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Commit 5750902a authored by Björn Töpel's avatar Björn Töpel Committed by Alexei Starovoitov
Browse files

libbpf: proper XSKMAP cleanup 



The bpf_map_update_elem() function, when used on an XSKMAP, will fail
if not a valid AF_XDP socket is passed as value. Therefore, this is
function cannot be used to clear the XSKMAP. Instead, the
bpf_map_delete_elem() function should be used for that.

This patch also simplifies the code by breaking up
xsk_update_bpf_maps() into three smaller functions.

Reported-by: default avatarWilliam Tu <u9012063@gmail.com>
Fixes: 1cad0788 ("libbpf: add support for using AF_XDP sockets")
Signed-off-by: default avatarBjörn Töpel <bjorn.topel@intel.com>
Tested-by: default avatarWilliam Tu <u9012063@gmail.com>
Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
parent 0e6741f0

tools/lib/bpf/xsk.c

+60 −55
Original line number Diff line number Diff line
@@ -387,21 +387,17 @@ static void xsk_delete_bpf_maps(struct xsk_socket *xsk) 
{

	close(xsk->qidconf_map_fd);

	close(xsk->xsks_map_fd);

	xsk->qidconf_map_fd = -1;

	xsk->xsks_map_fd = -1;

}



static int xsk_update_bpf_maps(struct xsk_socket *xsk, int qidconf_value,

			       int xsks_value)

static int xsk_lookup_bpf_maps(struct xsk_socket *xsk)

{

	bool qidconf_map_updated = false, xsks_map_updated = false;

	__u32 i, *map_ids, num_maps, prog_len = sizeof(struct bpf_prog_info);

	__u32 map_len = sizeof(struct bpf_map_info);

	struct bpf_prog_info prog_info = {};

	__u32 prog_len = sizeof(prog_info);

	struct bpf_map_info map_info;

	__u32 map_len = sizeof(map_info);

	__u32 *map_ids;

	int reset_value = 0;

	__u32 num_maps;

	unsigned int i;

	int err;

	int fd, err;



	err = bpf_obj_get_info_by_fd(xsk->prog_fd, &prog_info, &prog_len);

	if (err)
@@ -422,66 +418,71 @@ static int xsk_update_bpf_maps(struct xsk_socket *xsk, int qidconf_value, 
		goto out_map_ids;



	for (i = 0; i < prog_info.nr_map_ids; i++) {

		int fd;

		if (xsk->qidconf_map_fd != -1 && xsk->xsks_map_fd != -1)

			break;



		fd = bpf_map_get_fd_by_id(map_ids[i]);

		if (fd < 0) {

			err = -errno;

			goto out_maps;

		}

		if (fd < 0)

			continue;



		err = bpf_obj_get_info_by_fd(fd, &map_info, &map_len);

		if (err)

			goto out_maps;

		if (err) {

			close(fd);

			continue;

		}



		if (!strcmp(map_info.name, "qidconf_map")) {

			err = bpf_map_update_elem(fd, &xsk->queue_id,

						  &qidconf_value, 0);

			if (err)

				goto out_maps;

			qidconf_map_updated = true;

			xsk->qidconf_map_fd = fd;

		} else if (!strcmp(map_info.name, "xsks_map")) {

			err = bpf_map_update_elem(fd, &xsk->queue_id,

						  &xsks_value, 0);

			if (err)

				goto out_maps;

			xsks_map_updated = true;

			xsk->xsks_map_fd = fd;

			continue;

		}



		if (qidconf_map_updated && xsks_map_updated)

			break;

		if (!strcmp(map_info.name, "xsks_map")) {

			xsk->xsks_map_fd = fd;

			continue;

		}



	if (!(qidconf_map_updated && xsks_map_updated)) {

		err = -ENOENT;

		goto out_maps;

		close(fd);

	}



	err = 0;

	goto out_success;

	if (xsk->qidconf_map_fd < 0 || xsk->xsks_map_fd < 0) {

		err = -ENOENT;

		xsk_delete_bpf_maps(xsk);

	}



out_maps:

	if (qidconf_map_updated)

		(void)bpf_map_update_elem(xsk->qidconf_map_fd, &xsk->queue_id,

					  &reset_value, 0);

	if (xsks_map_updated)

		(void)bpf_map_update_elem(xsk->xsks_map_fd, &xsk->queue_id,

					  &reset_value, 0);

out_success:

	if (qidconf_map_updated)

		close(xsk->qidconf_map_fd);

	if (xsks_map_updated)

		close(xsk->xsks_map_fd);

out_map_ids:

	free(map_ids);

	return err;

}



static void xsk_clear_bpf_maps(struct xsk_socket *xsk)

{

	int qid = false;



	(void)bpf_map_update_elem(xsk->qidconf_map_fd, &xsk->queue_id, &qid, 0);

	(void)bpf_map_delete_elem(xsk->xsks_map_fd, &xsk->queue_id);

}



static int xsk_set_bpf_maps(struct xsk_socket *xsk)

{

	int qid = true, fd = xsk->fd, err;



	err = bpf_map_update_elem(xsk->qidconf_map_fd, &xsk->queue_id, &qid, 0);

	if (err)

		goto out;



	err = bpf_map_update_elem(xsk->xsks_map_fd, &xsk->queue_id, &fd, 0);

	if (err)

		goto out;



	return 0;

out:

	xsk_clear_bpf_maps(xsk);

	return err;

}



static int xsk_setup_xdp_prog(struct xsk_socket *xsk)

{

	bool prog_attached = false;

	__u32 prog_id = 0;

	int err;
@@ -491,7 +492,6 @@ static int xsk_setup_xdp_prog(struct xsk_socket *xsk) 
		return err;



	if (!prog_id) {

		prog_attached = true;

		err = xsk_create_bpf_maps(xsk);

		if (err)

			return err;
@@ -501,19 +501,20 @@ static int xsk_setup_xdp_prog(struct xsk_socket *xsk) 
			goto out_maps;

	} else {

		xsk->prog_fd = bpf_prog_get_fd_by_id(prog_id);

		err = xsk_lookup_bpf_maps(xsk);

		if (err)

			goto out_load;

	}



	err = xsk_update_bpf_maps(xsk, true, xsk->fd);

	err = xsk_set_bpf_maps(xsk);

	if (err)

		goto out_load;



	return 0;



out_load:

	if (prog_attached)

	close(xsk->prog_fd);

out_maps:

	if (prog_attached)

	xsk_delete_bpf_maps(xsk);

	return err;

}
@@ -642,6 +643,9 @@ int xsk_socket__create(struct xsk_socket **xsk_ptr, const char *ifname, 
		goto out_mmap_tx;

	}



	xsk->qidconf_map_fd = -1;

	xsk->xsks_map_fd = -1;



	if (!(xsk->config.libbpf_flags & XSK_LIBBPF_FLAGS__INHIBIT_PROG_LOAD)) {

		err = xsk_setup_xdp_prog(xsk);

		if (err)
@@ -706,7 +710,8 @@ void xsk_socket__delete(struct xsk_socket *xsk) 
	if (!xsk)

		return;



	(void)xsk_update_bpf_maps(xsk, 0, 0);

	xsk_clear_bpf_maps(xsk);

	xsk_delete_bpf_maps(xsk);



	optlen = sizeof(off);

	err = getsockopt(xsk->fd, SOL_XDP, XDP_MMAP_OFFSETS, &off, &optlen);