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Date: Thu, 21 Feb 2019 13:59:07 +0800
From: Ye Xiaolong <xiaolong.ye@...el.com>
To: Magnus Karlsson <magnus.karlsson@...el.com>
Cc: bjorn.topel@...el.com, ast@...nel.org, daniel@...earbox.net,
netdev@...r.kernel.org, jakub.kicinski@...ronome.com,
bjorn.topel@...il.com, qi.z.zhang@...el.com, brouer@...hat.com
Subject: Re: [PATCH bpf-next v5 1/3] libbpf: add support for using AF_XDP
sockets
Hi Magnus
On 02/19, Magnus Karlsson wrote:
[snip]
>+static int xsk_setup_xdp_prog(struct xsk_socket *xsk)
>+{
>+ bool prog_attached = false;
>+ __u32 prog_id = 0;
>+ int err;
>+
>+ err = bpf_get_link_xdp_id(xsk->ifindex, &prog_id,
>+ xsk->config.xdp_flags);
>+ if (err)
>+ return err;
>+
>+ if (!prog_id) {
>+ prog_attached = true;
>+ err = xsk_create_bpf_maps(xsk);
>+ if (err)
>+ return err;
>+
>+ err = xsk_load_xdp_prog(xsk);
>+ if (err)
>+ goto out_maps;
>+ } else {
>+ xsk->fd = bpf_prog_get_fd_by_id(prog_id);
I suppose it should be
xsk->prog_fd = bpf_prog_get_fd_by_id(prog_id);
>+ }
>+
>+ err = xsk_update_bpf_maps(xsk, true, xsk->fd);
>+ if (err)
>+ goto out_load;
>+
>+ return 0;
>+
>+out_load:
>+ if (prog_attached)
>+ close(xsk->prog_fd);
>+out_maps:
>+ if (prog_attached)
>+ xsk_delete_bpf_maps(xsk);
>+ return err;
>+}
>+
>+int xsk_socket__create(struct xsk_socket **xsk_ptr, const char *ifname,
>+ __u32 queue_id, struct xsk_umem *umem,
>+ struct xsk_ring_cons *rx, struct xsk_ring_prod *tx,
>+ const struct xsk_socket_config *usr_config)
>+{
>+ struct sockaddr_xdp sxdp = {};
>+ struct xdp_mmap_offsets off;
>+ struct xsk_socket *xsk;
>+ socklen_t optlen;
>+ void *map;
>+ int err;
>+
>+ if (!umem || !xsk_ptr || !rx || !tx)
>+ return -EFAULT;
>+
>+ if (umem->refcount) {
>+ pr_warning("Error: shared umems not supported by libbpf.\n");
>+ return -EBUSY;
>+ }
>+
>+ xsk = calloc(1, sizeof(*xsk));
>+ if (!xsk)
>+ return -ENOMEM;
>+
>+ if (umem->refcount++ > 0) {
>+ xsk->fd = socket(AF_XDP, SOCK_RAW, 0);
>+ if (xsk->fd < 0) {
>+ err = -errno;
>+ goto out_xsk_alloc;
>+ }
>+ } else {
>+ xsk->fd = umem->fd;
>+ }
>+
>+ xsk->outstanding_tx = 0;
>+ xsk->queue_id = queue_id;
>+ xsk->umem = umem;
>+ xsk->ifindex = if_nametoindex(ifname);
>+ if (!xsk->ifindex) {
>+ err = -errno;
>+ goto out_socket;
>+ }
>+ strncpy(xsk->ifname, ifname, IFNAMSIZ);
>+
>+ xsk_set_xdp_socket_config(&xsk->config, usr_config);
>+
>+ if (rx) {
>+ err = setsockopt(xsk->fd, SOL_XDP, XDP_RX_RING,
>+ &xsk->config.rx_size,
>+ sizeof(xsk->config.rx_size));
>+ if (err) {
>+ err = -errno;
>+ goto out_socket;
>+ }
>+ }
>+ if (tx) {
>+ err = setsockopt(xsk->fd, SOL_XDP, XDP_TX_RING,
>+ &xsk->config.tx_size,
>+ sizeof(xsk->config.tx_size));
>+ if (err) {
>+ err = -errno;
>+ goto out_socket;
>+ }
>+ }
>+
>+ optlen = sizeof(off);
>+ err = getsockopt(xsk->fd, SOL_XDP, XDP_MMAP_OFFSETS, &off, &optlen);
>+ if (err) {
>+ err = -errno;
>+ goto out_socket;
>+ }
>+
>+ if (rx) {
>+ map = xsk_mmap(NULL, off.rx.desc +
