[PATCH 5/5][djprobe] delayed invoking commit_djprobes()

[Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>]

Hi,

This patch invokes commit_djprobes() function from a worker.
This worker is scheduled automatically by register/
unregister_djprobe() functions and is executed in 0.1 second.
If the worker fails freezing processes, it will try again
after 0.1 second.

Thanks,
-- 
Masami HIRAMATSU
Linux Technology Center
Hitachi, Ltd., Systems Development Laboratory
E-mail: masami.hiramatsu.pt@hitachi.com

---
 kernel/djprobe.c |   23 ++++++++++++++++++++---
 1 file changed, 20 insertions(+), 3 deletions(-)

Index: linux-2.6.19-rc1-mm1/kernel/djprobe.c
===================================================================
--- linux-2.6.19-rc1-mm1.orig/kernel/djprobe.c	2006-10-16 22:06:22.000000000 +0900
+++ linux-2.6.19-rc1-mm1/kernel/djprobe.c	2006-10-16 22:06:44.000000000 +0900
@@ -64,6 +64,15 @@
 static LIST_HEAD(registering_list);
 static LIST_HEAD(unregistering_list);

+static void commit_work_fn(void * data);
+static DECLARE_WORK(commit_work, commit_work_fn, 0);
+#define DJPROBE_COMMIT_DELAY (HZ/10)
+
+static __always_inline void kick_delayed_commit(void)
+{
+	schedule_delayed_work(&commit_work, DJPROBE_COMMIT_DELAY);
+}
+
 static int __djprobe_pre_handler(struct kprobe *kp, struct pt_regs *regs)
 {
 	struct djprobe_instance *djpi =
@@ -211,12 +220,18 @@

 int __kprobes commit_djprobes(void)
 {
-	int ret;
+	int ret = 0;
 	BUG_ON(in_interrupt());
+	commit_work_fn(NULL);
+	return ret;
+}
+
+static void commit_work_fn(void * data)
+{
 	mutex_lock(&djprobe_mutex);
-	ret = __commit_djprobes();
+	if (__commit_djprobes() < 0)
+		kick_delayed_commit();/* try again */
 	mutex_unlock(&djprobe_mutex);
-	return ret;
 }

 int __kprobes register_djprobe(struct djprobe *djp)
@@ -265,6 +280,7 @@
 	djp->inst = djpi;
 	INIT_LIST_HEAD(&djp->plist);
 	list_add_rcu(&djp->plist, &djpi->plist);
+	kick_delayed_commit();

       out:
 	mutex_unlock(&djprobe_mutex);
@@ -286,6 +302,7 @@
 			list_del_init(&djpi->rlist);
 		arch_pre_remove_djprobe_instance(djpi);
 		list_add(&djpi->rlist, &unregistering_list);
+		kick_delayed_commit();
 	}
 	mutex_unlock(&djprobe_mutex);
 }