Fix: ambiguous ownership of kernel context by multiple channels
[lttng-tools.git] / src / bin / lttng-relayd / session.c
1 /*
2 * Copyright (C) 2013 - Julien Desfossez <jdesfossez@efficios.com>
3 * David Goulet <dgoulet@efficios.com>
4 * 2015 - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
5 *
6 * This program is free software; you can redistribute it and/or modify it
7 * under the terms of the GNU General Public License, version 2 only, as
8 * published by the Free Software Foundation.
9 *
10 * This program is distributed in the hope that it will be useful, but WITHOUT
11 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
12 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
13 * more details.
14 *
15 * You should have received a copy of the GNU General Public License along with
16 * this program; if not, write to the Free Software Foundation, Inc., 51
17 * Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
18 */
19
20 #define _LGPL_SOURCE
21 #include <common/common.h>
22 #include <urcu/rculist.h>
23
24 #include "lttng-relayd.h"
25 #include "ctf-trace.h"
26 #include "session.h"
27 #include "stream.h"
28
29 /* Global session id used in the session creation. */
30 static uint64_t last_relay_session_id;
31 static pthread_mutex_t last_relay_session_id_lock = PTHREAD_MUTEX_INITIALIZER;
32
33 /*
34 * Create a new session by assigning a new session ID.
35 *
36 * Return allocated session or else NULL.
37 */
38 struct relay_session *session_create(const char *session_name,
39 const char *hostname, uint32_t live_timer,
40 bool snapshot, uint32_t major, uint32_t minor)
41 {
42 struct relay_session *session;
43
44 session = zmalloc(sizeof(*session));
45 if (!session) {
46 PERROR("relay session zmalloc");
47 goto error;
48 }
49 if (lttng_strncpy(session->session_name, session_name,
50 sizeof(session->session_name))) {
51 goto error;
52 }
53 if (lttng_strncpy(session->hostname, hostname,
54 sizeof(session->hostname))) {
55 goto error;
56 }
57 session->ctf_traces_ht = lttng_ht_new(0, LTTNG_HT_TYPE_STRING);
58 if (!session->ctf_traces_ht) {
59 goto error;
60 }
61
62 pthread_mutex_lock(&last_relay_session_id_lock);
63 session->id = ++last_relay_session_id;
64 pthread_mutex_unlock(&last_relay_session_id_lock);
65
66 session->major = major;
67 session->minor = minor;
68 lttng_ht_node_init_u64(&session->session_n, session->id);
69 urcu_ref_init(&session->ref);
70 CDS_INIT_LIST_HEAD(&session->recv_list);
71 pthread_mutex_init(&session->lock, NULL);
72 pthread_mutex_init(&session->recv_list_lock, NULL);
73
74 session->live_timer = live_timer;
75 session->snapshot = snapshot;
76
77 lttng_ht_add_unique_u64(sessions_ht, &session->session_n);
78 return session;
79
80 error:
81 free(session);
82 return NULL;
83 }
84
85 /* Should be called with RCU read-side lock held. */
86 bool session_get(struct relay_session *session)
87 {
88 return urcu_ref_get_unless_zero(&session->ref);
89 }
90
91 /*
92 * Lookup a session within the session hash table using the session id
93 * as key. A session reference is taken when a session is returned.
94 * session_put() must be called on that session.
95 *
96 * Return session or NULL if not found.
97 */
98 struct relay_session *session_get_by_id(uint64_t id)
99 {
100 struct relay_session *session = NULL;
101 struct lttng_ht_node_u64 *node;
102 struct lttng_ht_iter iter;
103
104 rcu_read_lock();
105 lttng_ht_lookup(sessions_ht, &id, &iter);
106 node = lttng_ht_iter_get_node_u64(&iter);
107 if (!node) {
108 DBG("Session find by ID %" PRIu64 " id NOT found", id);
109 goto end;
110 }
111 session = caa_container_of(node, struct relay_session, session_n);
112 DBG("Session find by ID %" PRIu64 " id found", id);
113 if (!session_get(session)) {
114 session = NULL;
115 }
116 end:
117 rcu_read_unlock();
118 return session;
119 }
120
121 static void rcu_destroy_session(struct rcu_head *rcu_head)
122 {
123 struct relay_session *session =
124 caa_container_of(rcu_head, struct relay_session,
125 rcu_node);
126 /*
127 * Since each trace has a reference on the session, it means
128 * that if we are at the point where we teardown the session, no
129 * trace belonging to that session exist at this point.