>+ xsk->config.rx_size * sizeof(struct xdp_desc),
>+ PROT_READ | PROT_WRITE,
>+ MAP_SHARED | MAP_POPULATE,
>+ xsk->fd, XDP_PGOFF_RX_RING);
>+ if (map == MAP_FAILED) {
>+ err = -errno;
>+ goto out_socket;
>+ }
>+
>+ rx->mask = xsk->config.rx_size - 1;
>+ rx->size = xsk->config.rx_size;
>+ rx->producer = map + off.rx.producer;
>+ rx->consumer = map + off.rx.consumer;
>+ rx->ring = map + off.rx.desc;
>+ }
>+ xsk->rx = rx;
>+
>+ if (tx) {
>+ map = xsk_mmap(NULL, off.tx.desc +
>+ xsk->config.tx_size * sizeof(struct xdp_desc),
>+ PROT_READ | PROT_WRITE,
>+ MAP_SHARED | MAP_POPULATE,
>+ xsk->fd, XDP_PGOFF_TX_RING);
>+ if (map == MAP_FAILED) {
>+ err = -errno;
>+ goto out_mmap_rx;
>+ }
>+
>+ tx->mask = xsk->config.tx_size - 1;
>+ tx->size = xsk->config.tx_size;
>+ tx->producer = map + off.tx.producer;
>+ tx->consumer = map + off.tx.consumer;
>+ tx->ring = map + off.tx.desc;
>+ tx->cached_cons = xsk->config.tx_size;
>+ }
>+ xsk->tx = tx;
>+
>+ sxdp.sxdp_family = PF_XDP;
>+ sxdp.sxdp_ifindex = xsk->ifindex;
>+ sxdp.sxdp_queue_id = xsk->queue_id;
>+ sxdp.sxdp_flags = xsk->config.bind_flags;
>+
>+ err = bind(xsk->fd, (struct sockaddr *)&sxdp, sizeof(sxdp));
>+ if (err) {
>+ err = -errno;
>+ goto out_mmap_tx;
>+ }
>+
>+ if (!(xsk->config.libbpf_flags & XSK_LIBBPF_FLAGS__INHIBIT_PROG_LOAD)) {
>+ err = xsk_setup_xdp_prog(xsk);
>+ if (err)
>+ goto out_mmap_tx;
>+ }
>+
>+ *xsk_ptr = xsk;
>+ return 0;
>+
>+out_mmap_tx:
>+ if (tx)
>+ munmap(xsk->tx,
>+ off.tx.desc +
>+ xsk->config.tx_size * sizeof(struct xdp_desc));
>+out_mmap_rx:
>+ if (rx)
>+ munmap(xsk->rx,
>+ off.rx.desc +
>+ xsk->config.rx_size * sizeof(struct xdp_desc));
>+out_socket:
>+ if (--umem->refcount)
>+ close(xsk->fd);
>+out_xsk_alloc:
>+ free(xsk);
>+ return err;
>+}
>+
>+int xsk_umem__delete(struct xsk_umem *umem)
>+{
>+ struct xdp_mmap_offsets off;
>+ socklen_t optlen;
>+ int err;
>+
>+ if (!umem)
>+ return 0;
>+
>+ if (umem->refcount)
>+ return -EBUSY;
>+
>+ optlen = sizeof(off);
>+ err = getsockopt(umem->fd, SOL_XDP, XDP_MMAP_OFFSETS, &off, &optlen);
>+ if (!err) {
>+ munmap(umem->fill->ring,
>+ off.fr.desc + umem->config.fill_size * sizeof(__u64));
>+ munmap(umem->comp->ring,
>+ off.cr.desc + umem->config.comp_size * sizeof(__u64));
>+ }
>+
>+ close(umem->fd);
>+ free(umem);
>+
>+ return 0;
>+}
>+
>+void xsk_socket__delete(struct xsk_socket *xsk)
>+{
>+ struct xdp_mmap_offsets off;
>+ socklen_t optlen;
>+ int err;
>+
>+ if (!xsk)
>+ return;
>+
>+ (void)xsk_update_bpf_maps(xsk, 0, 0);
>+
>+ optlen = sizeof(off);
>+ err = getsockopt(xsk->fd, SOL_XDP, XDP_MMAP_OFFSETS, &off, &optlen);
>+ if (!err) {
>+ if (xsk->rx)
>+ munmap(xsk->rx->ring,
>+ off.rx.desc +
>+ xsk->config.rx_size * sizeof(struct xdp_desc));
>+ if (xsk->tx)
>+ munmap(xsk->tx->ring,
>+ off.tx.desc +
>+ xsk->config.tx_size * sizeof(struct xdp_desc));
>+ }
>+
>+ xsk->umem->refcount--;
>+ /* Do not close an fd that also has an associated umem connected
>+ * to it.
