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Message-ID: <49067E49.4040304@cn.fujitsu.com>
Date: Tue, 28 Oct 2008 10:51:53 +0800
From: Lai Jiangshan <laijs@...fujitsu.com>
To: Ingo Molnar <mingo@...e.hu>
CC: Mathieu Desnoyers <mathieu.desnoyers@...ymtl.ca>,
Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: [PATCH 2/2] tracepoint: introduce *_noupdate APIs.
new APIs separate tracepoint_probe_register(),
tracepoint_probe_unregister() into 2 steps. The first step of them
is just update tracepoint_entry, not connect or disconnect.
this patch introduce tracepoint_probe_update_all() for update all.
these APIs are very useful for registering a lots of probes
but just update once only. and a very important thing is that
*_noupdate APIs do not require module_mutex.
Signed-off-by: Lai Jiangshan <laijs@...fujitsu.com>
---
diff --git a/include/linux/tracepoint.h b/include/linux/tracepoint.h
index c5bb39c..63064e9 100644
--- a/include/linux/tracepoint.h
+++ b/include/linux/tracepoint.h
@@ -112,6 +112,10 @@ extern int tracepoint_probe_register(const char *name, void *probe);
*/
extern int tracepoint_probe_unregister(const char *name, void *probe);
+extern int tracepoint_probe_register_noupdate(const char *name, void *probe);
+extern int tracepoint_probe_unregister_noupdate(const char *name, void *probe);
+extern void tracepoint_probe_update_all(void);
+
struct tracepoint_iter {
struct module *module;
struct tracepoint *tracepoint;
diff --git a/kernel/tracepoint.c b/kernel/tracepoint.c
index 76d4571..f81902b 100644
--- a/kernel/tracepoint.c
+++ b/kernel/tracepoint.c
@@ -59,7 +59,10 @@ struct tracepoint_entry {
};
struct tp_probes {
- struct rcu_head rcu;
+ union {
+ struct rcu_head rcu;
+ struct list_head list;
+ } u;
void *probes[0];
};
@@ -72,7 +75,7 @@ static inline void *allocate_probes(int count)
static void rcu_free_old_probes(struct rcu_head *head)
{
- kfree(container_of(head, struct tp_probes, rcu));
+ kfree(container_of(head, struct tp_probes, u.rcu));
}
static inline void release_probes(void *old)
@@ -80,7 +83,7 @@ static inline void release_probes(void *old)
if (old) {
struct tp_probes *tp_probes = container_of(old,
struct tp_probes, probes[0]);
- call_rcu(&tp_probes->rcu, rcu_free_old_probes);
+ call_rcu_sched(&tp_probes->u.rcu, rcu_free_old_probes);
}
}
@@ -296,6 +299,23 @@ static void tracepoint_update_probes(void)
module_update_tracepoints();
}
+static void *tracepoint_add_probe(const char *name, void *probe)
+{
+ struct tracepoint_entry *entry;
+ void *old;
+
+ entry = get_tracepoint(name);
+ if (!entry) {
+ entry = add_tracepoint(name);
+ if (IS_ERR(entry))
+ return entry;
+ }
+ old = tracepoint_entry_add_probe(entry, probe);
+ if (IS_ERR(old) && !entry->refcount)
+ remove_tracepoint(entry);
+ return old;
+}
+
/**
* tracepoint_probe_register - Connect a probe to a tracepoint
* @name: tracepoint name
@@ -306,36 +326,36 @@ static void tracepoint_update_probes(void)
*/
int tracepoint_probe_register(const char *name, void *probe)
{
- struct tracepoint_entry *entry;
- int ret = 0;
void *old;
mutex_lock(&tracepoints_mutex);
- entry = get_tracepoint(name);
- if (!entry) {
- entry = add_tracepoint(name);
- if (IS_ERR(entry)) {
- ret = PTR_ERR(entry);
- goto end;
- }
- }
- old = tracepoint_entry_add_probe(entry, probe);
- if (IS_ERR(old)) {
- if (!entry->refcount)
- remove_tracepoint(entry);
- ret = PTR_ERR(old);
- goto end;
- }
+ old = tracepoint_add_probe(name, probe);
mutex_unlock(&tracepoints_mutex);
+ if (IS_ERR(old))
+ return PTR_ERR(old);
+
tracepoint_update_probes(); /* may update entry */
release_probes(old);
return 0;
-end:
