Commit 4d22ea94 authored by Andrea Righi's avatar Andrea Righi Committed by Andrii Nakryiko
Browse files

libbpf: Add ring__consume_n / ring_buffer__consume_n 



Introduce a new API to consume items from a ring buffer, limited to a
specified amount, and return to the caller the actual number of items
consumed.

Signed-off-by: default avatarAndrea Righi <andrea.righi@canonical.com>
Signed-off-by: default avatarAndrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/lkml/20240310154726.734289-1-andrea.righi@canonical.com/T
Link: https://lore.kernel.org/bpf/20240406092005.92399-4-andrea.righi@canonical.com
parent 13e8125a

tools/lib/bpf/libbpf.h

+12 −0
Original line number Diff line number Diff line
@@ -1293,6 +1293,7 @@ LIBBPF_API int ring_buffer__add(struct ring_buffer *rb, int map_fd, 
				ring_buffer_sample_fn sample_cb, void *ctx);

LIBBPF_API int ring_buffer__poll(struct ring_buffer *rb, int timeout_ms);

LIBBPF_API int ring_buffer__consume(struct ring_buffer *rb);

LIBBPF_API int ring_buffer__consume_n(struct ring_buffer *rb, size_t n);

LIBBPF_API int ring_buffer__epoll_fd(const struct ring_buffer *rb);



/**
@@ -1367,6 +1368,17 @@ LIBBPF_API int ring__map_fd(const struct ring *r); 
 */

LIBBPF_API int ring__consume(struct ring *r);



/**

 * @brief **ring__consume_n()** consumes up to a requested amount of items from

 * a ringbuffer without event polling.

 *

 * @param r A ringbuffer object.

 * @param n Maximum amount of items to consume.

 * @return The number of items consumed, or a negative number if any of the

 * callbacks return an error.

 */

LIBBPF_API int ring__consume_n(struct ring *r, size_t n);



struct user_ring_buffer_opts {

	size_t sz; /* size of this struct, for forward/backward compatibility */

};

tools/lib/bpf/libbpf.map

+3 −0
Original line number Diff line number Diff line
@@ -418,4 +418,7 @@ LIBBPF_1.4.0 { 
} LIBBPF_1.3.0;



LIBBPF_1.5.0 {

	global:

		ring__consume_n;

		ring_buffer__consume_n;

} LIBBPF_1.4.0;

tools/lib/bpf/ringbuf.c

+35 −3
Original line number Diff line number Diff line
@@ -277,6 +277,33 @@ static int64_t ringbuf_process_ring(struct ring *r, size_t n) 
	return cnt;

}



/* Consume available ring buffer(s) data without event polling, up to n

 * records.

 *

 * Returns number of records consumed across all registered ring buffers (or

 * n, whichever is less), or negative number if any of the callbacks return

 * error.

 */

int ring_buffer__consume_n(struct ring_buffer *rb, size_t n)

{

	int64_t err, res = 0;

	int i;



	for (i = 0; i < rb->ring_cnt; i++) {

		struct ring *ring = rb->rings[i];



		err = ringbuf_process_ring(ring, n);

		if (err < 0)

			return libbpf_err(err);

		res += err;

		n -= err;



		if (n == 0)

			break;

	}

	return res;

}



/* Consume available ring buffer(s) data without event polling.

 * Returns number of records consumed across all registered ring buffers (or

 * INT_MAX, whichever is less), or negative number if any of the callbacks
@@ -376,17 +403,22 @@ int ring__map_fd(const struct ring *r) 
	return r->map_fd;

}



int ring__consume(struct ring *r)

int ring__consume_n(struct ring *r, size_t n)

{

	int64_t res;

	int res;



	res = ringbuf_process_ring(r, INT_MAX);

	res = ringbuf_process_ring(r, n);

	if (res < 0)

		return libbpf_err(res);



	return res > INT_MAX ? INT_MAX : res;

}



int ring__consume(struct ring *r)

{

	return ring__consume_n(r, INT_MAX);

}



static void user_ringbuf_unmap_ring(struct user_ring_buffer *rb)

{

	if (rb->consumer_pos) {