Allow users to append 'clear' to an existing trigger in order to have
the hash table cleared.
This expands the hist trigger syntax from this:
# echo hist:keys=xxx:vals=yyy:sort=zzz.descending:pause/cont \
[ if filter] > event/trigger
to this:
# echo hist:keys=xxx:vals=yyy:sort=zzz.descending:pause/cont/clear \
[ if filter] > event/trigger
Signed-off-by: Tom Zanussi <[email protected]>
---
kernel/trace/trace.c | 5 ++++-
kernel/trace/trace_events_hist.c | 25 ++++++++++++++++++++++++-
2 files changed, 28 insertions(+), 2 deletions(-)
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 12fc91c..4260a8f 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -3791,7 +3791,7 @@ static const char readme_msg[] =
"\t [:values=<field1[,field2,...]]\n"
"\t [:sort=field1,field2,...]\n"
"\t [:size=#entries]\n"
- "\t [:pause][:continue]\n"
+ "\t [:pause][:continue][:clear]\n"
"\t [if <filter>]\n\n"
"\t When a matching event is hit, an entry is added to a hash\n"
"\t table using the key(s) and value(s) named, and the value of a\n"
@@ -3811,6 +3811,9 @@ static const char readme_msg[] =
"\t trigger or to start a hist trigger but not log any events\n"
"\t until told to do so. 'continue' can be used to start or\n"
"\t restart a paused hist trigger.\n\n"
+ "\t The 'clear' parameter will clear the contents of a running\n"
+ "\t hist trigger and leave its current paused/active state\n"
+ "\t unchanged.\n\n"
#endif
;
diff --git a/kernel/trace/trace_events_hist.c b/kernel/trace/trace_events_hist.c
index 8753c3b..96732c8 100644
--- a/kernel/trace/trace_events_hist.c
+++ b/kernel/trace/trace_events_hist.c
@@ -80,6 +80,7 @@ struct hist_trigger_attrs {
char *sort_key_str;
bool pause;
bool cont;
+ bool clear;
unsigned int map_bits;
};
@@ -188,6 +189,8 @@ static struct hist_trigger_attrs
*parse_hist_trigger_attrs(char *trigger_str)
attrs->sort_key_str = kstrdup(str, GFP_KERNEL);
else if (!strncmp(str, "pause", strlen("pause")))
attrs->pause = true;
+ else if (!strncmp(str, "clear", strlen("clear")))
+ attrs->clear = true;
else if (!strncmp(str, "continue", strlen("continue")) ||
!strncmp(str, "cont", strlen("cont")))
attrs->cont = true;
@@ -888,6 +891,24 @@ static struct event_trigger_ops
*event_hist_get_trigger_ops(char *cmd,
return &event_hist_trigger_ops;
}
+static void hist_clear(struct event_trigger_data *data)
+{
+ struct hist_trigger_data *hist_data = data->private_data;
+ bool paused;
+
+ paused = data->paused;
+ data->paused = true;
+
+ synchronize_sched();
+
+ tracing_map_clear(hist_data->map);
+
+ atomic64_set(&hist_data->total_hits, 0);
+ atomic64_set(&hist_data->drops, 0);
+
+ data->paused = paused;
+}
+
static int hist_register_trigger(char *glob, struct event_trigger_ops *ops,
struct event_trigger_data *data,
struct trace_event_file *file)
@@ -902,6 +923,8 @@ static int hist_register_trigger(char *glob, struct
event_trigger_ops *ops,
test->paused = true;
else if (hist_data->attrs->cont)
test->paused = false;
+ else if (hist_data->attrs->clear)
+ hist_clear(test);
else
ret = -EEXIST;
goto out;
@@ -1003,7 +1026,7 @@ static int event_hist_trigger_func(struct event_command
*cmd_ops,
* triggers registered a failure too.
*/
if (!ret) {
- if (!(attrs->pause || attrs->cont))
+ if (!(attrs->pause || attrs->cont || attrs->clear))
ret = -ENOENT;
goto out_free;
} else if (ret < 0)
--
1.9.3
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