Andrii Nakryiko <andriin@xxxxxx> writes:
Further refactor XDP attachment code. dev_change_xdp_fd() is
split into two
parts: getting bpf_progs from FDs and attachment logic, working
with
bpf_progs. This makes attachment logic a bit more
straightforward and
prepares code for bpf_xdp_link inclusion, which will share the
common logic.
Signed-off-by: Andrii Nakryiko <andriin@xxxxxx>
---
net/core/dev.c | 165
+++++++++++++++++++++++++++----------------------
1 file changed, 91 insertions(+), 74 deletions(-)
diff --git a/net/core/dev.c b/net/core/dev.c
index 7e753e248cef..abf573b2dcf4 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -8815,111 +8815,128 @@ static void dev_xdp_uninstall(struct
net_device *dev)
}
}
-/**
- * dev_change_xdp_fd - set or clear a bpf program for a
device rx path
- * @dev: device
- * @extack: netlink extended ack
- * @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)
+static int dev_xdp_attach(struct net_device *dev, struct
netlink_ext_ack *extack,
+ struct bpf_prog *new_prog, struct
bpf_prog *old_prog,
+ u32 flags)
{
- const struct net_device_ops *ops = dev->netdev_ops;
- enum bpf_xdp_mode mode = dev_xdp_mode(flags);
- bool offload = mode == XDP_MODE_HW;
- u32 prog_id, expected_id = 0;
- struct bpf_prog *prog;
+ struct bpf_prog *cur_prog;
+ enum bpf_xdp_mode mode;
bpf_op_t bpf_op;
int err;
ASSERT_RTNL();
- bpf_op = dev_xdp_bpf_op(dev, mode);
- if (!bpf_op) {
- NL_SET_ERR_MSG(extack, "underlying driver does not
support XDP in native mode");
- return -EOPNOTSUPP;
+ /* just one XDP mode bit should be set, zero defaults to
SKB mode */
+ if (hweight32(flags & XDP_FLAGS_MODES) > 1) {
Not sure if it's more efficient but running
if ((flags & XDP) & ((flags & XDP) - 1) != 0)
returns whether a number is a multiple of 2.
Should be equivalent to what you checked with hweight32. It is
less readable though. Just thought I'd throw that in.
Taken from
https://graphics.stanford.edu/~seander/bithacks.html#DetermineIfPowerOf2
+ NL_SET_ERR_MSG(extack, "Only one XDP mode flag can
be set");
+ return -EINVAL;
+ }
+ /* old_prog != NULL implies XDP_FLAGS_REPLACE is set */
+ if (old_prog && !(flags & XDP_FLAGS_REPLACE)) {
+ NL_SET_ERR_MSG(extack, "XDP_FLAGS_REPLACE is not
specified");
+ return -EINVAL;
}
- prog_id = dev_xdp_prog_id(dev, mode);
- if (flags & XDP_FLAGS_REPLACE) {
- if (expected_fd >= 0) {
- prog = bpf_prog_get_type_dev(expected_fd,
-
BPF_PROG_TYPE_XDP,
- bpf_op ==
ops->ndo_bpf);
- if (IS_ERR(prog))
- return PTR_ERR(prog);
- expected_id = prog->aux->id;
- bpf_prog_put(prog);
- }
-
- if (prog_id != expected_id) {
- NL_SET_ERR_MSG(extack, "Active program
does not match expected");
- return -EEXIST;
- }
+ mode = dev_xdp_mode(flags);
+ cur_prog = dev_xdp_prog(dev, mode);
+ if ((flags & XDP_FLAGS_REPLACE) && cur_prog != old_prog) {
+ NL_SET_ERR_MSG(extack, "Active program does not
match expected");
+ return -EEXIST;
}
- if (fd >= 0) {
+ if ((flags & XDP_FLAGS_UPDATE_IF_NOEXIST) && cur_prog) {
+ NL_SET_ERR_MSG(extack, "XDP program already
attached");
+ return -EBUSY;
