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Date: Wed, 23 Aug 2017 10:54:16 +0200 From: Daniel Borkmann <daniel@...earbox.net> To: Jesper Dangaard Brouer <brouer@...hat.com> CC: netdev@...r.kernel.org, John Fastabend <john.fastabend@...il.com> Subject: Re: [PATCH net-next 5/5] xdp: get tracepoints xdp_exception and xdp_redirect in sync On 08/23/2017 09:41 AM, Jesper Dangaard Brouer wrote: > On Tue, 22 Aug 2017 23:30:21 +0200 > Daniel Borkmann <daniel@...earbox.net> wrote: >> On 08/22/2017 10:47 PM, Jesper Dangaard Brouer wrote: >>> Remove the net_device string name from the xdp_exception tracepoint, >>> like the xdp_redirect tracepoint. >>> >>> Align the TP_STRUCT to have common entries between these two >>> tracepoint. >>> >>> Signed-off-by: Jesper Dangaard Brouer <brouer@...hat.com> >>> --- >>> include/trace/events/xdp.h | 24 ++++++++++++------------ >>> 1 file changed, 12 insertions(+), 12 deletions(-) >>> >>> diff --git a/include/trace/events/xdp.h b/include/trace/events/xdp.h >>> index 7511bed80558..6495b0d9d5c7 100644 >>> --- a/include/trace/events/xdp.h >>> +++ b/include/trace/events/xdp.h >>> @@ -31,22 +31,22 @@ TRACE_EVENT(xdp_exception, >>> TP_ARGS(dev, xdp, act), >>> >>> TP_STRUCT__entry( >>> - __string(name, dev->name) >>> __array(u8, prog_tag, 8) >>> __field(u32, act) >>> + __field(int, ifindex) >>> ), >>> >>> TP_fast_assign( >>> BUILD_BUG_ON(sizeof(__entry->prog_tag) != sizeof(xdp->tag)); >>> memcpy(__entry->prog_tag, xdp->tag, sizeof(xdp->tag)); >>> - __assign_str(name, dev->name); >>> - __entry->act = act; >>> + __entry->act = act; >>> + __entry->ifindex = dev->ifindex; >>> ), >>> >> [...] >>> TRACE_EVENT(xdp_redirect, >>> @@ -57,26 +57,26 @@ TRACE_EVENT(xdp_redirect, >>> TP_ARGS(from_index, to_index, xdp, act, err), >>> >>> TP_STRUCT__entry( >>> - __field(int, from_index) >>> - __field(int, to_index) >>> __array(u8, prog_tag, 8) >>> __field(u32, act) >>> + __field(int, from_index) >>> + __field(int, to_index) >>> __field(int, err) >>> ), >>> >>> TP_fast_assign( >>> BUILD_BUG_ON(sizeof(__entry->prog_tag) != sizeof(xdp->tag)); >>> memcpy(__entry->prog_tag, xdp->tag, sizeof(xdp->tag)); >>> + __entry->act = act; >>> __entry->from_index = from_index; >>> __entry->to_index = to_index; >>> - __entry->act = act; >> >> If you already get them in sync, could you also make it consistent >> that for both tracepoints in TP_ARGS() we use either ifindex >> directly or device pointer and extract it from TP_fast_assign(). >> Right now, it's mixed. > > I did this because, in the (bpf_redirect)_map case, I was hoping that > "from_index" could be come the index from the map. Looking closer at > the devmap design, I cannot see how we can ever know what (the bpf_prog > thinks) is the corresponding map-ingress/from_index. > > Based on that, I think we can/should use the device pointer as arg (as > you suggested). And then rename "from_index" to "ifindex", where > ifindex is the XDP ifindex the xdp_buff arrived on. > > I guess we can keep the "to_index". We also need to extend the > tracepoint args with a "map", to let the trace user tell whether the > "to_index" is an ifindex or a map-index. Yeah, makes sense, right now we cannot differentiate between that. > I'll code this up and submit at V2. Thanks!
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