kernel/trace/trace_dynevent.h

   1 /* SPDX-License-Identifier: GPL-2.0 */
   2 /*
   3  * Common header file for generic dynamic events.
   4  */
   5
   6 #ifndef _TRACE_DYNEVENT_H
   7 #define _TRACE_DYNEVENT_H
   8
   9 #include <linux/kernel.h>
  10 #include <linux/list.h>
  11 #include <linux/mutex.h>
  12 #include <linux/seq_file.h>
  13
  14 #include "trace.h"
  15
  16 struct dyn_event;
  17
  18 /**
  19  * struct dyn_event_operations - Methods for each type of dynamic events
  20  *
  21  * These methods must be set for each type, since there is no default method.
  22  * Before using this for dyn_event_init(), it must be registered by
  23  * dyn_event_register().
  24  *
  25  * @create: Parse and create event method. This is invoked when user passes
  26  *  a event definition to dynamic_events interface. This must not destruct
  27  *  the arguments and return -ECANCELED if given arguments doesn't match its
  28  *  command prefix.
  29  * @show: Showing method. This is invoked when user reads the event definitions
  30  *  via dynamic_events interface.
  31  * @is_busy: Check whether given event is busy so that it can not be deleted.
  32  *  Return true if it is busy, otherwides false.
  33  * @free: Delete the given event. Return 0 if success, otherwides error.
  34  * @match: Check whether given event and system name match this event.
  35  *  Return true if it matches, otherwides false.
  36  *
  37  * Except for @create, these methods are called under holding event_mutex.
  38  */
  39 struct dyn_event_operations {
  40         struct list_head        list;
  41         int (*create)(int argc, const char *argv[]);
  42         int (*show)(struct seq_file *m, struct dyn_event *ev);
  43         bool (*is_busy)(struct dyn_event *ev);
  44         int (*free)(struct dyn_event *ev);
  45         bool (*match)(const char *system, const char *event,
  46                         struct dyn_event *ev);
  47 };
  48
  49 /* Register new dyn_event type -- must be called at first */
  50 int dyn_event_register(struct dyn_event_operations *ops);
  51
  52 /**
  53  * struct dyn_event - Dynamic event list header
  54  *
  55  * The dyn_event structure encapsulates a list and a pointer to the operators
  56  * for making a global list of dynamic events.
  57  * User must includes this in each event structure, so that those events can
  58  * be added/removed via dynamic_events interface.
  59  */
  60 struct dyn_event {
  61         struct list_head                list;
  62         struct dyn_event_operations     *ops;
  63 };
  64
  65 extern struct list_head dyn_event_list;
  66
  67 static inline
  68 int dyn_event_init(struct dyn_event *ev, struct dyn_event_operations *ops)
  69 {
  70         if (!ev || !ops)
  71                 return -EINVAL;
  72
  73         INIT_LIST_HEAD(&ev->list);
  74         ev->ops = ops;
  75         return 0;
  76 }
  77
  78 static inline int dyn_event_add(struct dyn_event *ev)
  79 {
  80         lockdep_assert_held(&event_mutex);
  81
  82         if (!ev || !ev->ops)
  83                 return -EINVAL;
  84
  85         list_add_tail(&ev->list, &dyn_event_list);
  86         return 0;
  87 }
  88
  89 static inline void dyn_event_remove(struct dyn_event *ev)
  90 {
  91         lockdep_assert_held(&event_mutex);
  92         list_del_init(&ev->list);
  93 }
  94
  95 void *dyn_event_seq_start(struct seq_file *m, loff_t *pos);
  96 void *dyn_event_seq_next(struct seq_file *m, void *v, loff_t *pos);
  97 void dyn_event_seq_stop(struct seq_file *m, void *v);
  98 int dyn_events_release_all(struct dyn_event_operations *type);
  99 int dyn_event_release(int argc, char **argv, struct dyn_event_operations *type);
 100
 101 /*
 102  * for_each_dyn_event   -       iterate over the dyn_event list
 103  * @pos:        the struct dyn_event * to use as a loop cursor
 104  *
 105  * This is just a basement of for_each macro. Wrap this for
 106  * each actual event structure with ops filtering.
 107  */
 108 #define for_each_dyn_event(pos) \
 109         list_for_each_entry(pos, &dyn_event_list, list)
 110
 111 /*
 112  * for_each_dyn_event   -       iterate over the dyn_event list safely
 113  * @pos:        the struct dyn_event * to use as a loop cursor
 114  * @n:          the struct dyn_event * to use as temporary storage
 115  */
 116 #define for_each_dyn_event_safe(pos, n) \
 117         list_for_each_entry_safe(pos, n, &dyn_event_list, list)
 118
 119 #endif