Fix: add missing rcu_barrier at end of sessiond main
[lttng-tools.git] / src / bin / lttng-sessiond / main.c
index 91dd047e763d76968044cc5e038f93215d539a7f..43f750a820fbf7c087ca9e5df4d275b3cc065cc9 100644 (file)
@@ -73,6 +73,7 @@
 #include "save.h"
 #include "load-session-thread.h"
 #include "syscall.h"
+#include "agent.h"
 
 #define CONSUMERD_FILE "lttng-consumerd"
 
@@ -305,6 +306,9 @@ const char * const config_section_name = "sessiond";
 /* Load session thread information to operate. */
 struct load_session_thread_data *load_info;
 
+/* Global hash tables */
+struct lttng_ht *agent_apps_ht_by_sock = NULL;
+
 /*
  * Whether sessiond is ready for commands/health check requests.
  * NR_LTTNG_SESSIOND_READY must match the number of calls to
@@ -1212,6 +1216,9 @@ static void *thread_manage_consumer(void *data)
 
        DBG("[thread] Manage consumer started");
 
+       rcu_register_thread();
+       rcu_thread_online();
+
        health_register(health_sessiond, HEALTH_SESSIOND_TYPE_CONSUMER);
 
        health_code_update();
@@ -1510,6 +1517,9 @@ error_poll:
        health_unregister(health_sessiond);
        DBG("consumer thread cleanup completed");
 
+       rcu_thread_offline();
+       rcu_unregister_thread();
+
        return NULL;
 }
 
@@ -2021,6 +2031,22 @@ error:
                free(wait_node);
        }
 
+       /* Empty command queue. */
+       for (;;) {
+               /* Dequeue command for registration */
+               node = cds_wfcq_dequeue_blocking(&ust_cmd_queue.head, &ust_cmd_queue.tail);
+               if (node == NULL) {
+                       break;
+               }
+               ust_cmd = caa_container_of(node, struct ust_command, node);
+               ret = close(ust_cmd->sock);
+               if (ret < 0) {
+                       PERROR("close ust sock exit dispatch %d", ust_cmd->sock);
+               }
+               lttng_fd_put(LTTNG_FD_APPS, 1);
+               free(ust_cmd);
+       }
+
 error_testpoint:
        DBG("Dispatch thread dying");
        if (err) {
@@ -2153,6 +2179,10 @@ static void *thread_registration_apps(void *data)
                                        ust_cmd = zmalloc(sizeof(struct ust_command));
                                        if (ust_cmd == NULL) {
                                                PERROR("ust command zmalloc");
+                                               ret = close(sock);
+                                               if (ret) {
+                                                       PERROR("close");
+                                               }
                                                goto error;
                                        }
 
