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Message-ID: <20200115121648.GA16763@ranger.igk.intel.com>
Date: Wed, 15 Jan 2020 13:16:48 +0100
From: Maciej Fijalkowski <maciej.fijalkowski@...el.com>
To: Toke Høiland-Jørgensen <toke@...hat.com>
Cc: netdev@...r.kernel.org, bpf@...r.kernel.org,
Daniel Borkmann <daniel@...earbox.net>,
Alexei Starovoitov <ast@...nel.org>,
David Miller <davem@...emloft.net>,
Jesper Dangaard Brouer <brouer@...hat.com>,
Björn Töpel <bjorn.topel@...il.com>,
John Fastabend <john.fastabend@...il.com>
Subject: Re: [PATCH bpf-next v2 2/2] xdp: Use bulking for non-map
XDP_REDIRECT and consolidate code paths
On Mon, Jan 13, 2020 at 07:10:56PM +0100, Toke Høiland-Jørgensen wrote:
> From: Toke Høiland-Jørgensen <toke@...hat.com>
>
> Since the bulk queue used by XDP_REDIRECT now lives in struct net_device,
> we can re-use the bulking for the non-map version of the bpf_redirect()
> helper. This is a simple matter of having xdp_do_redirect_slow() queue the
> frame on the bulk queue instead of sending it out with __bpf_tx_xdp().
>
> Unfortunately we can't make the bpf_redirect() helper return an error if
> the ifindex doesn't exit (as bpf_redirect_map() does), because we don't
> have a reference to the network namespace of the ingress device at the time
> the helper is called. So we have to leave it as-is and keep the device
> lookup in xdp_do_redirect_slow().
>
> Since this leaves less reason to have the non-map redirect code in a
> separate function, so we get rid of the xdp_do_redirect_slow() function
> entirely. This does lose us the tracepoint disambiguation, but fortunately
> the xdp_redirect and xdp_redirect_map tracepoints use the same tracepoint
> entry structures. This means both can contain a map index, so we can just
> amend the tracepoint definitions so we always emit the xdp_redirect(_err)
> tracepoints, but with the map ID only populated if a map is present. This
> means we retire the xdp_redirect_map(_err) tracepoints entirely, but keep
> the definitions around in case someone is still listening for them.
>
> With this change, the performance of the xdp_redirect sample program goes
> from 5Mpps to 8.4Mpps (a 68% increase).
>
> Signed-off-by: Toke Høiland-Jørgensen <toke@...hat.com>
> ---
> include/linux/bpf.h | 13 +++++-
> include/trace/events/xdp.h | 102 +++++++++++++++++++-------------------------
> kernel/bpf/devmap.c | 31 +++++++++----
> net/core/filter.c | 86 +++++++------------------------------
> 4 files changed, 95 insertions(+), 137 deletions(-)
>
> diff --git a/include/linux/bpf.h b/include/linux/bpf.h
> index b14e51d56a82..25c050202536 100644
> --- a/include/linux/bpf.h
> +++ b/include/linux/bpf.h
> @@ -962,7 +962,9 @@ struct sk_buff;
>
> struct bpf_dtab_netdev *__dev_map_lookup_elem(struct bpf_map *map, u32 key);
> struct bpf_dtab_netdev *__dev_map_hash_lookup_elem(struct bpf_map *map, u32 key);
> -void __dev_map_flush(void);
> +void __dev_flush(void);
> +int dev_xdp_enqueue(struct net_device *dev, struct xdp_buff *xdp,
> + struct net_device *dev_rx);
> int dev_map_enqueue(struct bpf_dtab_netdev *dst, struct xdp_buff *xdp,
> struct net_device *dev_rx);
> int dev_map_generic_redirect(struct bpf_dtab_netdev *dst, struct sk_buff *skb,
> @@ -1071,13 +1073,20 @@ static inline struct net_device *__dev_map_hash_lookup_elem(struct bpf_map *map
> return NULL;
> }
>
> -static inline void __dev_map_flush(void)
> +static inline void __dev_flush(void)
