Commit 80348d88 authored Oct 07, 2020 by Magnus Karlsson Committed by Daniel Borkmann Oct 07, 2020

libbpf: Fix compatibility problem in xsk_socket__create

Fix a compatibility problem when the old XDP_SHARED_UMEM mode is used
together with the xsk_socket__create() call. In the old XDP_SHARED_UMEM
mode, only sharing of the same device and queue id was allowed, and
in this mode, the fill ring and completion ring were shared between
the AF_XDP sockets.

Therefore, it was perfectly fine to call the xsk_socket__create() API
for each socket and not use the new xsk_socket__create_shared() API.
This behavior was ruined by the commit introducing XDP_SHARED_UMEM
support between different devices and/or queue ids. This patch restores
the ability to use xsk_socket__create in these circumstances so that
backward compatibility is not broken.

Fixes: 2f6324a3 ("libbpf: Support shared umems between queues and devices")
Signed-off-by: Magnus Karlsson <magnus.karlsson@intel.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/1602070946-11154-1-git-send-email-magnus.karlsson@gmail.com

parent 49f3d12b

tools/lib/bpf/xsk.c

+6 −1

Original line number	Diff line number	Diff line
		@@ -705,7 +705,7 @@ int xsk_socket__create_shared(struct xsk_socket **xsk_ptr,
		struct xsk_ctx *ctx;
		int err, ifindex;

		if (!umem \|\| !xsk_ptr \|\| !(rx \|\| tx) \|\| !fill \|\| !comp)
		if (!umem \|\| !xsk_ptr \|\| !(rx \|\| tx))
		return -EFAULT;

		xsk = calloc(1, sizeof(*xsk));
		@@ -735,6 +735,11 @@ int xsk_socket__create_shared(struct xsk_socket **xsk_ptr,

		ctx = xsk_get_ctx(umem, ifindex, queue_id);
		if (!ctx) {
		if (!fill \|\| !comp) {
		err = -EFAULT;
		goto out_socket;
		}

		ctx = xsk_create_ctx(xsk, umem, ifindex, ifname, queue_id,
		fill, comp);
		if (!ctx) {

Admin message