Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752477AbbHEJkZ (ORCPT ); Wed, 5 Aug 2015 05:40:25 -0400 Received: from bombadil.infradead.org ([198.137.202.9]:46109 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752368AbbHEJkW (ORCPT ); Wed, 5 Aug 2015 05:40:22 -0400 Date: Wed, 5 Aug 2015 11:39:58 +0200 From: Peter Zijlstra To: Kaixu Xia Cc: ast@plumgrid.com, davem@davemloft.net, acme@kernel.org, mingo@redhat.com, masami.hiramatsu.pt@hitachi.com, jolsa@kernel.org, daniel@iogearbox.net, wangnan0@huawei.com, linux-kernel@vger.kernel.org, pi3orama@163.com, hekuang@huawei.com, netdev@vger.kernel.org Subject: Re: [PATCH v6 2/4] bpf: Add new bpf map type to store the pointer to struct perf_event Message-ID: <20150805093958.GW25159@twins.programming.kicks-ass.net> References: <1438678696-88289-1-git-send-email-xiakaixu@huawei.com> <1438678696-88289-3-git-send-email-xiakaixu@huawei.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1438678696-88289-3-git-send-email-xiakaixu@huawei.com> User-Agent: Mutt/1.5.21 (2012-12-30) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1734 Lines: 58 On Tue, Aug 04, 2015 at 08:58:14AM +0000, Kaixu Xia wrote: > diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h > index 2027809..81fc99e 100644 > --- a/include/linux/perf_event.h > +++ b/include/linux/perf_event.h > @@ -641,6 +641,8 @@ extern int perf_event_init_task(struct task_struct *child); > extern void perf_event_exit_task(struct task_struct *child); > extern void perf_event_free_task(struct task_struct *task); > extern void perf_event_delayed_put(struct task_struct *task); > +extern struct perf_event *perf_event_get(unsigned int fd); > +extern struct perf_event_attr *perf_event_attrs(struct perf_event *event); const struct perf_event_attr *perf_event_attrs(); > +static void *perf_event_fd_array_get_ptr(struct bpf_map *map, int fd) > +{ > + struct perf_event *event; > + struct perf_event_attr *attr; Also const > + > + 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; > +} > +struct perf_event_attr *perf_event_attrs(struct perf_event *event) Also const > +{ > + if (!event) > + return ERR_PTR(-EINVAL); > + > + return &event->attr; > +} It doesn't make sense (ever) to allow users of this function to change attributes of the event, inspecting them is fine. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/