- mutex_unlock(&tracepoints_mutex);
- return ret;
}
EXPORT_SYMBOL_GPL(tracepoint_probe_register);
+static void *tracepoint_remove_probe(const char *name, void *probe)
+{
+ struct tracepoint_entry *entry;
+ void *old;
+
+ entry = get_tracepoint(name);
+ if (!entry)
+ return ERR_PTR(-ENOENT);
+ old = tracepoint_entry_remove_probe(entry, probe);
+ if (IS_ERR(old))
+ return old;
+ if (!entry->refcount)
+ remove_tracepoint(entry);
+ return old;
+}
+
/**
* tracepoint_probe_unregister - Disconnect a probe from a tracepoint
* @name: tracepoint name
@@ -348,31 +368,105 @@ EXPORT_SYMBOL_GPL(tracepoint_probe_register);
*/
int tracepoint_probe_unregister(const char *name, void *probe)
{
- struct tracepoint_entry *entry;
void *old;
- int ret = -ENOENT;
mutex_lock(&tracepoints_mutex);
- entry = get_tracepoint(name);
- if (!entry)
- goto end;
- old = tracepoint_entry_remove_probe(entry, probe);
- if (IS_ERR(old)) {
- ret = PTR_ERR(old);
- goto end;
- }
- if (!entry->refcount)
- remove_tracepoint(entry);
+ old = tracepoint_remove_probe(name, probe);
mutex_unlock(&tracepoints_mutex);
+ if (IS_ERR(old))
+ return PTR_ERR(old);
+
tracepoint_update_probes(); /* may update entry */
release_probes(old);
return 0;
-end:
- mutex_unlock(&tracepoints_mutex);
- return ret;
}
EXPORT_SYMBOL_GPL(tracepoint_probe_unregister);
+static LIST_HEAD(old_probes);
+static int need_update;
+
+static void tracepoint_add_old_probes(void *old)
+{
+ need_update = 1;
+ if (old) {
+ struct tp_probes *tp_probes = container_of(old,
+ struct tp_probes, probes[0]);
+ list_add(&tp_probes->u.list, &old_probes);
+ }
+}
+
+/**
+ * tracepoint_probe_register_noupdate - register a probe but not connect
+ * @name: tracepoint name
+ * @probe: probe handler
+ *
+ * caller must call tracepoint_probe_update_all()
+ */
+int tracepoint_probe_register_noupdate(const char *name, void *probe)
+{
+ void *old;
+
+ mutex_lock(&tracepoints_mutex);
+ old = tracepoint_add_probe(name, probe);
+ if (IS_ERR(old)) {
+ mutex_unlock(&tracepoints_mutex);
+ return PTR_ERR(old);
+ }
+ tracepoint_add_old_probes(old);
+ mutex_unlock(&tracepoints_mutex);
+ return 0;
+}
+EXPORT_SYMBOL_GPL(tracepoint_probe_register_noupdate);
+
+/**
+ * tracepoint_probe_unregister_noupdate - remove a probe but not disconnect
+ * @name: tracepoint name
+ * @probe: probe function pointer
+ *
+ * caller must call tracepoint_probe_update_all()
+ */
+int tracepoint_probe_unregister_noupdate(const char *name, void *probe)
+{
+ void *old;
+
+ mutex_lock(&tracepoints_mutex);
+ old = tracepoint_remove_probe(name, probe);
+ if (IS_ERR(old)) {
+ mutex_unlock(&tracepoints_mutex);
+ return PTR_ERR(old);
+ }
+ tracepoint_add_old_probes(old);
+ mutex_unlock(&tracepoints_mutex);
+ return 0;
+}
+EXPORT_SYMBOL_GPL(tracepoint_probe_unregister_noupdate);
+
+/**
+ * tracepoint_probe_update_all - update tracepoints
+ */
+void tracepoint_probe_update_all(void)
+{
+ LIST_HEAD(release_probes);
+ struct tp_probes *pos, *next;
+
+ mutex_lock(&tracepoints_mutex);
+ if (!need_update) {
+ mutex_unlock(&tracepoints_mutex);
+ return;
+ }
+ if (!list_empty(&old_probes))
+ list_replace_init(&old_probes, &release_probes);
+ need_update = 0;
+ mutex_unlock(&tracepoints_mutex);
+
+ tracepoint_update_probes();
+ list_for_each_entry_safe(pos, next, &release_probes, u.list) {
+ list_del(&pos->u.list);
+ call_rcu_sched(&pos->u.rcu, rcu_free_old_probes);
+ }
+}
+EXPORT_SYMBOL_GPL(tracepoint_probe_update_all);
+
/**
* tracepoint_get_iter_range - Get a next tracepoint iterator given a range.
* @tracepoint: current tracepoints (in), next tracepoint (out)
--
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