[PATCH v6 19/37] tracing: Generalize per-element hist trigger data

Tom Zanussi
2017-11-17T20:41:30Z

Up until now, hist triggers only needed per-element support for saving
'comm' data, which was saved directly as a private data pointer.

In anticipation of the need to save other data besides 'comm', add a
new hist_elt_data struct for the purpose, and switch the current
'comm'-related code over to that.

Signed-off-by: Tom Zanussi <tom.zanussi@linux.intel.com>
---
kernel/trace/trace_events_hist.c | 76 +++++++++++++++++++++++-----------------
1 file changed, 43 insertions(+), 33 deletions(-)

diff --git a/kernel/trace/trace_events_hist.c b/kernel/trace/trace_events_hist.c
index f6c59a5..d9f24b7 100644
--- a/kernel/trace/trace_events_hist.c
+++ b/kernel/trace/trace_events_hist.c
@@ -289,6 +289,10 @@ static struct hist_field *find_var(struct hist_trigger_data *hist_data,
return NULL;
}

+struct hist_elt_data {
+ char *comm;
+};
+
static const char *hist_field_name(struct hist_field *field,
unsigned int level)
{
@@ -503,45 +507,61 @@ static inline void save_comm(char *comm, struct task_struct *task)
memcpy(comm, task->comm, TASK_COMM_LEN);
}

-static void hist_trigger_elt_comm_free(struct tracing_map_elt *elt)
+static void hist_elt_data_free(struct hist_elt_data *elt_data)
+{
+ kfree(elt_data->comm);
+ kfree(elt_data);
+}
+
+static void hist_trigger_elt_data_free(struct tracing_map_elt *elt)
{
- kfree((char *)elt->private_data);
+ struct hist_elt_data *elt_data = elt->private_data;
+
+ hist_elt_data_free(elt_data);
}

-static int hist_trigger_elt_comm_alloc(struct tracing_map_elt *elt)
+static int hist_trigger_elt_data_alloc(struct tracing_map_elt *elt)
{
struct hist_trigger_data *hist_data = elt->map->private_data;
+ unsigned int size = TASK_COMM_LEN + 1;
+ struct hist_elt_data *elt_data;
struct hist_field *key_field;
unsigned int i;

+ elt_data = kzalloc(sizeof(*elt_data), GFP_KERNEL);
+ if (!elt_data)
+ return -ENOMEM;
+
for_each_hist_key_field(i, hist_data) {
key_field = hist_data->fields[i];

if (key_field->flags & HIST_FIELD_FL_EXECNAME) {
- unsigned int size = TASK_COMM_LEN + 1;
-
- elt->private_data = kzalloc(size, GFP_KERNEL);
- if (!elt->private_data)
+ elt_data->comm = kzalloc(size, GFP_KERNEL);
+ if (!elt_data->comm) {
+ kfree(elt_data);
return -ENOMEM;
+ }
break;
}
}

+ elt->private_data = elt_data;
+
return 0;
}

-static void hist_trigger_elt_comm_init(struct tracing_map_elt *elt)
+static void hist_trigger_elt_data_init(struct tracing_map_elt *elt)
{
- char *comm = elt->private_data;
+ struct hist_elt_data *elt_data = elt->private_data;

- if (comm)
- save_comm(comm, current);
+ if (elt_data->comm)
+ save_comm(elt_data->comm, current);
}

-static const struct tracing_map_ops hist_trigger_elt_comm_ops = {
- .elt_alloc = hist_trigger_elt_comm_alloc,
- .elt_free = hist_trigger_elt_comm_free,
- .elt_init = hist_trigger_elt_comm_init,
+static const struct tracing_map_ops hist_trigger_elt_data_ops = {
+ .elt_alloc = hist_trigger_elt_data_alloc,
+ .elt_free = hist_trigger_elt_data_free,
+ .elt_init = hist_trigger_elt_data_init,
};

static const char *get_hist_field_flags(struct hist_field *hist_field)
@@ -1512,21 +1532,6 @@ static int create_tracing_map_fields(struct hist_trigger_data *hist_data)
return 0;
}

-static bool need_tracing_map_ops(struct hist_trigger_data *hist_data)
-{
- struct hist_field *key_field;
- unsigned int i;
-
- for_each_hist_key_field(i, hist_data) {
- key_field = hist_data->fields[i];
-
- if (key_field->flags & HIST_FIELD_FL_EXECNAME)
- return true;
- }
-
- return false;
-}
-
static struct hist_trigger_data *
create_hist_data(unsigned int map_bits,
struct hist_trigger_attrs *attrs,
@@ -1552,8 +1557,7 @@ static bool need_tracing_map_ops(struct hist_trigger_data *hist_data)
if (ret)
goto free;

- if (need_tracing_map_ops(hist_data))
- map_ops = &hist_trigger_elt_comm_ops;
+ map_ops = &hist_trigger_elt_data_ops;

hist_data->map = tracing_map_create(map_bits, hist_data->key_size,
map_ops, hist_data);
@@ -1741,7 +1745,13 @@ static void hist_trigger_stacktrace_print(struct seq_file *m,
seq_printf(m, "%s: [%llx] %-55s", field_name,
uval, str);
} else if (key_field->flags & HIST_FIELD_FL_EXECNAME) {
- char *comm = elt->private_data;
+ struct hist_elt_data *elt_data = elt->private_data;
+ char *comm;
+
+ if (WARN_ON_ONCE(!elt_data))
+ return;
+
+ comm = elt_data->comm;

uval = *(u64 *)(key + key_field->offset);
seq_printf(m, "%s: %-16s[%10llu]", field_name,
--
1.9.3