linux-stable/kernel/trace/trace_dynevent.h
Steven Rostedt (VMware) 8b0e6c744f tracing: Add DYNAMIC flag for dynamic events
To differentiate between static and dynamic events, add a new flag
DYNAMIC to the event flags that all dynamic events have set. This will
allow to differentiate when attaching to a dynamic event from a static
event.

Static events have a mod pointer that references the module they were
created in (or NULL for core kernel). This can be incremented when the
event has something attached to it. But there exists no such mechanism for
dynamic events. This is dangerous as the dynamic events may now disappear
without the "attachment" knowing that it no longer exists.

To enforce the dynamic flag, change dyn_event_add() to pass the event that
is being created such that it can set the DYNAMIC flag of the event. This
helps make sure that no location that creates a dynamic event misses
setting this flag.

Link: https://lore.kernel.org/linux-trace-devel/20210813004448.51c7de69ce432d338f4d226b@kernel.org/
Link: https://lkml.kernel.org/r/20210817035026.936958254@goodmis.org

Suggested-by: Masami Hiramatsu <mhiramat@kernel.org>
Acked-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
2021-08-18 18:10:32 -04:00

154 lines
4.7 KiB
C

/* SPDX-License-Identifier: GPL-2.0 */
/*
* Common header file for generic dynamic events.
*/
#ifndef _TRACE_DYNEVENT_H
#define _TRACE_DYNEVENT_H
#include <linux/kernel.h>
#include <linux/list.h>
#include <linux/mutex.h>
#include <linux/seq_file.h>
#include "trace.h"
struct dyn_event;
/**
* struct dyn_event_operations - Methods for each type of dynamic events
*
* These methods must be set for each type, since there is no default method.
* Before using this for dyn_event_init(), it must be registered by
* dyn_event_register().
*
* @create: Parse and create event method. This is invoked when user passes
* a event definition to dynamic_events interface. This must not destruct
* the arguments and return -ECANCELED if given arguments doesn't match its
* command prefix.
* @show: Showing method. This is invoked when user reads the event definitions
* via dynamic_events interface.
* @is_busy: Check whether given event is busy so that it can not be deleted.
* Return true if it is busy, otherwise false.
* @free: Delete the given event. Return 0 if success, otherwise error.
* @match: Check whether given event and system name match this event. The argc
* and argv is used for exact match. Return true if it matches, otherwise
* false.
*
* Except for @create, these methods are called under holding event_mutex.
*/
struct dyn_event_operations {
struct list_head list;
int (*create)(const char *raw_command);
int (*show)(struct seq_file *m, struct dyn_event *ev);
bool (*is_busy)(struct dyn_event *ev);
int (*free)(struct dyn_event *ev);
bool (*match)(const char *system, const char *event,
int argc, const char **argv, struct dyn_event *ev);
};
/* Register new dyn_event type -- must be called at first */
int dyn_event_register(struct dyn_event_operations *ops);
/**
* struct dyn_event - Dynamic event list header
*
* The dyn_event structure encapsulates a list and a pointer to the operators
* for making a global list of dynamic events.
* User must includes this in each event structure, so that those events can
* be added/removed via dynamic_events interface.
*/
struct dyn_event {
struct list_head list;
struct dyn_event_operations *ops;
};
extern struct list_head dyn_event_list;
static inline
int dyn_event_init(struct dyn_event *ev, struct dyn_event_operations *ops)
{
if (!ev || !ops)
return -EINVAL;
INIT_LIST_HEAD(&ev->list);
ev->ops = ops;
return 0;
}
static inline int dyn_event_add(struct dyn_event *ev,
struct trace_event_call *call)
{
lockdep_assert_held(&event_mutex);
if (!ev || !ev->ops)
return -EINVAL;
call->flags |= TRACE_EVENT_FL_DYNAMIC;
list_add_tail(&ev->list, &dyn_event_list);
return 0;
}
static inline void dyn_event_remove(struct dyn_event *ev)
{
lockdep_assert_held(&event_mutex);
list_del_init(&ev->list);
}
void *dyn_event_seq_start(struct seq_file *m, loff_t *pos);
void *dyn_event_seq_next(struct seq_file *m, void *v, loff_t *pos);
void dyn_event_seq_stop(struct seq_file *m, void *v);
int dyn_events_release_all(struct dyn_event_operations *type);
int dyn_event_release(const char *raw_command, struct dyn_event_operations *type);
/*
* for_each_dyn_event - iterate over the dyn_event list
* @pos: the struct dyn_event * to use as a loop cursor
*
* This is just a basement of for_each macro. Wrap this for
* each actual event structure with ops filtering.
*/
#define for_each_dyn_event(pos) \
list_for_each_entry(pos, &dyn_event_list, list)
/*
* for_each_dyn_event - iterate over the dyn_event list safely
* @pos: the struct dyn_event * to use as a loop cursor
* @n: the struct dyn_event * to use as temporary storage
*/
#define for_each_dyn_event_safe(pos, n) \
list_for_each_entry_safe(pos, n, &dyn_event_list, list)
extern void dynevent_cmd_init(struct dynevent_cmd *cmd, char *buf, int maxlen,
enum dynevent_type type,
dynevent_create_fn_t run_command);
typedef int (*dynevent_check_arg_fn_t)(void *data);
struct dynevent_arg {
const char *str;
char separator; /* e.g. ';', ',', or nothing */
};
extern void dynevent_arg_init(struct dynevent_arg *arg,
char separator);
extern int dynevent_arg_add(struct dynevent_cmd *cmd,
struct dynevent_arg *arg,
dynevent_check_arg_fn_t check_arg);
struct dynevent_arg_pair {
const char *lhs;
const char *rhs;
char operator; /* e.g. '=' or nothing */
char separator; /* e.g. ';', ',', or nothing */
};
extern void dynevent_arg_pair_init(struct dynevent_arg_pair *arg_pair,
char operator, char separator);
extern int dynevent_arg_pair_add(struct dynevent_cmd *cmd,
struct dynevent_arg_pair *arg_pair,
dynevent_check_arg_fn_t check_arg);
extern int dynevent_str_add(struct dynevent_cmd *cmd, const char *str);
#endif