[PATCH 3/3] kretprobe spinlock deadlock patch

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Hi,
Function kprobe_flush_task possibly calls kfree function during holding kretprobe_lock spinlock, if kfree function is probed by kretprobe that will incur spinlock deadlock. This patch moves kfree function out scope of kretprobe_lock.

Signed-off-by: bibo, mao <[email protected]>
Signed-off-by: Ananth N Mavinakayanahalli <[email protected]>
thanks
bibo,mao

arch/i386/kernel/kprobes.c    |    9 +++++++--
arch/ia64/kernel/kprobes.c    |    9 +++++++--
arch/powerpc/kernel/kprobes.c |    9 +++++++--
arch/s390/kernel/kprobes.c    |    9 +++++++--
arch/x86_64/kernel/kprobes.c  |    9 +++++++--
include/linux/kprobes.h       |    2 +-
kernel/kprobes.c              |   15 +++++++++++----
7 files changed, 47 insertions(+), 15 deletions(-)
diff -Nruap 2.6.18-mm1.org/arch/i386/kernel/kprobes.c 2.6.18-mm1/arch/i386/kernel/kprobes.c
--- 2.6.18-mm1.org/arch/i386/kernel/kprobes.c	2006-09-26 10:49:26.000000000 +0800
+++ 2.6.18-mm1/arch/i386/kernel/kprobes.c	2006-09-26 10:53:16.000000000 +0800
@@ -396,11 +396,12 @@ no_kprobe:
fastcall void *__kprobes trampoline_handler(struct pt_regs *regs)
{
	struct kretprobe_instance *ri = NULL;
-	struct hlist_head *head;
+	struct hlist_head *head, empty_rp;
	struct hlist_node *node, *tmp;
	unsigned long flags, orig_ret_address = 0;
	unsigned long trampoline_address =(unsigned long)&kretprobe_trampoline;

+	INIT_HLIST_HEAD(&empty_rp);
	spin_lock_irqsave(&kretprobe_lock, flags);
	head = kretprobe_inst_table_head(current);

@@ -429,7 +430,7 @@ fastcall void *__kprobes trampoline_hand
		}

		orig_ret_address = (unsigned long)ri->ret_addr;
-		recycle_rp_inst(ri);
+		recycle_rp_inst(ri, &empty_rp);

		if (orig_ret_address != trampoline_address)
			/*
@@ -444,6 +445,10 @@ fastcall void *__kprobes trampoline_hand

	spin_unlock_irqrestore(&kretprobe_lock, flags);

+	hlist_for_each_entry_safe(ri, node, tmp, &empty_rp, hlist) {
+		hlist_del(&ri->hlist);
+		kfree(ri);
+	}
	return (void*)orig_ret_address;
}

diff -Nruap 2.6.18-mm1.org/arch/ia64/kernel/kprobes.c 2.6.18-mm1/arch/ia64/kernel/kprobes.c
--- 2.6.18-mm1.org/arch/ia64/kernel/kprobes.c	2006-09-26 10:49:26.000000000 +0800
+++ 2.6.18-mm1/arch/ia64/kernel/kprobes.c	2006-09-26 10:53:16.000000000 +0800
@@ -340,12 +340,13 @@ static void kretprobe_trampoline(void)
int __kprobes trampoline_probe_handler(struct kprobe *p, struct pt_regs *regs)
{
	struct kretprobe_instance *ri = NULL;
-	struct hlist_head *head;
+	struct hlist_head *head, empty_rp;
	struct hlist_node *node, *tmp;
	unsigned long flags, orig_ret_address = 0;
	unsigned long trampoline_address =
		((struct fnptr *)kretprobe_trampoline)->ip;

+	INIT_HLIST_HEAD(&empty_rp);
	spin_lock_irqsave(&kretprobe_lock, flags);
	head = kretprobe_inst_table_head(current);

@@ -371,7 +372,7 @@ int __kprobes trampoline_probe_handler(s
			ri->rp->handler(ri, regs);

		orig_ret_address = (unsigned long)ri->ret_addr;
-		recycle_rp_inst(ri);
+		recycle_rp_inst(ri, &empty_rp);

		if (orig_ret_address != trampoline_address)
			/*
@@ -389,6 +390,10 @@ int __kprobes trampoline_probe_handler(s
	spin_unlock_irqrestore(&kretprobe_lock, flags);
	preempt_enable_no_resched();

