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author | Jesper Dangaard Brouer <brouer@redhat.com> | 2018-01-03 13:25:13 +0300 |
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committer | Alexei Starovoitov <ast@kernel.org> | 2018-01-06 02:21:20 +0300 |
commit | aecd67b60722dd24353b0bc50e78a55b30707dcd (patch) | |
tree | d9c107a5ab64864470ab7d2173340cc428cd562c /include/net/xdp.h | |
parent | 5f103c5d4dbadec0f2cacd39b6429e1b8a8cf983 (diff) | |
download | linux-aecd67b60722dd24353b0bc50e78a55b30707dcd.tar.xz |
xdp: base API for new XDP rx-queue info concept
This patch only introduce the core data structures and API functions.
All XDP enabled drivers must use the API before this info can used.
There is a need for XDP to know more about the RX-queue a given XDP
frames have arrived on. For both the XDP bpf-prog and kernel side.
Instead of extending xdp_buff each time new info is needed, the patch
creates a separate read-mostly struct xdp_rxq_info, that contains this
info. We stress this data/cache-line is for read-only info. This is
NOT for dynamic per packet info, use the data_meta for such use-cases.
The performance advantage is this info can be setup at RX-ring init
time, instead of updating N-members in xdp_buff. A possible (driver
level) micro optimization is that xdp_buff->rxq assignment could be
done once per XDP/NAPI loop. The extra pointer deref only happens for
program needing access to this info (thus, no slowdown to existing
use-cases).
Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Diffstat (limited to 'include/net/xdp.h')
-rw-r--r-- | include/net/xdp.h | 47 |
1 files changed, 47 insertions, 0 deletions
diff --git a/include/net/xdp.h b/include/net/xdp.h new file mode 100644 index 000000000000..86c41631a908 --- /dev/null +++ b/include/net/xdp.h @@ -0,0 +1,47 @@ +/* include/net/xdp.h + * + * Copyright (c) 2017 Jesper Dangaard Brouer, Red Hat Inc. + * Released under terms in GPL version 2. See COPYING. + */ +#ifndef __LINUX_NET_XDP_H__ +#define __LINUX_NET_XDP_H__ + +/** + * DOC: XDP RX-queue information + * + * The XDP RX-queue info (xdp_rxq_info) is associated with the driver + * level RX-ring queues. It is information that is specific to how + * the driver have configured a given RX-ring queue. + * + * Each xdp_buff frame received in the driver carry a (pointer) + * reference to this xdp_rxq_info structure. This provides the XDP + * data-path read-access to RX-info for both kernel and bpf-side + * (limited subset). + * + * For now, direct access is only safe while running in NAPI/softirq + * context. Contents is read-mostly and must not be updated during + * driver NAPI/softirq poll. + * + * The driver usage API is a register and unregister API. + * + * The struct is not directly tied to the XDP prog. A new XDP prog + * can be attached as long as it doesn't change the underlying + * RX-ring. If the RX-ring does change significantly, the NIC driver + * naturally need to stop the RX-ring before purging and reallocating + * memory. In that process the driver MUST call unregistor (which + * also apply for driver shutdown and unload). The register API is + * also mandatory during RX-ring setup. + */ + +struct xdp_rxq_info { + struct net_device *dev; + u32 queue_index; + u32 reg_state; +} ____cacheline_aligned; /* perf critical, avoid false-sharing */ + +int xdp_rxq_info_reg(struct xdp_rxq_info *xdp_rxq, + struct net_device *dev, u32 queue_index); +void xdp_rxq_info_unreg(struct xdp_rxq_info *xdp_rxq); +void xdp_rxq_info_unused(struct xdp_rxq_info *xdp_rxq); + +#endif /* __LINUX_NET_XDP_H__ */ |