Commit 2734b629 authored by Tom Zanussi's avatar Tom Zanussi Committed by Steven Rostedt (VMware)
Browse files

tracing: Add per-element variable support to tracing_map 

In order to allow information to be passed between trace events, add
support for per-element variables to tracing_map.  This provides a
means for histograms to associate a value or values with an entry when
it's saved or updated, and retrieved by a subsequent event occurrences.

Variables can be set using tracing_map_set_var() and read using
tracing_map_read_var().  tracing_map_var_set() returns true or false
depending on whether or not the variable has been set or not, which is
important for event-matching applications.

tracing_map_read_var_once() reads the variable and resets it to the
'unset' state, implementing read-once variables, which are also
important for event-matching uses.

Link: http://lkml.kernel.org/r/7fa001108252556f0c6dd9d63145eabfe3370d1a.1516069914.git.tom.zanussi@linux.intel.com



Signed-off-by: default avatarTom Zanussi <tom.zanussi@linux.intel.com>
Signed-off-by: default avatarSteven Rostedt (VMware) <rostedt@goodmis.org>
parent ad42febe

kernel/trace/tracing_map.c

+108 −0
Original line number Diff line number Diff line
@@ -66,6 +66,73 @@ u64 tracing_map_read_sum(struct tracing_map_elt *elt, unsigned int i) 
	return (u64)atomic64_read(&elt->fields[i].sum);

}



/**

 * tracing_map_set_var - Assign a tracing_map_elt's variable field

 * @elt: The tracing_map_elt

 * @i: The index of the given variable associated with the tracing_map_elt

 * @n: The value to assign

 *

 * Assign n to variable i associated with the specified tracing_map_elt

 * instance.  The index i is the index returned by the call to

 * tracing_map_add_var() when the tracing map was set up.

 */

void tracing_map_set_var(struct tracing_map_elt *elt, unsigned int i, u64 n)

{

	atomic64_set(&elt->vars[i], n);

	elt->var_set[i] = true;

}



/**

 * tracing_map_var_set - Return whether or not a variable has been set

 * @elt: The tracing_map_elt

 * @i: The index of the given variable associated with the tracing_map_elt

 *

 * Return true if the variable has been set, false otherwise.  The

 * index i is the index returned by the call to tracing_map_add_var()

 * when the tracing map was set up.

 */

bool tracing_map_var_set(struct tracing_map_elt *elt, unsigned int i)

{

	return elt->var_set[i];

}



/**

 * tracing_map_read_var - Return the value of a tracing_map_elt's variable field

 * @elt: The tracing_map_elt

 * @i: The index of the given variable associated with the tracing_map_elt

 *

 * Retrieve the value of the variable i associated with the specified

 * tracing_map_elt instance.  The index i is the index returned by the

 * call to tracing_map_add_var() when the tracing map was set

 * up.

 *

 * Return: The variable value associated with field i for elt.

 */

u64 tracing_map_read_var(struct tracing_map_elt *elt, unsigned int i)

{

	return (u64)atomic64_read(&elt->vars[i]);

}



/**

 * tracing_map_read_var_once - Return and reset a tracing_map_elt's variable field

 * @elt: The tracing_map_elt

 * @i: The index of the given variable associated with the tracing_map_elt

 *

 * Retrieve the value of the variable i associated with the specified

 * tracing_map_elt instance, and reset the variable to the 'not set'

 * state.  The index i is the index returned by the call to

 * tracing_map_add_var() when the tracing map was set up.  The reset

 * essentially makes the variable a read-once variable if it's only

 * accessed using this function.

 *

 * Return: The variable value associated with field i for elt.

 */

u64 tracing_map_read_var_once(struct tracing_map_elt *elt, unsigned int i)

{

	elt->var_set[i] = false;

	return (u64)atomic64_read(&elt->vars[i]);

}



int tracing_map_cmp_string(void *val_a, void *val_b)

{

	char *a = val_a;
@@ -170,6 +237,28 @@ int tracing_map_add_sum_field(struct tracing_map *map) 
	return tracing_map_add_field(map, tracing_map_cmp_atomic64);

}



/**

 * tracing_map_add_var - Add a field describing a tracing_map var

 * @map: The tracing_map

 *

 * Add a var to the map and return the index identifying it in the map

 * and associated tracing_map_elts.  This is the index used for

 * instance to update a var for a particular tracing_map_elt using

 * tracing_map_update_var() or reading it via tracing_map_read_var().

