[PATCH RFC bpf-next 08/52] net, xdp: factor out XDP install arguments to a separate structure

Alexander Lobakin
2022-06-28T19:51:10Z

The current way of passing parameters from userland/rtnetlink
(do_set_link()) to dev_change_xdp_fd() and in the end to the drivers
separately does not scale a lot: each new parameter/argument
requires changing the prototypes of several functions at once.
To be able to pass more, derive them into a structure which for now
will contain:
* dev, the actual netdevice,
* extack, Netlink extack to pass arbitrary messages to userland,
* flags, XDP install flags passed from the user.
and use it in the following functions instead of the separate
arguments: dev_change_xdp_fd(), dev_xdp_attach() and
dev_xdp_install(). Adjust the rest accordingly.
Those three are being used in the whole chain 'user -> driver', the
rest can {,dis}appear later, thus not included.

Signed-off-by: Alexander Lobakin <alexandr.lobakin@intel.com>
---
include/linux/netdevice.h | 10 +++++--
net/bpf/dev.c | 61 ++++++++++++++++++++++++---------------
net/core/rtnetlink.c | 10 +++++--
3 files changed, 53 insertions(+), 28 deletions(-)

diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index 0b8169c23f22..1e342c285f48 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -3848,11 +3848,17 @@ struct sk_buff *validate_xmit_skb_list(struct sk_buff *skb, struct net_device *d
struct sk_buff *dev_hard_start_xmit(struct sk_buff *skb, struct net_device *dev,
struct netdev_queue *txq, int *ret);

+struct xdp_install_args {
+ struct net_device *dev;
+ struct netlink_ext_ack *extack;
+ u32 flags;
+};
+
DECLARE_STATIC_KEY_FALSE(generic_xdp_needed_key);

int bpf_xdp_link_attach(const union bpf_attr *attr, struct bpf_prog *prog);
-int dev_change_xdp_fd(struct net_device *dev, struct netlink_ext_ack *extack,
- int fd, int expected_fd, u32 flags);
+int dev_change_xdp_fd(const struct xdp_install_args *args, int fd,
+ int expected_fd);
void dev_xdp_uninstall(struct net_device *dev);
u8 dev_xdp_prog_count(struct net_device *dev);
u32 dev_xdp_prog_id(struct net_device *dev, enum bpf_xdp_mode mode);
diff --git a/net/bpf/dev.c b/net/bpf/dev.c
index 0010b20719e8..7df42bb886ad 100644
--- a/net/bpf/dev.c
+++ b/net/bpf/dev.c
@@ -350,17 +350,17 @@ static void dev_xdp_set_prog(struct net_device *dev, enum bpf_xdp_mode mode,
dev->xdp_state[mode].prog = prog;
}

-static int dev_xdp_install(struct net_device *dev, enum bpf_xdp_mode mode,
- bpf_op_t bpf_op, struct netlink_ext_ack *extack,
- u32 flags, struct bpf_prog *prog)
+static int dev_xdp_install(const struct xdp_install_args *args,
+ enum bpf_xdp_mode mode, bpf_op_t bpf_op,
+ struct bpf_prog *prog)
{
struct netdev_bpf xdp;
int err;

memset(&xdp, 0, sizeof(xdp));
xdp.command = mode == XDP_MODE_HW ? XDP_SETUP_PROG_HW : XDP_SETUP_PROG;
- xdp.extack = extack;
- xdp.flags = flags;
+ xdp.extack = args->extack;
+ xdp.flags = args->flags;
xdp.prog = prog;

/* Drivers assume refcnt is already incremented (i.e, prog pointer is
@@ -371,7 +371,7 @@ static int dev_xdp_install(struct net_device *dev, enum bpf_xdp_mode mode,
*/
if (prog)
bpf_prog_inc(prog);
- err = bpf_op(dev, &xdp);
+ err = bpf_op(args->dev, &xdp);
if (err) {
if (prog)
bpf_prog_put(prog);
@@ -379,13 +379,16 @@ static int dev_xdp_install(struct net_device *dev, enum bpf_xdp_mode mode,
}

if (mode != XDP_MODE_HW)
- bpf_prog_change_xdp(dev_xdp_prog(dev, mode), prog);
+ bpf_prog_change_xdp(dev_xdp_prog(args->dev, mode), prog);

return 0;
}

void dev_xdp_uninstall(struct net_device *dev)
{
+ struct xdp_install_args args = {
+ .dev = dev,
+ };
struct bpf_xdp_link *link;
struct bpf_prog *prog;
enum bpf_xdp_mode mode;
@@ -402,7 +405,7 @@ void dev_xdp_uninstall(struct net_device *dev)
if (!bpf_op)
continue;

- WARN_ON(dev_xdp_install(dev, mode, bpf_op, NULL, 0, NULL));
+ WARN_ON(dev_xdp_install(&args, mode, bpf_op, NULL));

/* auto-detach link from net device */
link = dev_xdp_link(dev, mode);
@@ -415,13 +418,16 @@ void dev_xdp_uninstall(struct net_device *dev)
}
}

