add ltt-probes.c

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

diff --git a/libust/ltt-probes.c b/libust/ltt-probes.c
new file mode 100644 (file)
index 0000000..45d2dab
--- /dev/null
+++ b/libust/ltt-probes.c
@@ -0,0 +1,163 @@
+/*
+ * ltt-probes.c
+ *
+ * Copyright 2010 (c) - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
+ *
+ * Holds LTTng probes registry.
+ *
+ * Dual LGPL v2.1/GPL v2 license.
+ */
+
+#include <linux/module.h>
+#include <linux/list.h>
+#include <linux/mutex.h>
+#include <linux/seq_file.h>
+
+#include "ltt-events.h"
+
+static LIST_HEAD(probe_list);
+static DEFINE_MUTEX(probe_mutex);
+
+static
+const struct lttng_event_desc *find_event(const char *name)
+{
+       struct lttng_probe_desc *probe_desc;
+       int i;
+
+       list_for_each_entry(probe_desc, &probe_list, head) {
+               for (i = 0; i < probe_desc->nr_events; i++) {
+                       if (!strcmp(probe_desc->event_desc[i].name, name))
+                               return &probe_desc->event_desc[i];
+               }
+       }
+       return NULL;
+}
+
+int ltt_probe_register(struct lttng_probe_desc *desc)
+{
+       int ret = 0;
+       int i;
+
+       mutex_lock(&probe_mutex);
+       /*
+        * TODO: This is O(N^2). Turn into a hash table when probe registration
+        * overhead becomes an issue.
+        */
+       for (i = 0; i < desc->nr_events; i++) {
+               if (find_event(desc->event_desc[i].name)) {
+                       ret = -EEXIST;
+                       goto end;
+               }
+       }
+       list_add(&desc->head, &probe_list);
+end:
+       mutex_unlock(&probe_mutex);
+       return ret;
+}
+EXPORT_SYMBOL_GPL(ltt_probe_register);
+
+void ltt_probe_unregister(struct lttng_probe_desc *desc)
+{
+       mutex_lock(&probe_mutex);
+       list_del(&desc->head);
+       mutex_unlock(&probe_mutex);
+}
+EXPORT_SYMBOL_GPL(ltt_probe_unregister);
+
+const struct lttng_event_desc *ltt_event_get(const char *name)
+{
+       const struct lttng_event_desc *event;
+       int ret;
+
+       mutex_lock(&probe_mutex);
+       event = find_event(name);
+       mutex_unlock(&probe_mutex);
+       if (!event)
+               return NULL;
+       ret = try_module_get(event->owner);
+       WARN_ON_ONCE(!ret);
+       return event;
+}
+EXPORT_SYMBOL_GPL(ltt_event_get);
+
+void ltt_event_put(const struct lttng_event_desc *event)
+{
+       module_put(event->owner);
+}
+EXPORT_SYMBOL_GPL(ltt_event_put);
+
+static
+void *tp_list_start(struct seq_file *m, loff_t *pos)
+{
+       struct lttng_probe_desc *probe_desc;
+       int iter = 0, i;
+
+       mutex_lock(&probe_mutex);
+       list_for_each_entry(probe_desc, &probe_list, head) {
+               for (i = 0; i < probe_desc->nr_events; i++) {
+                       if (iter++ >= *pos)
+                               return (void *) &probe_desc->event_desc[i];
+               }
+       }
+       /* End of list */
+       return NULL;
+}
+
+static
+void *tp_list_next(struct seq_file *m, void *p, loff_t *ppos)
+{
+       struct lttng_probe_desc *probe_desc;
+       int iter = 0, i;
+
+       (*ppos)++;
+       list_for_each_entry(probe_desc, &probe_list, head) {
+               for (i = 0; i < probe_desc->nr_events; i++) {
+                       if (iter++ >= *ppos)
+                               return (void *) &probe_desc->event_desc[i];
+               }
+       }
+       /* End of list */
+       return NULL;
+}
+
+static
+void tp_list_stop(struct seq_file *m, void *p)
+{
+       mutex_unlock(&probe_mutex);
+}
+
+static
+int tp_list_show(struct seq_file *m, void *p)
+{
+       const struct lttng_event_desc *probe_desc = p;
+
+       /*
+        * Don't export lttng internal events (metadata).
+        */
+       if (!strncmp(probe_desc->name, "lttng_", sizeof("lttng_") - 1))
+               return 0;
+       seq_printf(m,   "event { name = %s; };\n",
+                  probe_desc->name);
+       return 0;
+}
+
+static
+const struct seq_operations lttng_tracepoint_list_seq_ops = {
+       .start = tp_list_start,
+       .next = tp_list_next,
+       .stop = tp_list_stop,
+       .show = tp_list_show,
+};
+
+static
+int lttng_tracepoint_list_open(struct inode *inode, struct file *file)
+{
+       return seq_open(file, &lttng_tracepoint_list_seq_ops);
+}
+
+const struct file_operations lttng_tracepoint_list_fops = {
+       .open = lttng_tracepoint_list_open,
+       .read = seq_read,
+       .llseek = seq_lseek,
+       .release = seq_release,
+};