* [PATCH bpf,perf]] bpf,perf: return EOPNOTSUPP for attaching bpf handler on PERF_COUNT_SW_DUMMY
@ 2020-11-14 13:51 Florian Lehner
2020-11-14 16:07 ` Alexei Starovoitov
0 siblings, 1 reply; 3+ messages in thread
From: Florian Lehner @ 2020-11-14 13:51 UTC (permalink / raw)
To: bpf
Cc: netdev, linux-kernel, ast, daniel, andrii, john.fastabend,
peterz, mingo, acme, Florian Lehner
At the moment it is not possible to attach a bpf handler to a perf event
of type PERF_TYPE_SOFTWARE with a configuration of PERF_COUNT_SW_DUMMY.
Signed-off-by: Florian Lehner <dev@der-flo.net>
---
kernel/events/core.c | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/kernel/events/core.c b/kernel/events/core.c
index da467e1dd49a..4e8846b7ceda 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -9668,6 +9668,10 @@ static int perf_event_set_bpf_handler(struct perf_event *event, u32 prog_fd)
if (event->prog)
return -EEXIST;
+ if (event->attr.type == PERF_TYPE_SOFTWARE &&
+ event->attr.config == PERF_COUNT_SW_DUMMY)
+ return -EOPNOTSUPP;
+
prog = bpf_prog_get_type(prog_fd, BPF_PROG_TYPE_PERF_EVENT);
if (IS_ERR(prog))
return PTR_ERR(prog);
--
2.28.0
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH bpf,perf]] bpf,perf: return EOPNOTSUPP for attaching bpf handler on PERF_COUNT_SW_DUMMY
2020-11-14 13:51 [PATCH bpf,perf]] bpf,perf: return EOPNOTSUPP for attaching bpf handler on PERF_COUNT_SW_DUMMY Florian Lehner
@ 2020-11-14 16:07 ` Alexei Starovoitov
2020-11-14 18:49 ` Florian Lehner
0 siblings, 1 reply; 3+ messages in thread
From: Alexei Starovoitov @ 2020-11-14 16:07 UTC (permalink / raw)
To: Florian Lehner
Cc: bpf, Network Development, LKML, Alexei Starovoitov,
Daniel Borkmann, Andrii Nakryiko, John Fastabend, Peter Zijlstra,
Ingo Molnar, Arnaldo Carvalho de Melo
On Sat, Nov 14, 2020 at 5:53 AM Florian Lehner <dev@der-flo.net> wrote:
>
> At the moment it is not possible to attach a bpf handler to a perf event
> of type PERF_TYPE_SOFTWARE with a configuration of PERF_COUNT_SW_DUMMY.
It is possible or it is not possible?
Such "commit log as an abstract statement" patches are a mystery to a reader.
Please explain what problem you're trying to solve and how it's being addressed.
> Signed-off-by: Florian Lehner <dev@der-flo.net>
> ---
> kernel/events/core.c | 4 ++++
> 1 file changed, 4 insertions(+)
>
> diff --git a/kernel/events/core.c b/kernel/events/core.c
> index da467e1dd49a..4e8846b7ceda 100644
> --- a/kernel/events/core.c
> +++ b/kernel/events/core.c
> @@ -9668,6 +9668,10 @@ static int perf_event_set_bpf_handler(struct perf_event *event, u32 prog_fd)
> if (event->prog)
> return -EEXIST;
>
> + if (event->attr.type == PERF_TYPE_SOFTWARE &&
> + event->attr.config == PERF_COUNT_SW_DUMMY)
> + return -EOPNOTSUPP;
Is it a fix or a feature?
If it is a fix please add 'Fixes:' tag.
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH bpf,perf]] bpf,perf: return EOPNOTSUPP for attaching bpf handler on PERF_COUNT_SW_DUMMY
2020-11-14 16:07 ` Alexei Starovoitov
@ 2020-11-14 18:49 ` Florian Lehner
0 siblings, 0 replies; 3+ messages in thread
From: Florian Lehner @ 2020-11-14 18:49 UTC (permalink / raw)
To: Alexei Starovoitov
Cc: acme, andrii, ast, bpf, daniel, john.fastabend, linux-kernel,
mingo, netdev, peterz
On Sat, Nov 14, 2020 at 08:07:29AM -0800, Alexei Starovoitov wrote:
> On Sat, Nov 14, 2020 at 5:53 AM Florian Lehner <dev@der-flo.net> wrote:
> >
> > At the moment it is not possible to attach a bpf handler to a perf event
> > of type PERF_TYPE_SOFTWARE with a configuration of PERF_COUNT_SW_DUMMY.
>
> It is possible or it is not possible?
>
> Such "commit log as an abstract statement" patches are a mystery to a reader.
> Please explain what problem you're trying to solve and how it's being addressed.
Perf events of type software/dummy are just placeholder events and don't
require a counting event. So attaching the bpf handler to the
overflow_handler of this event does not trigger the execution of the bpf
handler.
So the idea of this fix was to indicate to the user that attaching a bpf
handler to such a perf event is not (yet) supported.
> > Signed-off-by: Florian Lehner <dev@der-flo.net>
> > ---
> > kernel/events/core.c | 4 ++++
> > 1 file changed, 4 insertions(+)
> >
> > diff --git a/kernel/events/core.c b/kernel/events/core.c
> > index da467e1dd49a..4e8846b7ceda 100644
> > --- a/kernel/events/core.c
> > +++ b/kernel/events/core.c
> > @@ -9668,6 +9668,10 @@ static int perf_event_set_bpf_handler(struct perf_event *event, u32 prog_fd)
> > if (event->prog)
> > return -EEXIST;
> >
> > + if (event->attr.type == PERF_TYPE_SOFTWARE &&
> > + event->attr.config == PERF_COUNT_SW_DUMMY)
> > + return -EOPNOTSUPP;
>
> Is it a fix or a feature?
> If it is a fix please add 'Fixes:' tag.
I was not sure how to address it and so I have chosen PATCH. As bpf
handlers are still not executed on such events, I also would not call it
a feature.
^ permalink raw reply [flat|nested] 3+ messages in thread
end of thread, other threads:[~2020-11-14 18:51 UTC | newest]
Thread overview: 3+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2020-11-14 13:51 [PATCH bpf,perf]] bpf,perf: return EOPNOTSUPP for attaching bpf handler on PERF_COUNT_SW_DUMMY Florian Lehner
2020-11-14 16:07 ` Alexei Starovoitov
2020-11-14 18:49 ` Florian Lehner
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).