X-Git-Url: https://git.lttng.org/?p=lttng-tools.git;a=blobdiff_plain;f=src%2Fbin%2Flttng-sessiond%2Fmain.c;h=5cfd57971f7423fe21f69c1d58b2cfafca99a05b;hp=3c917b25f51c87f484a33096873f441c0c2da92b;hb=ceed52b545103258e84f1c7040700be9dbbbaec6;hpb=4063050c0e90b27d34ee8de570b049cc076119a4 diff --git a/src/bin/lttng-sessiond/main.c b/src/bin/lttng-sessiond/main.c index 3c917b25f..5cfd57971 100644 --- a/src/bin/lttng-sessiond/main.c +++ b/src/bin/lttng-sessiond/main.c @@ -33,7 +33,7 @@ #include #include #include -#include +#include #include #include @@ -43,12 +43,12 @@ #include #include #include +#include #include "lttng-sessiond.h" #include "channel.h" #include "context.h" #include "event.h" -#include "futex.h" #include "kernel.h" #include "modprobe.h" #include "shm.h" @@ -179,6 +179,40 @@ static const char *consumerd64_bin = CONFIG_CONSUMERD64_BIN; static const char *consumerd32_libdir = CONFIG_CONSUMERD32_LIBDIR; static const char *consumerd64_libdir = CONFIG_CONSUMERD64_LIBDIR; +/* + * Consumer daemon state which is changed when spawning it, killing it or in + * case of a fatal error. + */ +enum consumerd_state { + CONSUMER_STARTED = 1, + CONSUMER_STOPPED = 2, + CONSUMER_ERROR = 3, +}; + +/* + * This consumer daemon state is used to validate if a client command will be + * able to reach the consumer. If not, the client is informed. For instance, + * doing a "lttng start" when the consumer state is set to ERROR will return an + * error to the client. + * + * The following example shows a possible race condition of this scheme: + * + * consumer thread error happens + * client cmd arrives + * client cmd checks state -> still OK + * consumer thread exit, sets error + * client cmd try to talk to consumer + * ... + * + * However, since the consumer is a different daemon, we have no way of making + * sure the command will reach it safely even with this state flag. This is why + * we consider that up to the state validation during command processing, the + * command is safe. After that, we can not guarantee the correctness of the + * client request vis-a-vis the consumer. + */ +static enum consumerd_state ust_consumerd_state; +static enum consumerd_state kernel_consumerd_state; + static void setup_consumerd_path(void) { @@ -450,7 +484,6 @@ static void cleanup(void) if (ret) { PERROR("close"); } - } } for (i = 0; i < 2; i++) { @@ -1090,6 +1123,17 @@ restart_poll: ERR("consumer return code : %s", lttcomm_get_readable_code(-code)); error: + /* Immediately set the consumerd state to stopped */ + if (consumer_data->type == LTTNG_CONSUMER_KERNEL) { + uatomic_set(&kernel_consumerd_state, CONSUMER_ERROR); + } else if (consumer_data->type == LTTNG_CONSUMER64_UST || + consumer_data->type == LTTNG_CONSUMER32_UST) { + uatomic_set(&ust_consumerd_state, CONSUMER_ERROR); + } else { + /* Code flow error... */ + assert(0); + } + if (consumer_data->err_sock >= 0) { ret = close(consumer_data->err_sock); if (ret) { @@ -2846,6 +2890,36 @@ error: return -ret; } +/* + * Command LTTNG_LIST_TRACEPOINT_FIELDS processed by the client thread. + */ +static ssize_t cmd_list_tracepoint_fields(int domain, + struct lttng_event_field **fields) +{ + int ret; + ssize_t nb_fields = 0; + + switch (domain) { + case LTTNG_DOMAIN_UST: + nb_fields = ust_app_list_event_fields(fields); + if (nb_fields < 0) { + ret = LTTCOMM_UST_LIST_FAIL; + goto error; + } + break; + case LTTNG_DOMAIN_KERNEL: + default: /* fall-through */ + ret = LTTCOMM_UND; + goto error; + } + + return nb_fields; + +error: + /* Return negative value to differentiate return code */ + return -ret; +} + /* * Command LTTNG_START_TRACE processed by the client thread. */ @@ -3294,6 +3368,7 @@ static int process_client_msg(struct command_ctx *cmd_ctx) switch(cmd_ctx->lsm->cmd_type) { case LTTNG_LIST_SESSIONS: case LTTNG_LIST_TRACEPOINTS: + case LTTNG_LIST_TRACEPOINT_FIELDS: case LTTNG_LIST_DOMAINS: case LTTNG_LIST_CHANNELS: case LTTNG_LIST_EVENTS: @@ -3313,6 +3388,7 @@ static int process_client_msg(struct command_ctx *cmd_ctx) case LTTNG_CALIBRATE: case LTTNG_LIST_SESSIONS: case LTTNG_LIST_TRACEPOINTS: + case LTTNG_LIST_TRACEPOINT_FIELDS: need_tracing_session = 0; break; default: @@ -3361,6 +3437,12 @@ static int process_client_msg(struct command_ctx *cmd_ctx) } } + /* Consumer is in an ERROR state. Report back to client */ + if (uatomic_read(&kernel_consumerd_state) == CONSUMER_ERROR) { + ret = LTTCOMM_NO_KERNCONSUMERD; + goto error; + } + /* Need a session for kernel command */ if (need_tracing_session) { if (cmd_ctx->session->kernel_session == NULL) { @@ -3381,13 +3463,21 @@ static int process_client_msg(struct command_ctx *cmd_ctx) ret = LTTCOMM_KERN_CONSUMER_FAIL; goto error; } + uatomic_set(&kernel_consumerd_state, CONSUMER_STARTED); } else { pthread_mutex_unlock(&kconsumer_data.pid_mutex); } } + break; case LTTNG_DOMAIN_UST: { + /* Consumer is in an ERROR state. Report back to client */ + if (uatomic_read(&ust_consumerd_state) == CONSUMER_ERROR) { + ret = LTTCOMM_NO_USTCONSUMERD; + goto error; + } + if (need_tracing_session) { if (cmd_ctx->session->ust_session == NULL) { ret = create_ust_session(cmd_ctx->session, @@ -3411,6 +3501,7 @@ static int process_client_msg(struct command_ctx *cmd_ctx) } ust_consumerd64_fd = ustconsumer64_data.cmd_sock; + uatomic_set(&ust_consumerd_state, CONSUMER_STARTED); } else { pthread_mutex_unlock(&ustconsumer64_data.pid_mutex); } @@ -3425,7 +3516,9 @@ static int process_client_msg(struct command_ctx *cmd_ctx) ust_consumerd32_fd = -EINVAL; goto error; } + ust_consumerd32_fd = ustconsumer32_data.cmd_sock; + uatomic_set(&ust_consumerd_state, CONSUMER_STARTED); } else { pthread_mutex_unlock(&ustconsumer32_data.pid_mutex); } @@ -3437,6 +3530,25 @@ static int process_client_msg(struct command_ctx *cmd_ctx) } skip_domain: + /* Validate consumer daemon state when start/stop trace command */ + if (cmd_ctx->lsm->cmd_type == LTTNG_START_TRACE || + cmd_ctx->lsm->cmd_type == LTTNG_STOP_TRACE) { + switch (cmd_ctx->lsm->domain.type) { + case LTTNG_DOMAIN_UST: + if (uatomic_read(&ust_consumerd_state) != CONSUMER_STARTED) { + ret = LTTCOMM_NO_USTCONSUMERD; + goto error; + } + break; + case LTTNG_DOMAIN_KERNEL: + if (uatomic_read(&kernel_consumerd_state) != CONSUMER_STARTED) { + ret = LTTCOMM_NO_KERNCONSUMERD; + goto error; + } + break; + } + } + /* * Check that the UID or GID match that of the tracing session. * The root user can interact with all sessions. @@ -3533,6 +3645,37 @@ skip_domain: ret = LTTCOMM_OK; break; } + case LTTNG_LIST_TRACEPOINT_FIELDS: + { + struct lttng_event_field *fields; + ssize_t nb_fields; + + nb_fields = cmd_list_tracepoint_fields(cmd_ctx->lsm->domain.type, &fields); + if (nb_fields < 0) { + ret = -nb_fields; + goto error; + } + + /* + * Setup lttng message with payload size set to the event list size in + * bytes and then copy list into the llm payload. + */ + ret = setup_lttng_msg(cmd_ctx, sizeof(struct lttng_event_field) * nb_fields); + if (ret < 0) { + free(fields); + goto setup_error; + } + + /* Copy event list into message payload */ + memcpy(cmd_ctx->llm->payload, fields, + sizeof(struct lttng_event_field) * nb_fields); + + free(fields); + + ret = LTTCOMM_OK; + break; + } + case LTTNG_START_TRACE: { ret = cmd_start_trace(cmd_ctx->session); @@ -3587,7 +3730,7 @@ skip_domain: } case LTTNG_LIST_CHANNELS: { - size_t nb_chan; + int nb_chan; struct lttng_channel *channels; nb_chan = cmd_list_channels(cmd_ctx->lsm->domain.type, @@ -4117,13 +4260,15 @@ static int set_permissions(char *rundir) int ret; gid_t gid; - gid = allowed_group(); - if (gid < 0) { + ret = allowed_group(); + if (ret < 0) { WARN("No tracing group detected"); ret = 0; goto end; } + gid = ret; + /* Set lttng run dir */ ret = chown(rundir, 0, gid); if (ret < 0) { @@ -4402,11 +4547,6 @@ int main(int argc, char **argv) rcu_register_thread(); - /* Create thread quit pipe */ - if ((ret = init_thread_quit_pipe()) < 0) { - goto error; - } - setup_consumerd_path(); /* Parse arguments */ @@ -4417,11 +4557,31 @@ int main(int argc, char **argv) /* Daemonize */ if (opt_daemon) { + int i; + + /* + * fork + * child: setsid, close FD 0, 1, 2, chdir / + * parent: exit (if fork is successful) + */ ret = daemon(0, 0); if (ret < 0) { PERROR("daemon"); goto error; } + /* + * We are in the child. Make sure all other file + * descriptors are closed, in case we are called with + * more opened file descriptors than the standard ones. + */ + for (i = 3; i < sysconf(_SC_OPEN_MAX); i++) { + (void) close(i); + } + } + + /* Create thread quit pipe */ + if ((ret = init_thread_quit_pipe()) < 0) { + goto error; } /* Check if daemon is UID = 0 */ @@ -4504,6 +4664,10 @@ int main(int argc, char **argv) } } + /* Set consumer initial state */ + kernel_consumerd_state = CONSUMER_STOPPED; + ust_consumerd_state = CONSUMER_STOPPED; + DBG("Client socket path %s", client_unix_sock_path); DBG("Application socket path %s", apps_unix_sock_path); DBG("LTTng run directory path: %s", rundir);