From: Steven Rostedt <rostedt@goodmis.org>
To: linux-kernel@vger.kernel.org
Cc: Ingo Molnar <mingo@kernel.org>,
Andrew Morton <akpm@linux-foundation.org>
Subject: [for-next][PATCH 32/34] tracing: Fix synchronizing to event changes with tracepoint_synchronize_unregister()
Date: Sat, 11 Aug 2018 09:50:00 -0400 [thread overview]
Message-ID: <20180811135016.978955328@goodmis.org> (raw)
In-Reply-To: 20180811134928.034373761@goodmis.org
From: "Steven Rostedt (VMware)" <rostedt@goodmis.org>
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) <rostedt@goodmis.org>
---
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
next prev parent reply other threads:[~2018-08-11 13:50 UTC|newest]
Thread overview: 35+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-08-11 13:49 [for-next][PATCH 00/34] tracing: My official queue finally passed testing and ready for linux-next Steven Rostedt
2018-08-11 13:49 ` [for-next][PATCH 01/34] srcu: Add notrace variants of srcu_read_{lock,unlock} Steven Rostedt
2018-08-11 13:49 ` [for-next][PATCH 02/34] srcu: Add notrace variant of srcu_dereference Steven Rostedt
2018-08-11 13:49 ` [for-next][PATCH 03/34] tracing/irqsoff: Split reset into separate functions Steven Rostedt
2018-08-11 13:49 ` [for-next][PATCH 04/34] lib: Add module for testing preemptoff/irqsoff latency tracers Steven Rostedt
2018-08-11 13:49 ` [for-next][PATCH 05/34] kselftests: Add tests for the preemptoff and irqsoff tracers Steven Rostedt
2018-08-11 13:49 ` [for-next][PATCH 06/34] tracing: Make unregister_trigger() static Steven Rostedt
2018-08-11 13:49 ` [for-next][PATCH 07/34] tracing: Remove orphaned function using_ftrace_ops_list_func() Steven Rostedt
2018-08-11 13:49 ` [for-next][PATCH 08/34] tracing: Remove orphaned function ftrace_nr_registered_ops() Steven Rostedt
2018-08-11 13:49 ` [for-next][PATCH 09/34] tracing/kprobes: Simplify the logic of enable_trace_kprobe() Steven Rostedt
2018-08-11 13:49 ` [for-next][PATCH 10/34] tracing: preemptirq_delay_run() can be static Steven Rostedt
2018-08-11 13:49 ` [for-next][PATCH 11/34] tracing: kprobes: Prohibit probing on notrace function Steven Rostedt
2018-08-11 13:49 ` [for-next][PATCH 12/34] selftest/ftrace: Move kprobe selftest function to separate compile unit Steven Rostedt
2018-08-11 13:49 ` [for-next][PATCH 13/34] selftests/ftrace: Fix kprobe string testcase to not probe notrace function Steven Rostedt
2018-08-11 13:49 ` [for-next][PATCH 14/34] lockdep: Use this_cpu_ptr instead of get_cpu_var stats Steven Rostedt
2018-08-11 13:49 ` [for-next][PATCH 15/34] tracepoint: Make rcuidle tracepoint callers use SRCU Steven Rostedt
2018-08-11 13:49 ` [for-next][PATCH 16/34] tracing: Centralize preemptirq tracepoints and unify their usage Steven Rostedt
2018-08-11 13:49 ` [for-next][PATCH 17/34] tracefs: Annotate tracefs_ops with __ro_after_init Steven Rostedt
2018-08-11 13:49 ` [for-next][PATCH 18/34] tracing: Do not call start/stop() functions when tracing_on does not change Steven Rostedt
2018-08-11 13:49 ` [for-next][PATCH 19/34] ftrace: Add missing check for existing hwlat thread Steven Rostedt
2018-08-11 13:49 ` [for-next][PATCH 20/34] tracing: Do a WARN_ON() if start_thread() in hwlat is called when thread exists Steven Rostedt
2018-08-11 13:49 ` [for-next][PATCH 21/34] tracing: Make tracer_tracing_is_on() return bool Steven Rostedt
2018-08-11 13:49 ` [for-next][PATCH 22/34] ring-buffer: Make ring_buffer_record_is_on() " Steven Rostedt
2018-08-11 13:49 ` [for-next][PATCH 23/34] ring-buffer: Make ring_buffer_record_is_set_on() " Steven Rostedt
2018-08-11 13:49 ` [for-next][PATCH 24/34] ftrace: Use true and false for boolean values in ops_references_rec() Steven Rostedt
2018-08-11 13:49 ` [for-next][PATCH 25/34] tracing/kprobes: Fix within_notrace_func() to check only notrace functions Steven Rostedt
2018-08-11 13:49 ` [for-next][PATCH 26/34] trace: Use rcu_dereference_raw for hooks from trace-event subsystem Steven Rostedt
2018-08-11 13:49 ` [for-next][PATCH 27/34] tracing: irqsoff: Account for additional preempt_disable Steven Rostedt
2018-08-11 13:49 ` [for-next][PATCH 28/34] tracing: Partial revert of "tracing: Centralize preemptirq tracepoints and unify their usage" Steven Rostedt
2018-08-11 13:49 ` [for-next][PATCH 29/34] tracing/irqsoff: Handle preempt_count for different configs Steven Rostedt
2018-08-11 13:49 ` [for-next][PATCH 30/34] tracing: More reverting of "tracing: Centralize preemptirq tracepoints and unify their usage" Steven Rostedt
2018-08-11 13:49 ` [for-next][PATCH 31/34] ftrace: Remove unused pointer ftrace_swapper_pid Steven Rostedt
2018-08-11 13:50 ` Steven Rostedt [this message]
2018-08-11 13:50 ` [for-next][PATCH 33/34] uprobes: Use synchronize_rcu() not synchronize_sched() Steven Rostedt
2018-08-11 13:50 ` [for-next][PATCH 34/34] tracepoints: Free early tracepoints after RCU is initialized Steven Rostedt
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