+	hlist_for_each_entry_safe(ri, node, tmp, &empty_rp, hlist) {
+		hlist_del(&ri->hlist);
+		kfree(ri);
+	}
	/*
	 * By returning a non-zero value, we are telling
	 * kprobe_handler() that we don't want the post_handler
diff -Nruap 2.6.18-mm1.org/arch/powerpc/kernel/kprobes.c 2.6.18-mm1/arch/powerpc/kernel/kprobes.c
--- 2.6.18-mm1.org/arch/powerpc/kernel/kprobes.c	2006-09-26 10:49:26.000000000 +0800
+++ 2.6.18-mm1/arch/powerpc/kernel/kprobes.c	2006-09-26 10:53:16.000000000 +0800
@@ -260,11 +260,12 @@ void kretprobe_trampoline_holder(void)
int __kprobes trampoline_probe_handler(struct kprobe *p, struct pt_regs *regs)
{
	struct kretprobe_instance *ri = NULL;
-	struct hlist_head *head;
+	struct hlist_head *head, empty_rp;
	struct hlist_node *node, *tmp;
	unsigned long flags, orig_ret_address = 0;
	unsigned long trampoline_address =(unsigned long)&kretprobe_trampoline;

+	INIT_HLIST_HEAD(&empty_rp);
	spin_lock_irqsave(&kretprobe_lock, flags);
	head = kretprobe_inst_table_head(current);

@@ -290,7 +291,7 @@ int __kprobes trampoline_probe_handler(s
			ri->rp->handler(ri, regs);

		orig_ret_address = (unsigned long)ri->ret_addr;
-		recycle_rp_inst(ri);
+		recycle_rp_inst(ri, &empty_rp);

		if (orig_ret_address != trampoline_address)
			/*
@@ -308,6 +309,10 @@ int __kprobes trampoline_probe_handler(s
	spin_unlock_irqrestore(&kretprobe_lock, flags);
	preempt_enable_no_resched();

+	hlist_for_each_entry_safe(ri, node, tmp, &empty_rp, hlist) {
+		hlist_del(&ri->hlist);
+		kfree(ri);
+	}
	/*
	 * By returning a non-zero value, we are telling
	 * kprobe_handler() that we don't want the post_handler
diff -Nruap 2.6.18-mm1.org/arch/s390/kernel/kprobes.c 2.6.18-mm1/arch/s390/kernel/kprobes.c
--- 2.6.18-mm1.org/arch/s390/kernel/kprobes.c	2006-09-25 16:11:56.000000000 +0800
+++ 2.6.18-mm1/arch/s390/kernel/kprobes.c	2006-09-26 10:53:16.000000000 +0800
@@ -368,11 +368,12 @@ void __kprobes kretprobe_trampoline_hold
int __kprobes trampoline_probe_handler(struct kprobe *p, struct pt_regs *regs)
{
	struct kretprobe_instance *ri = NULL;
-	struct hlist_head *head;
+	struct hlist_head *head, empty_rp;
	struct hlist_node *node, *tmp;
	unsigned long flags, orig_ret_address = 0;
	unsigned long trampoline_address = (unsigned long)&kretprobe_trampoline;

+	INIT_HLIST_HEAD(&empty_rp);
	spin_lock_irqsave(&kretprobe_lock, flags);
	head = kretprobe_inst_table_head(current);

@@ -398,7 +399,7 @@ int __kprobes trampoline_probe_handler(s
			ri->rp->handler(ri, regs);

		orig_ret_address = (unsigned long)ri->ret_addr;
-		recycle_rp_inst(ri);
+		recycle_rp_inst(ri, &empty_rp);

		if (orig_ret_address != trampoline_address) {
			/*
@@ -416,6 +417,10 @@ int __kprobes trampoline_probe_handler(s
	spin_unlock_irqrestore(&kretprobe_lock, flags);
	preempt_enable_no_resched();

+	hlist_for_each_entry_safe(ri, node, tmp, &empty_rp, hlist) {
+		hlist_del(&ri->hlist);
+		kfree(ri);
+	}
	/*
	 * By returning a non-zero value, we are telling
	 * kprobe_handler() that we don't want the post_handler
diff -Nruap 2.6.18-mm1.org/arch/x86_64/kernel/kprobes.c 2.6.18-mm1/arch/x86_64/kernel/kprobes.c
--- 2.6.18-mm1.org/arch/x86_64/kernel/kprobes.c	2006-09-26 10:49:26.000000000 +0800
+++ 2.6.18-mm1/arch/x86_64/kernel/kprobes.c	2006-09-26 10:53:16.000000000 +0800
@@ -405,11 +405,12 @@ no_kprobe:
int __kprobes trampoline_probe_handler(struct kprobe *p, struct pt_regs *regs)
{
	struct kretprobe_instance *ri = NULL;
-	struct hlist_head *head;
+	struct hlist_head *head, empty_rp;
	struct hlist_node *node, *tmp;
	unsigned long flags, orig_ret_address = 0;
	unsigned long trampoline_address =(unsigned long)&kretprobe_trampoline;

