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Message-ID: <20200116122400.499c2b1e@carbon>
Date: Thu, 16 Jan 2020 12:24:00 +0100
From: Jesper Dangaard Brouer <brouer@...hat.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>,
Björn Töpel <bjorn.topel@...il.com>,
John Fastabend <john.fastabend@...il.com>, brouer@...hat.com
Subject: Re: [PATCH bpf-next v2 1/2] xdp: Move devmap bulk queue into struct
net_device
On Wed, 15 Jan 2020 23:11:21 +0100
Toke Høiland-Jørgensen <toke@...hat.com> wrote:
> Jesper Dangaard Brouer <brouer@...hat.com> writes:
>
> > On Mon, 13 Jan 2020 19:10:55 +0100
> > Toke Høiland-Jørgensen <toke@...hat.com> wrote:
> >
> >> diff --git a/kernel/bpf/devmap.c b/kernel/bpf/devmap.c
> >> index da9c832fc5c8..030d125c3839 100644
> >> --- a/kernel/bpf/devmap.c
> >> +++ b/kernel/bpf/devmap.c
> > [...]
> >> @@ -346,8 +340,7 @@ static int bq_xmit_all(struct xdp_bulk_queue *bq, u32 flags)
> >> out:
> >> bq->count = 0;
> >>
> >> - trace_xdp_devmap_xmit(&obj->dtab->map, obj->idx,
> >> - sent, drops, bq->dev_rx, dev, err);
> >> + trace_xdp_devmap_xmit(NULL, 0, sent, drops, bq->dev_rx, dev, err);
> >
> > Hmm ... I don't like that we lose the map_id and map_index identifier.
> > This is part of our troubleshooting interface.
>
> Hmm, I guess I can take another look at whether there's a way to avoid
> that. Any ideas?
Looking at the code and the other tracepoints...
I will actually suggest to remove these two arguments, because the
trace_xdp_redirect_map tracepoint also contains the ifindex'es, and to
troubleshoot people can record both tracepoints and do the correlation
themselves.
When changing the tracepoint I would like to keep member 'drops' and
'sent' at the same struct offsets. As our xdp_monitor example reads
these and I hope we can kept it working this way.
I've coded it up, and tested it. The new xdp_monitor will work on
older kernels, but the old xdp_monitor will fail attaching on newer
kernels. I think this is fair enough, as we are backwards compatible.
[PATCH] devmap: adjust tracepoing after Tokes changes
From: Jesper Dangaard Brouer <brouer@...hat.com>
Signed-off-by: Jesper Dangaard Brouer <brouer@...hat.com>
---
include/trace/events/xdp.h | 29 ++++++++++++-----------------
kernel/bpf/devmap.c | 2 +-
samples/bpf/xdp_monitor_kern.c | 8 +++-----
3 files changed, 16 insertions(+), 23 deletions(-)
diff --git a/include/trace/events/xdp.h b/include/trace/events/xdp.h
index cf568a38f852..f1e64689ce94 100644
--- a/include/trace/events/xdp.h
+++ b/include/trace/events/xdp.h
@@ -247,43 +247,38 @@ TRACE_EVENT(xdp_cpumap_enqueue,
TRACE_EVENT(xdp_devmap_xmit,
- TP_PROTO(const struct bpf_map *map, u32 map_index,
- int sent, int drops,
- const struct net_device *from_dev,
- const struct net_device *to_dev, int err),
+ TP_PROTO(const struct net_device *from_dev,
+ const struct net_device *to_dev,
+ int sent, int drops, int err),
- TP_ARGS(map, map_index, sent, drops, from_dev, to_dev, err),
+ TP_ARGS(from_dev, to_dev, sent, drops, err),
TP_STRUCT__entry(
- __field(int, map_id)
+ __field(int, from_ifindex)
__field(u32, act)
- __field(u32, map_index)
+ __field(int, to_ifindex)
__field(int, drops)
__field(int, sent)
- __field(int, from_ifindex)
- __field(int, to_ifindex)
__field(int, err)
),
TP_fast_assign(
- __entry->map_id = map ? map->id : 0;
+ __entry->from_ifindex = from_dev->ifindex;
__entry->act = XDP_REDIRECT;
- __entry->map_index = map_index;
+ __entry->to_ifindex = to_dev->ifindex;
__entry->drops = drops;
__entry->sent = sent;
- __entry->from_ifindex = from_dev->ifindex;
- __entry->to_ifindex = to_dev->ifindex;
__entry->err = err;
),
TP_printk("ndo_xdp_xmit"
- " map_id=%d map_index=%d action=%s"
+ " from_ifindex=%d to_ifindex=%d action=%s"
" sent=%d drops=%d"
- " from_ifindex=%d to_ifindex=%d err=%d",
- __entry->map_id, __entry->map_index,
+ " err=%d",
+ __entry->from_ifindex, __entry->to_ifindex,
__print_symbolic(__entry->act, __XDP_ACT_SYM_TAB),
__entry->sent, __entry->drops,
- __entry->from_ifindex, __entry->to_ifindex, __entry->err)
+ __entry->err)
);
/* Expect users already include <net/xdp.h>, but not xdp_priv.h */
diff --git a/kernel/bpf/devmap.c b/kernel/bpf/devmap.c
index db32272c4f77..1b4bfe4e06d6 100644
--- a/kernel/bpf/devmap.c
+++ b/kernel/bpf/devmap.c
@@ -340,7 +340,7 @@ static int bq_xmit_all(struct xdp_dev_bulk_queue *bq, u32 flags)
out:
bq->count = 0;
- trace_xdp_devmap_xmit(NULL, 0, sent, drops, bq->dev_rx, dev, err);
+ trace_xdp_devmap_xmit(bq->dev_rx, dev, sent, drops, err);
bq->dev_rx = NULL;
__list_del_clearprev(&bq->flush_node);
return 0;
diff --git a/samples/bpf/xdp_monitor_kern.c b/samples/bpf/xdp_monitor_kern.c
index ad10fe700d7d..39458a44472e 100644
--- a/samples/bpf/xdp_monitor_kern.c
+++ b/samples/bpf/xdp_monitor_kern.c
@@ -222,14 +222,12 @@ struct bpf_map_def SEC("maps") devmap_xmit_cnt = {
*/
struct devmap_xmit_ctx {
u64 __pad; // First 8 bytes are not accessible by bpf code
- int map_id; // offset:8; size:4; signed:1;
+ int from_ifindex; // offset:8; size:4; signed:1;
u32 act; // offset:12; size:4; signed:0;
- u32 map_index; // offset:16; size:4; signed:0;
+ int to_ifindex; // offset:16; size:4; signed:1;
int drops; // offset:20; size:4; signed:1;
int sent; // offset:24; size:4; signed:1;
- int from_ifindex; // offset:28; size:4; signed:1;
- int to_ifindex; // offset:32; size:4; signed:1;
- int err; // offset:36; size:4; signed:1;
+ int err; // offset:28; size:4; signed:1;
};
SEC("tracepoint/xdp/xdp_devmap_xmit")
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