_sock_info(&local_apps, exiting); - } - /* - * 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_events_exit(); - lttng_context_exit(); - lttng_perf_counter_exit(); - lttng_ring_buffer_client_discard_rt_exit(); - lttng_ring_buffer_client_discard_exit(); - lttng_ring_buffer_client_overwrite_rt_exit(); - lttng_ring_buffer_client_overwrite_exit(); - lttng_ring_buffer_metadata_client_exit(); - lttng_ust_baddr_statedump_destroy(); - 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_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); -} - -/* - * 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(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; - - 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(); - rcu_bp_before_fork(); -} - -static void ust_after_fork_common(sigset_t *restore_sigset) -{ - int ret; - - DBG("process %d", getpid()); - ust_unlock(); - - pthread_mutex_unlock(&ust_fork_mutex); - - /* Restore signals */ - ret = sigprocmask(SIG_SETMASK, restore_sigset, NULL); - if (ret == -1) { - PERROR("sigprocmask"); - } -} - -void ust_after_fork_parent(sigset_t *restore_sigset) -{ - if (URCU_TLS(lttng_ust_nest_count)) - return; - DBG("process %d", getpid()); - rcu_bp_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 ust_after_fork_child(sigset_t *restore_sigset) -{ - if (URCU_TLS(lttng_ust_nest_count)) - return; - 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(restore_sigset); - lttng_ust_init(); -} - -void lttng_ust_sockinfo_session_enabled(void *owner) -{ - struct sock_info *sock_info = owner; - sock_info->statedump_pending = 1; -}