> {
> }
>
> struct xdp_buff;
> struct bpf_dtab_netdev;
>
> +static inline
> +int dev_xdp_enqueue(struct net_device *dev, struct xdp_buff *xdp,
> + struct net_device *dev_rx)
> +{
> + return 0;
> +}
> +
> static inline
> int dev_map_enqueue(struct bpf_dtab_netdev *dst, struct xdp_buff *xdp,
> struct net_device *dev_rx)
> diff --git a/include/trace/events/xdp.h b/include/trace/events/xdp.h
> index 72bad13d4a3c..cf568a38f852 100644
> --- a/include/trace/events/xdp.h
> +++ b/include/trace/events/xdp.h
> @@ -79,14 +79,27 @@ TRACE_EVENT(xdp_bulk_tx,
> __entry->sent, __entry->drops, __entry->err)
> );
>
> +#ifndef __DEVMAP_OBJ_TYPE
> +#define __DEVMAP_OBJ_TYPE
> +struct _bpf_dtab_netdev {
> + struct net_device *dev;
> +};
> +#endif /* __DEVMAP_OBJ_TYPE */
> +
> +#define devmap_ifindex(tgt, map) \
> + (((map->map_type == BPF_MAP_TYPE_DEVMAP || \
> + map->map_type == BPF_MAP_TYPE_DEVMAP_HASH)) ? \
> + ((struct _bpf_dtab_netdev *)tgt)->dev->ifindex : 0)
> +
Delete one blank line
> +
> DECLARE_EVENT_CLASS(xdp_redirect_template,
>
> TP_PROTO(const struct net_device *dev,
> const struct bpf_prog *xdp,
> - int to_ifindex, int err,
> - const struct bpf_map *map, u32 map_index),
> + const void *tgt, int err,
> + const struct bpf_map *map, u32 index),
>
> - TP_ARGS(dev, xdp, to_ifindex, err, map, map_index),
> + TP_ARGS(dev, xdp, tgt, err, map, index),
>
> TP_STRUCT__entry(
> __field(int, prog_id)
> @@ -103,90 +116,65 @@ DECLARE_EVENT_CLASS(xdp_redirect_template,
> __entry->act = XDP_REDIRECT;
> __entry->ifindex = dev->ifindex;
> __entry->err = err;
> - __entry->to_ifindex = to_ifindex;
> + __entry->to_ifindex = map ? devmap_ifindex(tgt, map) :
> + index;
> __entry->map_id = map ? map->id : 0;
> - __entry->map_index = map_index;
> + __entry->map_index = map ? index : 0;
> ),
>
> - TP_printk("prog_id=%d action=%s ifindex=%d to_ifindex=%d err=%d",
> + TP_printk("prog_id=%d action=%s ifindex=%d to_ifindex=%d err=%d"
> + " map_id=%d map_index=%d",
> __entry->prog_id,
> __print_symbolic(__entry->act, __XDP_ACT_SYM_TAB),
> __entry->ifindex, __entry->to_ifindex,
> - __entry->err)
> + __entry->err, __entry->map_id, __entry->map_index)
> );
>
> DEFINE_EVENT(xdp_redirect_template, xdp_redirect,
> TP_PROTO(const struct net_device *dev,
> const struct bpf_prog *xdp,
> - int to_ifindex, int err,
> - const struct bpf_map *map, u32 map_index),
> - TP_ARGS(dev, xdp, to_ifindex, err, map, map_index)
> + const void *tgt, int err,
> + const struct bpf_map *map, u32 index),
> + TP_ARGS(dev, xdp, tgt, err, map, index)
> );
>
> DEFINE_EVENT(xdp_redirect_template, xdp_redirect_err,
> TP_PROTO(const struct net_device *dev,
> const struct bpf_prog *xdp,
> - int to_ifindex, int err,
> - const struct bpf_map *map, u32 map_index),
> - TP_ARGS(dev, xdp, to_ifindex, err, map, map_index)
> + const void *tgt, int err,
> + const struct bpf_map *map, u32 index),
> + TP_ARGS(dev, xdp, tgt, err, map, index)
> );
>
> #define _trace_xdp_redirect(dev, xdp, to) \
> - trace_xdp_redirect(dev, xdp, to, 0, NULL, 0);
> + trace_xdp_redirect(dev, xdp, NULL, 0, NULL, to);
>
> #define _trace_xdp_redirect_err(dev, xdp, to, err) \
> - trace_xdp_redirect_err(dev, xdp, to, err, NULL, 0);
> + trace_xdp_redirect_err(dev, xdp, NULL, err, NULL, to);
> +
> +#define _trace_xdp_redirect_map(dev, xdp, to, map, index) \
> + trace_xdp_redirect(dev, xdp, to, 0, map, index);
>
> -DEFINE_EVENT_PRINT(xdp_redirect_template, xdp_redirect_map,
