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=-1.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,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 C1F41C46470 for ; Thu, 9 Aug 2018 21:07:00 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 7861F21EFC for ; Thu, 9 Aug 2018 21:07:00 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 7861F21EFC Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=goodmis.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727490AbeHIXde (ORCPT ); Thu, 9 Aug 2018 19:33:34 -0400 Received: from mail.kernel.org ([198.145.29.99]:35764 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727407AbeHIXdd (ORCPT ); Thu, 9 Aug 2018 19:33:33 -0400 Received: from gandalf.local.home (cpe-66-24-56-78.stny.res.rr.com [66.24.56.78]) (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 3245322399; Thu, 9 Aug 2018 21:06:56 +0000 (UTC) Received: from rostedt by gandalf.local.home with local (Exim 4.91) (envelope-from ) id 1fns91-0001Sd-7Q; Thu, 09 Aug 2018 17:06:55 -0400 Message-Id: <20180809210655.120730709@goodmis.org> User-Agent: quilt/0.65 Date: Thu, 09 Aug 2018 17:03:38 -0400 From: Steven Rostedt To: linux-kernel@vger.kernel.org Cc: Ingo Molnar , Andrew Morton , joel@joelfernandes.org Subject: [for-next][PATCH 5/6] tracing: Fix synchronizing to event changes with tracepoint_synchronize_unregister() References: <20180809210333.588854137@goodmis.org> MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-15 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: "Steven Rostedt (VMware)" Now that some trace events can be protected by srcu_read_lock(tracepoint_srcu), we need to make sure all locations that depend on this are also protected. There were many places that did a synchronize_sched() thinking that it was enough to protect againts access to trace events. This use to be the case, but now that we use SRCU for _rcuidle() trace events, they may not be protected by synchronize_sched(), as they may be called in paths that RCU is not watching for preempt disable. Fixes: e6753f23d961d ("tracepoint: Make rcuidle tracepoint callers use SRCU") Signed-off-by: Steven Rostedt (VMware) --- kernel/trace/trace_events.c | 8 ++++---- kernel/trace/trace_events_filter.c | 15 ++++++++------- kernel/trace/trace_events_hist.c | 2 +- kernel/trace/trace_events_trigger.c | 6 ++++-- 4 files changed, 17 insertions(+), 14 deletions(-) diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c index 7b508ce8ac44..808cf29febe2 100644 --- a/kernel/trace/trace_events.c +++ b/kernel/trace/trace_events.c @@ -636,7 +636,7 @@ static void __ftrace_clear_event_pids(struct trace_array *tr) rcu_assign_pointer(tr->filtered_pids, NULL); /* Wait till all users are no longer using pid filtering */ - synchronize_sched(); + tracepoint_synchronize_unregister(); trace_free_pid_list(pid_list); } @@ -1622,7 +1622,7 @@ ftrace_event_pid_write(struct file *filp, const char __user *ubuf, } if (filtered_pids) { - synchronize_sched(); + tracepoint_synchronize_unregister(); trace_free_pid_list(filtered_pids); } else if (pid_list) { /* @@ -3036,8 +3036,8 @@ int event_trace_del_tracer(struct trace_array *tr) /* Disable any running events */ __ftrace_set_clr_event_nolock(tr, NULL, NULL, NULL, 0); - /* Access to events are within rcu_read_lock_sched() */ - synchronize_sched(); + /* Make sure no more events are being executed */ + tracepoint_synchronize_unregister(); down_write(&trace_event_sem); __trace_remove_event_dirs(tr); diff --git a/kernel/trace/trace_events_filter.c b/kernel/trace/trace_events_filter.c index 893a206bcba4..184c7685d5ea 100644 --- a/kernel/trace/trace_events_filter.c +++ b/kernel/trace/trace_events_filter.c @@ -899,7 +899,8 @@ int filter_match_preds(struct event_filter *filter, void *rec) if (!filter) return 1; - prog = rcu_dereference_sched(filter->prog); + /* Protected by either SRCU(tracepoint_srcu) or preempt_disable */ + prog = rcu_dereference_raw(filter->prog); if (!prog) return 1; @@ -1626,10 +1627,10 @@ static int process_system_preds(struct trace_subsystem_dir *dir, /* * The calls can still be using the old filters. - * Do a synchronize_sched() to ensure all calls are + * Do a synchronize_sched() and to ensure all calls are * done with them before we free them. */ - synchronize_sched(); + tracepoint_synchronize_unregister(); list_for_each_entry_safe(filter_item, tmp, &filter_list, list) { __free_filter(filter_item->filter); list_del(&filter_item->list); @@ -1648,7 +1649,7 @@ static int process_system_preds(struct trace_subsystem_dir *dir, kfree(filter); /* If any call succeeded, we still need to sync */ if (!fail) - synchronize_sched(); + tracepoint_synchronize_unregister(); list_for_each_entry_safe(filter_item, tmp, &filter_list, list) { __free_filter(filter_item->filter); list_del(&filter_item->list); @@ -1790,7 +1791,7 @@ int apply_event_filter(struct trace_event_file *file, char *filter_string) event_clear_filter(file); /* Make sure the filter is not being used */ - synchronize_sched(); + tracepoint_synchronize_unregister(); __free_filter(filter); return 0; @@ -1817,7 +1818,7 @@ int apply_event_filter(struct trace_event_file *file, char *filter_string) if (tmp) { /* Make sure the call is done with the filter */ - synchronize_sched(); + tracepoint_synchronize_unregister(); __free_filter(tmp); } } @@ -1847,7 +1848,7 @@ int apply_subsystem_event_filter(struct trace_subsystem_dir *dir, filter = system->filter; system->filter = NULL; /* Ensure all filters are no longer used */ - synchronize_sched(); + tracepoint_synchronize_unregister(); filter_free_subsystem_filters(dir, tr); __free_filter(filter); goto out_unlock; diff --git a/kernel/trace/trace_events_hist.c b/kernel/trace/trace_events_hist.c index aae18af94c94..c522b51d9909 100644 --- a/kernel/trace/trace_events_hist.c +++ b/kernel/trace/trace_events_hist.c @@ -5141,7 +5141,7 @@ static void hist_clear(struct event_trigger_data *data) if (data->name) pause_named_trigger(data); - synchronize_sched(); + tracepoint_synchronize_unregister(); tracing_map_clear(hist_data->map); diff --git a/kernel/trace/trace_events_trigger.c b/kernel/trace/trace_events_trigger.c index 58d21fd52932..750044ef15e8 100644 --- a/kernel/trace/trace_events_trigger.c +++ b/kernel/trace/trace_events_trigger.c @@ -34,7 +34,9 @@ void trigger_data_free(struct event_trigger_data *data) if (data->cmd_ops->set_filter) data->cmd_ops->set_filter(NULL, data, NULL); - synchronize_sched(); /* make sure current triggers exit before free */ + /* make sure current triggers exit before free */ + tracepoint_synchronize_unregister(); + kfree(data); } @@ -752,7 +754,7 @@ int set_trigger_filter(char *filter_str, if (tmp) { /* Make sure the call is done with the filter */ - synchronize_sched(); + tracepoint_synchronize_unregister(); free_event_filter(tmp); } -- 2.18.0