liblttng-ust/ltt-probes.c

   1 /*
   2  * ltt-probes.c
   3  *
   4  * Copyright 2010 (c) - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
   5  *
   6  * Holds LTTng probes registry.
   7  *
   8  * Dual LGPL v2.1/GPL v2 license.
   9  */
  10
  11 #include <string.h>
  12 #include <errno.h>
  13 #include <urcu/list.h>
  14 #include <lttng/core.h>
  15 #include <lttng/ust-events.h>
  16
  17 #include "ltt-tracer-core.h"
  18
  19 /*
  20  * probe list is protected by ust_lock()/ust_unlock().
  21  */
  22 static CDS_LIST_HEAD(probe_list);
  23
  24 static
  25 const struct lttng_event_desc *find_event(const char *name)
  26 {
  27         struct lttng_probe_desc *probe_desc;
  28         int i;
  29
  30         cds_list_for_each_entry(probe_desc, &probe_list, head) {
  31                 for (i = 0; i < probe_desc->nr_events; i++) {
  32                         if (!strcmp(probe_desc->event_desc[i].name, name))
  33                                 return &probe_desc->event_desc[i];
  34                 }
  35         }
  36         return NULL;
  37 }
  38
  39 int ltt_probe_register(struct lttng_probe_desc *desc)
  40 {
  41         int ret = 0;
  42         int i;
  43
  44         ust_lock();
  45         /*
  46          * TODO: This is O(N^2). Turn into a hash table when probe registration
  47          * overhead becomes an issue.
  48          */
  49         for (i = 0; i < desc->nr_events; i++) {
  50                 if (find_event(desc->event_desc[i].name)) {
  51                         ret = -EEXIST;
  52                         goto end;
  53                 }
  54         }
  55         cds_list_add(&desc->head, &probe_list);
  56
  57         /*
  58          * fix the events awaiting probe load.
  59          */
  60         for (i = 0; i < desc->nr_events; i++) {
  61                 ret = pending_probe_fix_events(&desc->event_desc[i]);
  62                 assert(!ret);
  63         }
  64 end:
  65         ust_unlock();
  66         return ret;
  67 }
  68
  69 void ltt_probe_unregister(struct lttng_probe_desc *desc)
  70 {
  71         ust_lock();
  72         cds_list_del(&desc->head);
  73         ust_unlock();
  74 }
  75
  76 /*
  77  * called with UST lock held.
  78  */
  79 const struct lttng_event_desc *ltt_event_get(const char *name)
  80 {
  81         const struct lttng_event_desc *event;
  82
  83         event = find_event(name);
  84         if (!event)
  85                 return NULL;
  86         return event;
  87 }
  88
  89 void ltt_event_put(const struct lttng_event_desc *event)
  90 {
  91 }
  92
  93 #if 0
  94 static
  95 void *tp_list_start(struct seq_file *m, loff_t *pos)
  96 {
  97         struct lttng_probe_desc *probe_desc;
  98         int iter = 0, i;
  99
 100         pthread_mutex_lock(&probe_mutex);
 101         cds_list_for_each_entry(probe_desc, &probe_list, head) {
 102                 for (i = 0; i < probe_desc->nr_events; i++) {
 103                         if (iter++ >= *pos)
 104                                 return (void *) &probe_desc->event_desc[i];
 105                 }
 106         }
 107         /* End of list */
 108         return NULL;
 109 }
 110
 111 static
 112 void *tp_list_next(struct seq_file *m, void *p, loff_t *ppos)
 113 {
 114         struct lttng_probe_desc *probe_desc;
 115         int iter = 0, i;
 116
 117         (*ppos)++;
 118         cds_list_for_each_entry(probe_desc, &probe_list, head) {
 119                 for (i = 0; i < probe_desc->nr_events; i++) {
 120                         if (iter++ >= *ppos)
 121                                 return (void *) &probe_desc->event_desc[i];
 122                 }
 123         }
 124         /* End of list */
 125         return NULL;
 126 }
 127
 128 static
 129 void tp_list_stop(struct seq_file *m, void *p)
 130 {
 131         pthread_mutex_unlock(&probe_mutex);
 132 }
 133
 134 static
 135 int tp_list_show(struct seq_file *m, void *p)
 136 {
 137         const struct lttng_event_desc *probe_desc = p;
 138
 139         /*
 140          * Don't export lttng internal events (metadata).
 141          */
 142         if (!strncmp(probe_desc->name, "lttng_", sizeof("lttng_") - 1))
 143                 return 0;
 144         seq_printf(m,   "event { name = %s; };\n",
 145                    probe_desc->name);
 146         return 0;
 147 }
 148
 149 static
 150 const struct seq_operations lttng_tracepoint_list_seq_ops = {
 151         .start = tp_list_start,
 152         .next = tp_list_next,
 153         .stop = tp_list_stop,
 154         .show = tp_list_show,
 155 };
 156
 157 static
 158 int lttng_tracepoint_list_open(struct inode *inode, struct file *file)
 159 {
 160         return seq_open(file, &lttng_tracepoint_list_seq_ops);
 161 }
 162
 163 const struct file_operations lttng_tracepoint_list_fops = {
 164         .open = lttng_tracepoint_list_open,
 165         .read = seq_read,
 166         .llseek = seq_lseek,
 167         .release = seq_release,
 168 };
 169 #endif //0