linux-kernel - Re: [PATCH 1/2] tty: serial: samsung_tty: Fix a memory leak in s3c24xx_serial

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Date:   Sat, 10 Jun 2023 19:40:39 +0200
From:   Christophe JAILLET <christophe.jaillet@...adoo.fr>
To:     Andi Shyti <andi.shyti@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
Cc:     Alim Akhtar <alim.akhtar@...sung.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Jiri Slaby <jirislaby@...nel.org>,
        Thomas Abraham <thomas.abraham@...aro.org>,
        Kukjin Kim <kgene.kim@...sung.com>,
        linux-kernel@...r.kernel.org, kernel-janitors@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org,
        linux-samsung-soc@...r.kernel.org, linux-serial@...r.kernel.org
Subject: Re: [PATCH 1/2] tty: serial: samsung_tty: Fix a memory leak in
 s3c24xx_serial_getclk() in case of error

Le 10/06/2023 à 19:10, Andi Shyti a écrit :
> On Sat, Jun 10, 2023 at 06:23:58PM +0200, Krzysztof Kozlowski wrote:
>> On 10/06/2023 16:54, Andi Shyti wrote:
>>> On Sat, Jun 10, 2023 at 04:07:51PM +0200, Christophe JAILLET wrote:
>>>> Le 10/06/2023 à 12:26, Andi Shyti a écrit :
>>>>>> @@ -1459,8 +1459,10 @@ static unsigned int s3c24xx_serial_getclk(struct s3c24xx_uart_port *ourport,
>>>>>>    			continue;
>>>>>>    		rate = clk_get_rate(clk);
>>>>>> -		if (!rate)
>>>>>> +		if (!rate) {
>>>>>> +			clk_put(clk);
>>>>>>    			continue;
>>>>>
>>>>> could you also print an error here?
>>>>>
>>>>
>>>> Is:
>>>> 	dev_err(ourport->port.dev,
>>>> 		"Failed to get clock rate for %s.\n", clkname);
>>
>> Why do we need it? Most of other users of clk_get_rate() don't print.
> 
> that's not a reason not to print it.
> 
>> Probably because such condition is highly unlikely if not impossible.
> 
> still... that's not a reason not to print it.
> 
> All errors are unlikely and if it's unlikely, why there is no
> unlikely(!rate)? Which doesn't improve the reason not to print
> it.
> 
> The more unlikely, the lauder you need to be:
> 
> WARN_ON(!rate)... maybe too much!
> BUG_ON(!rate)... way too much!
> 
> But these are inversely proportional to the likeliness of the
> error.
> 
>> This makes simple function unnecessarily bigger...
> 
> and... that's not a reason not to print it :)
> 
> If it's needed, it's needed. If we are considering the error,
> then we need to treat it as an error.
> 
> In any case, I'm not strong with it, indeed, I r-b it anyway. I
> personally prefer and suggested printing the error. Up to
> Christophe.

git grep -A5 clk_get_rate | grep dev_err | wc -l
173
git grep clk_get_rate | wc -l
1464

(+ Krzysztof's argumentation)

So lets go for v1.

Can v1 be taken as is?
(knowing that I don't really care about the new 3/3 related to abs())

Or should I send a v3 to ease the process?

CJ


> 
> Thanks,
> Andi
>