> +#define _trace_xdp_redirect_map_err(dev, xdp, to, map, index, err) \
> + trace_xdp_redirect_err(dev, xdp, to, err, map, index);
> +
> +/* not used anymore, but kept around so as not to break old programs */
> +DEFINE_EVENT(xdp_redirect_template, xdp_redirect_map,
> TP_PROTO(const struct net_device *dev,
> const struct bpf_prog *xdp,
> - int to_ifindex, int err,
> - const struct bpf_map *map, u32 map_index),
> - TP_ARGS(dev, xdp, to_ifindex, err, map, map_index),
> - TP_printk("prog_id=%d action=%s ifindex=%d to_ifindex=%d err=%d"
> - " map_id=%d map_index=%d",
> - __entry->prog_id,
> - __print_symbolic(__entry->act, __XDP_ACT_SYM_TAB),
> - __entry->ifindex, __entry->to_ifindex,
> - __entry->err,
> - __entry->map_id, __entry->map_index)
> + const void *tgt, int err,
> + const struct bpf_map *map, u32 index),
> + TP_ARGS(dev, xdp, tgt, err, map, index)
> );
>
> -DEFINE_EVENT_PRINT(xdp_redirect_template, xdp_redirect_map_err,
> +DEFINE_EVENT(xdp_redirect_template, xdp_redirect_map_err,
> TP_PROTO(const struct net_device *dev,
> const struct bpf_prog *xdp,
> - int to_ifindex, int err,
> - const struct bpf_map *map, u32 map_index),
> - TP_ARGS(dev, xdp, to_ifindex, err, map, map_index),
> - TP_printk("prog_id=%d action=%s ifindex=%d to_ifindex=%d err=%d"
> - " map_id=%d map_index=%d",
> - __entry->prog_id,
> - __print_symbolic(__entry->act, __XDP_ACT_SYM_TAB),
> - __entry->ifindex, __entry->to_ifindex,
> - __entry->err,
> - __entry->map_id, __entry->map_index)
> + const void *tgt, int err,
> + const struct bpf_map *map, u32 index),
> + TP_ARGS(dev, xdp, tgt, err, map, index)
> );
>
> -#ifndef __DEVMAP_OBJ_TYPE
> -#define __DEVMAP_OBJ_TYPE
> -struct _bpf_dtab_netdev {
> - struct net_device *dev;
> -};
> -#endif /* __DEVMAP_OBJ_TYPE */
> -
> -#define devmap_ifindex(fwd, map) \
> - ((map->map_type == BPF_MAP_TYPE_DEVMAP || \
> - map->map_type == BPF_MAP_TYPE_DEVMAP_HASH) ? \
> - ((struct _bpf_dtab_netdev *)fwd)->dev->ifindex : 0)
> -
> -#define _trace_xdp_redirect_map(dev, xdp, fwd, map, idx) \
> - trace_xdp_redirect_map(dev, xdp, devmap_ifindex(fwd, map), \
> - 0, map, idx)
> -
> -#define _trace_xdp_redirect_map_err(dev, xdp, fwd, map, idx, err) \
> - trace_xdp_redirect_map_err(dev, xdp, devmap_ifindex(fwd, map), \
> - err, map, idx)
> -
> TRACE_EVENT(xdp_cpumap_kthread,
>
> TP_PROTO(int map_id, unsigned int processed, unsigned int drops,
> diff --git a/kernel/bpf/devmap.c b/kernel/bpf/devmap.c
> index 030d125c3839..db32272c4f77 100644
> --- a/kernel/bpf/devmap.c
> +++ b/kernel/bpf/devmap.c
> @@ -81,7 +81,7 @@ struct bpf_dtab {
> u32 n_buckets;
> };
>
> -static DEFINE_PER_CPU(struct list_head, dev_map_flush_list);
> +static DEFINE_PER_CPU(struct list_head, dev_flush_list);
> static DEFINE_SPINLOCK(dev_map_lock);
> static LIST_HEAD(dev_map_list);
>
> @@ -357,16 +357,16 @@ static int bq_xmit_all(struct xdp_dev_bulk_queue *bq, u32 flags)
> goto out;
> }
>
> -/* __dev_map_flush is called from xdp_do_flush_map() which _must_ be signaled
> +/* __dev_flush is called from xdp_do_flush_map() which _must_ be signaled
> * from the driver before returning from its napi->poll() routine. The poll()
> * routine is called either from busy_poll context or net_rx_action signaled
> * from NET_RX_SOFTIRQ. Either way the poll routine must complete before the
> * net device can be torn down. On devmap tear down we ensure the flush list
> * is empty before completing to ensure all flush operations have completed.