 *

 * Return: The index identifying the var in the map and associated

 * tracing_map_elts, or -EINVAL on error.

 */

int tracing_map_add_var(struct tracing_map *map)

{

	int ret = -EINVAL;



	if (map->n_vars < TRACING_MAP_VARS_MAX)

		ret = map->n_vars++;



	return ret;

}



/**

 * tracing_map_add_key_field - Add a field describing a tracing_map key

 * @map: The tracing_map
@@ -280,6 +369,11 @@ static void tracing_map_elt_clear(struct tracing_map_elt *elt) 
		if (elt->fields[i].cmp_fn == tracing_map_cmp_atomic64)

			atomic64_set(&elt->fields[i].sum, 0);



	for (i = 0; i < elt->map->n_vars; i++) {

		atomic64_set(&elt->vars[i], 0);

		elt->var_set[i] = false;

	}



	if (elt->map->ops && elt->map->ops->elt_clear)

		elt->map->ops->elt_clear(elt);

}
@@ -306,6 +400,8 @@ static void tracing_map_elt_free(struct tracing_map_elt *elt) 
	if (elt->map->ops && elt->map->ops->elt_free)

		elt->map->ops->elt_free(elt);

	kfree(elt->fields);

	kfree(elt->vars);

	kfree(elt->var_set);

	kfree(elt->key);

	kfree(elt);

}
@@ -333,6 +429,18 @@ static struct tracing_map_elt *tracing_map_elt_alloc(struct tracing_map *map) 
		goto free;

	}



	elt->vars = kcalloc(map->n_vars, sizeof(*elt->vars), GFP_KERNEL);

	if (!elt->vars) {

		err = -ENOMEM;

		goto free;

	}



	elt->var_set = kcalloc(map->n_vars, sizeof(*elt->var_set), GFP_KERNEL);

	if (!elt->var_set) {

		err = -ENOMEM;

		goto free;

	}



	tracing_map_elt_init_fields(elt);



	if (map->ops && map->ops->elt_alloc) {

kernel/trace/tracing_map.h

+11 −0
Original line number Diff line number Diff line
@@ -10,6 +10,7 @@ 
#define TRACING_MAP_VALS_MAX		3

#define TRACING_MAP_FIELDS_MAX		(TRACING_MAP_KEYS_MAX + \

					 TRACING_MAP_VALS_MAX)

#define TRACING_MAP_VARS_MAX		16

#define TRACING_MAP_SORT_KEYS_MAX	2



typedef int (*tracing_map_cmp_fn_t) (void *val_a, void *val_b);
@@ -137,6 +138,8 @@ struct tracing_map_field { 
struct tracing_map_elt {

	struct tracing_map		*map;

	struct tracing_map_field	*fields;

	atomic64_t			*vars;

	bool				*var_set;

	void				*key;

	void				*private_data;

};
@@ -192,6 +195,7 @@ struct tracing_map { 
	int				key_idx[TRACING_MAP_KEYS_MAX];

	unsigned int			n_keys;

	struct tracing_map_sort_key	sort_key;

	unsigned int			n_vars;

	atomic64_t			hits;

	atomic64_t			drops;

};
@@ -241,6 +245,7 @@ tracing_map_create(unsigned int map_bits, 
extern int tracing_map_init(struct tracing_map *map);



extern int tracing_map_add_sum_field(struct tracing_map *map);

extern int tracing_map_add_var(struct tracing_map *map);

extern int tracing_map_add_key_field(struct tracing_map *map,

				     unsigned int offset,

				     tracing_map_cmp_fn_t cmp_fn);
@@ -260,7 +265,13 @@ extern int tracing_map_cmp_none(void *val_a, void *val_b); 


extern void tracing_map_update_sum(struct tracing_map_elt *elt,

				   unsigned int i, u64 n);

extern void tracing_map_set_var(struct tracing_map_elt *elt,

				unsigned int i, u64 n);

extern bool tracing_map_var_set(struct tracing_map_elt *elt, unsigned int i);

extern u64 tracing_map_read_sum(struct tracing_map_elt *elt, unsigned int i);

extern u64 tracing_map_read_var(struct tracing_map_elt *elt, unsigned int i);

extern u64 tracing_map_read_var_once(struct tracing_map_elt *elt, unsigned int i);



extern void tracing_map_set_field_descr(struct tracing_map *map,

					unsigned int i,

					unsigned int key_offset,

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