linux-kernel - Re: [PATCH 2/2] thermal/drivers/mediatek/lvts

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Date: Mon, 8 Apr 2024 20:41:26 +0200
From: Christophe JAILLET <christophe.jaillet@...adoo.fr>
To: Dan Carpenter <dan.carpenter@...aro.org>
Cc: "Rafael J. Wysocki" <rafael@...nel.org>,
 Daniel Lezcano <daniel.lezcano@...aro.org>, Zhang Rui <rui.zhang@...el.com>,
 Lukasz Luba <lukasz.luba@....com>, Matthias Brugger
 <matthias.bgg@...il.com>,
 AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>,
 linux-kernel@...r.kernel.org, kernel-janitors@...r.kernel.org,
 linux-pm@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
 linux-mediatek@...ts.infradead.org
Subject: Re: [PATCH 2/2] thermal/drivers/mediatek/lvts_thermal: Improve some
 memory allocation

Le 08/04/2024 à 10:09, Dan Carpenter a écrit :
> On Sun, Apr 07, 2024 at 10:01:49PM +0200, Christophe JAILLET wrote:
>> diff --git a/drivers/thermal/mediatek/lvts_thermal.c b/drivers/thermal/mediatek/lvts_thermal.c
>> index 3003dc350766..b133f731c5ba 100644
>> --- a/drivers/thermal/mediatek/lvts_thermal.c
>> +++ b/drivers/thermal/mediatek/lvts_thermal.c
>> @@ -204,7 +204,7 @@ static const struct debugfs_reg32 lvts_regs[] = {
>>   
>>   static int lvts_debugfs_init(struct device *dev, struct lvts_domain *lvts_td)
>>   {
>> -	struct debugfs_regset32 *regset;
>> +	struct debugfs_regset32 *regsets;
>>   	struct lvts_ctrl *lvts_ctrl;
>>   	struct dentry *dentry;
>>   	char name[64];
>> @@ -214,8 +214,14 @@ static int lvts_debugfs_init(struct device *dev, struct lvts_domain *lvts_td)
>>   	if (IS_ERR(lvts_td->dom_dentry))
>>   		return 0;
>>   
>> +	regsets = devm_kcalloc(dev, lvts_td->num_lvts_ctrl,
>> +			       sizeof(*regsets), GFP_KERNEL);
>> +	if (!regsets)
>> +		return 0;
> 
> I understand that this preserved the behavior from the original code,
> but the original code was wrong.  This should return -ENOMEM.

Hi Dan,
I don't agree.

For me, this memory allocation is of the same type as all debugfs 
functions that we ignore the error code.

If it fails, it is not a reason good enough to have the probe fail. 
(anyway, if we are short on memory at this point other errors will 
likely occur)

> 
>> +
>>   	for (i = 0; i < lvts_td->num_lvts_ctrl; i++) {
>>   
>> +		struct debugfs_regset32 *regset = &regsets[i];
>>   		lvts_ctrl = &lvts_td->lvts_ctrl[i];
> 
> The blank line should come after the declaration.

The blank line was already there, and in this file, it looks like the 
preferred style (even if not completely consistent)

Let see if there is some comment about 0 or -ENOMEM in case of memory 
allocation error, and if needed, I'll repost without the blank line.

This patch being a really tiny tiny tiny improvement (IMHO), so it may 
also just be ignored.

CJ

> 
> regards,
> dan carpenter
> 
> 
>