linux-kernel - Re: [PATCH v3 1/3] bpf: Add new bpf map type to store the pointer to struct perf

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Message-ID: <20150803093801.GF19282@twins.programming.kicks-ass.net>
Date:	Mon, 3 Aug 2015 11:38:01 +0200
From:	Peter Zijlstra <peterz@...radead.org>
To:	Kaixu Xia <xiakaixu@...wei.com>
Cc:	ast@...mgrid.com, davem@...emloft.net, acme@...nel.org,
	mingo@...hat.com, masami.hiramatsu.pt@...achi.com,
	jolsa@...nel.org, wangnan0@...wei.com,
	linux-kernel@...r.kernel.org, pi3orama@....com, hekuang@...wei.com
Subject: Re: [PATCH v3 1/3] bpf: Add new bpf map type to store the pointer to
 struct perf_event

On Thu, Jul 23, 2015 at 09:42:40AM +0000, Kaixu Xia wrote:
> +static struct perf_event *convert_map_with_perf_event(void *value)
> +{
> +	struct perf_event *event;
> +	u32 fd;
> +
> +	fd = *(u32 *)value;
> +
> +	event = perf_event_get(fd);
> +	if (IS_ERR(event))
> +		return NULL;
> +
> +	/* limit the event type to PERF_TYPE_RAW
> +	 * and PERF_TYPE_HARDWARE.
> +	 */
> +	if (event->attr.type != PERF_TYPE_RAW &&
> +	    event->attr.type != PERF_TYPE_HARDWARE)
> +		return NULL;

Aside from the ref-leak already mentioned; please introduce something
like:

const struct perf_event_attr *perf_event_attrs(struct perf_event *event);

To avoid having to poke inside of the event outside of perf code.

> +
> +	return event;
> +}
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