[24/54] tracing: Generalize per-element hist trigger data

Commit Message

[e-mail] Aug. 29, 2018, 12:17 p.m. UTC

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.

Link: http://lkml.kernel.org/r/450[e-mail]

Signed-off-by: Tom Zanussi <[e-mail]>
Signed-off-by: Steven Rostedt (VMware) <[e-mail]>
(cherry picked from commit af6a29bcaf8ff260222a953536c13c167d5c4649)
Signed-off-by: Hirotaka MOTAI <[e-mail]>
---
 kernel/trace/trace_events_hist.c | 76 ++++++++++++++++++--------------
 1 file changed, 43 insertions(+), 33 deletions(-)

Patch

diff --git a/kernel/trace/trace_events_hist.c b/kernel/trace/trace_events_hist.c
index 4c3c7d78..f072ed31 100644
--- a/kernel/trace/trace_events_hist.c
+++ b/kernel/trace/trace_events_hist.c
@@ -284,16 +284,20 @@  static struct hist_field *find_var(struct hist_trigger_data *hist_data,
 			if (hist_field)
 				return hist_field;
 		}
 	}
 
 	return NULL;
 }
 
+struct hist_elt_data {
+	char *comm;
+};
+
 static const char *hist_field_name(struct hist_field *field,
 				   unsigned int level)
 {
 	const char *field_name = "";
 
 	if (level > 1)
 		return field_name;
 
@@ -498,55 +502,71 @@  static inline void save_comm(char *comm, struct task_struct *task)
 	if (WARN_ON_ONCE(task->pid < 0)) {
 		strcpy(comm, "<XXX>");
 		return;
 	}
 
 	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;
+	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)
 {
 	const char *flags_str = NULL;
 
 	if (hist_field->flags & HIST_FIELD_FL_HEX)
 		flags_str = "hex";
@@ -1479,31 +1499,16 @@  static int create_tracing_map_fields(struct hist_trigger_data *hist_data)
 			hist_field->var.idx = idx;
 			hist_field->var.hist_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,
 		 struct trace_event_file *file,
 		 bool remove)
 {
 	const struct tracing_map_ops *map_ops = NULL;
 	struct hist_trigger_data *hist_data;
@@ -1519,18 +1524,17 @@  create_hist_data(unsigned int map_bits,
 	ret = create_hist_fields(hist_data, file);
 	if (ret)
 		goto free;
 
 	ret = create_sort_keys(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);
 	if (IS_ERR(hist_data->map)) {
 		ret = PTR_ERR(hist_data->map);
 		hist_data->map = NULL;
 		goto free;
 	}
@@ -1708,17 +1712,23 @@  hist_trigger_entry_print(struct seq_file *m,
 			seq_printf(m, "%s: [%llx] %-45s", field_name,
 				   uval, str);
 		} else if (key_field->flags & HIST_FIELD_FL_SYM_OFFSET) {
 			uval = *(u64 *)(key + key_field->offset);
 			sprint_symbol(str, uval);
 			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,
 				   comm, uval);
 		} else if (key_field->flags & HIST_FIELD_FL_SYSCALL) {
 			const char *syscall_name;
 
 			uval = *(u64 *)(key + key_field->offset);