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Commit de40f033 authored by Tom Zanussi's avatar Tom Zanussi Committed by Steven Rostedt (VMware)
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tracing: Remove open-coding of hist trigger var_ref management 

Have create_var_ref() manage the hist trigger's var_ref list, rather
than having similar code doing it in multiple places.  This cleans up
the code and makes sure var_refs are always accounted properly.

Also, document the var_ref-related functions to make what their
purpose clearer.

Link: http://lkml.kernel.org/r/05ddae93ff514e66fc03897d6665231892939913.1545161087.git.tom.zanussi@linux.intel.com



Acked-by: default avatarNamhyung Kim <namhyung@kernel.org>
Reviewed-by: default avatarMasami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: default avatarTom Zanussi <tom.zanussi@linux.intel.com>
Signed-off-by: default avatarSteven Rostedt (VMware) <rostedt@goodmis.org>
parent e4f6d245

kernel/trace/trace_events_hist.c

+75 −18
Original line number Diff line number Diff line
@@ -1292,6 +1292,17 @@ static u64 hist_field_cpu(struct hist_field *hist_field, 
	return cpu;

}



/**

 * check_field_for_var_ref - Check if a VAR_REF field references a variable

 * @hist_field: The VAR_REF field to check

 * @var_data: The hist trigger that owns the variable

 * @var_idx: The trigger variable identifier

 *

 * Check the given VAR_REF field to see whether or not it references

 * the given variable associated with the given trigger.

 *

 * Return: The VAR_REF field if it does reference the variable, NULL if not

 */

static struct hist_field *

check_field_for_var_ref(struct hist_field *hist_field,

			struct hist_trigger_data *var_data,
@@ -1306,6 +1317,18 @@ check_field_for_var_ref(struct hist_field *hist_field, 
	return NULL;

}



/**

 * find_var_ref - Check if a trigger has a reference to a trigger variable

 * @hist_data: The hist trigger that might have a reference to the variable

 * @var_data: The hist trigger that owns the variable

 * @var_idx: The trigger variable identifier

 *

 * Check the list of var_refs[] on the first hist trigger to see

 * whether any of them are references to the variable on the second

 * trigger.

 *

 * Return: The VAR_REF field referencing the variable if so, NULL if not

 */

static struct hist_field *find_var_ref(struct hist_trigger_data *hist_data,

				       struct hist_trigger_data *var_data,

				       unsigned int var_idx)
@@ -1322,6 +1345,20 @@ static struct hist_field *find_var_ref(struct hist_trigger_data *hist_data, 
	return NULL;

}



/**

 * find_any_var_ref - Check if there is a reference to a given trigger variable

 * @hist_data: The hist trigger

 * @var_idx: The trigger variable identifier

 *

 * Check to see whether the given variable is currently referenced by

 * any other trigger.

 *

 * The trigger the variable is defined on is explicitly excluded - the

 * assumption being that a self-reference doesn't prevent a trigger

 * from being removed.

 *

 * Return: The VAR_REF field referencing the variable if so, NULL if not

 */

static struct hist_field *find_any_var_ref(struct hist_trigger_data *hist_data,

					   unsigned int var_idx)

{
@@ -1340,6 +1377,19 @@ static struct hist_field *find_any_var_ref(struct hist_trigger_data *hist_data, 
	return found;

}



/**

 * check_var_refs - Check if there is a reference to any of trigger's variables

 * @hist_data: The hist trigger

 *

 * A trigger can define one or more variables.  If any one of them is

 * currently referenced by any other trigger, this function will

 * determine that.



 * Typically used to determine whether or not a trigger can be removed

 * - if there are any references to a trigger's variables, it cannot.

 *

 * Return: True if there is a reference to any of trigger's variables

 */

static bool check_var_refs(struct hist_trigger_data *hist_data)

{

	struct hist_field *field;
@@ -2343,7 +2393,23 @@ static int init_var_ref(struct hist_field *ref_field, 
	goto out;

}



static struct hist_field *create_var_ref(struct hist_field *var_field,

/**

 * create_var_ref - Create a variable reference and attach it to trigger

 * @hist_data: The trigger that will be referencing the variable

 * @var_field: The VAR field to create a reference to

 * @system: The optional system string

 * @event_name: The optional event_name string

 *

 * Given a variable hist_field, create a VAR_REF hist_field that

 * represents a reference to it.

