+++ /dev/null
-/*
- * lttng-tracepoint.c
- *
- * LTTng adaptation layer for Linux kernel 3.15+ tracepoints.
- *
- * Copyright (C) 2014 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/list.h>
-#include <linux/mutex.h>
-#include <linux/err.h>
-#include <linux/notifier.h>
-#include <linux/tracepoint.h>
-#include <linux/slab.h>
-#include <linux/jhash.h>
-#include <linux/module.h>
-
-#include "lttng-tracepoint.h"
-
-/*
- * Protect the tracepoint table. lttng_tracepoint_mutex nests within
- * kernel/tracepoint.c tp_modlist_mutex. kernel/tracepoint.c
- * tracepoint_mutex nests within lttng_tracepoint_mutex.
- */
-static
-DEFINE_MUTEX(lttng_tracepoint_mutex);
-
-#define TRACEPOINT_HASH_BITS 6
-#define TRACEPOINT_TABLE_SIZE (1 << TRACEPOINT_HASH_BITS)
-static
-struct hlist_head tracepoint_table[TRACEPOINT_TABLE_SIZE];
-
-/*
- * The tracepoint entry is the node contained within the hash table. It
- * is a mapping from the "string" key to the struct tracepoint pointer.
- */
-struct tracepoint_entry {
- struct hlist_node hlist;
- struct tracepoint *tp;
- int refcount;
- struct list_head probes;
- char name[0];
-};
-
-struct lttng_tp_probe {
- struct tracepoint_func tp_func;
- struct list_head list;
-};
-
-static
-int add_probe(struct tracepoint_entry *e, void *probe, void *data)
-{
- struct lttng_tp_probe *p;
- int found = 0;
-
- list_for_each_entry(p, &e->probes, list) {
- if (p->tp_func.func == probe && p->tp_func.data == data) {
- found = 1;
- break;
- }
- }
- if (found)
- return -EEXIST;
- p = kmalloc(sizeof(struct lttng_tp_probe), GFP_KERNEL);
- if (!p)
- return -ENOMEM;
- p->tp_func.func = probe;
- p->tp_func.data = data;
- list_add(&p->list, &e->probes);
- return 0;
-}
-
-static
-int remove_probe(struct tracepoint_entry *e, void *probe, void *data)
-{
- struct lttng_tp_probe *p;
- int found = 0;
-
- list_for_each_entry(p, &e->probes, list) {
- if (p->tp_func.func == probe && p->tp_func.data == data) {
- found = 1;
- break;
- }
- }
- if (found) {
- list_del(&p->list);
- kfree(p);
- return 0;
- } else {
- WARN_ON(1);
- return -ENOENT;
- }
-}
-
-/*
- * Get tracepoint if the tracepoint is present in the tracepoint hash table.
- * Must be called with lttng_tracepoint_mutex held.
- * Returns NULL if not present.
- */
-static
-struct tracepoint_entry *get_tracepoint(const char *name)
-{
- struct hlist_head *head;
- struct tracepoint_entry *e;
- u32 hash = jhash(name, strlen(name), 0);
-
- head = &tracepoint_table[hash & (TRACEPOINT_TABLE_SIZE - 1)];
- hlist_for_each_entry(e, head, hlist) {
- if (!strcmp(name, e->name))
- return e;
- }
- return NULL;
-}
-
-/*
- * Add the tracepoint to the tracepoint hash table. Must be called with
- * lttng_tracepoint_mutex held.
- */
-static
-struct tracepoint_entry *add_tracepoint(const char *name)
-{
- struct hlist_head *head;
- struct tracepoint_entry *e;
- size_t name_len = strlen(name) + 1;
- u32 hash = jhash(name, name_len - 1, 0);
-
- head = &tracepoint_table[hash & (TRACEPOINT_TABLE_SIZE - 1)];
- hlist_for_each_entry(e, head, hlist) {
- if (!strcmp(name, e->name)) {
- printk(KERN_NOTICE
- "tracepoint %s busy\n", name);
- return ERR_PTR(-EEXIST); /* Already there */
- }
- }
- /*
- * Using kmalloc here to allocate a variable length element. Could
- * cause some memory fragmentation if overused.
