| Message ID | 20201114135126.29462-1-dev@der-flo.net (mailing list archive) |
|---|---|
| State | Changes Requested |
| Delegated to: | BPF |
| Headers | show |
| Series | [bpf,perf] ] bpf,perf: return EOPNOTSUPP for attaching bpf handler on PERF_COUNT_SW_DUMMY | expand |
| Context | Check | Description |
|---|---|---|
| netdev/cover_letter | success | Link |
| netdev/fixes_present | fail | Series targets non-next tree, but doesn't contain any Fixes tags |
| netdev/patch_count | success | Link |
| netdev/tree_selection | success | Clearly marked for bpf |
| netdev/subject_prefix | success | Link |
| netdev/source_inline | success | Was 0 now: 0 |
| netdev/verify_signedoff | success | Link |
| netdev/module_param | success | Was 0 now: 0 |
| netdev/build_32bit | success | Errors and warnings before: 47 this patch: 47 |
| netdev/kdoc | success | Errors and warnings before: 4 this patch: 4 |
| netdev/verify_fixes | success | Link |
| netdev/checkpatch | success | total: 0 errors, 0 warnings, 0 checks, 10 lines checked |
| netdev/build_allmodconfig_warn | success | Errors and warnings before: 47 this patch: 47 |
| netdev/header_inline | success | Link |
| netdev/stable | success | Stable not CCed |
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.
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.
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);
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(+)