tracing/user_events: Store register flags on events

Currently we don't have any available flags for user processes to use to
indicate options for user_events. We will soon have a flag to indicate
the event should or should not auto-delete once it's not being used by
anyone.

Add a reg_flags field to user_events and parameters to existing
functions to allow for this in future patches.

Link: https://lkml.kernel.org/r/[email protected]

Signed-off-by: Beau Belgrave <[email protected]>
Signed-off-by: Steven Rostedt (Google) <[email protected]>

Author: beaubelgrave

kernel/trace/trace_events_user.c

@@ -87,6 +87,7 @@ struct user_event {
 	struct list_head		validators;
 	refcount_t			refcnt;
 	int				min_size;
+	int				reg_flags;
 	char				status;
 };
 
@@ -165,7 +166,7 @@ typedef void (*user_event_func_t) (struct user_event *user, struct iov_iter *i,
 
 static int user_event_parse(struct user_event_group *group, char *name,
 			    char *args, char *flags,
-			    struct user_event **newuser);
+			    struct user_event **newuser, int reg_flags);
 
 static struct user_event_mm *user_event_mm_get(struct user_event_mm *mm);
 static struct user_event_mm *user_event_mm_get_all(struct user_event *user);
@@ -810,7 +811,8 @@ static struct list_head *user_event_get_fields(struct trace_event_call *call)
  * Upon success user_event has its ref count increased by 1.
  */
 static int user_event_parse_cmd(struct user_event_group *group,
-				char *raw_command, struct user_event **newuser)
+				char *raw_command, struct user_event **newuser,
+				int reg_flags)
 {
 	char *name = raw_command;
 	char *args = strpbrk(name, " ");
@@ -824,7 +826,7 @@ static int user_event_parse_cmd(struct user_event_group *group,
 	if (flags)
 		*flags++ = '\0';
 
-	return user_event_parse(group, name, args, flags, newuser);
+	return user_event_parse(group, name, args, flags, newuser, reg_flags);
 }
 
 static int user_field_array_size(const char *type)
@@ -1588,7 +1590,7 @@ static int user_event_create(const char *raw_command)
 
 	mutex_lock(&group->reg_mutex);
 
-	ret = user_event_parse_cmd(group, name, &user);
+	ret = user_event_parse_cmd(group, name, &user, 0);
 
 	if (!ret)
 		refcount_dec(&user->refcnt);
@@ -1751,7 +1753,7 @@ static int user_event_trace_register(struct user_event *user)
  */
 static int user_event_parse(struct user_event_group *group, char *name,
 			    char *args, char *flags,
-			    struct user_event **newuser)
+			    struct user_event **newuser, int reg_flags)
 {
 	int ret;
 	u32 key;
@@ -1846,6 +1848,8 @@ static int user_event_parse(struct user_event_group *group, char *name,
 	if (ret)
 		goto put_user_lock;
 
+	user->reg_flags = reg_flags;
+
 	/* Ensure we track self ref and caller ref (2) */
 	refcount_set(&user->refcnt, 2);
 
@@ -2144,7 +2148,7 @@ static long user_events_ioctl_reg(struct user_event_file_info *info,
 		return ret;
 	}
 
-	ret = user_event_parse_cmd(info->group, name, &user);
+	ret = user_event_parse_cmd(info->group, name, &user, reg.flags);
 
 	if (ret) {
 		kfree(name);