- */
- e = kmalloc(sizeof(struct tracepoint_entry) + name_len, GFP_KERNEL);
- if (!e)
- return ERR_PTR(-ENOMEM);
- memcpy(&e->name[0], name, name_len);
- e->tp = NULL;
- e->refcount = 0;
- INIT_LIST_HEAD(&e->probes);
- hlist_add_head(&e->hlist, head);
- return e;
-}
-
-/*
- * Remove the tracepoint from the tracepoint hash table. Must be called
- * with lttng_tracepoint_mutex held.
- */
-static
-void remove_tracepoint(struct tracepoint_entry *e)
-{
- hlist_del(&e->hlist);
- kfree(e);
-}
-
-int lttng_tracepoint_probe_register(const char *name, void *probe, void *data)
-{
- struct tracepoint_entry *e;
- int ret = 0;
-
- mutex_lock(<tng_tracepoint_mutex);
- e = get_tracepoint(name);
- if (!e) {
- e = add_tracepoint(name);
- if (IS_ERR(e)) {
- ret = PTR_ERR(e);
- goto end;
- }
- }
- /* add (probe, data) to entry */
- ret = add_probe(e, probe, data);
- if (ret)
- goto end;
- e->refcount++;
- if (e->tp) {
- ret = tracepoint_probe_register(e->tp, probe, data);
- WARN_ON_ONCE(ret);
- ret = 0;
- }
-end:
- mutex_unlock(<tng_tracepoint_mutex);
- return ret;
-}
-
-int lttng_tracepoint_probe_unregister(const char *name, void *probe, void *data)
-{
- struct tracepoint_entry *e;
- int ret = 0;
-
- mutex_lock(<tng_tracepoint_mutex);
- e = get_tracepoint(name);
- if (!e) {
- ret = -ENOENT;
- goto end;
- }
- /* remove (probe, data) from entry */
- ret = remove_probe(e, probe, data);
- if (ret)
- goto end;
- if (e->tp) {
- ret = tracepoint_probe_unregister(e->tp, probe, data);
- WARN_ON_ONCE(ret);
- ret = 0;
- }
- if (!--e->refcount)
- remove_tracepoint(e);
-end:
- mutex_unlock(<tng_tracepoint_mutex);
- return ret;
-}
-
-#ifdef CONFIG_MODULES
-
-static
-int lttng_tracepoint_coming(struct tp_module *tp_mod)
-{
- int i;
-
- mutex_lock(<tng_tracepoint_mutex);
- for (i = 0; i < tp_mod->mod->num_tracepoints; i++) {
- struct tracepoint *tp;
- struct tracepoint_entry *e;
- struct lttng_tp_probe *p;
-
- tp = tp_mod->mod->tracepoints_ptrs[i];
- e = get_tracepoint(tp->name);
- if (!e) {
- e = add_tracepoint(tp->name);
- if (IS_ERR(e)) {
- pr_warn("LTTng: error (%ld) adding tracepoint\n",
- PTR_ERR(e));
- continue;
- }
- }
- /* If already enabled, just check consistency */
- if (e->tp) {
- WARN_ON(e->tp != tp);
- continue;
- }
- e->tp = tp;
- e->refcount++;
- /* register each (probe, data) */
- list_for_each_entry(p, &e->probes, list) {
- int ret;
-
- ret = tracepoint_probe_register(e->tp,
- p->tp_func.func, p->tp_func.data);
- WARN_ON_ONCE(ret);
- }
- }
- mutex_unlock(<tng_tracepoint_mutex);
- return 0;
-}
-
-static
-int lttng_tracepoint_going(struct tp_module *tp_mod)
-{
- int i;
-
- mutex_lock(<tng_tracepoint_mutex);
- for (i = 0; i < tp_mod->mod->num_tracepoints; i++) {
- struct tracepoint *tp;
- struct tracepoint_entry *e;
- struct lttng_tp_probe *p;
-
- tp = tp_mod->mod->tracepoints_ptrs[i];
- e = get_tracepoint(tp->name);
- if (!e || !e->tp)
- continue;
- /* unregister each (probe, data) */
- list_for_each_entry(p, &e->probes, list) {
- int ret;
-
- ret = tracepoint_probe_unregister(e->tp,
- p->tp_func.func, p->tp_func.data);
- WARN_ON_ONCE(ret);
- }
- e->tp = NULL;
