Acquire a reference to a session when a timer is active

[lttng-tools.git] / src / bin / lttng-sessiond / timer.c

diff --git a/src/bin/lttng-sessiond/timer.c b/src/bin/lttng-sessiond/timer.c
index 06d1d4a9803213850366699992729f7a26f0e3dd..4bff7bd76cea0497c311f12b7026b0142761710c 100644 (file)
--- a/src/bin/lttng-sessiond/timer.c
+++ b/src/bin/lttng-sessiond/timer.c
@@ -149,7 +149,7 @@ void timer_signal_thread_qs(unsigned int signr)
  * a positive value if no timer was created (not an error).
  */
 static
-int timer_start(timer_t *timer_id, uint64_t session_id,
+int timer_start(timer_t *timer_id, struct ltt_session *session,
                unsigned int timer_interval_us, int signal, bool one_shot)
 {
        int ret = 0, delete_ret;
@@ -158,7 +158,7 @@ int timer_start(timer_t *timer_id, uint64_t session_id,
 
        sev.sigev_notify = SIGEV_SIGNAL;
        sev.sigev_signo = signal;
-       sev.sigev_value.sival_ptr = UINT_TO_PTR(session_id);
+       sev.sigev_value.sival_ptr = session;
        ret = timer_create(CLOCK_MONOTONIC, &sev, timer_id);
        if (ret == -1) {
                PERROR("timer_create");
@@ -214,6 +214,10 @@ int timer_session_rotation_pending_check_start(struct ltt_session *session,
 {
        int ret;
 
+       if (!session_get(session)) {
+               ret = -1;
+               goto end;
+       }
        DBG("Enabling session rotation pending check timer on session %" PRIu64,
                        session->id);
        /*
@@ -226,13 +230,13 @@ int timer_session_rotation_pending_check_start(struct ltt_session *session,
         * no need to go through the whole signal teardown scheme everytime.
         */
        ret = timer_start(&session->rotation_pending_check_timer,
-                       session->id, interval_us,
+                       session, interval_us,
                        LTTNG_SESSIOND_SIG_PENDING_ROTATION_CHECK,
                        /* one-shot */ true);
        if (ret == 0) {
                session->rotation_pending_check_timer_enabled = true;
        }
-
+end:
        return ret;
 }
 
@@ -253,6 +257,10 @@ int timer_session_rotation_pending_check_stop(struct ltt_session *session)
                ERR("Failed to stop rotate_pending_check timer");
        } else {
                session->rotation_pending_check_timer_enabled = false;
+               /*
+                * The timer's reference to the session can be released safely.
+                */
+               session_put(session);
        }
        return ret;
 }
@@ -265,9 +273,13 @@ int timer_session_rotation_schedule_timer_start(struct ltt_session *session,
 {
        int ret;
 
+       if (!session_get(session)) {
+               ret = -1;
+               goto end;
+       }
        DBG("Enabling scheduled rotation timer on session \"%s\" (%ui µs)", session->name,
                        interval_us);
-       ret = timer_start(&session->rotation_schedule_timer, session->id,
+       ret = timer_start(&session->rotation_schedule_timer, session,
                        interval_us, LTTNG_SESSIOND_SIG_SCHEDULED_ROTATION,
                        /* one-shot */ false);
        if (ret < 0) {
@@ -301,6 +313,8 @@ int timer_session_rotation_schedule_timer_stop(struct ltt_session *session)
        }
 
        session->rotation_schedule_timer_enabled = false;
+       /* The timer's reference to the session can be released safely. */
+       session_put(session);
        ret = 0;
 end:
        return ret;
@@ -370,13 +384,25 @@ void *timer_thread_func(void *data)
                } else if (signr == LTTNG_SESSIOND_SIG_EXIT) {
                        goto end;
                } else if (signr == LTTNG_SESSIOND_SIG_PENDING_ROTATION_CHECK) {
+                       struct ltt_session *session =
+                                       (struct ltt_session *) info.si_value.sival_ptr;
+
                        rotation_thread_enqueue_job(ctx->rotation_thread_job_queue,
                                        ROTATION_THREAD_JOB_TYPE_CHECK_PENDING_ROTATION,
-                                       /* session_id */ PTR_TO_UINT(info.si_value.sival_ptr));
+                                       session);
+                       session_lock_list();
+                       session_put(session);
+                       session_unlock_list();
                } else if (signr == LTTNG_SESSIOND_SIG_SCHEDULED_ROTATION) {
                        rotation_thread_enqueue_job(ctx->rotation_thread_job_queue,
                                        ROTATION_THREAD_JOB_TYPE_SCHEDULED_ROTATION,
-                                       /* session_id */ PTR_TO_UINT(info.si_value.sival_ptr));
+                                       (struct ltt_session *) info.si_value.sival_ptr);
+                       /*
+                        * The scheduled periodic rotation timer is not in
+                        * "one-shot" mode. The reference to the session is not
+                        * released since the timer is still enabled and can
+                        * still fire.
+                        */
                } else {
                        ERR("Unexpected signal %d\n", info.si_signo);
                }