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From: Andrii Nakryiko <andriin@fb.com>
To: <bpf@vger.kernel.org>, <netdev@vger.kernel.org>, <ast@fb.com>,
	<daniel@iogearbox.net>
Cc: <andrii.nakryiko@gmail.com>, <kernel-team@fb.com>,
	Andrii Nakryiko <andriin@fb.com>, Andrey Ignatov <rdna@fb.com>,
	Takshak Chahande <ctakshak@fb.com>
Subject: [PATCH bpf-next 3/7] bpf, xdp: implement LINK_UPDATE for BPF XDP link
Date: Sun, 12 Jul 2020 22:12:26 -0700	[thread overview]
Message-ID: <20200713051230.3250515-4-andriin@fb.com> (raw)
In-Reply-To: <20200713051230.3250515-1-andriin@fb.com>

Add support for LINK_UPDATE command for BPF XDP link to enable reliable
replacement of underlying BPF program.

Signed-off-by: Andrii Nakryiko <andriin@fb.com>
---
 net/core/dev.c | 43 +++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 43 insertions(+)

diff --git a/net/core/dev.c b/net/core/dev.c
index 84f755a1ec36..025687120442 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -8973,9 +8973,52 @@ static void bpf_xdp_link_dealloc(struct bpf_link *link)
 	kfree(xdp_link);
 }
 
+static int bpf_xdp_link_update(struct bpf_link *link, struct bpf_prog *new_prog,
+			       struct bpf_prog *old_prog)
+{
+	struct bpf_xdp_link *xdp_link = container_of(link, struct bpf_xdp_link, link);
+	enum bpf_xdp_mode mode;
+	bpf_op_t bpf_op;
+	int err = 0;
+
+	rtnl_lock();
+
+	/* link might have been auto-released already, so fail */
+	if (!xdp_link->dev) {
+		err = -ENOLINK;
+		goto out_unlock;
+	}
+
+	if (old_prog && link->prog != old_prog) {
+		err = -EPERM;
+		goto out_unlock;
+	}
+	old_prog = link->prog;
+	if (old_prog == new_prog) {
+		/* no-op, don't disturb drivers */
+		bpf_prog_put(new_prog);
+		goto out_unlock;
+	}
+
+	mode = dev_xdp_mode(xdp_link->flags);
+	bpf_op = dev_xdp_bpf_op(xdp_link->dev, mode);
+	err = dev_xdp_install(xdp_link->dev, mode, bpf_op, NULL,
+			      xdp_link->flags, new_prog);
+	if (err)
+		goto out_unlock;
+
+	old_prog = xchg(&link->prog, new_prog);
+	bpf_prog_put(old_prog);
+
+out_unlock:
+	rtnl_unlock();
+	return err;
+}
+
 static const struct bpf_link_ops bpf_xdp_link_lops = {
 	.release = bpf_xdp_link_release,
 	.dealloc = bpf_xdp_link_dealloc,
+	.update_prog = bpf_xdp_link_update,
 };
 
 int bpf_xdp_link_attach(const union bpf_attr *attr, struct bpf_prog *prog)
-- 
2.24.1


  parent reply	other threads:[~2020-07-13  5:13 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-07-13  5:12 [PATCH bpf-next 0/7] BPF XDP link Andrii Nakryiko
2020-07-13  5:12 ` [PATCH bpf-next 1/7] bpf, xdp: maintain info on attached XDP BPF programs in net_device Andrii Nakryiko
2020-07-13  5:12 ` [PATCH bpf-next 2/7] bpf, xdp: add bpf_link-based XDP attachment API Andrii Nakryiko
2020-07-13  5:12 ` Andrii Nakryiko [this message]
2020-07-13  5:12 ` [PATCH bpf-next 4/7] bpf: implement BPF XDP link-specific introspection APIs Andrii Nakryiko
2020-07-13  5:12 ` [PATCH bpf-next 5/7] libbpf: add support for BPF XDP link Andrii Nakryiko
2020-07-13  5:12 ` [PATCH bpf-next 6/7] selftests/bpf: add BPF XDP link selftests Andrii Nakryiko
2020-07-13  5:12 ` [PATCH bpf-next 7/7] bpf, xdp: remove XDP_QUERY_PROG and XDP_QUERY_PROG_HW XDP commands Andrii Nakryiko

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