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Date: Wed, 22 May 2019 14:53:51 +0200
From: Björn Töpel <bjorn.topel@...il.com>
To: toke@...hat.com, ast@...nel.org, daniel@...earbox.net,
netdev@...r.kernel.org
Cc: Björn Töpel <bjorn.topel@...el.com>,
magnus.karlsson@...el.com, brouer@...hat.com, bpf@...r.kernel.org,
jakub.kicinski@...ronome.com
Subject: [PATCH bpf-next 1/2] net: xdp: refactor XDP_QUERY_PROG{,_HW} to netdev
From: Björn Töpel <bjorn.topel@...el.com>
All XDP capable drivers need to implement the XDP_QUERY_PROG{,_HW}
command of ndo_bpf. The query code is fairly generic. This commit
refactors the query code up from the drivers to the netdev level.
The struct net_device has gained four new members tracking the XDP
program, the corresponding program flags, and which programs
(SKB_MODE, DRV_MODE or HW_MODE) that are activated.
The xdp_prog member, previously only used for SKB_MODE, is shared with
DRV_MODE, since they are mutually exclusive.
The program query operations is all done under the rtnl lock. However,
the xdp_prog member is __rcu annotated, and used in a lock-less manner
for the SKB_MODE. This is because the xdp_prog member is shared from a
query program perspective (again, SKB and DRV are mutual exclusive),
RCU read and assignments functions are still used when altering
xdp_prog, even when only for queries in DRV_MODE. This is for
sparse/lockdep correctness.
A minor behavioral change was done during this refactorization; When
passing a negative file descriptor to a netdev to disable XDP, the
same program flag as the running program is required. An example.
The eth0 is DRV_DRV capable. Previously, this was OK, but confusing:
# ip link set dev eth0 xdp obj foo.o sec main
# ip link set dev eth0 xdpgeneric off
Now, the same commands give:
# ip link set dev eth0 xdp obj foo.o sec main
# ip link set dev eth0 xdpgeneric off
Error: native and generic XDP can't be active at the same time.
Signed-off-by: Björn Töpel <bjorn.topel@...el.com>
---
include/linux/netdevice.h | 13 +++--
net/core/dev.c | 120 ++++++++++++++++++++------------------
net/core/rtnetlink.c | 33 ++---------
3 files changed, 76 insertions(+), 90 deletions(-)
diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index 44b47e9df94a..bdcb20a3946c 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -1940,6 +1940,11 @@ struct net_device {
#endif
struct hlist_node index_hlist;
+ struct bpf_prog *xdp_prog_hw;
+ unsigned int xdp_flags;
+ u32 xdp_prog_flags;
+ u32 xdp_prog_hw_flags;
+
/*
* Cache lines mostly used on transmit path
*/
@@ -2045,9 +2050,8 @@ struct net_device {
static inline bool netif_elide_gro(const struct net_device *dev)
{
- if (!(dev->features & NETIF_F_GRO) || dev->xdp_prog)
- return true;
- return false;
+ return !(dev->features & NETIF_F_GRO) ||
+ dev->xdp_flags & XDP_FLAGS_SKB_MODE;
}
#define NETDEV_ALIGN 32
@@ -3684,8 +3688,7 @@ 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);
-u32 __dev_xdp_query(struct net_device *dev, bpf_op_t xdp_op,
- enum bpf_netdev_command cmd);
+u32 dev_xdp_query(struct net_device *dev, unsigned int flags);
int xdp_umem_query(struct net_device *dev, u16 queue_id);
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 b6b8505cfb3e..ead16c3f955c 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -8005,31 +8005,31 @@ int dev_change_proto_down_generic(struct net_device *dev, bool proto_down)
}
EXPORT_SYMBOL(dev_change_proto_down_generic);
-u32 __dev_xdp_query(struct net_device *dev, bpf_op_t bpf_op,
- enum bpf_netdev_command cmd)
+u32 dev_xdp_query(struct net_device *dev, unsigned int flags)
{
- struct netdev_bpf xdp;
+ struct bpf_prog *prog = NULL;
- if (!bpf_op)
+ if (hweight32(flags) != 1)
return 0;
- memset(&xdp, 0, sizeof(xdp));
- xdp.command = cmd;
-
- /* Query must always succeed. */
- WARN_ON(bpf_op(dev, &xdp) < 0 && cmd == XDP_QUERY_PROG);
+ if (flags & (XDP_FLAGS_SKB_MODE | XDP_FLAGS_DRV_MODE))
+ prog = rtnl_dereference(dev->xdp_prog);
+ else if (flags & XDP_FLAGS_HW_MODE)
+ prog = dev->xdp_prog_hw;
- return xdp.prog_id;
+ return prog ? prog->aux->id : 0;
}
-static int dev_xdp_install(struct net_device *dev, bpf_op_t bpf_op,
+static int dev_xdp_install(struct net_device *dev, unsigned int target,
struct netlink_ext_ack *extack, u32 flags,
struct bpf_prog *prog)
{
+ bpf_op_t bpf_op = dev->netdev_ops->ndo_bpf;
struct netdev_bpf xdp;
+ int err;
memset(&xdp, 0, sizeof(xdp));
- if (flags & XDP_FLAGS_HW_MODE)
+ if (target == XDP_FLAGS_HW_MODE)
xdp.command = XDP_SETUP_PROG_HW;
else
xdp.command = XDP_SETUP_PROG;
@@ -8037,35 +8037,41 @@ static int dev_xdp_install(struct net_device *dev, bpf_op_t bpf_op,
xdp.flags = flags;
xdp.prog = prog;
- return bpf_op(dev, &xdp);
+ err = (target == XDP_FLAGS_SKB_MODE) ?
