Add APIs to get the producer and consumer position for a given
ringbuffer.
Signed-off-by: Martin Kelly <martin.kelly@xxxxxxxxxxxxxxx>
---
tools/lib/bpf/libbpf.h | 18 ++++++++++++++++++
tools/lib/bpf/libbpf.map | 2 ++
tools/lib/bpf/ringbuf.c | 14 ++++++++++++++
3 files changed, 34 insertions(+)
diff --git a/tools/lib/bpf/libbpf.h b/tools/lib/bpf/libbpf.h
index de3ef59b9641..ab470179b7fe 100644
--- a/tools/lib/bpf/libbpf.h
+++ b/tools/lib/bpf/libbpf.h
@@ -1264,6 +1264,24 @@ LIBBPF_API int ring_buffer__epoll_fd(const struct ring_buffer *rb);
LIBBPF_API struct ring *ring_buffer__ring(struct ring_buffer *rb,
unsigned int idx);
+/**
+ * @brief **ring__consumer_pos()** returns the current consumer position in the
+ * given ringbuffer.
+ *
+ * @param r A ringbuffer object.
+ * @return The current consumer position.
+ */
+LIBBPF_API unsigned long ring__consumer_pos(const struct ring *r);
+
+/**
+ * @brief **ring__producer_pos()** returns the current producer position in the
+ * given ringbuffer.
+ *
+ * @param r A ringbuffer object.
+ * @return The current producer position.
+ */
+LIBBPF_API unsigned long ring__producer_pos(const struct ring *r);
+
struct user_ring_buffer_opts {
size_t sz; /* size of this struct, for forward/backward compatibility */
};
diff --git a/tools/lib/bpf/libbpf.map b/tools/lib/bpf/libbpf.map
index 7a7370c2bc25..3bec002449d5 100644
--- a/tools/lib/bpf/libbpf.map
+++ b/tools/lib/bpf/libbpf.map
@@ -400,5 +400,7 @@ LIBBPF_1.3.0 {
bpf_program__attach_netfilter;
bpf_program__attach_tcx;
bpf_program__attach_uprobe_multi;
+ ring__consumer_pos;
+ ring__producer_pos;
ring_buffer__ring;
} LIBBPF_1.2.0;
diff --git a/tools/lib/bpf/ringbuf.c b/tools/lib/bpf/ringbuf.c
index efde453395b0..d14a607f6b66 100644
--- a/tools/lib/bpf/ringbuf.c
+++ b/tools/lib/bpf/ringbuf.c
@@ -338,6 +338,20 @@ struct ring *ring_buffer__ring(struct ring_buffer *rb, unsigned int idx)
return rb->rings[idx];
}
+unsigned long ring__consumer_pos(const struct ring *r)
+{
+ /* Synchronizes with smp_store_release() in ringbuf_process_ring(). */
+ return smp_load_acquire(r->consumer_pos);
+}
+
+unsigned long ring__producer_pos(const struct ring *r)
+{
+ /* Synchronizes with smp_store_release() in __bpf_ringbuf_reserve() in
+ * the kernel.
+ */
+ return smp_load_acquire(r->producer_pos);
+}
+
static void user_ringbuf_unmap_ring(struct user_ring_buffer *rb)
{
if (rb->consumer_pos) {
--
2.34.1
