src/bin/lttng-sessiond/lttng-sessiond.h

   1 /*
   2  * Copyright (C) 2011 David Goulet <david.goulet@polymtl.ca>
   3  * Copyright (C) 2013 Raphaël Beamonte <raphael.beamonte@gmail.com>
   4  *
   5  * SPDX-License-Identifier: GPL-2.0-only
   6  *
   7  */
   8
   9 #ifndef _LTT_SESSIOND_H
  10 #define _LTT_SESSIOND_H
  11
  12 #include <urcu.h>
  13 #include <urcu/wfcqueue.h>
  14
  15 #include <common/sessiond-comm/sessiond-comm.h>
  16 #include <common/payload.h>
  17 #include <common/compat/poll.h>
  18 #include <common/compat/socket.h>
  19 #include <common/uuid.h>
  20
  21 #include "session.h"
  22 #include "ust-app.h"
  23 #include "notification-thread.h"
  24 #include "sessiond-config.h"
  25
  26 /*
  27  * Consumer daemon state which is changed when spawning it, killing it or in
  28  * case of a fatal error.
  29  */
  30 enum consumerd_state {
  31         CONSUMER_STARTED = 1,
  32         CONSUMER_STOPPED = 2,
  33         CONSUMER_ERROR   = 3,
  34 };
  35
  36 /* Unique identifier of a session daemon instance. */
  37 extern lttng_uuid sessiond_uuid;
  38
  39 /*
  40  * This consumer daemon state is used to validate if a client command will be
  41  * able to reach the consumer. If not, the client is informed. For instance,
  42  * doing a "lttng start" when the consumer state is set to ERROR will return an
  43  * error to the client.
  44  *
  45  * The following example shows a possible race condition of this scheme:
  46  *
  47  * consumer thread error happens
  48  *                                    client cmd arrives
  49  *                                    client cmd checks state -> still OK
  50  * consumer thread exit, sets error
  51  *                                    client cmd try to talk to consumer
  52  *                                    ...
  53  *
  54  * However, since the consumer is a different daemon, we have no way of making
  55  * sure the command will reach it safely even with this state flag. This is why
  56  * we consider that up to the state validation during command processing, the
  57  * command is safe. After that, we can not guarantee the correctness of the
  58  * client request vis-a-vis the consumer.
  59  */
  60 extern enum consumerd_state ust_consumerd_state;
  61 extern enum consumerd_state kernel_consumerd_state;
  62
  63 extern const char default_home_dir[],
  64         default_tracing_group[],
  65         default_ust_sock_dir[],
  66         default_global_apps_pipe[];
  67
  68 /* Set in main.c at boot time of the daemon */
  69 extern struct lttng_kernel_tracer_version kernel_tracer_version;
  70 extern struct lttng_kernel_tracer_abi_version kernel_tracer_abi_version;
  71
  72 /* Notification thread handle. */
  73 extern struct notification_thread_handle *notification_thread_handle;
  74
  75 /*
  76  * This contains extra data needed for processing a command received by the
  77  * session daemon from the lttng client.
  78  */
  79 struct command_ctx {
  80         unsigned int lttng_msg_size;
  81         struct ltt_session *session;
  82         /* Input message */
  83         struct lttcomm_session_msg lsm;
  84         /* Reply content, starts with an lttcomm_lttng_msg header. */
  85         struct lttng_payload reply_payload;
  86         lttng_sock_cred creds;
  87 };
  88
  89 struct ust_command {
  90         int sock;
  91         struct ust_register_msg reg_msg;
  92         struct cds_wfcq_node node;
  93 };
  94
  95 /*
  96  * Queue used to enqueue UST registration request (ust_command) and synchronized
  97  * by a futex with a scheme N wakers / 1 waiters. See futex.c/.h
  98  */
  99 struct ust_cmd_queue {
 100         int32_t futex;
 101         struct cds_wfcq_head head;
 102         struct cds_wfcq_tail tail;
 103 };
 104
 105 /*
 106  * This is the wait queue containing wait nodes during the application
 107  * registration process.
 108  */
 109 struct ust_reg_wait_queue {
 110         unsigned long count;
 111         struct cds_list_head head;
 112 };
 113
 114 /*
 115  * Use by the dispatch registration to queue UST command socket to wait for the
 116  * notify socket.
 117  */
 118 struct ust_reg_wait_node {
 119         struct ust_app *app;
 120         struct cds_list_head head;
 121 };
 122
 123 /*
 124  * Used to notify that a hash table needs to be destroyed by dedicated
 125  * thread. Required by design because we don't want to move destroy
 126  * paths outside of large RCU read-side lock paths, and destroy cannot
 127  * be called by call_rcu thread, because it may hang (waiting for
 128  * call_rcu completion).
 129  */
 130 extern int ht_cleanup_pipe[2];
 131
 132 extern int kernel_poll_pipe[2];
 133
 134 /*
 135  * Populated when the daemon starts with the current page size of the system.
 136  * Set in main() with the current page size.
 137  */
 138 extern long page_size;
 139
 140 /* Application health monitoring */
 141 extern struct health_app *health_sessiond;
 142
 143 extern struct sessiond_config config;
 144
 145 extern int ust_consumerd64_fd, ust_consumerd32_fd;
 146
 147 /* Parent PID for --sig-parent option */
 148 extern pid_t ppid;
 149 /* Internal parent PID use with daemonize. */
 150 extern pid_t child_ppid;
 151
 152 /* Consumer daemon specific control data. */
 153 extern struct consumer_data ustconsumer32_data;
 154 extern struct consumer_data ustconsumer64_data;
 155 extern struct consumer_data kconsumer_data;
 156
 157 int sessiond_init_thread_quit_pipe(void);
 158 int sessiond_check_thread_quit_pipe(int fd, uint32_t events);
 159 int sessiond_wait_for_quit_pipe(int timeout_ms);
 160 int sessiond_notify_quit_pipe(void);
 161 void sessiond_close_quit_pipe(void);
 162
 163 int sessiond_set_thread_pollset(struct lttng_poll_event *events, size_t size);
 164 void sessiond_signal_parents(void);
 165
 166 void sessiond_set_client_thread_state(bool running);
 167 void sessiond_wait_client_thread_stopped(void);
 168
 169 void *thread_manage_consumer(void *data);
 170
 171 #endif /* _LTT_SESSIOND_H */