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Message-ID: <4518CE9A.7020401@gmail.com>
Date: Tue, 26 Sep 2006 08:54:18 +0200
From: Jiri Slaby <jirislaby@...il.com>
To: "bibo,mao" <bibo.mao@...el.com>
CC: Andrew Morton <akpm@...l.org>, linux-kernel@...r.kernel.org,
Ananth N Mavinakayanahalli <ananth@...ibm.com>,
Masami Hiramatsu <masami.hiramatsu.pt@...achi.com>,
"Keshavamurthy, Anil S" <anil.s.keshavamurthy@...el.com>
Subject: Re: [PATCH 3/3] kretprobe spinlock deadlock patch
bibo,mao wrote:
> 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 <bibo.mao@...el.com>
> Signed-off-by: Ananth N Mavinakayanahalli <ananth@...ibm.com>
> 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);
HLIST_HEAD(empty_rp); instead of that 2 changes?
> 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)
regards,
--
http://www.fi.muni.cz/~xslaby/ Jiri Slaby
faculty of informatics, masaryk university, brno, cz
e-mail: jirislaby gmail com, gpg pubkey fingerprint:
B674 9967 0407 CE62 ACC8 22A0 32CC 55C3 39D4 7A7E
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