> */
> -void __dev_map_flush(void)
> +void __dev_flush(void)
> {
> - struct list_head *flush_list = this_cpu_ptr(&dev_map_flush_list);
> + struct list_head *flush_list = this_cpu_ptr(&dev_flush_list);
> struct xdp_dev_bulk_queue *bq, *tmp;
>
> rcu_read_lock();
> @@ -398,7 +398,7 @@ static int bq_enqueue(struct net_device *dev, struct xdp_frame *xdpf,
> struct net_device *dev_rx)
>
^^^
While you're at this part of code maybe you could remove another blank
line? :)
> {
> - struct list_head *flush_list = this_cpu_ptr(&dev_map_flush_list);
> + struct list_head *flush_list = this_cpu_ptr(&dev_flush_list);
> struct xdp_dev_bulk_queue *bq = this_cpu_ptr(dev->xdp_bulkq);
>
> if (unlikely(bq->count == DEV_MAP_BULK_SIZE))
> @@ -419,10 +419,9 @@ static int bq_enqueue(struct net_device *dev, struct xdp_frame *xdpf,
> return 0;
> }
>
> -int dev_map_enqueue(struct bpf_dtab_netdev *dst, struct xdp_buff *xdp,
> - struct net_device *dev_rx)
> +static inline int _xdp_enqueue(struct net_device *dev, struct xdp_buff *xdp,
> + struct net_device *dev_rx)
> {
> - struct net_device *dev = dst->dev;
> struct xdp_frame *xdpf;
> int err;
>
> @@ -440,6 +439,20 @@ int dev_map_enqueue(struct bpf_dtab_netdev *dst, struct xdp_buff *xdp,
> return bq_enqueue(dev, xdpf, dev_rx);
> }
>
> +int dev_xdp_enqueue(struct net_device *dev, struct xdp_buff *xdp,
> + struct net_device *dev_rx)
> +{
> + return _xdp_enqueue(dev, xdp, dev_rx);
AFAIK normally the internal functions are prefixed with a double
underscore, no? Could we have it renamed to __xdp_enqueue?
> +}
> +
> +int dev_map_enqueue(struct bpf_dtab_netdev *dst, struct xdp_buff *xdp,
> + struct net_device *dev_rx)
> +{
> + struct net_device *dev = dst->dev;
> +
> + return _xdp_enqueue(dev, xdp, dev_rx);
> +}
> +
> int dev_map_generic_redirect(struct bpf_dtab_netdev *dst, struct sk_buff *skb,
> struct bpf_prog *xdp_prog)
> {
> @@ -762,7 +775,7 @@ static int __init dev_map_init(void)
> register_netdevice_notifier(&dev_map_notifier);
>
> for_each_possible_cpu(cpu)
> - INIT_LIST_HEAD(&per_cpu(dev_map_flush_list, cpu));
> + INIT_LIST_HEAD(&per_cpu(dev_flush_list, cpu));
> return 0;
> }
>
> diff --git a/net/core/filter.c b/net/core/filter.c
> index 42fd17c48c5f..f023f3a8f351 100644
> --- a/net/core/filter.c
> +++ b/net/core/filter.c
> @@ -3458,58 +3458,6 @@ static const struct bpf_func_proto bpf_xdp_adjust_meta_proto = {
> .arg2_type = ARG_ANYTHING,
> };
>
> -static int __bpf_tx_xdp(struct net_device *dev,
> - struct bpf_map *map,
> - struct xdp_buff *xdp,
> - u32 index)
> -{
> - struct xdp_frame *xdpf;
> - int err, sent;
> -
> - if (!dev->netdev_ops->ndo_xdp_xmit) {
> - return -EOPNOTSUPP;
> - }
> -
> - err = xdp_ok_fwd_dev(dev, xdp->data_end - xdp->data);
> - if (unlikely(err))
> - return err;
> -
> - xdpf = convert_to_xdp_frame(xdp);
> - if (unlikely(!xdpf))
> - return -EOVERFLOW;
> -
> - sent = dev->netdev_ops->ndo_xdp_xmit(dev, 1, &xdpf, XDP_XMIT_FLUSH);
