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Subject[PATCH -mm 2/5] kprobes: add (un)register_kprobes for batch registration
Introduce unregister_/register_kprobes() for kprobe batch
registration. This can reduce waiting time for
synchronized_sched() when a lot of probes have to be
unregistered at once.

Signed-off-by: Masami Hiramatsu <mhiramat@redhat.com>
---
I rewrote a patchset which had been discussed on LKML,
and simplified its interfaces.
http://lkml.org/lkml/2007/3/23/181

include/linux/kprobes.h | 9 +++
kernel/kprobes.c | 124 +++++++++++++++++++++++++++++++++---------------
2 files changed, 96 insertions(+), 37 deletions(-)

Index: 2.6.25-rc5-mm1/include/linux/kprobes.h
===================================================================
--- 2.6.25-rc5-mm1.orig/include/linux/kprobes.h
+++ 2.6.25-rc5-mm1/include/linux/kprobes.h
@@ -234,6 +234,8 @@ static inline struct kprobe_ctlblk *get_

int register_kprobe(struct kprobe *p);
void unregister_kprobe(struct kprobe *p);
+int register_kprobes(struct kprobe **kps, int num);
+void unregister_kprobes(struct kprobe **kps, int num);
int setjmp_pre_handler(struct kprobe *, struct pt_regs *);
int longjmp_break_handler(struct kprobe *, struct pt_regs *);
int register_jprobe(struct jprobe *p);
@@ -261,9 +263,16 @@ static inline int register_kprobe(struct
{
return -ENOSYS;
}
+static inline int register_kprobes(struct kprobe **kps, int num)
+{
+ return -ENOSYS;
+}
static inline void unregister_kprobe(struct kprobe *p)
{
}
+static inline void unregister_kprobes(struct kprobe **kps, int num)
+{
+}
static inline int register_jprobe(struct jprobe *p)
{
return -ENOSYS;
Index: 2.6.25-rc5-mm1/kernel/kprobes.c
===================================================================
--- 2.6.25-rc5-mm1.orig/kernel/kprobes.c
+++ 2.6.25-rc5-mm1/kernel/kprobes.c
@@ -580,6 +580,7 @@ static int __kprobes __register_kprobe(s
}

p->nmissed = 0;
+ INIT_LIST_HEAD(&p->list);
mutex_lock(&kprobe_mutex);
old_p = get_kprobe(p->addr);
if (old_p) {
@@ -606,35 +607,28 @@ out:
return ret;
}

-int __kprobes register_kprobe(struct kprobe *p)
-{
- return __register_kprobe(p, (unsigned long)__builtin_return_address(0));
-}
-
-void __kprobes unregister_kprobe(struct kprobe *p)
+/*
+ * Unregister a kprobe without a scheduler synchronization.
+ */
+static int __kprobes __unregister_kprobe_top(struct kprobe *p)
{
- struct module *mod;
struct kprobe *old_p, *list_p;
- int cleanup_p;

- mutex_lock(&kprobe_mutex);
old_p = get_kprobe(p->addr);
- if (unlikely(!old_p)) {
- mutex_unlock(&kprobe_mutex);
- return;
- }
+ if (unlikely(!old_p))
+ return -EINVAL;
+
if (p != old_p) {
list_for_each_entry_rcu(list_p, &old_p->list, list)
if (list_p == p)
/* kprobe p is a valid probe */
goto valid_p;
- mutex_unlock(&kprobe_mutex);
- return;
+ return -EINVAL;
}
valid_p:
if (old_p == p ||
(old_p->pre_handler == aggr_pre_handler &&
- p->list.next == &old_p->list && p->list.prev == &old_p->list)) {
+ list_singleton(&old_p->list))) {
/*
* Only probe on the hash list. Disarm only if kprobes are
* enabled - otherwise, the breakpoint would already have
@@ -643,43 +637,97 @@ valid_p:
if (kprobe_enabled)
arch_disarm_kprobe(p);
hlist_del_rcu(&old_p->hlist);
- cleanup_p = 1;
} else {
+ if (p->break_handler)
+ old_p->break_handler = NULL;
+ if (p->post_handler) {
+ list_for_each_entry_rcu(list_p, &old_p->list, list) {
+ if ((list_p != p) && (list_p->post_handler))
+ goto noclean;
+ }
+ old_p->post_handler = NULL;
+ }
+noclean:
list_del_rcu(&p->list);
- cleanup_p = 0;
}
+ return 0;
+}

