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linux/include/net/xdp.h

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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>
2018-01-03 18:25:13 +08:00
/* 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);
xdp/qede: setup xdp_rxq_info and intro xdp_rxq_info_is_reg The driver code qede_free_fp_array() depend on kfree() can be called with a NULL pointer. This stems from the qede_alloc_fp_array() function which either (kz)alloc memory for fp->txq or fp->rxq. This also simplifies error handling code in case of memory allocation failures, but xdp_rxq_info_unreg need to know the difference. Introduce xdp_rxq_info_is_reg() to handle if a memory allocation fails and detect this is the failure path by seeing that xdp_rxq_info was not registred yet, which first happens after successful alloaction in qede_init_fp(). Driver hook points for xdp_rxq_info: * reg : qede_init_fp * unreg: qede_free_fp_array Tested on actual hardware with samples/bpf program. V2: Driver have no proper error path for failed XDP RX-queue info reg, as qede_init_fp() is a void function. Cc: everest-linux-l2@cavium.com Cc: Ariel Elior <Ariel.Elior@cavium.com> Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2018-01-03 18:25:34 +08:00
bool xdp_rxq_info_is_reg(struct xdp_rxq_info *xdp_rxq);
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>
2018-01-03 18:25:13 +08:00
#endif /* __LINUX_NET_XDP_H__ */
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