- if (!--e->refcount)
- remove_tracepoint(e);
- }
- mutex_unlock(<tng_tracepoint_mutex);
- return 0;
-}
-
-static
-int lttng_tracepoint_notify(struct notifier_block *self,
- unsigned long val, void *data)
-{
- struct tp_module *tp_mod = data;
- int ret = 0;
-
- switch (val) {
- case MODULE_STATE_COMING:
- ret = lttng_tracepoint_coming(tp_mod);
- break;
- case MODULE_STATE_GOING:
- ret = lttng_tracepoint_going(tp_mod);
- break;
- default:
- break;
- }
- return ret;
-}
-
-static
-struct notifier_block lttng_tracepoint_notifier = {
- .notifier_call = lttng_tracepoint_notify,
- .priority = 0,
-};
-
-static
-int lttng_tracepoint_module_init(void)
-{
- return register_tracepoint_module_notifier(<tng_tracepoint_notifier);
-}
-
-static
-void lttng_tracepoint_module_exit(void)
-{
- WARN_ON(unregister_tracepoint_module_notifier(<tng_tracepoint_notifier));
-}
-
-#else /* #ifdef CONFIG_MODULES */
-
-static
-int lttng_tracepoint_module_init(void)
-{
- return 0;
-}
-
-static
-void lttng_tracepoint_module_exit(void)
-{
-}
-
-#endif /* #else #ifdef CONFIG_MODULES */
-
-static
-void lttng_kernel_tracepoint_add(struct tracepoint *tp, void *priv)
-{
- struct tracepoint_entry *e;
- struct lttng_tp_probe *p;
- int *ret = priv;
-
- mutex_lock(<tng_tracepoint_mutex);
- e = get_tracepoint(tp->name);
- if (!e) {
- e = add_tracepoint(tp->name);
- if (IS_ERR(e)) {
- pr_warn("LTTng: error (%ld) adding tracepoint\n",
- PTR_ERR(e));
- *ret = (int) PTR_ERR(e);
- goto end;
- }
- }
- /* If already enabled, just check consistency */
- if (e->tp) {
- WARN_ON(e->tp != tp);
- goto end;
- }
- e->tp = tp;
- e->refcount++;
- /* register each (probe, data) */
- list_for_each_entry(p, &e->probes, list) {
- int ret;
-
- ret = tracepoint_probe_register(e->tp,
- p->tp_func.func, p->tp_func.data);
- WARN_ON_ONCE(ret);
- }
-end:
- mutex_unlock(<tng_tracepoint_mutex);
-}
-
-static
-void lttng_kernel_tracepoint_remove(struct tracepoint *tp, void *priv)
-{
- struct tracepoint_entry *e;
- int *ret = priv;
-
- mutex_lock(<tng_tracepoint_mutex);
- e = get_tracepoint(tp->name);
- if (!e || e->refcount != 1 || !list_empty(&e->probes)) {
- *ret = -EINVAL;
- goto end;
- }
- remove_tracepoint(e);
-end:
- mutex_unlock(<tng_tracepoint_mutex);
-}
-
-int __init lttng_tracepoint_init(void)
-{
- int ret = 0;
-
- for_each_kernel_tracepoint(lttng_kernel_tracepoint_add, &ret);
- if (ret)
- goto error;
- ret = lttng_tracepoint_module_init();
- if (ret)
- goto error_module;
- return 0;
-
-error_module:
- {
- int error_ret = 0;
-
- for_each_kernel_tracepoint(lttng_kernel_tracepoint_remove,
- &error_ret);
- WARN_ON(error_ret);
- }
-error:
- return ret;
-}
-
-void lttng_tracepoint_exit(void)
-{
- int i, ret = 0;
-
- lttng_tracepoint_module_exit();
- for_each_kernel_tracepoint(lttng_kernel_tracepoint_remove, &ret);
- WARN_ON(ret);
- mutex_lock(<tng_tracepoint_mutex);
- for (i = 0; i < TRACEPOINT_TABLE_SIZE; i++) {
- struct hlist_head *head = &tracepoint_table[i];
-
- /* All tracepoints should be removed */
- WARN_ON(!hlist_empty(head));
- }
- mutex_unlock(<tng_tracepoint_mutex);
-}
projects / lttng-modules.git / blobdiff