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Re: [PATCH]kprobe booster for IA64
- From: Keshavamurthy Anil S <anil dot s dot keshavamurthy at intel dot com>
- To: Masami Hiramatsu <hiramatu at sdl dot hitachi dot co dot jp>
- Cc: "Keshavamurthy, Anil S" <anil dot s dot keshavamurthy at intel dot com>, Ananth N Mavinakayanahalli <ananth at in dot ibm dot com>, SystemTAP <systemtap at sources dot redhat dot com>, Yumiko Sugita <sugita at sdl dot hitachi dot co dot jp>, Satoshi Oshima <soshima at redhat dot com>, Hideo Aoki <haoki at redhat dot com>, Prasanna S Panchamukhi <prasanna at in dot ibm dot com>, Jim Keniston <jkenisto at us dot ibm dot com>
- Date: Wed, 28 Jun 2006 19:05:41 -0700
- Subject: Re: [PATCH]kprobe booster for IA64
- References: <4485223C.8090109@sdl.hitachi.co.jp>
- Reply-to: Keshavamurthy Anil S <anil dot s dot keshavamurthy at intel dot com>
On Tue, Jun 06, 2006 at 03:35:40PM +0900, Masami Hiramatsu wrote:
> +#ifdef CONFIG_PREEMPT
> + unsigned pre_preempt_count = preempt_count();
> +#else
> + unsigned pre_preempt_count = 1;
> +#endif
>
> /*
> * We don't want to be preempted for the entire
> @@ -681,6 +745,14 @@ static int __kprobes pre_kprobes_handler
> */
> return 1;
>
> + if (pre_preempt_count && p->ainsn.inst_flag == INST_FLAG_BOOSTABLE &&
> + !p->post_handler) {
pre_preempt_count will always be one here, since
notify_die()->atomic_notifier_call_chain()->read_rcu_lock()->preeempt_disable().
So currently you might be preparing for boosting even for
preemptable code path. Can you verify this.
-Anil