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. The argc
  35  *  and argv is used for exact match. Return true if it matches, otherwides
  36  *  false.
  37  *
  38  * Except for @create, these methods are called under holding event_mutex.
  39  */
  40 struct dyn_event_operations {
  41         struct list_head        list;
  42         int (*create)(int argc, const char *argv[]);
  43         int (*show)(struct seq_file *m, struct dyn_event *ev);
  44         bool (*is_busy)(struct dyn_event *ev);
  45         int (*free)(struct dyn_event *ev);
  46         bool (*match)(const char *system, const char *event,
  47                       int argc, const char **argv, struct dyn_event *ev);
  48 };
  49
  50 /* Register new dyn_event type -- must be called at first */
  51 int dyn_event_register(struct dyn_event_operations *ops);
  52
  53 /**
  54  * struct dyn_event - Dynamic event list header
  55  *
  56  * The dyn_event structure encapsulates a list and a pointer to the operators
  57  * for making a global list of dynamic events.
  58  * User must includes this in each event structure, so that those events can
  59  * be added/removed via dynamic_events interface.
  60  */
  61 struct dyn_event {
  62         struct list_head                list;
  63         struct dyn_event_operations     *ops;
  64 };
  65
  66 extern struct list_head dyn_event_list;
  67
  68 static inline
  69 int dyn_event_init(struct dyn_event *ev, struct dyn_event_operations *ops)
  70 {
  71         if (!ev || !ops)
  72                 return -EINVAL;
  73
  74         INIT_LIST_HEAD(&ev->list);
  75         ev->ops = ops;
  76         return 0;
  77 }
  78
  79 static inline int dyn_event_add(struct dyn_event *ev)
  80 {
  81         lockdep_assert_held(&event_mutex);
  82
  83         if (!ev || !ev->ops)
  84                 return -EINVAL;
  85
  86         list_add_tail(&ev->list, &dyn_event_list);
  87         return 0;
  88 }
  89
  90 static inline void dyn_event_remove(struct dyn_event *ev)
  91 {
  92         lockdep_assert_held(&event_mutex);
  93         list_del_init(&ev->list);
  94 }
  95
  96 void *dyn_event_seq_start(struct seq_file *m, loff_t *pos);
  97 void *dyn_event_seq_next(struct seq_file *m, void *v, loff_t *pos);
  98 void dyn_event_seq_stop(struct seq_file *m, void *v);
  99 int dyn_events_release_all(struct dyn_event_operations *type);
 100 int dyn_event_release(int argc, char **argv, struct dyn_event_operations *type);
 101
 102 /*
 103  * for_each_dyn_event   -       iterate over the dyn_event list
 104  * @pos:        the struct dyn_event * to use as a loop cursor
 105  *
 106  * This is just a basement of for_each macro. Wrap this for
 107  * each actual event structure with ops filtering.
 108  */
 109 #define for_each_dyn_event(pos) \
 110         list_for_each_entry(pos, &dyn_event_list, list)
 111
 112 /*
 113  * for_each_dyn_event   -       iterate over the dyn_event list safely
 114  * @pos:        the struct dyn_event * to use as a loop cursor
 115  * @n:          the struct dyn_event * to use as temporary storage
 116  */
 117 #define for_each_dyn_event_safe(pos, n) \
 118         list_for_each_entry_safe(pos, n, &dyn_event_list, list)
 119
 120 #endif