@@ -2709,7 +2739,7 @@ static int copy_session_consumer(int domain, struct ltt_session *session)
                 * domain.
                 */
                if (session->kernel_session->consumer) {
-                       consumer_destroy_output(session->kernel_session->consumer);
+                       consumer_output_put(session->kernel_session->consumer);
                }
                session->kernel_session->consumer =
                        consumer_copy_output(session->consumer);
@@ -2723,7 +2753,7 @@ static int copy_session_consumer(int domain, struct ltt_session *session)
        case LTTNG_DOMAIN_UST:
                DBG3("Copying tracing session consumer output in UST session");
                if (session->ust_session->consumer) {
-                       consumer_destroy_output(session->ust_session->consumer);
+                       consumer_output_put(session->ust_session->consumer);
                }
                session->ust_session->consumer =
                        consumer_copy_output(session->consumer);
@@ -2843,7 +2873,7 @@ static int create_kernel_session(struct ltt_session *session)
                                session->kernel_session->consumer->dst.trace_path,
                                S_IRWXU | S_IRWXG, session->uid, session->gid);
                if (ret < 0) {
-                       if (ret != -EEXIST) {
+                       if (errno != EEXIST) {
                                ERR("Trace directory creation error");
                                goto error;
                        }
@@ -3263,8 +3293,34 @@ skip_domain:
        }
        case LTTNG_DISABLE_EVENT:
        {
+
+               /*
+                * FIXME: handle filter; for now we just receive the filter's
+                * bytecode along with the filter expression which are sent by
+                * liblttng-ctl and discard them.
+                *
+                * This fixes an issue where the client may block while sending
+                * the filter payload and encounter an error because the session
+                * daemon closes the socket without ever handling this data.
+                */
+               size_t count = cmd_ctx->lsm->u.disable.expression_len +
+                       cmd_ctx->lsm->u.disable.bytecode_len;
+
+               if (count) {
+                       char data[LTTNG_FILTER_MAX_LEN];
+
+                       DBG("Discarding disable event command payload of size %zu", count);
+                       while (count) {
+                               ret = lttcomm_recv_unix_sock(sock, data,
+                                       count > sizeof(data) ? sizeof(data) : count);
+                               if (ret < 0) {
+                                       goto error;
+                               }
+
+                               count -= (size_t) ret;
+                       }
+               }
                /* FIXME: passing packed structure to non-packed pointer */
-               /* TODO: handle filter */
                ret = cmd_disable_event(cmd_ctx->session, cmd_ctx->lsm->domain.type,
                                cmd_ctx->lsm->u.disable.channel_name,
                                &cmd_ctx->lsm->u.disable.event);
@@ -3762,7 +3818,35 @@ skip_domain:
        }
        case LTTNG_DATA_PENDING:
        {
-               ret = cmd_data_pending(cmd_ctx->session);
+               int pending_ret;
+
+               /* 1 byte to return whether or not data is pending */
+               ret = setup_lttng_msg(cmd_ctx, 1);
+               if (ret < 0) {
+                       goto setup_error;
+               }
+
+               pending_ret = cmd_data_pending(cmd_ctx->session);
+               /*
+                * FIXME
+                *
+                * This function may returns 0 or 1 to indicate whether or not
+                * there is data pending. In case of error, it should return an
+                * LTTNG_ERR code. However, some code paths may still return
+                * a nondescript error code, which we handle by returning an
+                * "unknown" error.
+                */
+               if (pending_ret == 0 || pending_ret == 1) {
+                       ret = LTTNG_OK;
+               } else if (pending_ret < 0) {
+                       ret = LTTNG_ERR_UNK;
+                       goto setup_error;
+               } else {
+                       ret = pending_ret;
+                       goto setup_error;
+               }
+
+               *cmd_ctx->llm->payload = (uint8_t) pending_ret;
                break;
        }
        case LTTNG_SNAPSHOT_ADD_OUTPUT:
@@ -4329,9 +4413,10 @@ static void *thread_manage_clients(void *data)
 
                health_code_update();
 
-               DBG("Sending response (size: %d, retcode: %s)",
+               DBG("Sending response (size: %d, retcode: %s (%d))",
                                cmd_ctx->lttng_msg_size,
-                               lttng_strerror(-cmd_ctx->llm->ret_code));
+                               lttng_strerror(-cmd_ctx->llm->ret_code),
+                               cmd_ctx->llm->ret_code);
                ret = send_unix_sock(sock, cmd_ctx->llm, cmd_ctx->lttng_msg_size);
                if (ret < 0) {
                        ERR("Failed to send data back to client");
@@ -5904,6 +5989,10 @@ exit_apps:
        }
 exit_reg_apps:
 
+       /*
+        * Join dispatch thread after joining reg_apps_thread to ensure
+        * we don't leak applications in the queue.
+        */
        ret = pthread_join(dispatch_thread, &status);
        if (ret) {
                errno = ret;
@@ -5969,6 +6058,9 @@ exit_options:
        sessiond_cleanup_options();
 
 exit_set_signal_handler:
+       /* Ensure all prior call_rcu are done. */
+       rcu_barrier();
+
        if (!retval) {
                exit(EXIT_SUCCESS);
        } else {
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