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Subject[PATCH v2 28/40] tracing: Add support for 'field variables'
Date
Users should be able to directly specify event fields in hist trigger
'actions' rather than being forced to explicitly create a variable for
that purpose.

Add support allowing fields to be used directly in actions, which
essentially does just that - creates 'invisible' variables for each
bare field specified in an action. If a bare field refers to a field
on another (matching) event, it even creates a special histogram for
the purpose (since variables can't be defined on an existing histogram
after histogram creation).

Signed-off-by: Tom Zanussi <tom.zanussi@linux.intel.com>
---
kernel/trace/trace_events_hist.c | 452 ++++++++++++++++++++++++++++++++++++++-
1 file changed, 451 insertions(+), 1 deletion(-)

diff --git a/kernel/trace/trace_events_hist.c b/kernel/trace/trace_events_hist.c
index 2906b92..ea006a0 100644
--- a/kernel/trace/trace_events_hist.c
+++ b/kernel/trace/trace_events_hist.c
@@ -254,6 +254,16 @@ struct hist_trigger_attrs {
struct var_defs var_defs;
};

+struct field_var {
+ struct hist_field *var;
+ struct hist_field *val;
+};
+
+struct field_var_hist {
+ struct hist_trigger_data *hist_data;
+ char *cmd;
+};
+
struct hist_trigger_data {
struct hist_field *fields[HIST_FIELDS_MAX];
unsigned int n_vals;
@@ -274,6 +284,14 @@ struct hist_trigger_data {

struct action_data *actions[HIST_ACTIONS_MAX];
unsigned int n_actions;
+
+ struct hist_field *synth_var_refs[SYNTH_FIELDS_MAX];
+ unsigned int n_synth_var_refs;
+ struct field_var *field_vars[SYNTH_FIELDS_MAX];
+ unsigned int n_field_vars;
+ unsigned int n_field_var_str;
+ struct field_var_hist *field_var_hists[SYNTH_FIELDS_MAX];
+ unsigned int n_field_var_hists;
};

struct synth_field {
@@ -1392,6 +1410,7 @@ static struct hist_field *find_event_var(struct trace_array *tr,
struct hist_elt_data {
char *comm;
u64 *var_ref_vals;
+ char *field_var_str[SYNTH_FIELDS_MAX];
};

static u64 hist_field_var_ref(struct hist_field *hist_field,
@@ -1669,7 +1688,14 @@ static inline void save_comm(char *comm, struct task_struct *task)

static void hist_trigger_elt_data_free(struct tracing_map_elt *elt)
{
+ struct hist_trigger_data *hist_data = elt->map->private_data;
struct hist_elt_data *private_data = elt->private_data;
+ unsigned int i, n_str;
+
+ n_str = hist_data->n_field_var_str;
+
+ for (i = 0; i < n_str; i++)
+ kfree(private_data->field_var_str[i]);

kfree(private_data->comm);
kfree(private_data);
@@ -1681,7 +1707,7 @@ static int hist_trigger_elt_data_alloc(struct tracing_map_elt *elt)
unsigned int size = TASK_COMM_LEN + 1;
struct hist_elt_data *elt_data;
struct hist_field *key_field;
- unsigned int i;
+ unsigned int i, n_str;

elt->private_data = elt_data = kzalloc(sizeof(*elt_data), GFP_KERNEL);
if (!elt_data)
@@ -1701,6 +1727,18 @@ static int hist_trigger_elt_data_alloc(struct tracing_map_elt *elt)
}
}

+ n_str = hist_data->n_field_var_str;
+
+ size = STR_VAR_LEN_MAX;
+
+ for (i = 0; i < n_str; i++) {
+ elt_data->field_var_str[i] = kzalloc(size, GFP_KERNEL);
+ if (!elt_data->field_var_str[i]) {
+ hist_trigger_elt_data_free(elt);
+ return -ENOMEM;
+ }
+ }
+
return 0;
}

@@ -2347,6 +2385,387 @@ static struct hist_field *parse_expr(struct hist_trigger_data *hist_data,
return ERR_PTR(ret);
}

