Re: [PATCH 1/5] Kprobes: Temporary disarming of reentrant probe

[Ananth N Mavinakayanahalli <amavin at redhat dot com>]

Andi Kleen wrote:

Hi Andi,

> > @@ -55,6 +61,9 @@ struct kprobe {
> > 	/* list of kprobes for multi-handler support */
> > 	struct list_head list;
> >
> > +	/*count the number of times this probe was temporarily disarmed */
> > +	unsigned long nmissed;
>
>
> You declare a variable.
>
>
> > +
> > 	/* location of the probe point */
> > 	kprobe_opcode_t *addr;
> >
> > diff -puN kernel/kprobes.c~kprobes-temporary-disarming-on-reentrancy-generic kernel/kprobes.c
> > --- linux-2.6.12-rc4-mm2/kernel/kprobes.c~kprobes-temporary-disarming-on-reentrancy-generic	2005-05-24 15:28:08.000000000 +0530
> > +++ linux-2.6.12-rc4-mm2-prasanna/kernel/kprobes.c	2005-05-24 15:28:08.000000000 +0530
> > @@ -334,6 +334,7 @@ int register_kprobe(struct kprobe *p)
> > 	}
> > 	spin_lock_irqsave(&kprobe_lock, flags);
> > 	old_p = get_kprobe(p->addr);
> > +	p->nmissed = 0;
>
>
> And then you set it to 0.
>
> And nothing more. Surely this patch does not do anything. Looks like
> some code is missing.

No Andi - nmissed is incremented in the arch/xxx/kernel/kprobes.c
everytime the probe is "reentered". This is part of the subsequent
patches in the series.

Ananth