linux-kernel - Re: [PATCH] clocksource/drivers: Fix memory leak in ttc_setup

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Message-ID: <2a6cdb63-397b-280a-7379-740e8f43ddf6@xilinx.com>
Date:   Tue, 22 Oct 2019 10:51:11 +0200
From:   Michal Simek <michal.simek@...inx.com>
To:     Markus Elfring <Markus.Elfring@....de>,
        Navid Emamdoost <navid.emamdoost@...il.com>,
        linux-arm-kernel@...ts.infradead.org
Cc:     linux-kernel@...r.kernel.org, kernel-janitors@...r.kernel.org,
        Navid Emamdoost <emamd001@....edu>, Kangjie Lu <kjlu@....edu>,
        Stephen McCamant <smccaman@....edu>,
        Daniel Lezcano <daniel.lezcano@...aro.org>,
        Michal Simek <michal.simek@...inx.com>,
        Thomas Gleixner <tglx@...utronix.de>
Subject: Re: [PATCH] clocksource/drivers: Fix memory leak in
 ttc_setup_clockevent

On 22. 10. 19 10:26, Markus Elfring wrote:
>> In the impelementation of ttc_setup_clockevent() the allocated memory
>> for ttcce should be released if clk_notifier_register() fails.
> 
> * Please avoid the copying of typos from previous change descriptions.
> 
> * Under which circumstances will an “imperative mood” matter for you here?
>   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/Documentation/process/submitting-patches.rst?id=7d194c2100ad2a6dded545887d02754948ca5241#n151
> 
> 
>> +++ b/drivers/clocksource/timer-cadence-ttc.c
>> @@ -424,6 +424,7 @@ static int __init ttc_setup_clockevent(struct clk *clk,
>>  				    &ttcce->ttc.clk_rate_change_nb);
>>  	if (err) {
>>  		pr_warn("Unable to register clock notifier.\n");
>> +		kfree(ttcce);
>>  		return err;
>>  	}
> 
> This addition looks correct.
> But I would prefer to move such exception handling code to the end of
> this function implementation so that duplicate source code will be reduced.
> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/Documentation/process/coding-style.rst?id=7d194c2100ad2a6dded545887d02754948ca5241#n450

Just a note. Maybe you should also consider to fix this error path in
ttc_setup_clocksource() when notifier also can fail that there is no
need to continue with code execution.

Thanks,
Michal