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

   1 /*
   2  * Copyright (C) 2011 EfficiOS Inc.
   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 the_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 the_ust_consumerd_state;
  61 extern enum consumerd_state the_kernel_consumerd_state;
  62
  63 /* Set in main.c at boot time of the daemon */
  64 extern struct lttng_kernel_abi_tracer_version the_kernel_tracer_version;
  65 extern struct lttng_kernel_abi_tracer_abi_version the_kernel_tracer_abi_version;
  66
  67 /* Notification thread handle. */
  68 extern struct notification_thread_handle *the_notification_thread_handle;
  69
  70 /*
  71  * This contains extra data needed for processing a command received by the
  72  * session daemon from the lttng client.
  73  */
  74 struct command_ctx {
  75         unsigned int lttng_msg_size;
  76         struct ltt_session *session;
  77         /* Input message */
  78         struct lttcomm_session_msg lsm;
  79         /* Reply content, starts with an lttcomm_lttng_msg header. */
  80         struct lttng_payload reply_payload;
  81         lttng_sock_cred creds;
  82 };
  83
  84 struct ust_command {
  85         int sock;
  86         struct ust_register_msg reg_msg;
  87         struct cds_wfcq_node node;
  88 };
  89
  90 /*
  91  * Queue used to enqueue UST registration request (ust_command) and synchronized
  92  * by a futex with a scheme N wakers / 1 waiters. See futex.c/.h
  93  */
  94 struct ust_cmd_queue {
  95         int32_t futex;
  96         struct cds_wfcq_head head;
  97         struct cds_wfcq_tail tail;
  98 };
  99
 100 /*
 101  * This is the wait queue containing wait nodes during the application
 102  * registration process.
 103  */
 104 struct ust_reg_wait_queue {
 105         unsigned long count;
 106         struct cds_list_head head;
 107 };
 108
 109 /*
 110  * Use by the dispatch registration to queue UST command socket to wait for the
 111  * notify socket.
 112  */
 113 struct ust_reg_wait_node {
 114         struct ust_app *app;
 115         struct cds_list_head head;
 116 };
 117
 118 /*
 119  * Used to notify that a hash table needs to be destroyed by dedicated
 120  * thread. Required by design because we don't want to move destroy
 121  * paths outside of large RCU read-side lock paths, and destroy cannot
 122  * be called by call_rcu thread, because it may hang (waiting for
 123  * call_rcu completion).
 124  */
 125 extern int the_ht_cleanup_pipe[2];
 126
 127 extern int the_kernel_poll_pipe[2];
 128
 129 /*
 130  * Populated when the daemon starts with the current page size of the system.
 131  * Set in main() with the current page size.
 132  */
 133 extern long the_page_size;
 134
 135 /* Application health monitoring */
 136 extern struct health_app *the_health_sessiond;
 137
 138 extern struct sessiond_config the_config;
 139
 140 extern int the_ust_consumerd64_fd, the_ust_consumerd32_fd;
 141
 142 /* Parent PID for --sig-parent option */
 143 extern pid_t the_ppid;
 144 /* Internal parent PID use with daemonize. */
 145 extern pid_t the_child_ppid;
 146
 147 /* Consumer daemon specific control data. */
 148 extern struct consumer_data the_ustconsumer32_data;
 149 extern struct consumer_data the_ustconsumer64_data;
 150 extern struct consumer_data the_kconsumer_data;
 151
 152 int sessiond_init_thread_quit_pipe(void);
 153 int sessiond_check_thread_quit_pipe(int fd, uint32_t events);
 154 int sessiond_wait_for_quit_pipe(int timeout_ms);
 155 int sessiond_notify_quit_pipe(void);
 156 void sessiond_close_quit_pipe(void);
 157
 158 int sessiond_set_thread_pollset(struct lttng_poll_event *events, size_t size);
 159 void sessiond_signal_parents(void);
 160
 161 void sessiond_set_client_thread_state(bool running);
 162 void sessiond_wait_client_thread_stopped(void);
 163
 164 void *thread_manage_consumer(void *data);
 165
 166 #endif /* _LTT_SESSIOND_H */