if (head - local_read(&rb->wakeup) > rb->watermark)
local_add(rb->watermark, &rb->wakeup);
- handle->page = offset >> (PAGE_SHIFT + page_order(rb));
+ /* page is allways 0 for CONFIG_PERF_USE_VMALLOC option */
+ handle->page = offset >> PAGE_SHIFT;
handle->page &= rb->nr_pages - 1;
handle->size = offset & ((PAGE_SIZE << page_order(rb)) - 1);
handle->addr = rb->data_pages[handle->page];
}
#else
+/*
+ * Returns the total number of pages allocated
+ * by ring buffer including the user page.
+ */
+static int page_nr(struct ring_buffer *rb)
+{
+ return page_order(rb) == -1 ?
+ 1 : /* no data, just user page */
+ 1 + (1 << page_order(rb)); /* user page + data pages */
+}
struct page *
perf_mmap_to_page(struct ring_buffer *rb, unsigned long pgoff)
{
- if (pgoff > (1UL << page_order(rb)))
+ if (pgoff > page_nr(rb))
return NULL;
return vmalloc_to_page((void *)rb->user_page + pgoff * PAGE_SIZE);
int i, nr;
rb = container_of(work, struct ring_buffer, work);
- nr = 1 << page_order(rb);
+ nr = page_nr(rb);
base = rb->user_page;
- for (i = 0; i < nr + 1; i++)
+ for (i = 0; i < nr; i++)
perf_mmap_unmark_page(base + (i * PAGE_SIZE));
vfree(base);
goto fail_all_buf;
rb->user_page = all_buf;
- rb->data_pages[0] = all_buf + PAGE_SIZE;
- rb->page_order = ilog2(nr_pages);
- rb->nr_pages = 1;
+
+ /*
+ * For special case nr_pages == 0 we have
+ * only the user page mmaped plus:
+ *
+ * rb->data_pages[0] = NULL
+ * rb->nr_pages = 0
+ * rb->page_order = -1
+ *
+ * The perf_output_begin function is guarded
+ * by (rb->nr_pages > 0) condition, so no
+ * output code touches above setup if we
+ * have only user page allocated.
+ */
+
+ rb->data_pages[0] = nr_pages ? all_buf + PAGE_SIZE : NULL;
+ rb->nr_pages = nr_pages ? 1 : 0;
+ rb->page_order = ilog2(nr_pages);
ring_buffer_init(rb, watermark, flags);