+static char *find_trigger_filter(struct hist_trigger_data *hist_data,
+ struct trace_event_file *file)
+{
+ struct event_trigger_data *test;
+
+ list_for_each_entry_rcu(test, &file->triggers, list) {
+ if (test->cmd_ops->trigger_type == ETT_EVENT_HIST) {
+ if (test->private_data == hist_data)
+ return test->filter_str;
+ }
+ }
+
+ return NULL;
+}
+
+static struct event_command trigger_hist_cmd;
+static int event_hist_trigger_func(struct event_command *cmd_ops,
+ struct trace_event_file *file,
+ char *glob, char *cmd, char *param);
+
+static bool compatible_keys(struct hist_trigger_data *target_hist_data,
+ struct hist_trigger_data *hist_data,
+ unsigned int n_keys)
+{
+ struct hist_field *target_hist_field, *hist_field;
+ unsigned int n, i, j;
+
+ if (hist_data->n_fields - hist_data->n_vals != n_keys)
+ return false;
+
+ i = hist_data->n_vals;
+ j = target_hist_data->n_vals;
+
+ for (n = 0; n < n_keys; n++) {
+ hist_field = hist_data->fields[i + n];
+ target_hist_field = hist_data->fields[j + n];
+
+ if (strcmp(hist_field->type, target_hist_field->type) != 0)
+ return false;
+ if (hist_field->size != target_hist_field->size)
+ return false;
+ if (hist_field->is_signed != target_hist_field->is_signed)
+ return false;
+ }
+
+ return true;
+}
+
+static struct hist_trigger_data *
+find_compatible_hist(struct hist_trigger_data *target_hist_data,
+ struct trace_event_file *file)
+{
+ struct hist_trigger_data *hist_data;
+ struct event_trigger_data *test;
+ unsigned int n_keys;
+
+ n_keys = target_hist_data->n_fields - target_hist_data->n_vals;
+
+ list_for_each_entry_rcu(test, &file->triggers, list) {
+ if (test->cmd_ops->trigger_type == ETT_EVENT_HIST) {
+ hist_data = test->private_data;
+
+ if (compatible_keys(target_hist_data, hist_data, n_keys))
+ return hist_data;
+ }
+ }
+
+ return NULL;
+}
+
+static struct trace_event_file *event_file(struct trace_array *tr,
+ char *system, char *event_name)
+{
+ struct trace_event_file *file;
+
+ file = find_event_file(tr, system, event_name);
+ if (!file)
+ return ERR_PTR(-EINVAL);
+
+ return file;
+}
+
+static struct hist_field *
+create_field_var_hist(struct hist_trigger_data *target_hist_data,
+ char *system, char *event_name, char *field_name)
+{
+ struct trace_array *tr = target_hist_data->event_file->tr;
+ struct hist_field *event_var = ERR_PTR(-EINVAL);
+ struct hist_trigger_data *hist_data;
+ unsigned int i, n, first = true;
+ struct field_var_hist *var_hist;
+ struct trace_event_file *file;
+ struct hist_field *key_field;
+ char *saved_filter;
+ char *cmd;
+ int ret;
+
+ if (target_hist_data->n_field_var_hists >= SYNTH_FIELDS_MAX)
+ return ERR_PTR(-EINVAL);
+
+ file = event_file(tr, system, event_name);
+
+ if (IS_ERR(file)) {
+ ret = PTR_ERR(file);
+ return ERR_PTR(ret);
+ }
+
+ hist_data = find_compatible_hist(target_hist_data, file);
+ if (!hist_data)
+ return ERR_PTR(-EINVAL);
+
+ var_hist = kzalloc(sizeof(*var_hist), GFP_KERNEL);
+ if (!var_hist)
+ return ERR_PTR(-ENOMEM);
+
+ cmd = kzalloc(MAX_FILTER_STR_VAL, GFP_KERNEL);
+ if (!cmd) {
+ kfree(var_hist);
+ return ERR_PTR(-ENOMEM);
+ }
+
+ strcat(cmd, "keys=");
+
+ for_each_hist_key_field(i, hist_data) {
+ key_field = hist_data->fields[i];
+ if (!first)
+ strcat(cmd, ",");
+ strcat(cmd, key_field->field->name);
+ first = false;
+ }
+
+ strcat(cmd, ":synthetic_");
+ strcat(cmd, field_name);
+ strcat(cmd, "=");
+ strcat(cmd, field_name);
+
+ saved_filter = find_trigger_filter(hist_data, file);
+ if (saved_filter) {
+ strcat(cmd, " if ");
+ strcat(cmd, saved_filter);
+ }
+
+ var_hist->cmd = kstrdup(cmd, GFP_KERNEL);
+ if (!var_hist->cmd) {
+ kfree(cmd);
+ kfree(var_hist);
+ return ERR_PTR(-ENOMEM);
+ }
+
+ var_hist->hist_data = hist_data;
+
+ ret = event_hist_trigger_func(&trigger_hist_cmd, file,
+ "", "hist", cmd);
+ if (ret) {
+ kfree(cmd);
+ kfree(var_hist->cmd);
+ kfree(var_hist);
+ return ERR_PTR(ret);
+ }
+
+ strcpy(cmd, "synthetic_");
+ strcat(cmd, field_name);
+
+ event_var = find_event_var(tr, system, event_name, cmd);
+ if (!event_var) {
+ kfree(cmd);
+ kfree(var_hist->cmd);
+ kfree(var_hist);
+ return ERR_PTR(-EINVAL);
+ }
+
+ n = target_hist_data->n_field_var_hists;
+ target_hist_data->field_var_hists[n] = var_hist;
+ target_hist_data->n_field_var_hists++;
+
+ return event_var;
+}
+
+static struct hist_field *
+find_target_event_var(struct hist_trigger_data *hist_data,
+ char *system, char *event_name, char *var_name)
+{
+ struct trace_event_file *file = hist_data->event_file;
+ struct hist_field *hist_field = NULL;
+
+ if (system) {
