linux-kernel - Re: Re: [PATCH] devfreq: correctly check failed allocation

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Date:	Wed, 21 Oct 2015 08:27:56 +0000 (GMT)
From:	MyungJoo Ham <myungjoo.ham@...sung.com>
To:	Insu Yun <wuninsu@...il.com>
Cc:	박경민 <kyungmin.park@...sung.com>,
	"linux-pm@...r.kernel.org" <linux-pm@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"taesoo@...ech.edu" <taesoo@...ech.edu>,
	"yeongjin.jang@...ech.edu" <yeongjin.jang@...ech.edu>,
	"insu@...ech.edu" <insu@...ech.edu>,
	"changwoo@...ech.edu" <changwoo@...ech.edu>
Subject: Re: Re: [PATCH] devfreq: correctly check failed allocation

>On Mon, Oct 19, 2015 at 8:49 PM, MyungJoo Ham <myungjoo.ham@...sung.com> wrote:
>
>>Since devm_kzalloc can be failed in memory pressure,
> >check return value and handle error.
> >
> >Signed-off-by: Insu Yun <wuninsu@...il.com>
> >---
>> drivers/devfreq/devfreq.c | 14 ++++++++++++++
> > 1 file changed, 14 insertions(+)
> >
> >diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c
> >index ca1b362..814089f 100644
> >--- a/drivers/devfreq/devfreq.c
> >+++ b/drivers/devfreq/devfreq.c
> >@@ -482,9 +482,23 @@ struct devfreq *devfreq_add_device(struct device *dev,
> >                                               devfreq->profile->max_state *
> >                                               devfreq->profile->max_state,
> >                                               GFP_KERNEL);
> >+      if (!devfreq->trans_table) {
> >+              dev_err(dev, "%s: Unable to create transition table for the device\n",
> >+                      __func__);
> >+              err = -ENOMEM;
> >+              goto err_dev;
> >+      }
> >+
>
>  I don't see a label 'err_dev' in devfreq.c
>  And please note that you are under a mutex lock here as well; you must unlock it before returning.
>Oh, I think I need to unlock. 
>
>  For devfreq.c of most recent release candidate, please refer to
>  https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/tree/drivers/devfreq/devfreq.c?id=7379047d5585187d1288486d4627873170d0005a
>
>Sorry I used older version of linux. I will resend patch for current version.
>
>  You don't seem to be based on a recent RC as well.
>
>I cannot understand what RC means.
>

It's Release Candidate. Please refer to the git tags in the repo.

>
>And question is that, when device_register fails, it returns without freeing devfreq. Is it fine? 

We have a "release" callback defined for the struct device registered
with device_register(), which is called when that happens.


Cheers,
MyungJoo