libbpf: Add ring__avail_data_size
Add ring__avail_data_size for querying the currently available data in
the ringbuffer, similar to the BPF_RB_AVAIL_DATA flag in
bpf_ringbuf_query. This is racy during ongoing operations but is still
useful for overall information on how a ringbuffer is behaving.
Signed-off-by: Martin Kelly <martin.kelly@crowdstrike.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20230925215045.2375758-8-martin.kelly@crowdstrike.com
diff --git a/src/libbpf.h b/src/libbpf.h
index ab47017..d60254c 100644
--- a/src/libbpf.h
+++ b/src/libbpf.h
@@ -1282,6 +1282,17 @@
*/
LIBBPF_API unsigned long ring__producer_pos(const struct ring *r);
+/**
+ * @brief **ring__avail_data_size()** returns the number of bytes in the
+ * ringbuffer not yet consumed. This has no locking associated with it, so it
+ * can be inaccurate if operations are ongoing while this is called. However, it
+ * should still show the correct trend over the long-term.
+ *
+ * @param r A ringbuffer object.
+ * @return The number of bytes not yet consumed.
+ */
+LIBBPF_API size_t ring__avail_data_size(const struct ring *r);
+
struct user_ring_buffer_opts {
size_t sz; /* size of this struct, for forward/backward compatibility */
};
diff --git a/src/libbpf.map b/src/libbpf.map
index 3bec002..5184c94 100644
--- a/src/libbpf.map
+++ b/src/libbpf.map
@@ -400,6 +400,7 @@
bpf_program__attach_netfilter;
bpf_program__attach_tcx;
bpf_program__attach_uprobe_multi;
+ ring__avail_data_size;
ring__consumer_pos;
ring__producer_pos;
ring_buffer__ring;
diff --git a/src/ringbuf.c b/src/ringbuf.c
index d14a607..07fbc6a 100644
--- a/src/ringbuf.c
+++ b/src/ringbuf.c
@@ -352,6 +352,15 @@
return smp_load_acquire(r->producer_pos);
}
+size_t ring__avail_data_size(const struct ring *r)
+{
+ unsigned long cons_pos, prod_pos;
+
+ cons_pos = ring__consumer_pos(r);
+ prod_pos = ring__producer_pos(r);
+ return prod_pos - cons_pos;
+}
+
static void user_ringbuf_unmap_ring(struct user_ring_buffer *rb)
{
if (rb->consumer_pos) {
