linux-kernel - Re: [PATCH] ARM: 8351/1: perf: fix memory leak on return

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Message-ID: <20150520115705.GA5273@gmail.com>
Date:	Wed, 20 May 2015 13:57:05 +0200
From:	Ingo Molnar <mingo@...nel.org>
To:	Colin Ian King <colin.king@...onical.com>
Cc:	Will Deacon <will.deacon@....com>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Paul Mackerras <paulus@...ba.org>,
	Ingo Molnar <mingo@...hat.com>,
	Arnaldo Carvalho de Melo <acme@...nel.org>,
	Russell King <linux@....linux.org.uk>,
	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] ARM: 8351/1: perf: fix memory leak on return


* Colin Ian King <colin.king@...onical.com> wrote:

> On 16/05/15 08:09, Ingo Molnar wrote:
> > 
> > * Colin King <colin.king@...onical.com> wrote:
> > 
> >> From: Colin Ian King <colin.king@...onical.com>
> >>
> >> Recent commit 3b8786ff7a1b31645ae2c26a2ec32dbd42ac1094
> >> ("ARM: 8352/1: perf: Fix the pmu node name in warning message")
> >> introduced a memory leak of irqs on the "Don't bother with PPIs"
> >> return path. This was picked up by static analysis by cppcheck:
> >>
> >> [arch/arm/kernel/perf_event_cpu.c:315]: (error) Memory leak: irqs
> >>
> >> simpele fix is to free irqs when returning.
> >>
> >> Signed-off-by: Colin Ian King <colin.king@...onical.com>
> >> ---
> >>  arch/arm/kernel/perf_event_cpu.c | 4 +++-
> >>  1 file changed, 3 insertions(+), 1 deletion(-)
> >>
> >> diff --git a/arch/arm/kernel/perf_event_cpu.c b/arch/arm/kernel/perf_event_cpu.c
> >> index 213919b..9e5b2a5 100644
> >> --- a/arch/arm/kernel/perf_event_cpu.c
> >> +++ b/arch/arm/kernel/perf_event_cpu.c
> >> @@ -311,8 +311,10 @@ static int of_pmu_irq_cfg(struct platform_device *pdev)
> >>  
> >>  	/* Don't bother with PPIs; they're already affine */
> >>  	irq = platform_get_irq(pdev, 0);
> >> -	if (irq >= 0 && irq_is_percpu(irq))
> >> +	if (irq >= 0 && irq_is_percpu(irq)) {
> >> +		kfree(irqs);
> >>  		return 0;
> >> +	}
> >>  
> >>  	for (i = 0; i < pdev->num_resources; ++i) {
> >>  		struct device_node *dn;
> > 
> > So returning from the middle of a function isn't very clean.
> > 
> > Also, why do we return 0 in an error case?
> 
> I believe that's explained in commit
> 338d9dd3e2aee00a9198e8bf6e7d535d3feeaf32 ("ARM: 8351/1: perf: don't warn
> about missing interrupt-affinity property for PPIs"):
> 
> "PPIs are affine by nature, so the interrupt-affinity property is not
>  used and therefore we shouldn't print a warning in its absence."

That should probably be mentioned in the fine code as well, to keep 
future generations from wondering.

Thanks,

	Ingo
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