>+ */
>+ if (xsk->fd != xsk->umem->fd)
>+ close(xsk->fd);
>+ free(xsk);
>+}
>diff --git a/tools/lib/bpf/xsk.h b/tools/lib/bpf/xsk.h
>new file mode 100644
>index 0000000..a497f00
>--- /dev/null
>+++ b/tools/lib/bpf/xsk.h
>@@ -0,0 +1,203 @@
>+/* SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause) */
>+
>+/*
>+ * AF_XDP user-space access library.
>+ *
>+ * Copyright(c) 2018 - 2019 Intel Corporation.
>+ *
>+ * Author(s): Magnus Karlsson <magnus.karlsson@...el.com>
>+ */
>+
>+#ifndef __LIBBPF_XSK_H
>+#define __LIBBPF_XSK_H
>+
>+#include <stdio.h>
>+#include <stdint.h>
>+#include <linux/if_xdp.h>
>+
>+#include "libbpf.h"
>+
>+#ifdef __cplusplus
>+extern "C" {
>+#endif
>+
>+/* Do not access these members directly. Use the functions below. */
>+#define DEFINE_XSK_RING(name) \
>+struct name { \
>+ __u32 cached_prod; \
>+ __u32 cached_cons; \
>+ __u32 mask; \
>+ __u32 size; \
>+ __u32 *producer; \
>+ __u32 *consumer; \
>+ void *ring; \
>+}
>+
>+DEFINE_XSK_RING(xsk_ring_prod);
>+DEFINE_XSK_RING(xsk_ring_cons);
>+
>+struct xsk_umem;
>+struct xsk_socket;
>+
>+static inline __u64 *xsk_ring_prod__fill_addr(struct xsk_ring_prod *fill,
>+ __u32 idx)
>+{
>+ __u64 *addrs = (__u64 *)fill->ring;
>+
>+ return &addrs[idx & fill->mask];
>+}
>+
>+static inline const __u64 *
>+xsk_ring_cons__comp_addr(const struct xsk_ring_cons *comp, __u32 idx)
>+{
>+ const __u64 *addrs = (const __u64 *)comp->ring;
>+
>+ return &addrs[idx & comp->mask];
>+}
>+
>+static inline struct xdp_desc *xsk_ring_prod__tx_desc(struct xsk_ring_prod *tx,
>+ __u32 idx)
>+{
>+ struct xdp_desc *descs = (struct xdp_desc *)tx->ring;
>+
>+ return &descs[idx & tx->mask];
>+}
>+
>+static inline const struct xdp_desc *
>+xsk_ring_cons__rx_desc(const struct xsk_ring_cons *rx, __u32 idx)
>+{
>+ const struct xdp_desc *descs = (const struct xdp_desc *)rx->ring;
>+
>+ return &descs[idx & rx->mask];
>+}
>+
>+static inline __u32 xsk_prod_nb_free(struct xsk_ring_prod *r, __u32 nb)
>+{
>+ __u32 free_entries = r->cached_cons - r->cached_prod;
>+
>+ if (free_entries >= nb)
>+ return free_entries;
>+
>+ /* Refresh the local tail pointer.
>+ * cached_cons is r->size bigger than the real consumer pointer so
>+ * that this addition can be avoided in the more frequently
>+ * executed code that computs free_entries in the beginning of
>+ * this function. Without this optimization it whould have been
>+ * free_entries = r->cached_prod - r->cached_cons + r->size.