+ }
+
+ if (new_prog) {
+ bool offload = mode == XDP_MODE_HW;
enum bpf_xdp_mode other_mode = mode ==
XDP_MODE_SKB
? XDP_MODE_DRV :
XDP_MODE_SKB;
- if (!offload && dev_xdp_prog_id(dev, other_mode))
{
+ if (!offload && dev_xdp_prog(dev, other_mode)) {
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) &&
prog_id) {
- 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);
- if (IS_ERR(prog))
- return PTR_ERR(prog);
-
- if (!offload && bpf_prog_is_dev_bound(prog->aux))
{
+ if (!offload &&
bpf_prog_is_dev_bound(new_prog->aux)) {
NL_SET_ERR_MSG(extack, "Using device-bound
program without HW_MODE flag is not supported");
- bpf_prog_put(prog);
return -EINVAL;
}
-
- if (prog->expected_attach_type == BPF_XDP_DEVMAP)
{
+ if (new_prog->expected_attach_type ==
BPF_XDP_DEVMAP) {
NL_SET_ERR_MSG(extack, "BPF_XDP_DEVMAP
programs can not be attached to a device");
- bpf_prog_put(prog);
return -EINVAL;
}
-
- if (prog->expected_attach_type == BPF_XDP_CPUMAP)
{
- NL_SET_ERR_MSG(extack,
- "BPF_XDP_CPUMAP programs
can not be attached to a device");
- bpf_prog_put(prog);
+ if (new_prog->expected_attach_type ==
BPF_XDP_CPUMAP) {
+ NL_SET_ERR_MSG(extack, "BPF_XDP_CPUMAP
programs can not be attached to a device");
return -EINVAL;
}
+ }
- /* prog->aux->id may be 0 for orphaned
device-bound progs */
- if (prog->aux->id && prog->aux->id == prog_id) {
- bpf_prog_put(prog);
- return 0;
+ /* don't call drivers if the effective program didn't
change */
+ if (new_prog != cur_prog) {
+ bpf_op = dev_xdp_bpf_op(dev, mode);
+ if (!bpf_op) {
+ NL_SET_ERR_MSG(extack, "Underlying driver
does not support XDP in native mode");
+ return -EOPNOTSUPP;
}
- } else {
- if (!prog_id)
- return 0;
- prog = NULL;
- }
- err = dev_xdp_install(dev, mode, bpf_op, extack, flags,
prog);
- if (err < 0 && prog) {
- bpf_prog_put(prog);
- return err;
+ err = dev_xdp_install(dev, mode, bpf_op, extack,
flags, new_prog);
+ if (err)
+ return err;
}
- dev_xdp_set_prog(dev, mode, prog);
+
+ dev_xdp_set_prog(dev, mode, new_prog);
+ if (cur_prog)
+ bpf_prog_put(cur_prog);
return 0;
}
+/**
+ * dev_change_xdp_fd - set or clear a bpf program for a
device rx path
+ * @dev: device
+ * @extack: netlink extended ack
+ * @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)
+{
+ enum bpf_xdp_mode mode = dev_xdp_mode(flags);
+ struct bpf_prog *new_prog = NULL, *old_prog = NULL;
+ int err;
+
+ ASSERT_RTNL();
+
+ if (fd >= 0) {
+ new_prog = bpf_prog_get_type_dev(fd,
BPF_PROG_TYPE_XDP,
+ mode !=
XDP_MODE_SKB);
+ if (IS_ERR(new_prog))
+ return PTR_ERR(new_prog);
+ }
+
+ if (expected_fd >= 0) {
+ old_prog = bpf_prog_get_type_dev(expected_fd,
BPF_PROG_TYPE_XDP,
+ mode !=
XDP_MODE_SKB);
+ if (IS_ERR(old_prog)) {
+ err = PTR_ERR(old_prog);
+ old_prog = NULL;
+ goto err_out;
+ }
+ }
+
+ err = dev_xdp_attach(dev, extack, new_prog, old_prog,
flags);
+
+err_out:
+ if (err && new_prog)
+ bpf_prog_put(new_prog);
+ if (old_prog)
+ bpf_prog_put(old_prog);
+ return err;
+}
+
/**
* dev_new_index - allocate an ifindex
* @net: the applicable net namespace
