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Date: Wed, 08 Aug 2012 14:40:41 +0530
From: "Suzuki K. Poulose" <suzuki@...ibm.com>
To: Sebastian Andrzej Siewior <bigeasy@...utronix.de>
CC: linux-kernel@...r.kernel.org, x86@...nel.org,
Peter Zijlstra <a.p.zijlstra@...llo.nl>,
Arnaldo Carvalho de Melo <acme@...stprotocols.net>,
Roland McGrath <roland@...hat.com>,
Oleg Nesterov <oleg@...hat.com>,
Srikar Dronamraju <srikar@...ux.vnet.ibm.com>,
Ananth N Mavinakaynahalli <ananth@...ibm.com>,
stan_shebs@...tor.com
Subject: Re: [PATCH 3/5] uprobes: remove check for uprobe variable in handle_swbp()
On 08/07/2012 09:42 PM, Sebastian Andrzej Siewior wrote:
> by the time we get here (after we pass cleanup_ret) uprobe is always is
> set. If it is NULL we leave very early in the code.
>
> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@...utronix.de>
> ---
> kernel/events/uprobes.c | 16 +++++++---------
> 1 file changed, 7 insertions(+), 9 deletions(-)
>
> diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c
> index 41a2555..c8e5204 100644
> --- a/kernel/events/uprobes.c
> +++ b/kernel/events/uprobes.c
> @@ -1528,17 +1528,15 @@ cleanup_ret:
> utask->active_uprobe = NULL;
> utask->state = UTASK_RUNNING;
> }
> - if (uprobe) {
> - if (!(uprobe->flags & UPROBE_SKIP_SSTEP))
> + if (!(uprobe->flags & UPROBE_SKIP_SSTEP))
>
Shouldn't we check uprobe != NULL before we check the uprobe->flags ?
i.e, shouldn't the above line be :
if (uprobe && ! (uprobe->flags & UPROBE_SKIP_SSTEP)) ?
> - /*
> - * cannot singlestep; cannot skip instruction;
> - * re-execute the instruction.
> - */
> - instruction_pointer_set(regs, bp_vaddr);
> + /*
> + * cannot singlestep; cannot skip instruction;
> + * re-execute the instruction.
> + */
> + instruction_pointer_set(regs, bp_vaddr);
>
> - put_uprobe(uprobe);
> - }
> + put_uprobe(uprobe);
> }
Thanks
Suzuki
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