From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 4CF6AC28CC5 for ; Sat, 8 Jun 2019 22:27:25 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 24DED207E0 for ; Sat, 8 Jun 2019 22:27:25 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727591AbfFHW1Y (ORCPT ); Sat, 8 Jun 2019 18:27:24 -0400 Received: from mail.kernel.org ([198.145.29.99]:47106 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727486AbfFHW1Y (ORCPT ); Sat, 8 Jun 2019 18:27:24 -0400 Received: from oasis.local.home (unknown [12.156.218.74]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 5F6EF214C6; Sat, 8 Jun 2019 21:51:44 +0000 (UTC) Date: Sat, 8 Jun 2019 17:51:42 -0400 From: Steven Rostedt To: Divya Indi Cc: linux-kernel@vger.kernel.org, Srinivas Eeda Subject: Re: [PATCH 3/3] tracing: Add 2 new funcs. for kernel access to Ftrace instances. Message-ID: <20190608175142.1a4444a4@oasis.local.home> In-Reply-To: <1559695325-17155-4-git-send-email-divya.indi@oracle.com> References: <1559695325-17155-1-git-send-email-divya.indi@oracle.com> <1559695325-17155-2-git-send-email-divya.indi@oracle.com> <1559695325-17155-3-git-send-email-divya.indi@oracle.com> <1559695325-17155-4-git-send-email-divya.indi@oracle.com> X-Mailer: Claws Mail 3.17.3 (GTK+ 2.24.32; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 4 Jun 2019 17:42:05 -0700 Divya Indi wrote: > Adding 2 new functions - > 1) trace_array_lookup : Look up and return a trace array, given its > name. > 2) trace_array_set_clr_event : Enable/disable event recording to the > given trace array. > > Signed-off-by: Divya Indi > --- > include/linux/trace_events.h | 3 +++ > kernel/trace/trace.c | 11 +++++++++++ > kernel/trace/trace_events.c | 22 ++++++++++++++++++++++ > 3 files changed, 36 insertions(+) > > diff --git a/include/linux/trace_events.h b/include/linux/trace_events.h > index d7b7d85..0cc99a8 100644 > --- a/include/linux/trace_events.h > +++ b/include/linux/trace_events.h > @@ -545,7 +545,10 @@ int trace_array_printk(struct trace_array *tr, unsigned long ip, > struct trace_array *trace_array_create(const char *name); > int trace_array_destroy(struct trace_array *tr); > int ftrace_set_clr_event(struct trace_array *tr, char *buf, int set); > +struct trace_array *trace_array_lookup(const char *name); > int trace_set_clr_event(const char *system, const char *event, int set); > +int trace_array_set_clr_event(struct trace_array *tr, const char *system, > + const char *event, int set); > > /* > * The double __builtin_constant_p is because gcc will give us an error > diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c > index a60dc13..1d171fd 100644 > --- a/kernel/trace/trace.c > +++ b/kernel/trace/trace.c > @@ -8465,6 +8465,17 @@ static int instance_rmdir(const char *name) > return ret; > } > > +struct trace_array *trace_array_lookup(const char *name) > +{ > + struct trace_array *tr; > + list_for_each_entry(tr, &ftrace_trace_arrays, list) { Accessing the ftrace_trace_arrays requires taking the trace_types_lock. It should also probably increment the ref counter too, and then trace_array_put() needs to be called. This prevents the trace array from being freed while something has access to it. -- Steve > + if (tr->name && strcmp(tr->name, name) == 0) > + return tr; > + } > + return NULL; > +} > +EXPORT_SYMBOL_GPL(trace_array_lookup); > + > static __init void create_trace_instances(struct dentry *d_tracer) > { > trace_instance_dir = tracefs_create_instance_dir("instances", d_tracer, > diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c > index 445b059..c126d2c 100644 > --- a/kernel/trace/trace_events.c > +++ b/kernel/trace/trace_events.c > @@ -859,6 +859,28 @@ int trace_set_clr_event(const char *system, const char *event, int set) > } > EXPORT_SYMBOL_GPL(trace_set_clr_event); > > +/** > + * trace_array_set_clr_event - enable or disable an event for a trace array > + * @system: system name to match (NULL for any system) > + * @event: event name to match (NULL for all events, within system) > + * @set: 1 to enable, 0 to disable > + * > + * This is a way for other parts of the kernel to enable or disable > + * event recording to instances. > + * > + * Returns 0 on success, -EINVAL if the parameters do not match any > + * registered events. > + */ > +int trace_array_set_clr_event(struct trace_array *tr, const char *system, > + const char *event, int set) > +{ > + if (!tr) > + return -ENODEV; > + > + return __ftrace_set_clr_event(tr, NULL, system, event, set); > +} > +EXPORT_SYMBOL_GPL(trace_array_set_clr_event); > + > /* 128 should be much more than enough */ > #define EVENT_BUF_SIZE 127 >