From: David Ahern <dsahern@gmail•com>
To: "Toke Høiland-Jørgensen" <toke@redhat•com>,
"David Ahern" <dsahern@kernel•org>,
netdev@vger•kernel.org
Cc: davem@davemloft•net, kuba@kernel•org,
prashantbhole.linux@gmail•com, jasowang@redhat•com,
brouer@redhat•com, toshiaki.makita1@gmail•com,
daniel@iogearbox•net, john.fastabend@gmail•com, ast@kernel•org,
kafai@fb•com, songliubraving@fb•com, yhs@fb•com, andriin@fb•com,
David Ahern <dahern@digitalocean•com>
Subject: Re: [PATCH RFC-v5 bpf-next 09/12] dev: Support xdp in the Tx path for xdp_frames
Date: Thu, 16 Apr 2020 17:50:58 -0600 [thread overview]
Message-ID: <1a15e955-7018-cb86-e090-e2024f3e0dc9@gmail.com> (raw)
In-Reply-To: <87imhzlea3.fsf@toke.dk>
On 4/16/20 8:02 AM, Toke Høiland-Jørgensen wrote:
>> diff --git a/kernel/bpf/devmap.c b/kernel/bpf/devmap.c
>> index 58bdca5d978a..bedecd07d898 100644
>> --- a/kernel/bpf/devmap.c
>> +++ b/kernel/bpf/devmap.c
>> @@ -322,24 +322,33 @@ static int bq_xmit_all(struct xdp_dev_bulk_queue *bq, u32 flags)
>> {
>> struct net_device *dev = bq->dev;
>> int sent = 0, drops = 0, err = 0;
>> + unsigned int count = bq->count;
>> int i;
>>
>> - if (unlikely(!bq->count))
>> + if (unlikely(!count))
>> return 0;
>>
>> - for (i = 0; i < bq->count; i++) {
>> + for (i = 0; i < count; i++) {
>> struct xdp_frame *xdpf = bq->q[i];
>>
>> prefetch(xdpf);
>> }
>>
>> - sent = dev->netdev_ops->ndo_xdp_xmit(dev, bq->count, bq->q, flags);
>> + if (static_branch_unlikely(&xdp_egress_needed_key)) {
>> + count = do_xdp_egress_frame(dev, bq->q, &count);
>
> nit: seems a bit odd to pass the point to count, then reassign it with
> the return value?
thanks for noticing that. leftover from the evolution of this. changed to
count = do_xdp_egress_frame(dev, bq->q, count);
>> diff --git a/net/core/dev.c b/net/core/dev.c
>> index 1bbaeb8842ed..f23dc6043329 100644
>> --- a/net/core/dev.c
>> +++ b/net/core/dev.c
>> @@ -4720,6 +4720,76 @@ u32 do_xdp_egress_skb(struct net_device *dev, struct sk_buff *skb)
>> }
>> EXPORT_SYMBOL_GPL(do_xdp_egress_skb);
>>
>> +static u32 __xdp_egress_frame(struct net_device *dev,
>> + struct bpf_prog *xdp_prog,
>> + struct xdp_frame *xdp_frame,
>> + struct xdp_txq_info *txq)
>> +{
>> + struct xdp_buff xdp;
>> + u32 act;
>> +
>> + xdp.data_hard_start = xdp_frame->data - xdp_frame->headroom;
>> + xdp.data = xdp_frame->data;
>> + xdp.data_end = xdp.data + xdp_frame->len;
>> + xdp_set_data_meta_invalid(&xdp);
>
> Why invalidate the metadata? On the contrary we'd want metadata from the
> RX side to survive, wouldn't we?
