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Date: Mon, 14 Jan 2013 17:38:26 +0000
From: Cong Ding <dinggnu@gmail.com>
To: Russell King - ARM Linux <linux@arm.linux.org.uk>
Cc: Will Deacon <will.deacon@arm.com>, Peter Zijlstra <a.p.zijlstra@chello.nl>,
        Paul Mackerras <paulus@samba.org>, Ingo Molnar <mingo@redhat.com>,
        Arnaldo Carvalho de Melo <acme@ghostprotocols.net>,
        linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] arm: kernel/perf_event_cpu.c: fix error null pointer
 dereference check
Message-ID: <20130114173826.GA917@gmail.com>
References: <1358183933-29160-1-git-send-email-dinggnu@gmail.com>
 <20130114172346.GK23505@n2100.arm.linux.org.uk>
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On Mon, Jan 14, 2013 at 05:23:46PM +0000, Russell King - ARM Linux wrote:
> On Mon, Jan 14, 2013 at 05:18:53PM +0000, Cong Ding wrote:
> > the pointer cpu_pmu is used without null pointer dereference check, and is
> > checked after the using of it, so we move the null pointer check to before the
> > first use.
> 
> The NULL pointer check is not necessary.  cpu_pmu_init() is called
> after cpu_pmu has already been dereferenced by its caller:
> 
>         cpu_pmu = pmu;
>         cpu_pmu->plat_device = pdev;
>         cpu_pmu_init(cpu_pmu);
> 
> So...
> 
> > -	/* Ensure the PMU has sane values out of reset. */
> > -	if (cpu_pmu && cpu_pmu->reset)
> 
> Just replace this with:
> 	if (cpu_pmu->reset)
Thanks Russell, I will send version 2.

- cong