+ return event;
+}
+
+/* Only used for tracepoints for now. */
+static
+void register_event(struct lttng_event *event)
+{
+ const struct lttng_event_desc *desc;
+ int ret = -EINVAL;
+
+ if (event->registered)
+ return;
+
+ desc = event->desc;
+ switch (event->instrumentation) {
+ case LTTNG_KERNEL_TRACEPOINT:
+ ret = lttng_wrapper_tracepoint_probe_register(desc->kname,
+ desc->probe_callback,
+ event);
+ break;
+ case LTTNG_KERNEL_SYSCALL:
+ ret = lttng_syscall_filter_enable(event->chan,
+ desc->name);
+ break;
+ case LTTNG_KERNEL_KPROBE:
+ case LTTNG_KERNEL_KRETPROBE:
+ case LTTNG_KERNEL_FUNCTION:
+ case LTTNG_KERNEL_NOOP:
+ ret = 0;
+ break;
+ default:
+ WARN_ON_ONCE(1);
+ }
+ if (!ret)
+ event->registered = 1;
+}
+
+/*
+ * Only used internally at session destruction.
+ */
+int _lttng_event_unregister(struct lttng_event *event)
+{
+ const struct lttng_event_desc *desc;
+ int ret = -EINVAL;
+
+ if (!event->registered)
+ return 0;
+
+ desc = event->desc;
+ switch (event->instrumentation) {
+ case LTTNG_KERNEL_TRACEPOINT:
+ ret = lttng_wrapper_tracepoint_probe_unregister(event->desc->kname,
+ event->desc->probe_callback,
+ event);
+ break;
+ case LTTNG_KERNEL_KPROBE:
+ lttng_kprobes_unregister(event);
+ ret = 0;
+ break;
+ case LTTNG_KERNEL_KRETPROBE:
+ lttng_kretprobes_unregister(event);
+ ret = 0;
+ break;
+ case LTTNG_KERNEL_FUNCTION:
+ lttng_ftrace_unregister(event);
+ ret = 0;
+ break;
+ case LTTNG_KERNEL_SYSCALL:
+ ret = lttng_syscall_filter_disable(event->chan,
+ desc->name);
+ break;
+ case LTTNG_KERNEL_NOOP:
+ ret = 0;
+ break;
+ default:
+ WARN_ON_ONCE(1);
+ }
+ if (!ret)
+ event->registered = 0;
+ return ret;
+}
+
+/*
+ * Only used internally at session destruction.
+ */
+static
+void _lttng_event_destroy(struct lttng_event *event)
+{
+ switch (event->instrumentation) {
+ case LTTNG_KERNEL_TRACEPOINT:
+ lttng_event_put(event->desc);
+ break;
+ case LTTNG_KERNEL_KPROBE:
+ module_put(event->desc->owner);
+ lttng_kprobes_destroy_private(event);
+ break;
+ case LTTNG_KERNEL_KRETPROBE:
+ module_put(event->desc->owner);
+ lttng_kretprobes_destroy_private(event);
+ break;
+ case LTTNG_KERNEL_FUNCTION:
+ module_put(event->desc->owner);
+ lttng_ftrace_destroy_private(event);
+ break;
+ case LTTNG_KERNEL_NOOP:
+ case LTTNG_KERNEL_SYSCALL:
+ break;
+ default:
+ WARN_ON_ONCE(1);
+ }
+ list_del(&event->list);
+ lttng_destroy_context(event->ctx);
+ kmem_cache_free(event_cache, event);
+}
+
+int lttng_session_track_pid(struct lttng_session *session, int pid)
+{
+ int ret;
+
+ if (pid < -1)
+ return -EINVAL;
+ mutex_lock(&sessions_mutex);
+ if (pid == -1) {
+ /* track all pids: destroy tracker. */
+ if (session->pid_tracker) {
+ struct lttng_pid_tracker *lpf;
+
+ lpf = session->pid_tracker;
+ rcu_assign_pointer(session->pid_tracker, NULL);
+ synchronize_trace();
+ lttng_pid_tracker_destroy(lpf);
+ }
+ ret = 0;
+ } else {
+ if (!session->pid_tracker) {
+ struct lttng_pid_tracker *lpf;
+
+ lpf = lttng_pid_tracker_create();
+ if (!lpf) {
+ ret = -ENOMEM;
+ goto unlock;
+ }
+ ret = lttng_pid_tracker_add(lpf, pid);
+ rcu_assign_pointer(session->pid_tracker, lpf);
+ } else {
+ ret = lttng_pid_tracker_add(session->pid_tracker, pid);
+ }
+ }
+unlock:
+ mutex_unlock(&sessions_mutex);
+ return ret;
+}
+
+int lttng_session_untrack_pid(struct lttng_session *session, int pid)
+{
+ int ret;
+
+ if (pid < -1)
+ return -EINVAL;
+ mutex_lock(&sessions_mutex);
+ if (pid == -1) {
+ /* untrack all pids: replace by empty tracker. */
+ struct lttng_pid_tracker *old_lpf = session->pid_tracker;
+ struct lttng_pid_tracker *lpf;
+
+ lpf = lttng_pid_tracker_create();
+ if (!lpf) {
+ ret = -ENOMEM;
+ goto unlock;
+ }
+ rcu_assign_pointer(session->pid_tracker, lpf);
+ synchronize_trace();
+ if (old_lpf)
+ lttng_pid_tracker_destroy(old_lpf);
+ ret = 0;
+ } else {
+ if (!session->pid_tracker) {
+ ret = -ENOENT;
+ goto unlock;
+ }
+ ret = lttng_pid_tracker_del(session->pid_tracker, pid);
+ }
+unlock:
+ mutex_unlock(&sessions_mutex);
+ return ret;
+}
+
+static
+void *pid_list_start(struct seq_file *m, loff_t *pos)
+{
+ struct lttng_session *session = m->private;
+ struct lttng_pid_tracker *lpf;
+ struct lttng_pid_hash_node *e;
+ int iter = 0, i;
+
+ mutex_lock(&sessions_mutex);
+ lpf = session->pid_tracker;
+ if (lpf) {
+ for (i = 0; i < LTTNG_PID_TABLE_SIZE; i++) {
+ struct hlist_head *head = &lpf->pid_hash[i];
+
+ lttng_hlist_for_each_entry(e, head, hlist) {
+ if (iter++ >= *pos)
+ return e;
+ }
+ }
+ } else {
+ /* PID tracker disabled. */
+ if (iter >= *pos && iter == 0) {
+ return session; /* empty tracker */
+ }
+ iter++;
+ }
+ /* End of list */
+ return NULL;
+}
+
+/* Called with sessions_mutex held. */
+static
+void *pid_list_next(struct seq_file *m, void *p, loff_t *ppos)
+{
+ struct lttng_session *session = m->private;
+ struct lttng_pid_tracker *lpf;
+ struct lttng_pid_hash_node *e;
+ int iter = 0, i;
+
+ (*ppos)++;
+ lpf = session->pid_tracker;
+ if (lpf) {
+ for (i = 0; i < LTTNG_PID_TABLE_SIZE; i++) {
+ struct hlist_head *head = &lpf->pid_hash[i];
+
+ lttng_hlist_for_each_entry(e, head, hlist) {
+ if (iter++ >= *ppos)
+ return e;
+ }
+ }
+ } else {
+ /* PID tracker disabled. */
+ if (iter >= *ppos && iter == 0)
+ return session; /* empty tracker */
+ iter++;
+ }
+
+ /* End of list */
+ return NULL;
+}
+
+static
+void pid_list_stop(struct seq_file *m, void *p)
+{
+ mutex_unlock(&sessions_mutex);
+}
+
+static
+int pid_list_show(struct seq_file *m, void *p)
+{
+ int pid;
+
+ if (p == m->private) {
+ /* Tracker disabled. */
+ pid = -1;
+ } else {
+ const struct lttng_pid_hash_node *e = p;
+
+ pid = lttng_pid_tracker_get_node_pid(e);
+ }
+ seq_printf(m, "process { pid = %d; };\n", pid);
+ return 0;
+}
+
+static
+const struct seq_operations lttng_tracker_pids_list_seq_ops = {
+ .start = pid_list_start,
+ .next = pid_list_next,
+ .stop = pid_list_stop,
+ .show = pid_list_show,
+};
+
+static
+int lttng_tracker_pids_list_open(struct inode *inode, struct file *file)
+{
+ return seq_open(file, <tng_tracker_pids_list_seq_ops);
+}
+
+static
+int lttng_tracker_pids_list_release(struct inode *inode, struct file *file)
+{
+ struct seq_file *m = file->private_data;
+ struct lttng_session *session = m->private;
+ int ret;
+
+ WARN_ON_ONCE(!session);
+ ret = seq_release(inode, file);
+ if (!ret && session)
+ fput(session->file);
+ return ret;
+}
+
+const struct file_operations lttng_tracker_pids_list_fops = {