- mutex_unlock(&kprobe_mutex);
+static void __kprobes __unregister_kprobe_bottom(struct kprobe *p)
+{
+ struct module *mod;
+ struct kprobe *old_p;

- synchronize_sched();
if (p->mod_refcounted) {
mod = module_text_address((unsigned long)p->addr);
if (mod)
module_put(mod);
}

- if (cleanup_p) {
- if (p != old_p) {
- list_del_rcu(&p->list);
+ if (list_empty(&p->list) || list_singleton(&p->list)) {
+ if (!list_empty(&p->list)) {
+ /* "p" is the last child of an aggr_kprobe */
+ old_p = list_entry(p->list.next, struct kprobe, list);
+ list_del(&p->list);
kfree(old_p);
}
arch_remove_kprobe(p);
- } else {
- mutex_lock(&kprobe_mutex);
- if (p->break_handler)
- old_p->break_handler = NULL;
- if (p->post_handler){
- list_for_each_entry_rcu(list_p, &old_p->list, list){
- if (list_p->post_handler){
- cleanup_p = 2;
- break;
- }
- }
- if (cleanup_p == 0)
- old_p->post_handler = NULL;
+ }
+}
+
+static int __register_kprobes(struct kprobe **kps, int num,
+ unsigned long called_from)
+{
+ int i, ret = 0;
+
+ if (num <= 0)
+ return -EINVAL;
+ for (i = 0; i < num; i++) {
+ ret = __register_kprobe(kps[i], called_from);
+ if (ret < 0 && i > 0) {
+ unregister_kprobes(kps, i);
+ break;
}
- mutex_unlock(&kprobe_mutex);
}
+ return ret;
+}
+
+/*
+ * Registration and unregistration functions for kprobe.
+ */
+int __kprobes register_kprobe(struct kprobe *p)
+{
+ return __register_kprobes(&p, 1,
+ (unsigned long)__builtin_return_address(0));
+}
+
+void __kprobes unregister_kprobe(struct kprobe *p)
+{
+ unregister_kprobes(&p, 1);
+}
+
+int __kprobes register_kprobes(struct kprobe **kps, int num)
+{
+ return __register_kprobes(kps, num,
+ (unsigned long)__builtin_return_address(0));
+}
+
+void __kprobes unregister_kprobes(struct kprobe **kps, int num)
+{
+ int i;
+
+ if (num <= 0)
+ return;
+ mutex_lock(&kprobe_mutex);
+ for (i = 0; i < num; i++)
+ if (__unregister_kprobe_top(kps[i]) < 0)
+ kps[i]->addr = NULL;
+ mutex_unlock(&kprobe_mutex);
+
+ synchronize_sched();
+ for (i = 0; i < num; i++)
+ if (kps[i]->addr)
+ __unregister_kprobe_bottom(kps[i]);
}

static struct notifier_block kprobe_exceptions_nb = {
@@ -1118,6 +1166,8 @@ module_init(init_kprobes);

EXPORT_SYMBOL_GPL(register_kprobe);
EXPORT_SYMBOL_GPL(unregister_kprobe);
+EXPORT_SYMBOL_GPL(register_kprobes);
+EXPORT_SYMBOL_GPL(unregister_kprobes);
EXPORT_SYMBOL_GPL(register_jprobe);
EXPORT_SYMBOL_GPL(unregister_jprobe);
#ifdef CONFIG_KPROBES
--
Masami Hiramatsu
Software Engineer
Hitachi Computer Products (America) Inc.
Software Solutions Division

e-mail: mhiramat@redhat.com







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