>+ */
>+ r->cached_cons = *r->consumer + r->size;
>+
>+ return r->cached_cons - r->cached_prod;
>+}
>+
>+static inline __u32 xsk_cons_nb_avail(struct xsk_ring_cons *r, __u32 nb)
>+{
>+ __u32 entries = r->cached_prod - r->cached_cons;
>+
>+ if (entries == 0) {
>+ r->cached_prod = *r->producer;
>+ entries = r->cached_prod - r->cached_cons;
>+ }
>+
>+ return (entries > nb) ? nb : entries;
>+}
>+
>+static inline size_t xsk_ring_prod__reserve(struct xsk_ring_prod *prod,
>+ size_t nb, __u32 *idx)
>+{
>+ if (unlikely(xsk_prod_nb_free(prod, nb) < nb))
>+ return 0;
>+
>+ *idx = prod->cached_prod;
>+ prod->cached_prod += nb;
>+
>+ return nb;
>+}
>+
>+static inline void xsk_ring_prod__submit(struct xsk_ring_prod *prod, size_t nb)
>+{
>+ /* Make sure everything has been written to the ring before signalling
>+ * this to the kernel.
>+ */
>+ smp_wmb();
>+
>+ *prod->producer += nb;
>+}
>+
>+static inline size_t xsk_ring_cons__peek(struct xsk_ring_cons *cons,
>+ size_t nb, __u32 *idx)
>+{
>+ size_t entries = xsk_cons_nb_avail(cons, nb);
>+
>+ if (likely(entries > 0)) {
>+ /* Make sure we do not speculatively read the data before
>+ * we have received the packet buffers from the ring.
>+ */
>+ smp_rmb();
>+
>+ *idx = cons->cached_cons;
>+ cons->cached_cons += entries;
>+ }
>+
>+ return entries;
>+}
>+
>+static inline void xsk_ring_cons__release(struct xsk_ring_cons *cons, size_t nb)
>+{
>+ *cons->consumer += nb;
>+}
>+
>+static inline void *xsk_umem__get_data(void *umem_area, __u64 addr)
>+{
>+ return &((char *)umem_area)[addr];
>+}
>+
>+LIBBPF_API int xsk_umem__fd(const struct xsk_umem *umem);
>+LIBBPF_API int xsk_socket__fd(const struct xsk_socket *xsk);
>+
>+#define XSK_RING_CONS__DEFAULT_NUM_DESCS 2048
>+#define XSK_RING_PROD__DEFAULT_NUM_DESCS 2048
>+#define XSK_UMEM__DEFAULT_FRAME_SHIFT 11 /* 2048 bytes */
>+#define XSK_UMEM__DEFAULT_FRAME_SIZE (1 << XSK_UMEM__DEFAULT_FRAME_SHIFT)
>+#define XSK_UMEM__DEFAULT_FRAME_HEADROOM 0
>+
>+struct xsk_umem_config {
>+ __u32 fill_size;
>+ __u32 comp_size;
>+ __u32 frame_size;
>+ __u32 frame_headroom;
>+};
>+
>+/* Flags for the libbpf_flags field. */
>+#define XSK_LIBBPF_FLAGS__INHIBIT_PROG_LOAD (1 << 0)
>+
>+struct xsk_socket_config {
>+ __u32 rx_size;
>+ __u32 tx_size;
>+ __u32 libbpf_flags;
>+ __u32 xdp_flags;
>+ __u16 bind_flags;
>+};
>+
>+/* Set config to NULL to get the default configuration. */
>+LIBBPF_API int xsk_umem__create(struct xsk_umem **umem,
>+ void *umem_area, __u64 size,
>+ struct xsk_ring_prod *fill,
>+ struct xsk_ring_cons *comp,
>+ const struct xsk_umem_config *config);
>+LIBBPF_API int xsk_socket__create(struct xsk_socket **xsk,
>+ const char *ifname, __u32 queue_id,
>+ struct xsk_umem *umem,
>+ struct xsk_ring_cons *rx,
>+ struct xsk_ring_prod *tx,
>+ const struct xsk_socket_config *config);
>+
>+/* Returns 0 for success and -EBUSY if the umem is still in use. */
>+LIBBPF_API int xsk_umem__delete(struct xsk_umem *umem);
>+LIBBPF_API void xsk_socket__delete(struct xsk_socket *xsk);
>+
>+#ifdef __cplusplus
>+} /* extern "C" */
>+#endif
>+
>+#endif /* __LIBBPF_XSK_H */
>--
>2.7.4
>
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