+ .owner = THIS_MODULE,
+ .open = lttng_tracker_pids_list_open,
+ .read = seq_read,
+ .llseek = seq_lseek,
+ .release = lttng_tracker_pids_list_release,
+};
+
+int lttng_session_list_tracker_pids(struct lttng_session *session)
+{
+ struct file *tracker_pids_list_file;
+ struct seq_file *m;
+ int file_fd, ret;
+
+ file_fd = lttng_get_unused_fd();
+ if (file_fd < 0) {
+ ret = file_fd;
+ goto fd_error;
+ }
+
+ tracker_pids_list_file = anon_inode_getfile("[lttng_tracker_pids_list]",
+ <tng_tracker_pids_list_fops,
+ NULL, O_RDWR);
+ if (IS_ERR(tracker_pids_list_file)) {
+ ret = PTR_ERR(tracker_pids_list_file);
+ goto file_error;
+ }
+ if (atomic_long_add_unless(&session->file->f_count,
+ 1, INT_MAX) == INT_MAX) {
+ goto refcount_error;
+ }
+ ret = lttng_tracker_pids_list_fops.open(NULL, tracker_pids_list_file);
+ if (ret < 0)
+ goto open_error;
+ m = tracker_pids_list_file->private_data;
+ m->private = session;
+ fd_install(file_fd, tracker_pids_list_file);
+
+ return file_fd;
+
+open_error:
+ atomic_long_dec(&session->file->f_count);
+refcount_error:
+ fput(tracker_pids_list_file);
+file_error:
+ put_unused_fd(file_fd);
+fd_error:
+ return ret;
+}
+
+/*
+ * Enabler management.
+ */
+static
+int lttng_match_enabler_wildcard(const char *desc_name,
+ const char *name)
+{
+ /* Compare excluding final '*' */
+ if (strncmp(desc_name, name, strlen(name) - 1))
+ return 0;
+ return 1;
+}
+
+static
+int lttng_match_enabler_name(const char *desc_name,
+ const char *name)
+{
+ if (strcmp(desc_name, name))
+ return 0;
+ return 1;
+}
+
+static
+int lttng_desc_match_enabler(const struct lttng_event_desc *desc,
+ struct lttng_enabler *enabler)
+{
+ const char *desc_name, *enabler_name;
+
+ enabler_name = enabler->event_param.name;
+ switch (enabler->event_param.instrumentation) {
+ case LTTNG_KERNEL_TRACEPOINT:
+ desc_name = desc->name;
+ break;
+ case LTTNG_KERNEL_SYSCALL:
+ desc_name = desc->name;
+ if (!strncmp(desc_name, "compat_", strlen("compat_")))
+ desc_name += strlen("compat_");
+ if (!strncmp(desc_name, "syscall_exit_",
+ strlen("syscall_exit_"))) {
+ desc_name += strlen("syscall_exit_");
+ } else if (!strncmp(desc_name, "syscall_entry_",
+ strlen("syscall_entry_"))) {
+ desc_name += strlen("syscall_entry_");
+ } else {
+ WARN_ON_ONCE(1);
+ return -EINVAL;
+ }
+ break;
+ default:
+ WARN_ON_ONCE(1);
+ return -EINVAL;
+ }
+ switch (enabler->type) {
+ case LTTNG_ENABLER_WILDCARD:
+ return lttng_match_enabler_wildcard(desc_name, enabler_name);
+ case LTTNG_ENABLER_NAME:
+ return lttng_match_enabler_name(desc_name, enabler_name);
+ default:
+ return -EINVAL;
+ }
+}
+
+static
+int lttng_event_match_enabler(struct lttng_event *event,
+ struct lttng_enabler *enabler)
+{
+ if (enabler->event_param.instrumentation != event->instrumentation)
+ return 0;
+ if (lttng_desc_match_enabler(event->desc, enabler)
+ && event->chan == enabler->chan)
+ return 1;
+ else
+ return 0;
+}
+
+static
+struct lttng_enabler_ref *lttng_event_enabler_ref(struct lttng_event *event,
+ struct lttng_enabler *enabler)
+{
+ struct lttng_enabler_ref *enabler_ref;
+
+ list_for_each_entry(enabler_ref,
+ &event->enablers_ref_head, node) {
+ if (enabler_ref->ref == enabler)
+ return enabler_ref;
+ }