Commit c910db94 authored by Tom Zanussi's avatar Tom Zanussi Committed by Steven Rostedt (VMware)
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tracing: Dynamically allocate the per-elt hist_elt_data array 

Setting the hist_elt_data.field_var_str[] array unconditionally to a
size of SYNTH_FIELD_MAX elements wastes space unnecessarily.  The
actual number of elements needed can be calculated at run-time
instead.

In most cases, this will save a lot of space since it's a per-elt
array which isn't normally close to being full.  It also allows us to
increase SYNTH_FIELD_MAX without worrying about even more wastage when
we do that.

Link: https://lkml.kernel.org/r/d52ae0ad5e1b59af7c4f54faf3fc098461fd82b3.camel@kernel.org



Signed-off-by: default avatarTom Zanussi <zanussi@kernel.org>
Tested-by: default avatarArtem Bityutskiy <artem.bityutskiy@linux.intel.com>
Signed-off-by: default avatarSteven Rostedt (VMware) <rostedt@goodmis.org>
parent 0be083ce

kernel/trace/trace_events_hist.c

+12 −2
Original line number Diff line number Diff line
@@ -508,7 +508,8 @@ struct track_data { 
struct hist_elt_data {

	char *comm;

	u64 *var_ref_vals;

	char *field_var_str[SYNTH_FIELDS_MAX];

	char **field_var_str;

	int n_field_var_str;

};



struct snapshot_context {
@@ -1401,9 +1402,11 @@ static void hist_elt_data_free(struct hist_elt_data *elt_data) 
{

	unsigned int i;



	for (i = 0; i < SYNTH_FIELDS_MAX; i++)

	for (i = 0; i < elt_data->n_field_var_str; i++)

		kfree(elt_data->field_var_str[i]);



	kfree(elt_data->field_var_str);



	kfree(elt_data->comm);

	kfree(elt_data);

}
@@ -1451,6 +1454,13 @@ static int hist_trigger_elt_data_alloc(struct tracing_map_elt *elt) 


	size = STR_VAR_LEN_MAX;



	elt_data->field_var_str = kcalloc(n_str, sizeof(char *), GFP_KERNEL);

	if (!elt_data->field_var_str) {

		hist_elt_data_free(elt_data);

		return -EINVAL;

	}

	elt_data->n_field_var_str = n_str;



	for (i = 0; i < n_str; i++) {

		elt_data->field_var_str[i] = kzalloc(size, GFP_KERNEL);

		if (!elt_data->field_var_str[i]) {