+	INIT_HLIST_HEAD(&empty_rp);
	spin_lock_irqsave(&kretprobe_lock, flags);
	head = kretprobe_inst_table_head(current);

@@ -435,7 +436,7 @@ int __kprobes trampoline_probe_handler(s
			ri->rp->handler(ri, regs);

		orig_ret_address = (unsigned long)ri->ret_addr;
-		recycle_rp_inst(ri);
+		recycle_rp_inst(ri, &empty_rp);

		if (orig_ret_address != trampoline_address)
			/*
@@ -453,6 +454,10 @@ int __kprobes trampoline_probe_handler(s
	spin_unlock_irqrestore(&kretprobe_lock, flags);
	preempt_enable_no_resched();

+	hlist_for_each_entry_safe(ri, node, tmp, &empty_rp, hlist) {
+		hlist_del(&ri->hlist);
+		kfree(ri);
+	}
	/*
	 * By returning a non-zero value, we are telling
	 * kprobe_handler() that we don't want the post_handler
diff -Nruap 2.6.18-mm1.org/include/linux/kprobes.h 2.6.18-mm1/include/linux/kprobes.h
--- 2.6.18-mm1.org/include/linux/kprobes.h	2006-09-25 16:12:04.000000000 +0800
+++ 2.6.18-mm1/include/linux/kprobes.h	2006-09-26 10:53:16.000000000 +0800
@@ -202,7 +202,7 @@ void unregister_kretprobe(struct kretpro
struct kretprobe_instance *get_free_rp_inst(struct kretprobe *rp);
void add_rp_inst(struct kretprobe_instance *ri);
void kprobe_flush_task(struct task_struct *tk);
-void recycle_rp_inst(struct kretprobe_instance *ri);
+void recycle_rp_inst(struct kretprobe_instance *ri, struct hlist_head *head);
#else /* CONFIG_KPROBES */

#define __kprobes	/**/
diff -Nruap 2.6.18-mm1.org/kernel/kprobes.c 2.6.18-mm1/kernel/kprobes.c
--- 2.6.18-mm1.org/kernel/kprobes.c	2006-09-26 10:49:26.000000000 +0800
+++ 2.6.18-mm1/kernel/kprobes.c	2006-09-26 10:53:16.000000000 +0800
@@ -319,7 +319,8 @@ void __kprobes add_rp_inst(struct kretpr
}

/* Called with kretprobe_lock held */
-void __kprobes recycle_rp_inst(struct kretprobe_instance *ri)
+void __kprobes recycle_rp_inst(struct kretprobe_instance *ri,
+				struct hlist_head *head)
{
	/* remove rp inst off the rprobe_inst_table */
	hlist_del(&ri->hlist);
@@ -331,7 +332,7 @@ void __kprobes recycle_rp_inst(struct kr
		hlist_add_head(&ri->uflist, &ri->rp->free_instances);
	} else
		/* Unregistering */
-		kfree(ri);
+		hlist_add_head(&ri->hlist, head);
}

struct hlist_head __kprobes *kretprobe_inst_table_head(struct task_struct *tsk)
@@ -348,17 +349,23 @@ struct hlist_head __kprobes *kretprobe_i
void __kprobes kprobe_flush_task(struct task_struct *tk)
{
	struct kretprobe_instance *ri;
-	struct hlist_head *head;
+	struct hlist_head *head, empty_rp;
	struct hlist_node *node, *tmp;
	unsigned long flags = 0;

+	INIT_HLIST_HEAD(&empty_rp);
	spin_lock_irqsave(&kretprobe_lock, flags);
	head = kretprobe_inst_table_head(tk);
	hlist_for_each_entry_safe(ri, node, tmp, head, hlist) {
		if (ri->task == tk)
-			recycle_rp_inst(ri);
+			recycle_rp_inst(ri, &empty_rp);
	}
	spin_unlock_irqrestore(&kretprobe_lock, flags);
+
+	hlist_for_each_entry_safe(ri, node, tmp, &empty_rp, hlist) {
+		hlist_del(&ri->hlist);
+		kfree(ri);
+	}
}

static inline void free_rp_inst(struct kretprobe *rp)
-
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