Commit 059a8c0c authored by Martin Kelly's avatar Martin Kelly Committed by Andrii Nakryiko
Browse files

libbpf: Add ring__producer_pos, ring__consumer_pos 



Add APIs to get the producer and consumer position for a given
ringbuffer.

Signed-off-by: default avatarMartin Kelly <martin.kelly@crowdstrike.com>
Signed-off-by: default avatarAndrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20230925215045.2375758-6-martin.kelly@crowdstrike.com
parent c1ad2e47

tools/lib/bpf/libbpf.h

+18 −0
Original line number Diff line number Diff line
@@ -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 */

};

tools/lib/bpf/libbpf.map

+2 −0
Original line number Diff line number Diff line
@@ -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;

tools/lib/bpf/ringbuf.c

+14 −0
Original line number Diff line number Diff line
@@ -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) {