right, replaced with:
xdp.data_meta = xdp.data - metasize;
>
>> + xdp.txq = txq;
>> +
>> + act = bpf_prog_run_xdp(xdp_prog, &xdp);
>> + act = handle_xdp_egress_act(act, dev, xdp_prog);
>> +
>> + /* if not dropping frame, readjust pointers in case
>> + * program made changes to the buffer
>> + */
>> + if (act != XDP_DROP) {
>> + int headroom = xdp.data - xdp.data_hard_start;
>> + int metasize = xdp.data - xdp.data_meta;
>> +
>> + metasize = metasize > 0 ? metasize : 0;
>> + if (unlikely((headroom - metasize) < sizeof(*xdp_frame)))
>> + return XDP_DROP;
>> +
>> + xdp_frame = xdp.data_hard_start;
>> + xdp_frame->data = xdp.data;
>> + xdp_frame->len = xdp.data_end - xdp.data;
>> + xdp_frame->headroom = headroom - sizeof(*xdp_frame);
>> + xdp_frame->metasize = metasize;
>> + /* xdp_frame->mem is unchanged */
>> + }
>> +
>> + return act;
>> +}
>> +
>> +unsigned int do_xdp_egress_frame(struct net_device *dev,
>> + struct xdp_frame **frames,
>> + unsigned int *pcount)
>> +{
>> + struct bpf_prog *xdp_prog;
>> + unsigned int count = *pcount;
>> +
>> + xdp_prog = rcu_dereference(dev->xdp_egress_prog);
>> + if (xdp_prog) {
>> + struct xdp_txq_info txq = { .dev = dev };
>
> Do you have any thoughts on how to populate this for the redirect case?
not sure I understand. This is the redirect case. ie.., On rx a program
is run, XDP_REDIRECT is returned and the packet is queued. Once the
queue fills or flush is done, bq_xmit_all is called to send the frames.
> I guess using Magnus' HWQ abstraction when that lands? Or did you have
> something different in mind?
>
next prev parent reply other threads:[~2020-04-16 23:51 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-04-13 17:17 [PATCH RFC-v5 bpf-next 00/12] Add support for XDP in egress path David Ahern
2020-04-13 17:17 ` [PATCH RFC-v5 bpf-next 01/12] net: Add XDP setup and query commands for Tx programs David Ahern
2020-04-13 17:17 ` [PATCH RFC-v5 bpf-next 02/12] net: Add BPF_XDP_EGRESS as a bpf_attach_type David Ahern
2020-04-16 14:01 ` Toke Høiland-Jørgensen
2020-04-16 16:35 ` David Ahern
2020-04-17 9:23 ` Toke Høiland-Jørgensen
2020-04-13 17:17 ` [PATCH RFC-v5 bpf-next 03/12] xdp: Add xdp_txq_info to xdp_buff David Ahern
2020-04-13 17:17 ` [PATCH RFC-v5 bpf-next 04/12] net: Add IFLA_XDP_EGRESS for XDP programs in the egress path David Ahern
2020-04-13 17:17 ` [PATCH RFC-v5 bpf-next 05/12] net: core: rename netif_receive_generic_xdp to do_generic_xdp_core David Ahern
2020-04-16 14:00 ` Toke Høiland-Jørgensen
2020-04-13 17:17 ` [PATCH RFC-v5 bpf-next 06/12] net: core: Rename do_xdp_generic to do_xdp_generic_rx David Ahern
2020-04-13 17:17 ` [PATCH RFC-v5 bpf-next 07/12] dev: set egress XDP program David Ahern
2020-04-13 17:17 ` [PATCH RFC-v5 bpf-next 08/12] dev: Support xdp in the Tx path for packets as an skb David Ahern
2020-04-13 17:17 ` [PATCH RFC-v5 bpf-next 09/12] dev: Support xdp in the Tx path for xdp_frames David Ahern
2020-04-16 14:02 ` Toke Høiland-Jørgensen
2020-04-16 23:50 ` David Ahern [this message]
2020-04-17 9:25 ` Toke Høiland-Jørgensen
2020-04-17 20:06 ` David Ahern
2020-04-17 8:30 ` Jesper Dangaard Brouer
2020-04-17 21:29 ` David Ahern
2020-04-13 17:17 ` [PATCH RFC-v5 bpf-next 10/12] libbpf: Add egress XDP support David Ahern
2020-04-13 17:18 ` [PATCH RFC-v5 bpf-next 11/12] bpftool: Add support for XDP egress David Ahern
2020-04-13 17:18 ` [PATCH RFC-v5 bpf-next 12/12] samples/bpf: add XDP egress support to xdp1 David Ahern
2020-04-15 15:01 ` Alexei Starovoitov
2020-04-16 13:59 ` [PATCH RFC-v5 bpf-next 00/12] Add support for XDP in egress path Toke Høiland-Jørgensen
2020-04-16 23:55 ` David Ahern
2020-04-17 9:28 ` Toke Høiland-Jørgensen
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