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ce5aef0b MD |
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 <linux/module.h> | |
12 | #include <linux/list.h> | |
13 | #include <linux/mutex.h> | |
14 | #include <linux/seq_file.h> | |
f4681817 | 15 | #include <ust/lttng-events.h> |
ce5aef0b MD |
16 | |
17 | static LIST_HEAD(probe_list); | |
18 | static DEFINE_MUTEX(probe_mutex); | |
19 | ||
20 | static | |
21 | const struct lttng_event_desc *find_event(const char *name) | |
22 | { | |
23 | struct lttng_probe_desc *probe_desc; | |
24 | int i; | |
25 | ||
26 | list_for_each_entry(probe_desc, &probe_list, head) { | |
27 | for (i = 0; i < probe_desc->nr_events; i++) { | |
28 | if (!strcmp(probe_desc->event_desc[i].name, name)) | |
29 | return &probe_desc->event_desc[i]; | |
30 | } | |
31 | } | |
32 | return NULL; | |
33 | } | |
34 | ||
35 | int ltt_probe_register(struct lttng_probe_desc *desc) | |
36 | { | |
37 | int ret = 0; | |
38 | int i; | |
39 | ||
40 | mutex_lock(&probe_mutex); | |
41 | /* | |
42 | * TODO: This is O(N^2). Turn into a hash table when probe registration | |
43 | * overhead becomes an issue. | |
44 | */ | |
45 | for (i = 0; i < desc->nr_events; i++) { | |
46 | if (find_event(desc->event_desc[i].name)) { | |
47 | ret = -EEXIST; | |
48 | goto end; | |
49 | } | |
50 | } | |
51 | list_add(&desc->head, &probe_list); | |
52 | end: | |
53 | mutex_unlock(&probe_mutex); | |
54 | return ret; | |
55 | } | |
56 | EXPORT_SYMBOL_GPL(ltt_probe_register); | |
57 | ||
58 | void ltt_probe_unregister(struct lttng_probe_desc *desc) | |
59 | { | |
60 | mutex_lock(&probe_mutex); | |
61 | list_del(&desc->head); | |
62 | mutex_unlock(&probe_mutex); | |
63 | } | |
64 | EXPORT_SYMBOL_GPL(ltt_probe_unregister); | |
65 | ||
66 | const struct lttng_event_desc *ltt_event_get(const char *name) | |
67 | { | |
68 | const struct lttng_event_desc *event; | |
69 | int ret; | |
70 | ||
71 | mutex_lock(&probe_mutex); | |
72 | event = find_event(name); | |
73 | mutex_unlock(&probe_mutex); | |
74 | if (!event) | |
75 | return NULL; | |
76 | ret = try_module_get(event->owner); | |
77 | WARN_ON_ONCE(!ret); | |
78 | return event; | |
79 | } | |
80 | EXPORT_SYMBOL_GPL(ltt_event_get); | |
81 | ||
82 | void ltt_event_put(const struct lttng_event_desc *event) | |
83 | { | |
84 | module_put(event->owner); | |
85 | } | |
86 | EXPORT_SYMBOL_GPL(ltt_event_put); | |
87 | ||
88 | static | |
89 | void *tp_list_start(struct seq_file *m, loff_t *pos) | |
90 | { | |
91 | struct lttng_probe_desc *probe_desc; | |
92 | int iter = 0, i; | |
93 | ||
94 | mutex_lock(&probe_mutex); | |
95 | list_for_each_entry(probe_desc, &probe_list, head) { | |
96 | for (i = 0; i < probe_desc->nr_events; i++) { | |
97 | if (iter++ >= *pos) | |
98 | return (void *) &probe_desc->event_desc[i]; | |
99 | } | |
100 | } | |
101 | /* End of list */ | |
102 | return NULL; | |
103 | } | |
104 | ||
105 | static | |
106 | void *tp_list_next(struct seq_file *m, void *p, loff_t *ppos) | |
107 | { | |
108 | struct lttng_probe_desc *probe_desc; | |
109 | int iter = 0, i; | |
110 | ||
111 | (*ppos)++; | |
112 | list_for_each_entry(probe_desc, &probe_list, head) { | |
113 | for (i = 0; i < probe_desc->nr_events; i++) { | |
114 | if (iter++ >= *ppos) | |
115 | return (void *) &probe_desc->event_desc[i]; | |
116 | } | |
117 | } | |
118 | /* End of list */ | |
119 | return NULL; | |
120 | } | |
121 | ||
122 | static | |
123 | void tp_list_stop(struct seq_file *m, void *p) | |
124 | { | |
125 | mutex_unlock(&probe_mutex); | |
126 | } | |
127 | ||
128 | static | |
129 | int tp_list_show(struct seq_file *m, void *p) | |
130 | { | |
131 | const struct lttng_event_desc *probe_desc = p; | |
132 | ||
133 | /* | |
134 | * Don't export lttng internal events (metadata). | |
135 | */ | |
136 | if (!strncmp(probe_desc->name, "lttng_", sizeof("lttng_") - 1)) | |
137 | return 0; | |
138 | seq_printf(m, "event { name = %s; };\n", | |
139 | probe_desc->name); | |
140 | return 0; | |
141 | } | |
142 | ||
143 | static | |
144 | const struct seq_operations lttng_tracepoint_list_seq_ops = { | |
145 | .start = tp_list_start, | |
146 | .next = tp_list_next, | |
147 | .stop = tp_list_stop, | |
148 | .show = tp_list_show, | |
149 | }; | |
150 | ||
151 | static | |
152 | int lttng_tracepoint_list_open(struct inode *inode, struct file *file) | |
153 | { | |
154 | return seq_open(file, <tng_tracepoint_list_seq_ops); | |
155 | } | |
156 | ||
157 | const struct file_operations lttng_tracepoint_list_fops = { | |
158 | .open = lttng_tracepoint_list_open, | |
159 | .read = seq_read, | |
160 | .llseek = seq_lseek, | |
161 | .release = seq_release, | |
162 | }; |