 *

 * This function also adds the reference to the trigger that

 * now references the variable.

 *

 * Return: The VAR_REF field if successful, NULL if not

 */

static struct hist_field *create_var_ref(struct hist_trigger_data *hist_data,

					 struct hist_field *var_field,

					 char *system, char *event_name)

{

	unsigned long flags = HIST_FIELD_FL_VAR_REF;
@@ -2355,6 +2421,9 @@ static struct hist_field *create_var_ref(struct hist_field *var_field, 
			destroy_hist_field(ref_field, 0);

			return NULL;

		}



		hist_data->var_refs[hist_data->n_var_refs] = ref_field;

		ref_field->var_ref_idx = hist_data->n_var_refs++;

	}



	return ref_field;
@@ -2428,7 +2497,8 @@ static struct hist_field *parse_var_ref(struct hist_trigger_data *hist_data, 


	var_field = find_event_var(hist_data, system, event_name, var_name);

	if (var_field)

		ref_field = create_var_ref(var_field, system, event_name);

		ref_field = create_var_ref(hist_data, var_field,

					   system, event_name);



	if (!ref_field)

		hist_err_event("Couldn't find variable: $",
@@ -2546,8 +2616,6 @@ static struct hist_field *parse_atom(struct hist_trigger_data *hist_data, 
	if (!s) {

		hist_field = parse_var_ref(hist_data, ref_system, ref_event, ref_var);

		if (hist_field) {

			hist_data->var_refs[hist_data->n_var_refs] = hist_field;

			hist_field->var_ref_idx = hist_data->n_var_refs++;

			if (var_name) {

				hist_field = create_alias(hist_data, hist_field, var_name);

				if (!hist_field) {
@@ -3321,7 +3389,6 @@ static int onmax_create(struct hist_trigger_data *hist_data, 
	unsigned int var_ref_idx = hist_data->n_var_refs;

	struct field_var *field_var;

	char *onmax_var_str, *param;

	unsigned long flags;

	unsigned int i;

	int ret = 0;
@@ -3338,18 +3405,10 @@ static int onmax_create(struct hist_trigger_data *hist_data, 
		return -EINVAL;

	}



	flags = HIST_FIELD_FL_VAR_REF;

	ref_field = create_hist_field(hist_data, NULL, flags, NULL);

	ref_field = create_var_ref(hist_data, var_field, NULL, NULL);

	if (!ref_field)

		return -ENOMEM;



	if (init_var_ref(ref_field, var_field, NULL, NULL)) {

		destroy_hist_field(ref_field, 0);

		ret = -ENOMEM;

		goto out;

	}

	hist_data->var_refs[hist_data->n_var_refs] = ref_field;

	ref_field->var_ref_idx = hist_data->n_var_refs++;

	data->onmax.var = ref_field;



	data->fn = onmax_save;
@@ -3538,9 +3597,6 @@ static void save_synth_var_ref(struct hist_trigger_data *hist_data, 
			 struct hist_field *var_ref)

{

	hist_data->synth_var_refs[hist_data->n_synth_var_refs++] = var_ref;



	hist_data->var_refs[hist_data->n_var_refs] = var_ref;

	var_ref->var_ref_idx = hist_data->n_var_refs++;

}



static int check_synth_field(struct synth_event *event,
@@ -3694,7 +3750,8 @@ static int onmatch_create(struct hist_trigger_data *hist_data, 
		}



		if (check_synth_field(event, hist_field, field_pos) == 0) {

			var_ref = create_var_ref(hist_field, system, event_name);

			var_ref = create_var_ref(hist_data, hist_field,

						 system, event_name);

			if (!var_ref) {

				kfree(p);

				ret = -ENOMEM;