From: Tom Zanussi <tom.zanussi@linux.intel.com>
Date: Mon, 26 Jun 2017 17:49:11 -0500
Subject: tracing: Add NO_DISCARD event file flag
Git-repo: git://git.kernel.org/pub/scm/linux/kernel/git/rt/linux-rt-devel.git
Git-commit: ad6048a5bfa807dc02dbeb485ba310ea59f0113b
Patch-mainline: Queued in subsystem maintainer repository
References: SLE Realtime Extension
Whenever an event_command has a post-trigger that needs access to the
event record, the event record can't be discarded, or the post-trigger
will eventually see bogus data.
In order to allow the discard check to treat this case separately, add
an EVENT_FILE_FL_NO_DISCARD flag to the event file flags, along with
code in the discard check that checks the flag and avoids the discard
when the flag is set.
Signed-off-by: Tom Zanussi <tom.zanussi@linux.intel.com>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Mike Galbraith <mgalbraith@suse.de>
---
include/linux/trace_events.h | 3 +++
kernel/trace/trace.h | 3 +++
kernel/trace/trace_events_trigger.c | 16 +++++++++++++---
3 files changed, 19 insertions(+), 3 deletions(-)
diff --git a/include/linux/trace_events.h b/include/linux/trace_events.h
index f2c926c65961..0f26132487b4 100644
--- a/include/linux/trace_events.h
+++ b/include/linux/trace_events.h
@@ -324,6 +324,7 @@ enum {
EVENT_FILE_FL_TRIGGER_MODE_BIT,
EVENT_FILE_FL_TRIGGER_COND_BIT,
EVENT_FILE_FL_PID_FILTER_BIT,
+ EVENT_FILE_FL_NO_DISCARD_BIT,
};
/*
@@ -338,6 +339,7 @@ enum {
* TRIGGER_MODE - When set, invoke the triggers associated with the event
* TRIGGER_COND - When set, one or more triggers has an associated filter
* PID_FILTER - When set, the event is filtered based on pid
+ * NO_DISCARD - When set, do not discard events, something needs them later
*/
enum {
EVENT_FILE_FL_ENABLED = (1 << EVENT_FILE_FL_ENABLED_BIT),
@@ -349,6 +351,7 @@ enum {
EVENT_FILE_FL_TRIGGER_MODE = (1 << EVENT_FILE_FL_TRIGGER_MODE_BIT),
EVENT_FILE_FL_TRIGGER_COND = (1 << EVENT_FILE_FL_TRIGGER_COND_BIT),
EVENT_FILE_FL_PID_FILTER = (1 << EVENT_FILE_FL_PID_FILTER_BIT),
+ EVENT_FILE_FL_NO_DISCARD = (1 << EVENT_FILE_FL_NO_DISCARD_BIT),
};
struct trace_event_file {
diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index 556489096116..12ee5e0018e6 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -1324,6 +1324,9 @@ __event_trigger_test_discard(struct trace_event_file *file,
!filter_match_preds(file->filter, entry))
goto discard;
+ if (test_bit(EVENT_FILE_FL_NO_DISCARD_BIT, &file->flags))
+ return false;
+
if ((file->flags & EVENT_FILE_FL_PID_FILTER) &&
trace_event_ignore_this_pid(file))
goto discard;
diff --git a/kernel/trace/trace_events_trigger.c b/kernel/trace/trace_events_trigger.c
index 35297a27ea38..1ad9b9b7e1c3 100644
--- a/kernel/trace/trace_events_trigger.c
+++ b/kernel/trace/trace_events_trigger.c
@@ -512,20 +512,30 @@ clear_event_triggers(struct trace_array *tr)
void update_cond_flag(struct trace_event_file *file)
{
struct event_trigger_data *data;
- bool set_cond = false;
+ bool set_cond = false, set_no_discard = false;
list_for_each_entry_rcu(data, &file->triggers, list) {
if (data->filter || event_command_post_trigger(data->cmd_ops) ||
- event_command_needs_rec(data->cmd_ops)) {
+ event_command_needs_rec(data->cmd_ops))
set_cond = true;
+
+ if (event_command_post_trigger(data->cmd_ops) &&
+ event_command_needs_rec(data->cmd_ops))
+ set_no_discard = true;
+
+ if (set_cond && set_no_discard)
break;
- }
}
if (set_cond)
set_bit(EVENT_FILE_FL_TRIGGER_COND_BIT, &file->flags);
else
clear_bit(EVENT_FILE_FL_TRIGGER_COND_BIT, &file->flags);
+
+ if (set_no_discard)
+ set_bit(EVENT_FILE_FL_NO_DISCARD_BIT, &file->flags);
+ else
+ clear_bit(EVENT_FILE_FL_NO_DISCARD_BIT, &file->flags);
}
/**
--
2.26.2