130 * Calling lttng_ht_destroy in call_rcu worker thread so we
131 * don't hold the RCU read-side lock while calling it.
132 */
133 lttng_ht_destroy(session->ctf_traces_ht);
134 free(session);
135 }
136
137 /*
138 * Delete session from the given hash table.
139 *
140 * Return lttng ht del error code being 0 on success and 1 on failure.
141 */
142 static int session_delete(struct relay_session *session)
143 {
144 struct lttng_ht_iter iter;
145
146 iter.iter.node = &session->session_n.node;
147 return lttng_ht_del(sessions_ht, &iter);
148 }
149
150
151 static void destroy_session(struct relay_session *session)
152 {
153 int ret;
154
155 ret = session_delete(session);
156 assert(!ret);
157 call_rcu(&session->rcu_node, rcu_destroy_session);
158 }
159
160 void session_release(struct urcu_ref *ref)
161 {
162 struct relay_session *session =
163 caa_container_of(ref, struct relay_session, ref);
164
165 destroy_session(session);
166 }
167
168 void session_put(struct relay_session *session)
169 {
170 rcu_read_lock();
171 urcu_ref_put(&session->ref, session_release);
172 rcu_read_unlock();
173 }
174
175 int session_close(struct relay_session *session)
176 {
177 int ret = 0;
178 struct ctf_trace *trace;
179 struct lttng_ht_iter iter;
180 struct relay_stream *stream;
181
182 pthread_mutex_lock(&session->lock);
183 DBG("closing session %" PRIu64 ": is conn already closed %d",
184 session->id, session->connection_closed);
185 if (session->connection_closed) {
186 ret = -1;
187 goto unlock;
188 }
189 session->connection_closed = true;
190 unlock:
191 pthread_mutex_unlock(&session->lock);
192 if (ret) {
193 return ret;
194 }
195
196 rcu_read_lock();
197 cds_lfht_for_each_entry(session->ctf_traces_ht->ht,
198 &iter.iter, trace, node.node) {
199 ret = ctf_trace_close(trace);
200 if (ret) {
201 goto rcu_unlock;
202 }
203 }
204 cds_list_for_each_entry_rcu(stream, &session->recv_list,
205 recv_node) {
206 /* Close streams which have not been published yet. */
207 try_stream_close(stream);
208 }
209 rcu_unlock:
210 rcu_read_unlock();
211 if (ret) {
212 return ret;
213 }
214 /* Put self-reference from create. */
215 session_put(session);
216 return ret;
217 }
218
219 int session_abort(struct relay_session *session)
220 {
221 int ret = 0;
222
223 if (!session) {
224 return 0;
225 }
226
227 pthread_mutex_lock(&session->lock);
228 DBG("aborting session %" PRIu64, session->id);
229 if (session->aborted) {
230 ERR("session %" PRIu64 " is already aborted", session->id);
231 ret = -1;
232 goto unlock;
233 }
234 session->aborted = true;
235 unlock:
236 pthread_mutex_unlock(&session->lock);
237 return ret;
238 }
239
240 void print_sessions(void)
241 {
242 struct lttng_ht_iter iter;
243 struct relay_session *session;
244
245 if (!sessions_ht) {
246 return;
247 }
248
249 rcu_read_lock();
250 cds_lfht_for_each_entry(sessions_ht->ht, &iter.iter, session,
251 session_n.node) {
252 if (!session_get(session)) {
253 continue;
254 }
255 DBG("session %p refcount %ld session %" PRIu64,
256 session,
257 session->ref.refcount,
258 session->id);
259 session_put(session);
260 }
261 rcu_read_unlock();
262 }
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