From aecd67b60722dd24353b0bc50e78a55b30707dcd Mon Sep 17 00:00:00 2001
From: Jesper Dangaard Brouer <brouer@redhat.com>
Date: Wed, 3 Jan 2018 11:25:13 +0100
Subject: xdp: base API for new XDP rx-queue info concept
This patch only introduce the core data structures and API functions.
All XDP enabled drivers must use the API before this info can used.
There is a need for XDP to know more about the RX-queue a given XDP
frames have arrived on. For both the XDP bpf-prog and kernel side.
Instead of extending xdp_buff each time new info is needed, the patch
creates a separate read-mostly struct xdp_rxq_info, that contains this
info. We stress this data/cache-line is for read-only info. This is
NOT for dynamic per packet info, use the data_meta for such use-cases.
The performance advantage is this info can be setup at RX-ring init
time, instead of updating N-members in xdp_buff. A possible (driver
level) micro optimization is that xdp_buff->rxq assignment could be
done once per XDP/NAPI loop. The extra pointer deref only happens for
program needing access to this info (thus, no slowdown to existing
use-cases).
Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
---
net/core/xdp.c | 67 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 67 insertions(+)
create mode 100644 net/core/xdp.c
(limited to 'net/core/xdp.c')
diff --git a/net/core/xdp.c b/net/core/xdp.c
new file mode 100644
index 000000000000..229bc5a0ee04
--- /dev/null
+++ b/net/core/xdp.c
@@ -0,0 +1,67 @@
+/* net/core/xdp.c
+ *
+ * Copyright (c) 2017 Jesper Dangaard Brouer, Red Hat Inc.
+ * Released under terms in GPL version 2. See COPYING.
+ */
+#include <linux/types.h>
+#include <linux/mm.h>
+
+#include <net/xdp.h>
+
+#define REG_STATE_NEW 0x0
+#define REG_STATE_REGISTERED 0x1
+#define REG_STATE_UNREGISTERED 0x2
+#define REG_STATE_UNUSED 0x3
+
+void xdp_rxq_info_unreg(struct xdp_rxq_info *xdp_rxq)
+{
+ /* Simplify driver cleanup code paths, allow unreg "unused" */
+ if (xdp_rxq->reg_state == REG_STATE_UNUSED)
+ return;
+
+ WARN(!(xdp_rxq->reg_state == REG_STATE_REGISTERED), "Driver BUG");
+
+ xdp_rxq->reg_state = REG_STATE_UNREGISTERED;
+ xdp_rxq->dev = NULL;
+}
+EXPORT_SYMBOL_GPL(xdp_rxq_info_unreg);
+
+static void xdp_rxq_info_init(struct xdp_rxq_info *xdp_rxq)
+{
+ memset(xdp_rxq, 0, sizeof(*xdp_rxq));
+}
+
+/* Returns 0 on success, negative on failure */
+int xdp_rxq_info_reg(struct xdp_rxq_info *xdp_rxq,
+ struct net_device *dev, u32 queue_index)
+{
+ if (xdp_rxq->reg_state == REG_STATE_UNUSED) {
+ WARN(1, "Driver promised not to register this");
+ return -EINVAL;
+ }
+
+ if (xdp_rxq->reg_state == REG_STATE_REGISTERED) {
+ WARN(1, "Missing unregister, handled but fix driver");
+ xdp_rxq_info_unreg(xdp_rxq);
+ }
+
+ if (!dev) {
+ WARN(1, "Missing net_device from driver");
+ return -ENODEV;
+ }
+
+ /* State either UNREGISTERED or NEW */
+ xdp_rxq_info_init(xdp_rxq);
+ xdp_rxq->dev = dev;
+ xdp_rxq->queue_index = queue_index;
+
+ xdp_rxq->reg_state = REG_STATE_REGISTERED;
+ return 0;
+}
+EXPORT_SYMBOL_GPL(xdp_rxq_info_reg);
+
+void xdp_rxq_info_unused(struct xdp_rxq_info *xdp_rxq)
+{
+ xdp_rxq->reg_state = REG_STATE_UNUSED;
+}
+EXPORT_SYMBOL_GPL(xdp_rxq_info_unused);
--
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