+++ /dev/null
-/*
- * lttng-probes.c
- *
- * Holds LTTng probes registry.
- *
- * Copyright (C) 2010-2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
- *
- * This library is free software; you can redistribute it and/or
- * modify it under the terms of the GNU Lesser General Public
- * License as published by the Free Software Foundation; only
- * version 2.1 of the License.
- *
- * This library is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
- * Lesser General Public License for more details.
- *
- * You should have received a copy of the GNU Lesser General Public
- * License along with this library; if not, write to the Free Software
- * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
- */
-
-#include <linux/module.h>
-#include <linux/list.h>
-#include <linux/mutex.h>
-#include <linux/seq_file.h>
-
-#include "lttng-events.h"
-
-/*
- * probe list is protected by sessions lock.
- */
-static LIST_HEAD(_probe_list);
-
-/*
- * List of probes registered by not yet processed.
- */
-static LIST_HEAD(lazy_probe_init);
-
-/*
- * lazy_nesting counter ensures we don't trigger lazy probe registration
- * fixup while we are performing the fixup. It is protected by the
- * sessions lock.
- */
-static int lazy_nesting;
-
-/*
- * Called under sessions lock.
- */
-static
-int check_event_provider(struct lttng_probe_desc *desc)
-{
- int i;
- size_t provider_name_len;
-
- provider_name_len = strnlen(desc->provider,
- LTTNG_KERNEL_SYM_NAME_LEN - 1);
- for (i = 0; i < desc->nr_events; i++) {
- if (strncmp(desc->event_desc[i]->name,
- desc->provider,
- provider_name_len))
- return 0; /* provider mismatch */
- }
- return 1;
-}
-
-/*
- * Called under sessions lock.
- */
-static
-void lttng_lazy_probe_register(struct lttng_probe_desc *desc)
-{
- struct lttng_probe_desc *iter;
- struct list_head *probe_list;
-
- /*
- * Each provider enforce that every event name begins with the
- * provider name. Check this in an assertion for extra
- * carefulness. This ensures we cannot have duplicate event
- * names across providers.
- */
- WARN_ON_ONCE(!check_event_provider(desc));
-
- /*
- * The provider ensures there are no duplicate event names.
- * Duplicated TRACEPOINT_EVENT event names would generate a
- * compile-time error due to duplicated symbol names.
- */
-
- /*
- * We sort the providers by struct lttng_probe_desc pointer
- * address.
- */
- probe_list = &_probe_list;
- list_for_each_entry_reverse(iter, probe_list, head) {
- BUG_ON(iter == desc); /* Should never be in the list twice */
- if (iter < desc) {
- /* We belong to the location right after iter. */
- list_add(&desc->head, &iter->head);
- goto desc_added;
- }
- }
- /* We should be added at the head of the list */
- list_add(&desc->head, probe_list);
-desc_added:
- printk(KERN_DEBUG "just registered probe %s containing %u events\n",
- desc->provider, desc->nr_events);
-}
-
-/*
- * Called under sessions lock.
- */
-static
-void fixup_lazy_probes(void)
-{
- struct lttng_probe_desc *iter, *tmp;
- int ret;
-
- lazy_nesting++;
- list_for_each_entry_safe(iter, tmp,
- &lazy_probe_init, lazy_init_head) {
- lttng_lazy_probe_register(iter);
- iter->lazy = 0;
- list_del(&iter->lazy_init_head);
- }
- ret = lttng_fix_pending_events();
- WARN_ON_ONCE(ret);
- lazy_nesting--;
-}
-
-/*
- * Called under sessions lock.
- */
-struct list_head *lttng_get_probe_list_head(void)
-{
- if (!lazy_nesting && !list_empty(&lazy_probe_init))
- fixup_lazy_probes();
- return &_probe_list;
-}
-
-static
-const struct lttng_probe_desc *find_provider(const char *provider)
-{
- struct lttng_probe_desc *iter;
- struct list_head *probe_list;
-
- probe_list = lttng_get_probe_list_head();
- list_for_each_entry(iter, probe_list, head) {
- if (!strcmp(iter->provider, provider))
- return iter;
- }
- return NULL;
-}
-
-int lttng_probe_register(struct lttng_probe_desc *desc)
-{
- int ret = 0;
-
- lttng_lock_sessions();
-
- /*
- * Check if the provider has already been registered.
- */
- if (find_provider(desc->provider)) {
- ret = -EEXIST;
- goto end;
- }
- list_add(&desc->lazy_init_head, &lazy_probe_init);
- desc->lazy = 1;
- printk(KERN_DEBUG "adding probe %s containing %u events to lazy registration list\n",
- desc->provider, desc->nr_events);
- /*
- * If there is at least one active session, we need to register
- * the probe immediately, since we cannot delay event
- * registration because they are needed ASAP.
- */
- if (lttng_session_active())
- fixup_lazy_probes();
-end:
- lttng_unlock_sessions();
- return ret;
-}
-EXPORT_SYMBOL_GPL(lttng_probe_register);
-
-void lttng_probe_unregister(struct lttng_probe_desc *desc)
-{
- lttng_lock_sessions();
- if (!desc->lazy)
- list_del(&desc->head);
- else
- list_del(&desc->lazy_init_head);
- printk(KERN_DEBUG "just unregistered probe %s\n", desc->provider);
- lttng_unlock_sessions();
-}
-EXPORT_SYMBOL_GPL(lttng_probe_unregister);
-
-/*
- * TODO: this is O(nr_probes * nb_events), could be faster.
- * Called with sessions lock held.
- */
-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;
-}
-
-/*
- * Called with sessions lock held.
- */
-const struct lttng_event_desc *lttng_event_get(const char *name)
-{
- const struct lttng_event_desc *event;
- int ret;
-
- event = find_event(name);
- if (!event)
- return NULL;
- ret = try_module_get(event->owner);
- WARN_ON_ONCE(!ret);
- return event;
-}
-EXPORT_SYMBOL_GPL(lttng_event_get);
-
-/*
- * Called with sessions lock held.
- */
-void lttng_event_put(const struct lttng_event_desc *event)
-{
- module_put(event->owner);
-}
-EXPORT_SYMBOL_GPL(lttng_event_put);
-
-static
-void *tp_list_start(struct seq_file *m, loff_t *pos)
-{
- struct lttng_probe_desc *probe_desc;
- int iter = 0, i;
-
- lttng_lock_sessions();
- 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)
-{
- lttng_unlock_sessions();
-}
-
-static
-int tp_list_show(struct seq_file *m, void *p)
-{
- const struct lttng_event_desc *probe_desc = p;
-
- 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, <tng_tracepoint_list_seq_ops);
-}
-
-const struct file_operations lttng_tracepoint_list_fops = {
- .owner = THIS_MODULE,
- .open = lttng_tracepoint_list_open,
- .read = seq_read,
- .llseek = seq_lseek,
- .release = seq_release,
-};
projects / lttng-modules.git / blobdiff