+ struct trace_event_call *call;
+
+ if (!event_name)
+ return NULL;
+
+ call = file->event_call;
+
+ if (strcmp(system, call->class->system) != 0)
+ return NULL;
+
+ if (strcmp(event_name, trace_event_name(call)) != 0)
+ return NULL;
+ }
+
+ hist_field = find_var_field(hist_data, var_name);
+
+ return hist_field;
+}
+
+static inline void __update_field_vars(struct tracing_map_elt *elt,
+ struct ring_buffer_event *rbe,
+ void *rec,
+ struct field_var **field_vars,
+ unsigned int n_field_vars,
+ unsigned int field_var_str_start)
+{
+ struct hist_elt_data *elt_data = elt->private_data;
+ unsigned int i, j, var_idx;
+ u64 var_val;
+
+ for (i = 0, j = field_var_str_start; i < n_field_vars; i++) {
+ struct field_var *field_var = field_vars[i];
+ struct hist_field *var = field_var->var;
+ struct hist_field *val = field_var->val;
+
+ var_val = val->fn(val, elt, rbe, rec);
+ var_idx = var->var.idx;
+
+ if (val->flags & HIST_FIELD_FL_STRING) {
+ char *str = elt_data->field_var_str[j++];
+ char *val_str = (char *)(uintptr_t)var_val;
+
+ strncpy(str, val_str, STR_VAR_LEN_MAX);
+ var_val = (u64)(uintptr_t)str;
+ }
+ tracing_map_set_var(elt, var_idx, var_val);
+ }
+}
+
+static void update_field_vars(struct hist_trigger_data *hist_data,
+ struct tracing_map_elt *elt,
+ struct ring_buffer_event *rbe,
+ void *rec)
+{
+ __update_field_vars(elt, rbe, rec, hist_data->field_vars,
+ hist_data->n_field_vars, 0);
+}
+
+static struct hist_field *create_var(struct hist_trigger_data *hist_data,
+ struct trace_event_file *file,
+ char *name, int size, const char *type)
+{
+ struct hist_field *var;
+ int idx;
+
+ if (find_var(file, name) && !hist_data->remove) {
+ var = ERR_PTR(-EINVAL);
+ goto out;
+ }
+
+ var = kzalloc(sizeof(struct hist_field), GFP_KERNEL);
+ if (!var) {
+ var = ERR_PTR(-ENOMEM);
+ goto out;
+ }
+
+ idx = tracing_map_add_var(hist_data->map);
+ if (idx < 0) {
+ kfree(var);
+ var = ERR_PTR(-EINVAL);
+ goto out;
+ }
+
+ var->flags = HIST_FIELD_FL_VAR;
+ var->var.idx = idx;
+ var->var.hist_data = var->hist_data = hist_data;
+ var->size = size;
+ var->var.name = kstrdup(name, GFP_KERNEL);
+ var->type = kstrdup(type, GFP_KERNEL);
+ if (!var->var.name || !var->type) {
+ kfree(var->var.name);
+ kfree(var->type);
+ kfree(var);
+ var = ERR_PTR(-ENOMEM);
+ }
+ out:
+ return var;
+}
+
+static struct field_var *create_field_var(struct hist_trigger_data *hist_data,
+ struct trace_event_file *file,
+ char *field_name)
+{
+ struct hist_field *val = NULL, *var = NULL;
+ unsigned long flags = HIST_FIELD_FL_VAR;
+ struct field_var *field_var;
+ int ret = 0;
+
+ if (hist_data->n_field_vars >= SYNTH_FIELDS_MAX) {
+ ret = -EINVAL;
+ goto err;
+ }
+
+ val = parse_atom(hist_data, file, field_name, &flags, NULL);
+ if (IS_ERR(val)) {
+ ret = PTR_ERR(val);
+ goto err;
+ }
+
+ var = create_var(hist_data, file, field_name, val->size, val->type);
+ if (IS_ERR(var)) {
+ kfree(val);
+ ret = PTR_ERR(var);
+ goto err;
+ }
+
+ field_var = kzalloc(sizeof(struct field_var), GFP_KERNEL);
+ if (!field_var) {
+ kfree(val);
+ kfree(var);
+ ret = -ENOMEM;
+ goto err;
+ }
+
+ field_var->var = var;
+ field_var->val = val;
+ out:
+ return field_var;
+ err:
+ field_var = ERR_PTR(ret);
+ goto out;
+}
+
+static struct field_var *
+create_target_field_var(struct hist_trigger_data *hist_data,
+ char *system, char *event_name, char *var_name)
+{
+ struct trace_event_file *file = hist_data->event_file;
+
+ if (system) {
+ struct trace_event_call *call;
+
+ if (!event_name)
+ return NULL;
+
+ call = file->event_call;
+
+ if (strcmp(system, call->class->system) != 0)
+ return NULL;
+
+ if (strcmp(event_name, trace_event_name(call)) != 0)
+ return NULL;
+ }
+
+ return create_field_var(hist_data, file, var_name);
+}
+
+static void destroy_field_var(struct field_var *field_var)
+{
+ if (!field_var)
+ return;
+
+ destroy_hist_field(field_var->var, 0);
+ destroy_hist_field(field_var->val, 0);
+
+ kfree(field_var);
+}
+
+static void destroy_field_vars(struct hist_trigger_data *hist_data)
+{
+ unsigned int i;
+
+ for (i = 0; i < hist_data->n_field_vars; i++)
+ destroy_field_var(hist_data->field_vars[i]);
+}
+
+static void save_field_var(struct hist_trigger_data *hist_data,
+ struct field_var *field_var)
+{
+ hist_data->field_vars[hist_data->n_field_vars++] = field_var;
+
+ if (field_var->val->flags & HIST_FIELD_FL_STRING)
+ hist_data->n_field_var_str++;
+}
+
static int create_hitcount_val(struct hist_trigger_data *hist_data)
{
hist_data->fields[HITCOUNT_IDX] =
@@ -2814,6 +3233,16 @@ static void print_actions_spec(struct seq_file *m,
}
}

