> 7f0a838254bd ("bpf, xdp: Maintain info on attached XDP BPF programs in
> net_device")
> inadvertently changed which XDP mode is assumed when no mode flags are
> specified explicitly. Previously, driver mode was preferred, if driver
> supported it. If not, generic SKB mode was chosen. That commit changed default
> to SKB mode always. This patch fixes the issue and restores the original
> logic.
>
> Reported-by: Lorenzo Bianconi <[email protected]>
> Fixes: 7f0a838254bd ("bpf, xdp: Maintain info on attached XDP BPF programs in
> net_device")
> Signed-off-by: Andrii Nakryiko <[email protected]>Hi Andrii, Regarding this patch: Tested-by: Lorenzo Bianconi <[email protected]> I found another similar issue (not sure if it is related yet), the program removal is failing: $ip link show dev eth0 2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 xdp qdisc mq state UP mode DEFAULT group default qlen 1024 link/ether f0:ad:4e:09:6b:57 brd ff:ff:ff:ff:ff:ff prog/xdp id 1 tag 3b185187f1855c4c jited $ip link set dev eth0 xdp off Error: XDP program already attached. Regards, Lorenzo > --- > net/core/dev.c | 14 ++++++++------ > 1 file changed, 8 insertions(+), 6 deletions(-) > > diff --git a/net/core/dev.c b/net/core/dev.c > index b5d1129d8310..d42c9ea0c3c0 100644 > --- a/net/core/dev.c > +++ b/net/core/dev.c > @@ -8742,13 +8742,15 @@ struct bpf_xdp_link { > int flags; > }; > > -static enum bpf_xdp_mode dev_xdp_mode(u32 flags) > +static enum bpf_xdp_mode dev_xdp_mode(struct net_device *dev, u32 flags) > { > if (flags & XDP_FLAGS_HW_MODE) > return XDP_MODE_HW; > if (flags & XDP_FLAGS_DRV_MODE) > return XDP_MODE_DRV; > - return XDP_MODE_SKB; > + if (flags & XDP_FLAGS_SKB_MODE) > + return XDP_MODE_SKB; > + return dev->netdev_ops->ndo_bpf ? XDP_MODE_DRV : XDP_MODE_SKB; > } > > static bpf_op_t dev_xdp_bpf_op(struct net_device *dev, enum bpf_xdp_mode > mode) > @@ -8896,7 +8898,7 @@ static int dev_xdp_attach(struct net_device *dev, > struct netlink_ext_ack *extack > return -EINVAL; > } > > - mode = dev_xdp_mode(flags); > + mode = dev_xdp_mode(dev, flags); > /* can't replace attached link */ > if (dev_xdp_link(dev, mode)) { > NL_SET_ERR_MSG(extack, "Can't replace active BPF XDP link"); > @@ -8984,7 +8986,7 @@ static int dev_xdp_detach_link(struct net_device *dev, > > ASSERT_RTNL(); > > - mode = dev_xdp_mode(link->flags); > + mode = dev_xdp_mode(dev, link->flags); > if (dev_xdp_link(dev, mode) != link) > return -EINVAL; > > @@ -9080,7 +9082,7 @@ static int bpf_xdp_link_update(struct bpf_link *link, > struct bpf_prog *new_prog, > goto out_unlock; > } > > - mode = dev_xdp_mode(xdp_link->flags); > + 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); > @@ -9164,7 +9166,7 @@ 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) > { > - enum bpf_xdp_mode mode = dev_xdp_mode(flags); > + enum bpf_xdp_mode mode = dev_xdp_mode(dev, flags); > struct bpf_prog *new_prog = NULL, *old_prog = NULL; > int err; > > -- > 2.24.1 >
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