> - if (sent <= 0)
> - return sent;
> - return 0;
> -}
> -
> -static noinline int
> -xdp_do_redirect_slow(struct net_device *dev, struct xdp_buff *xdp,
> - struct bpf_prog *xdp_prog, struct bpf_redirect_info *ri)
> -{
> - struct net_device *fwd;
> - u32 index = ri->tgt_index;
> - int err;
> -
> - fwd = dev_get_by_index_rcu(dev_net(dev), index);
> - ri->tgt_index = 0;
> - if (unlikely(!fwd)) {
> - err = -EINVAL;
> - goto err;
> - }
> -
> - err = __bpf_tx_xdp(fwd, NULL, xdp, 0);
> - if (unlikely(err))
> - goto err;
> -
> - _trace_xdp_redirect(dev, xdp_prog, index);
> - return 0;
> -err:
> - _trace_xdp_redirect_err(dev, xdp_prog, index, err);
> - return err;
> -}
> -
> static int __bpf_tx_xdp_map(struct net_device *dev_rx, void *fwd,
> struct bpf_map *map, struct xdp_buff *xdp)
> {
> @@ -3529,7 +3477,7 @@ static int __bpf_tx_xdp_map(struct net_device *dev_rx, void *fwd,
>
> void xdp_do_flush_map(void)
> {
> - __dev_map_flush();
> + __dev_flush();
Hmm maybe it's also time for s/xdp_do_flush_map/xdp_do_flush ? Drivers
changes, though :<
> __cpu_map_flush();
> __xsk_map_flush();
> }
> @@ -3568,10 +3516,11 @@ void bpf_clear_redirect_map(struct bpf_map *map)
> }
> }
>
> -static int xdp_do_redirect_map(struct net_device *dev, struct xdp_buff *xdp,
> - struct bpf_prog *xdp_prog, struct bpf_map *map,
> - struct bpf_redirect_info *ri)
> +int xdp_do_redirect(struct net_device *dev, struct xdp_buff *xdp,
> + struct bpf_prog *xdp_prog)
> {
> + struct bpf_redirect_info *ri = this_cpu_ptr(&bpf_redirect_info);
> + struct bpf_map *map = READ_ONCE(ri->map);
> u32 index = ri->tgt_index;
> void *fwd = ri->tgt_value;
> int err;
> @@ -3580,7 +3529,18 @@ static int xdp_do_redirect_map(struct net_device *dev, struct xdp_buff *xdp,
> ri->tgt_value = NULL;
> WRITE_ONCE(ri->map, NULL);
>
> - err = __bpf_tx_xdp_map(dev, fwd, map, xdp);
> + if (unlikely(!map)) {
> + fwd = dev_get_by_index_rcu(dev_net(dev), index);
> + if (unlikely(!fwd)) {
> + err = -EINVAL;
> + goto err;
> + }
> +
> + err = dev_xdp_enqueue(fwd, xdp, dev);
> + } else {
> + err = __bpf_tx_xdp_map(dev, fwd, map, xdp);
> + }
> +
> if (unlikely(err))
> goto err;
>
> @@ -3590,18 +3550,6 @@ static int xdp_do_redirect_map(struct net_device *dev, struct xdp_buff *xdp,
> _trace_xdp_redirect_map_err(dev, xdp_prog, fwd, map, index, err);
> return err;
> }
> -
> -int xdp_do_redirect(struct net_device *dev, struct xdp_buff *xdp,
> - struct bpf_prog *xdp_prog)
> -{
> - struct bpf_redirect_info *ri = this_cpu_ptr(&bpf_redirect_info);
> - struct bpf_map *map = READ_ONCE(ri->map);
> -
> - if (likely(map))
> - return xdp_do_redirect_map(dev, xdp, xdp_prog, map, ri);
> -
> - return xdp_do_redirect_slow(dev, xdp, xdp_prog, ri);
> -}
> EXPORT_SYMBOL_GPL(xdp_do_redirect);
>
> static int xdp_do_generic_redirect_map(struct net_device *dev,
>
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