struct lttng_ust_lib_ring_buffer_backend_pages_shmp *rpages;
unsigned long sb_bindex, id;
+ if (caa_unlikely(!len))
+ return;
offset &= chanb->buf_size - 1;
sbidx = offset >> chanb->subbuf_size_order;
id = shmp_index(handle, bufb->buf_wsb, sbidx)->id;