+ generic_xdp_install(dev, &xdp) :
+ bpf_op(dev, &xdp);
+ if (!err) {
+ if (prog)
+ dev->xdp_flags |= target;
+ else
+ dev->xdp_flags &= ~target;
+
+ if (target == XDP_FLAGS_HW_MODE) {
+ dev->xdp_prog_hw = prog;
+ dev->xdp_prog_hw_flags = flags;
+ } else if (target == XDP_FLAGS_DRV_MODE) {
+ rcu_assign_pointer(dev->xdp_prog, prog);
+ dev->xdp_prog_flags = flags;
+ }
+ }
+
+ return err;
}
static void dev_xdp_uninstall(struct net_device *dev)
{
- struct netdev_bpf xdp;
- bpf_op_t ndo_bpf;
-
- /* Remove generic XDP */
- WARN_ON(dev_xdp_install(dev, generic_xdp_install, NULL, 0, NULL));
-
- /* Remove from the driver */
- ndo_bpf = dev->netdev_ops->ndo_bpf;
- if (!ndo_bpf)
- return;
-
- memset(&xdp, 0, sizeof(xdp));
- xdp.command = XDP_QUERY_PROG;
- WARN_ON(ndo_bpf(dev, &xdp));
- if (xdp.prog_id)
- WARN_ON(dev_xdp_install(dev, ndo_bpf, NULL, xdp.prog_flags,
- NULL));
-
- /* Remove HW offload */
- memset(&xdp, 0, sizeof(xdp));
- xdp.command = XDP_QUERY_PROG_HW;
- if (!ndo_bpf(dev, &xdp) && xdp.prog_id)
- WARN_ON(dev_xdp_install(dev, ndo_bpf, NULL, xdp.prog_flags,
- NULL));
+ if (dev->xdp_flags & XDP_FLAGS_SKB_MODE) {
+ WARN_ON(dev_xdp_install(dev, XDP_FLAGS_SKB_MODE,
+ NULL, 0, NULL));
+ }
+ if (dev->xdp_flags & XDP_FLAGS_DRV_MODE) {
+ WARN_ON(dev_xdp_install(dev, XDP_FLAGS_DRV_MODE,
+ NULL, dev->xdp_prog_flags, NULL));
+ }
+ if (dev->xdp_flags & XDP_FLAGS_HW_MODE) {
+ WARN_ON(dev_xdp_install(dev, XDP_FLAGS_HW_MODE,
+ NULL, dev->xdp_prog_hw_flags, NULL));
+ }
}
/**
@@ -8080,41 +8086,41 @@ static void dev_xdp_uninstall(struct net_device *dev)
int dev_change_xdp_fd(struct net_device *dev, struct netlink_ext_ack *extack,
int fd, u32 flags)
{
- const struct net_device_ops *ops = dev->netdev_ops;
- enum bpf_netdev_command query;
+ bool offload, drv_supp = !!dev->netdev_ops->ndo_bpf;
struct bpf_prog *prog = NULL;
- bpf_op_t bpf_op, bpf_chk;
- bool offload;
+ unsigned int target;
int err;
ASSERT_RTNL();
offload = flags & XDP_FLAGS_HW_MODE;
- query = offload ? XDP_QUERY_PROG_HW : XDP_QUERY_PROG;
+ target = offload ? XDP_FLAGS_HW_MODE : XDP_FLAGS_DRV_MODE;
- bpf_op = bpf_chk = ops->ndo_bpf;
- if (!bpf_op && (flags & (XDP_FLAGS_DRV_MODE | XDP_FLAGS_HW_MODE))) {
+ if (!drv_supp && (flags & (XDP_FLAGS_DRV_MODE | XDP_FLAGS_HW_MODE))) {
NL_SET_ERR_MSG(extack, "underlying driver does not support XDP in native mode");
return -EOPNOTSUPP;
}
- if (!bpf_op || (flags & XDP_FLAGS_SKB_MODE))
- bpf_op = generic_xdp_install;
- if (bpf_op == bpf_chk)
- bpf_chk = generic_xdp_install;
+
+ if (!drv_supp || (flags & XDP_FLAGS_SKB_MODE))
+ target = XDP_FLAGS_SKB_MODE;
+
+ if ((target == XDP_FLAGS_SKB_MODE &&
+ dev->xdp_flags & XDP_FLAGS_DRV_MODE) ||
+ (target == XDP_FLAGS_DRV_MODE &&
+ dev->xdp_flags & XDP_FLAGS_SKB_MODE)) {
+ NL_SET_ERR_MSG(extack, "native and generic XDP can't be active at the same time");
