-/*
- * Setup necessary data for kernel tracer action.
- */
-static int init_kernel_tracer(void)
-{
- int ret;
-
- /* Modprobe lttng kernel modules */
- ret = modprobe_lttng_control();
- if (ret < 0) {
- goto error;
- }
-
- /* Open debugfs lttng */
- kernel_tracer_fd = open(module_proc_lttng, O_RDWR);
- if (kernel_tracer_fd < 0) {
- DBG("Failed to open %s", module_proc_lttng);
- goto error_open;
- }
-
- /* Validate kernel version */
- ret = kernel_validate_version(kernel_tracer_fd, &kernel_tracer_version,
- &kernel_tracer_abi_version);
- if (ret < 0) {
- goto error_version;
- }
-
- ret = modprobe_lttng_data();
- if (ret < 0) {
- goto error_modules;
- }
-
- ret = kernel_supports_ring_buffer_snapshot_sample_positions(
- kernel_tracer_fd);
- if (ret < 0) {
- goto error_modules;
- }
-
- if (ret < 1) {
- WARN("Kernel tracer does not support buffer monitoring. "
- "The monitoring timer of channels in the kernel domain "
- "will be set to 0 (disabled).");
- }
-
- DBG("Kernel tracer fd %d", kernel_tracer_fd);
- return 0;
-
-error_version:
- modprobe_remove_lttng_control();
- ret = close(kernel_tracer_fd);
- if (ret) {
- PERROR("close");
- }
- kernel_tracer_fd = -1;
- return LTTNG_ERR_KERN_VERSION;
-
-error_modules:
- ret = close(kernel_tracer_fd);
- if (ret) {
- PERROR("close");
- }
-
-error_open:
- modprobe_remove_lttng_control();
-
-error:
- WARN("No kernel tracer available");
- kernel_tracer_fd = -1;
- if (!is_root) {
- return LTTNG_ERR_NEED_ROOT_SESSIOND;
- } else {
- return LTTNG_ERR_KERN_NA;
- }
-}
-