Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756704Ab3GDMtA (ORCPT ); Thu, 4 Jul 2013 08:49:00 -0400 Received: from mail7.hitachi.co.jp ([133.145.228.42]:38483 "EHLO mail7.hitachi.co.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756688Ab3GDMsw (ORCPT ); Thu, 4 Jul 2013 08:48:52 -0400 Message-ID: <51D56F29.2040700@hitachi.com> Date: Thu, 04 Jul 2013 21:48:41 +0900 From: Masami Hiramatsu Organization: Hitachi, Ltd., Japan User-Agent: Mozilla/5.0 (Windows NT 5.2; rv:13.0) Gecko/20120614 Thunderbird/13.0.1 MIME-Version: 1.0 To: Steven Rostedt Cc: linux-kernel@vger.kernel.org, Oleg Nesterov , "zhangwei(Jovi)" , Jiri Olsa , Peter Zijlstra , Arnaldo Carvalho de Melo , Srikar Dronamraju , Frederic Weisbecker , Ingo Molnar , Andrew Morton Subject: Re: [RFC][PATCH 2/4] tracing: trace_remove_event_call() should fail if call/file is in use References: <20130704033347.807661713@goodmis.org> <20130704034038.665930010@goodmis.org> In-Reply-To: <20130704034038.665930010@goodmis.org> Content-Type: text/plain; charset=ISO-2022-JP Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3545 Lines: 109 (2013/07/04 12:33), Steven Rostedt wrote: > From: Oleg Nesterov > > Change trace_remove_event_call(call) to return the error if this > call is active. This is what the callers assume but can't verify > outside of the tracing locks. Both trace_kprobe.c/trace_uprobe.c > need the additional changes, unregister_trace_probe() should abort > if trace_remove_event_call() fails. > > We also check TRACE_EVENT_FL_REF_MASK to ensure that nobody opened > the files we are going to remove, these means that nobody can access > the soon-to-be-freed ftrace_event_file/call via filp->private_data. > > Link: http://lkml.kernel.org/r/20130702222359.GA27629@redhat.com This looks good for me ;) Reviewed-by: Masami Hiramatsu Thanks! > > Signed-off-by: Oleg Nesterov > Signed-off-by: Steven Rostedt > --- > include/linux/ftrace_event.h | 2 +- > kernel/trace/trace_events.c | 33 +++++++++++++++++++++++++++++++-- > 2 files changed, 32 insertions(+), 3 deletions(-) > > diff --git a/include/linux/ftrace_event.h b/include/linux/ftrace_event.h > index 72ff2c6..bdf6bdd 100644 > --- a/include/linux/ftrace_event.h > +++ b/include/linux/ftrace_event.h > @@ -338,7 +338,7 @@ extern int trace_define_field(struct ftrace_event_call *call, const char *type, > const char *name, int offset, int size, > int is_signed, int filter_type); > extern int trace_add_event_call(struct ftrace_event_call *call); > -extern void trace_remove_event_call(struct ftrace_event_call *call); > +extern int trace_remove_event_call(struct ftrace_event_call *call); > > #define is_signed_type(type) (((type)(-1)) < (type)1) > > diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c > index 90cf243..1a5547e 100644 > --- a/kernel/trace/trace_events.c > +++ b/kernel/trace/trace_events.c > @@ -1766,16 +1766,45 @@ static void __trace_remove_event_call(struct ftrace_event_call *call) > destroy_preds(call); > } > > +static int probe_remove_event_call(struct ftrace_event_call *call) > +{ > + struct trace_array *tr; > + struct ftrace_event_file *file; > + > + if (call->flags & TRACE_EVENT_FL_REF_MASK) > + return -EBUSY; > + > +#ifdef CONFIG_PERF_EVENTS > + if (call->perf_refcount) > + return -EBUSY; > +#endif > + do_for_each_event_file(tr, file) { > + if (file->event_call != call) > + continue; > + if (file->flags & FTRACE_EVENT_FL_ENABLED) > + return -EBUSY; > + break; > + } while_for_each_event_file(); > + > + __trace_remove_event_call(call); > + > + return 0; > +} > + > /* Remove an event_call */ > -void trace_remove_event_call(struct ftrace_event_call *call) > +int trace_remove_event_call(struct ftrace_event_call *call) > { > + int ret; > + > mutex_lock(&trace_types_lock); > mutex_lock(&event_mutex); > down_write(&trace_event_sem); > - __trace_remove_event_call(call); > + ret = probe_remove_event_call(call); > up_write(&trace_event_sem); > mutex_unlock(&event_mutex); > mutex_unlock(&trace_types_lock); > + > + return ret; > } > > #define for_each_event(event, start, end) \ > -- Masami HIRAMATSU IT Management Research Dept. Linux Technology Center Hitachi, Ltd., Yokohama Research Laboratory E-mail: masami.hiramatsu.pt@hitachi.com -- 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/