Re: [PATCH v6 2/4] bpf: Add new bpf map type to store the pointer to struct perf_event

[Peter Zijlstra <peterz@infradead.org>]

On Tue, Aug 04, 2015 at 10:43:35AM -0700, Alexei Starovoitov wrote:
> >+static void *perf_event_fd_array_get_ptr(struct bpf_map *map, int fd)
> >+{
> >+	struct perf_event *event;
> >+	struct perf_event_attr *attr;
> >+
> >+	event = perf_event_get(fd);
> >+	if (IS_ERR(event))
> >+		return event;
> >+
> >+	attr = perf_event_attrs(event);
> >+	if (IS_ERR(attr))
> >+		return attr;
> >+
> >+	if (attr->type != PERF_TYPE_RAW &&
> >+	    attr->type != PERF_TYPE_HARDWARE) {
> >+		perf_event_release_kernel(event);
> >+		return ERR_PTR(-EINVAL);
> >+	}
> >+	return event;
> >+}
> 
> I'm not sure whether Peter wanted to see the above function to be
> in events/core.c or not.
> imo it's fine here, since perf_event_attr is an uapi struct.

Right, aside from the const issue this is fine, for the exact reason you
state, perf_event_attr is an exposed interface.