linux-kernel - Re: [PATCH 2/5] uprobes: Do not setup ->active

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Date:	Thu, 20 Sep 2012 19:25:25 +0530
From:	Srikar Dronamraju <srikar@...ux.vnet.ibm.com>
To:	Oleg Nesterov <oleg@...hat.com>
Cc:	Ingo Molnar <mingo@...e.hu>, Peter Zijlstra <peterz@...radead.org>,
	Ananth N Mavinakayanahalli <ananth@...ibm.com>,
	Anton Arapov <anton@...hat.com>,
	Sebastian Andrzej Siewior <bigeasy@...utronix.de>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/5] uprobes: Do not setup ->active_uprobe/state
 prematurely

* Oleg Nesterov <oleg@...hat.com> [2012-09-14 19:15:54]:

> handle_swbp() sets utask->active_uprobe before handler_chain(),
> and UTASK_SSTEP before pre_ssout(). This complicates the code
> for no reason,  arch_ hooks or consumer->handler() should not
> (and can't) use this info.
> 
> Change handle_swbp() to initialize them after pre_ssout(), and
> remove the no longer needed cleanup-utask code.
> 
> Signed-off-by: Oleg Nesterov <oleg@...hat.com>
> ---
>  kernel/events/uprobes.c |    9 +++------
>  1 files changed, 3 insertions(+), 6 deletions(-)
> 
> diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c
> index 760acc1..9893cba 100644
> --- a/kernel/events/uprobes.c
> +++ b/kernel/events/uprobes.c
> @@ -1496,22 +1496,19 @@ static void handle_swbp(struct pt_regs *regs)
>  		if (!utask)
>  			goto cleanup_ret;
>  	}
> -	utask->active_uprobe = uprobe;
> +
>  	handler_chain(uprobe, regs);
>  	if (uprobe->flags & UPROBE_SKIP_SSTEP && can_skip_sstep(uprobe, regs))
>  		goto cleanup_ret;
> 
> -	utask->state = UTASK_SSTEP;
>  	if (!pre_ssout(uprobe, regs, bp_vaddr)) {
>  		arch_uprobe_enable_step(&uprobe->arch);
> +		utask->active_uprobe = uprobe;
> +		utask->state = UTASK_SSTEP;
>  		return;
>  	}
> 
>  cleanup_ret:
> -	if (utask) {
> -		utask->active_uprobe = NULL;
> -		utask->state = UTASK_RUNNING;
> -	}
>  	if (!(uprobe->flags & UPROBE_SKIP_SSTEP))
> 
>  		/*

Acked-by: Srikar Dronamraju <srikar@...ux.vnet.ibm.com>

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