Add 'snapshot' event_command. snapshot event triggers are added by
the user via this command in a similar way and using practically the
same syntax as the analogous 'snapshot' ftrace function command, but
instead of writing to the set_ftrace_filter file, the snapshot event
trigger is written to the per-event 'trigger' files:
echo 'snapshot' > .../somesys/someevent/trigger
The above command will turn on snapshots for someevent i.e. whenever
someevent is hit, a snapshot will be done.
This also adds a 'count' version that limits the number of times the
command will be invoked:
echo 'snapshot:N' > .../somesys/someevent/trigger
Where N is the number of times the command will be invoked.
The above command will snapshot N times for someevent i.e. whenever
someevent is hit N times, a snapshot will be done.
Also adds a new ftrace_alloc_snapshot() function - the ftrace snapshot
command defines code that allocates a snapshot, which would be nice to
be able to reuse, which this does.
Signed-off-by: Tom Zanussi <tom.zanu...@linux.intel.com>
---
include/linux/ftrace_event.h | 1 +
kernel/trace/trace.c | 9 +++++
kernel/trace/trace.h | 1 +
kernel/trace/trace_events_trigger.c | 74 +++++++++++++++++++++++++++++++++++++
4 files changed, 85 insertions(+)
diff --git a/include/linux/ftrace_event.h b/include/linux/ftrace_event.h
index 239738c..bfd81f3 100644
--- a/include/linux/ftrace_event.h
+++ b/include/linux/ftrace_event.h
@@ -319,6 +319,7 @@ struct ftrace_event_file {
enum event_trigger_type {
ETT_NONE = (0),
ETT_TRACE_ONOFF = (1 << 0),
+ ETT_SNAPSHOT = (1 << 1),
};
extern void destroy_preds(struct ftrace_event_call *call);
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 7974ba2..53bd5e1 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -5355,6 +5355,15 @@ static const struct file_operations
tracing_dyn_info_fops = {
};
#endif /* CONFIG_DYNAMIC_FTRACE */
+#if defined(CONFIG_TRACER_SNAPSHOT)
+int ftrace_alloc_snapshot(void)
+{
+ return alloc_snapshot(&global_trace);
+}
+#else
+int ftrace_alloc_snapshot(void) { return -ENOSYS; }
+#endif
+
#if defined(CONFIG_TRACER_SNAPSHOT) && defined(CONFIG_DYNAMIC_FTRACE)
static void
ftrace_snapshot(unsigned long ip, unsigned long parent_ip, void **data)
diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index e9e7c1b..e2afe25 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -1200,6 +1200,7 @@ struct event_command {
extern int trace_event_enable_disable(struct ftrace_event_file *file,
int enable, int soft_disable);
+extern int ftrace_alloc_snapshot(void);
extern const char *__start___trace_bprintk_fmt[];
extern const char *__stop___trace_bprintk_fmt[];
diff --git a/kernel/trace/trace_events_trigger.c
b/kernel/trace/trace_events_trigger.c
index 3634061..f32fa31 100644
--- a/kernel/trace/trace_events_trigger.c
+++ b/kernel/trace/trace_events_trigger.c
@@ -696,6 +696,74 @@ static struct event_command trigger_traceoff_cmd = {
.get_trigger_ops = onoff_get_trigger_ops,
};
+static void
+snapshot_trigger(struct event_trigger_data *data)
+{
+ tracing_snapshot();
+}
+
+static void
+snapshot_count_trigger(struct event_trigger_data *data)
+{
+ if (!data->count)
+ return;
+
+ if (data->count != -1)
+ (data->count)--;
+
+ snapshot_trigger(data);
+}
+
+static int
+register_snapshot_trigger(char *glob, struct event_trigger_ops *ops,
+ struct event_trigger_data *data,
+ struct ftrace_event_file *file)
+{
+ int ret = register_trigger(glob, ops, data, file);
+
+ if (ret > 0)
+ ftrace_alloc_snapshot();
+
+ return ret;
+}
+
+static int
+snapshot_trigger_print(struct seq_file *m, struct event_trigger_ops *ops,
+ struct event_trigger_data *data)
+{
+ return event_trigger_print("snapshot", m, (void *)data->count,
+ data->filter_str);
+}
+
+static struct event_trigger_ops snapshot_trigger_ops = {
+ .func = snapshot_trigger,
+ .print = snapshot_trigger_print,
+ .init = event_trigger_init,
+ .free = event_trigger_free,
+};
+
+static struct event_trigger_ops snapshot_count_trigger_ops = {
+ .func = snapshot_count_trigger,
+ .print = snapshot_trigger_print,
+ .init = event_trigger_init,
+ .free = event_trigger_free,
+};
+
+static struct event_trigger_ops *
+snapshot_get_trigger_ops(char *cmd, char *param)
+{
+ return param ? &snapshot_count_trigger_ops : &snapshot_trigger_ops;
+}
+
+static struct event_command trigger_snapshot_cmd = {
+ .name = "snapshot",
+ .trigger_type = ETT_SNAPSHOT,
+ .func = event_trigger_callback,
+ .reg = register_snapshot_trigger,
+ .unreg = unregister_trigger,
+ .get_trigger_ops = snapshot_get_trigger_ops,
+};
+
static __init void unregister_trigger_traceon_traceoff_cmds(void)
{
unregister_event_command(&trigger_traceon_cmd);
@@ -726,5 +794,11 @@ __init int register_trigger_cmds(void)
return ret;
}
+ ret = register_event_command(&trigger_snapshot_cmd);
+ if (WARN_ON(ret < 0)) {
+ unregister_trigger_traceon_traceoff_cmds();
+ return ret;
+ }
+
return 0;
}
--
1.7.11.4
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