netdev - [RFC net-next 1/6] net: xdp: avoid output parameters when querying XDP prog

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Message-Id: <20171124023613.16855-2-jakub.kicinski@netronome.com>
Date:   Thu, 23 Nov 2017 18:36:08 -0800
From:   Jakub Kicinski <jakub.kicinski@...ronome.com>
To:     netdev@...r.kernel.org
Cc:     oss-drivers@...ronome.com, daniel@...earbox.net,
        alexei.starovoitov@...il.com, jiri@...nulli.us,
        Jakub Kicinski <jakub.kicinski@...ronome.com>
Subject: [RFC net-next 1/6] net: xdp: avoid output parameters when querying XDP prog

The output parameters will get unwieldy if we want to add more
information about the program.  Simply pass the entire
struct netdev_bpf in.

Signed-off-by: Jakub Kicinski <jakub.kicinski@...ronome.com>
Reviewed-by: Simon Horman <simon.horman@...ronome.com>
---
 include/linux/netdevice.h |  3 ++-
 net/core/dev.c            | 24 ++++++++++++++----------
 net/core/rtnetlink.c      |  6 +++++-
 3 files changed, 21 insertions(+), 12 deletions(-)

diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index ef789e1d679e..667bdd3ad33e 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -3330,7 +3330,8 @@ struct sk_buff *dev_hard_start_xmit(struct sk_buff *skb, struct net_device *dev,
 typedef int (*bpf_op_t)(struct net_device *dev, struct netdev_bpf *bpf);
 int dev_change_xdp_fd(struct net_device *dev, struct netlink_ext_ack *extack,
 		      int fd, u32 flags);
-u8 __dev_xdp_attached(struct net_device *dev, bpf_op_t xdp_op, u32 *prog_id);
+void __dev_xdp_query(struct net_device *dev, bpf_op_t xdp_op,
+		     struct netdev_bpf *xdp);
 
 int __dev_forward_skb(struct net_device *dev, struct sk_buff *skb);
 int dev_forward_skb(struct net_device *dev, struct sk_buff *skb);
diff --git a/net/core/dev.c b/net/core/dev.c
index 07ed21d64f92..3f271c9cb5e0 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -7073,17 +7073,21 @@ int dev_change_proto_down(struct net_device *dev, bool proto_down)
 }
 EXPORT_SYMBOL(dev_change_proto_down);
 
-u8 __dev_xdp_attached(struct net_device *dev, bpf_op_t bpf_op, u32 *prog_id)
+void __dev_xdp_query(struct net_device *dev, bpf_op_t bpf_op,
+		     struct netdev_bpf *xdp)
 {
-	struct netdev_bpf xdp;
-
-	memset(&xdp, 0, sizeof(xdp));
-	xdp.command = XDP_QUERY_PROG;
+	memset(xdp, 0, sizeof(*xdp));
+	xdp->command = XDP_QUERY_PROG;
 
 	/* Query must always succeed. */
-	WARN_ON(bpf_op(dev, &xdp) < 0);
-	if (prog_id)
-		*prog_id = xdp.prog_id;
+	WARN_ON(bpf_op(dev, xdp) < 0);
+}
+
+static u8 __dev_xdp_attached(struct net_device *dev, bpf_op_t bpf_op)
+{
+	struct netdev_bpf xdp;
+
+	__dev_xdp_query(dev, bpf_op, &xdp);
 
 	return xdp.prog_attached;
 }
@@ -7134,10 +7138,10 @@ int dev_change_xdp_fd(struct net_device *dev, struct netlink_ext_ack *extack,
 		bpf_chk = generic_xdp_install;
 
 	if (fd >= 0) {
-		if (bpf_chk && __dev_xdp_attached(dev, bpf_chk, NULL))
+		if (bpf_chk && __dev_xdp_attached(dev, bpf_chk))
 			return -EEXIST;
 		if ((flags & XDP_FLAGS_UPDATE_IF_NOEXIST) &&
-		    __dev_xdp_attached(dev, bpf_op, NULL))
+		    __dev_xdp_attached(dev, bpf_op))
 			return -EBUSY;
 
 		prog = bpf_prog_get_type_dev(fd, BPF_PROG_TYPE_XDP,
diff --git a/net/core/rtnetlink.c b/net/core/rtnetlink.c
index dabba2a91fc8..9c4cb584bfb0 100644
--- a/net/core/rtnetlink.c
+++ b/net/core/rtnetlink.c
@@ -1261,6 +1261,7 @@ static u8 rtnl_xdp_attached_mode(struct net_device *dev, u32 *prog_id)
 {
 	const struct net_device_ops *ops = dev->netdev_ops;
 	const struct bpf_prog *generic_xdp_prog;
+	struct netdev_bpf xdp;
 
 	ASSERT_RTNL();
 
@@ -1273,7 +1274,10 @@ static u8 rtnl_xdp_attached_mode(struct net_device *dev, u32 *prog_id)
 	if (!ops->ndo_bpf)
 		return XDP_ATTACHED_NONE;
 
-	return __dev_xdp_attached(dev, ops->ndo_bpf, prog_id);
+	__dev_xdp_query(dev, ops->ndo_bpf, &xdp);
+	*prog_id = xdp.prog_id;
+
+	return xdp.prog_attached;
 }
 
 static int rtnl_xdp_fill(struct sk_buff *skb, struct net_device *dev)
-- 
2.14.1