+ return -EEXIST;
+ }
if (fd >= 0) {
- if (!offload && __dev_xdp_query(dev, bpf_chk, XDP_QUERY_PROG)) {
- NL_SET_ERR_MSG(extack, "native and generic XDP can't be active at the same time");
- return -EEXIST;
- }
- if ((flags & XDP_FLAGS_UPDATE_IF_NOEXIST) &&
- __dev_xdp_query(dev, bpf_op, query)) {
+ if (flags & XDP_FLAGS_UPDATE_IF_NOEXIST &&
+ dev_xdp_query(dev, target)) {
NL_SET_ERR_MSG(extack, "XDP program already attached");
return -EBUSY;
}
- prog = bpf_prog_get_type_dev(fd, BPF_PROG_TYPE_XDP,
- bpf_op == ops->ndo_bpf);
+ prog = bpf_prog_get_type_dev(fd, BPF_PROG_TYPE_XDP, drv_supp);
+
if (IS_ERR(prog))
return PTR_ERR(prog);
@@ -8125,7 +8131,7 @@ int dev_change_xdp_fd(struct net_device *dev, struct netlink_ext_ack *extack,
}
}
- err = dev_xdp_install(dev, bpf_op, extack, flags, prog);
+ err = dev_xdp_install(dev, target, extack, flags, prog);
if (err < 0 && prog)
bpf_prog_put(prog);
diff --git a/net/core/rtnetlink.c b/net/core/rtnetlink.c
index adcc045952c2..99ca58db297f 100644
--- a/net/core/rtnetlink.c
+++ b/net/core/rtnetlink.c
@@ -1360,37 +1360,14 @@ static int rtnl_fill_link_ifmap(struct sk_buff *skb, struct net_device *dev)
return 0;
}
-static u32 rtnl_xdp_prog_skb(struct net_device *dev)
-{
- const struct bpf_prog *generic_xdp_prog;
-
- ASSERT_RTNL();
-
- generic_xdp_prog = rtnl_dereference(dev->xdp_prog);
- if (!generic_xdp_prog)
- return 0;
- return generic_xdp_prog->aux->id;
-}
-
-static u32 rtnl_xdp_prog_drv(struct net_device *dev)
-{
- return __dev_xdp_query(dev, dev->netdev_ops->ndo_bpf, XDP_QUERY_PROG);
-}
-
-static u32 rtnl_xdp_prog_hw(struct net_device *dev)
-{
- return __dev_xdp_query(dev, dev->netdev_ops->ndo_bpf,
- XDP_QUERY_PROG_HW);
-}
-
static int rtnl_xdp_report_one(struct sk_buff *skb, struct net_device *dev,
u32 *prog_id, u8 *mode, u8 tgt_mode, u32 attr,
- u32 (*get_prog_id)(struct net_device *dev))
+ unsigned int tgt_flags)
{
u32 curr_id;
int err;
- curr_id = get_prog_id(dev);
+ curr_id = dev_xdp_query(dev, tgt_flags);
if (!curr_id)
return 0;
@@ -1421,15 +1398,15 @@ static int rtnl_xdp_fill(struct sk_buff *skb, struct net_device *dev)
prog_id = 0;
mode = XDP_ATTACHED_NONE;
err = rtnl_xdp_report_one(skb, dev, &prog_id, &mode, XDP_ATTACHED_SKB,
- IFLA_XDP_SKB_PROG_ID, rtnl_xdp_prog_skb);
+ IFLA_XDP_SKB_PROG_ID, XDP_FLAGS_SKB_MODE);
if (err)
goto err_cancel;
err = rtnl_xdp_report_one(skb, dev, &prog_id, &mode, XDP_ATTACHED_DRV,
- IFLA_XDP_DRV_PROG_ID, rtnl_xdp_prog_drv);
+ IFLA_XDP_DRV_PROG_ID, XDP_FLAGS_DRV_MODE);
if (err)
goto err_cancel;
err = rtnl_xdp_report_one(skb, dev, &prog_id, &mode, XDP_ATTACHED_HW,
- IFLA_XDP_HW_PROG_ID, rtnl_xdp_prog_hw);
+ IFLA_XDP_HW_PROG_ID, XDP_FLAGS_HW_MODE);
if (err)
goto err_cancel;
--
2.20.1
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