+ stream_fd = get_unused_fd();
+ if (stream_fd < 0) {
+ ret = stream_fd;
+ goto fd_error;
+ }
+ stream_file = anon_inode_getfile("[lttng_stream]",
+ &lib_ring_buffer_file_operations,
+ buf, O_RDWR);
+ if (IS_ERR(stream_file)) {
+ ret = PTR_ERR(stream_file);
+ goto file_error;
+ }
+ /*
+ * OPEN_FMODE, called within anon_inode_getfile/alloc_file, don't honor
+ * FMODE_LSEEK, FMODE_PREAD nor FMODE_PWRITE. We need to read from this
+ * file descriptor, so we set FMODE_PREAD here.
+ */
+ stream_file->f_mode |= FMODE_PREAD;
+ fd_install(stream_fd, stream_file);
+ /*
+ * The stream holds a reference to the channel within the generic ring
+ * buffer library, so no need to hold a refcount on the channel and
+ * session files here.
+ */
+ return stream_fd;
+
+file_error:
+ put_unused_fd(stream_fd);
+fd_error:
+ channel->ops->buffer_read_close(buf);
+ return ret;
+}
+
+static
+int lttng_abi_create_event(struct file *channel_file,
+ struct lttng_kernel_event __user *uevent_param)
+{
+ struct ltt_channel *channel = channel_file->private_data;
+ struct ltt_event *event;
+ char *event_name;
+ struct lttng_kernel_event event_param;
+ int event_fd, ret;
+ struct file *event_file;
+
+ if (copy_from_user(&event_param, uevent_param, sizeof(event_param)))
+ return -EFAULT;
+ event_name = kmalloc(PATH_MAX, GFP_KERNEL);
+ if (!event_name)
+ return -ENOMEM;
+ if (strncpy_from_user(event_name, uevent_param->name, PATH_MAX) < 0) {
+ ret = -EFAULT;
+ goto name_error;
+ }
+ event_name[PATH_MAX - 1] = '\0';
+ switch (event_param.instrumentation) {
+ case LTTNG_KERNEL_KPROBES:
+ event_param.u.kprobe.symbol_name[LTTNG_SYM_NAME_LEN - 1] = '\0';
+ break;
+ case LTTNG_KERNEL_FUNCTION_TRACER:
+ event_param.u.ftrace.symbol_name[LTTNG_SYM_NAME_LEN - 1] = '\0';
+ break;
+ default:
+ break;
+ }
+ event_fd = get_unused_fd();
+ if (event_fd < 0) {
+ ret = event_fd;
+ goto fd_error;
+ }
+ event_file = anon_inode_getfile("[lttng_event]",
+ <tng_event_fops,
+ NULL, O_RDWR);
+ if (IS_ERR(event_file)) {
+ ret = PTR_ERR(event_file);
+ goto file_error;
+ }
+ /*
+ * We tolerate no failure path after event creation. It will stay
+ * invariant for the rest of the session.
+ */
+ event = ltt_event_create(channel, event_name, &event_param, NULL);
+ if (!event) {
+ ret = -EEXIST;
+ goto event_error;
+ }
+ event_file->private_data = event;
+ fd_install(event_fd, event_file);
+ /* The event holds a reference on the channel */
+ atomic_long_inc(&channel_file->f_count);
+ kfree(event_name);
+ return event_fd;
+
+event_error:
+ fput(event_file);
+file_error:
+ put_unused_fd(event_fd);
+fd_error:
+name_error:
+ kfree(event_name);
+ return ret;
+}
+
+/**
+ * lttng_channel_ioctl - lttng syscall through ioctl
+ *
+ * @file: the file
+ * @cmd: the command
+ * @arg: command arg
+ *
+ * This ioctl implements lttng commands:
+ * LTTNG_KERNEL_STREAM
+ * Returns an event stream file descriptor or failure.
+ * (typically, one event stream records events from one CPU)
+ * LTTNG_KERNEL_EVENT
+ * Returns an event file descriptor or failure.
+ *
+ * Channel and event file descriptors also hold a reference on the session.
+ */
+static
+long lttng_channel_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
+{