From: Tom Zanussi 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: Tom Zanussi Signed-off-by: Steven Rostedt (VMware) --- kernel/trace/tracing_map.c | 108 +++++++++++++++++++++++++++++++++++++++++++++ kernel/trace/tracing_map.h | 11 +++++ 2 files changed, 119 insertions(+) diff --git a/kernel/trace/tracing_map.c b/kernel/trace/tracing_map.c index f47a4d54bcf0..5cadb1b8b5fe 100644 --- a/kernel/trace/tracing_map.c +++ b/kernel/trace/tracing_map.c @@ -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) { diff --git a/kernel/trace/tracing_map.h b/kernel/trace/tracing_map.h index de57887c0670..053eb92b2d31 100644 --- a/kernel/trace/tracing_map.h +++ b/kernel/trace/tracing_map.h @@ -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, -- 2.15.1