-static int dev_xdp_attach(struct net_device *dev, struct netlink_ext_ack *extack,
+static int dev_xdp_attach(const struct xdp_install_args *args,
struct bpf_xdp_link *link, struct bpf_prog *new_prog,
- struct bpf_prog *old_prog, u32 flags)
+ struct bpf_prog *old_prog)
{
- unsigned int num_modes = hweight32(flags & XDP_FLAGS_MODES);
+ unsigned int num_modes = hweight32(args->flags & XDP_FLAGS_MODES);
+ struct netlink_ext_ack *extack = args->extack;
+ struct net_device *dev = args->dev;
struct bpf_prog *cur_prog;
struct net_device *upper;
+ u32 flags = args->flags;
struct list_head *iter;
enum bpf_xdp_mode mode;
bpf_op_t bpf_op;
@@ -519,7 +525,7 @@ static int dev_xdp_attach(struct net_device *dev, struct netlink_ext_ack *extack
return -EOPNOTSUPP;
}

- err = dev_xdp_install(dev, mode, bpf_op, extack, flags, new_prog);
+ err = dev_xdp_install(args, mode, bpf_op, new_prog);
if (err)
return err;
}
@@ -536,12 +542,20 @@ static int dev_xdp_attach(struct net_device *dev, struct netlink_ext_ack *extack

static int dev_xdp_attach_link(struct bpf_xdp_link *link)
{
- return dev_xdp_attach(link->dev, NULL, link, NULL, NULL, link->flags);
+ struct xdp_install_args args = {
+ .dev = link->dev,
+ .flags = link->flags,
+ };
+
+ return dev_xdp_attach(&args, link, NULL, NULL);
}

static int dev_xdp_detach_link(struct bpf_xdp_link *link)
{
struct net_device *dev = link->dev;
+ struct xdp_install_args args = {
+ .dev = dev,
+ };
enum bpf_xdp_mode mode;
bpf_op_t bpf_op;

@@ -552,7 +566,7 @@ static int dev_xdp_detach_link(struct bpf_xdp_link *link)
return -EINVAL;

bpf_op = dev_xdp_bpf_op(dev, mode);
- WARN_ON(dev_xdp_install(dev, mode, bpf_op, NULL, 0, NULL));
+ WARN_ON(dev_xdp_install(&args, mode, bpf_op, NULL));
dev_xdp_set_link(dev, mode, NULL);
return 0;
}
@@ -622,6 +636,10 @@ static int bpf_xdp_link_update(struct bpf_link *link,
struct bpf_prog *old_prog)
{
struct bpf_xdp_link *xdp_link = container_of(link, struct bpf_xdp_link, link);
+ struct xdp_install_args args = {
+ .dev = xdp_link->dev,
+ .flags = xdp_link->flags,
+ };
enum bpf_xdp_mode mode;
bpf_op_t bpf_op;
int err = 0;
@@ -653,8 +671,7 @@ static int bpf_xdp_link_update(struct bpf_link *link,

mode = dev_xdp_mode(xdp_link->dev, 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);
+ err = dev_xdp_install(&args, mode, bpf_op, new_prog);
if (err)
goto out_unlock;

@@ -730,18 +747,16 @@ int bpf_xdp_link_attach(const union bpf_attr *attr, struct bpf_prog *prog)

/**
* dev_change_xdp_fd - set or clear a bpf program for a device rx path
- * @dev: device
- * @extack: netlink extended ack
+ * @args: common XDP arguments (device, extended ack, flags etc.)
* @fd: new program fd or negative value to clear
* @expected_fd: old program fd that userspace expects to replace or clear
- * @flags: xdp-related flags
*
* Set or clear a bpf program for a device
*/
-int dev_change_xdp_fd(struct net_device *dev, struct netlink_ext_ack *extack,
- int fd, int expected_fd, u32 flags)
+int dev_change_xdp_fd(const struct xdp_install_args *args, int fd,
+ int expected_fd)
{
- enum bpf_xdp_mode mode = dev_xdp_mode(dev, flags);
+ enum bpf_xdp_mode mode = dev_xdp_mode(args->dev, args->flags);
struct bpf_prog *new_prog = NULL, *old_prog = NULL;
int err;

@@ -764,7 +779,7 @@ int dev_change_xdp_fd(struct net_device *dev, struct netlink_ext_ack *extack,
}
}

- err = dev_xdp_attach(dev, extack, NULL, new_prog, old_prog, flags);
+ err = dev_xdp_attach(args, NULL, new_prog, old_prog);

err_out:
if (err && new_prog)
diff --git a/net/core/rtnetlink.c b/net/core/rtnetlink.c
index ac45328607f7..5b06ded689b2 100644
--- a/net/core/rtnetlink.c
+++ b/net/core/rtnetlink.c
@@ -2987,6 +2987,11 @@ static int do_setlink(const struct sk_buff *skb,
}

if (xdp[IFLA_XDP_FD]) {
+ struct xdp_install_args args = {
+ .dev = dev,
+ .extack = extack,
+ .flags = xdp_flags,
+ };
int expected_fd = -1;

if (xdp_flags & XDP_FLAGS_REPLACE) {
@@ -2998,10 +3003,9 @@ static int do_setlink(const struct sk_buff *skb,
nla_get_s32(xdp[IFLA_XDP_EXPECTED_FD]);
}

- err = dev_change_xdp_fd(dev, extack,
+ err = dev_change_xdp_fd(&args,
nla_get_s32(xdp[IFLA_XDP_FD]),
- expected_fd,
- xdp_flags);
+ expected_fd);
if (err)
goto errout;
status |= DO_SETLINK_NOTIFY;
--
2.36.1