+static void destroy_field_var_hists(struct hist_trigger_data *hist_data)
+{
+ unsigned int i;
+
+ for (i = 0; i < hist_data->n_field_var_hists; i++) {
+ kfree(hist_data->field_var_hists[i]->cmd);
+ kfree(hist_data->field_var_hists[i]);
+ }
+}
+
static void destroy_hist_data(struct hist_trigger_data *hist_data)
{
if (!hist_data)
@@ -2824,6 +3253,8 @@ static void destroy_hist_data(struct hist_trigger_data *hist_data)
tracing_map_destroy(hist_data->map);

destroy_actions(hist_data);
+ destroy_field_vars(hist_data);
+ destroy_field_var_hists(hist_data);

kfree(hist_data);
}
@@ -2957,6 +3388,8 @@ static void hist_trigger_elt_update(struct hist_trigger_data *hist_data,
tracing_map_set_var(elt, var_idx, hist_val);
}
}
+
+ update_field_vars(hist_data, elt, rbe, rec);
}

static inline void add_to_key(char *compound_key, void *key,
@@ -3677,6 +4110,21 @@ static bool hist_trigger_check_refs(struct event_trigger_data *data,
return false;
}

+static void unregister_field_var_hists(struct hist_trigger_data *hist_data)
+{
+ struct trace_event_file *file;
+ unsigned int i;
+ char *cmd;
+ int ret;
+
+ for (i = 0; i < hist_data->n_field_var_hists; i++) {
+ file = hist_data->field_var_hists[i]->hist_data->event_file;
+ cmd = hist_data->field_var_hists[i]->cmd;
+ ret = event_hist_trigger_func(&trigger_hist_cmd, file,
+ "!hist", "hist", cmd);
+ }
+}
+
static void hist_unregister_trigger(char *glob, struct event_trigger_ops *ops,
struct event_trigger_data *data,
struct trace_event_file *file)
@@ -3692,6 +4140,7 @@ static void hist_unregister_trigger(char *glob, struct event_trigger_ops *ops,
if (test->cmd_ops->trigger_type == ETT_EVENT_HIST) {
if (!hist_trigger_match(data, test, named_data, false))
continue;
+ unregister_field_var_hists(test->private_data);
unregistered = true;
list_del_rcu(&test->list);
trace_event_trigger_enable_disable(file, 0);
@@ -3733,6 +4182,7 @@ static void hist_unreg_all(struct trace_event_file *file)

list_for_each_entry_safe(test, n, &file->triggers, list) {
if (test->cmd_ops->trigger_type == ETT_EVENT_HIST) {
+ unregister_field_var_hists(test->private_data);
list_del_rcu(&test->list);
trace_event_trigger_enable_disable(file, 0);
update_cond_flag(file);
--
1.9.3
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