linux-kernel - Re: [PATCH] clocksource/drivers/integrator-ap: add missing of_node

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Date:   Sat, 24 Nov 2018 20:49:11 +0100
From:   Daniel Lezcano <daniel.lezcano@...aro.org>
To:     Frank Lee <tiny.windzz@...il.com>, tglx@...utronix.de
Cc:     linux-kernel@...r.kernel.org
Subject: Re: [PATCH] clocksource/drivers/integrator-ap: add missing
 of_node_put()

On 24/11/2018 15:58, Frank Lee wrote:
> On Thu, Nov 22, 2018 at 11:23 PM Yangtao Li <tiny.windzz@...il.com> wrote:
>>
>> of_find_node_by_path() acquires a reference to the node
>> returned by it and that reference needs to be dropped by its caller.
>> integrator_ap_timer_init_of() doesn't do that, so fix it.
>>
>> Signed-off-by: Yangtao Li <tiny.windzz@...il.com>
>> ---
>>  drivers/clocksource/timer-integrator-ap.c | 20 ++++++++++++++------
>>  1 file changed, 14 insertions(+), 6 deletions(-)
>>
>> diff --git a/drivers/clocksource/timer-integrator-ap.c b/drivers/clocksource/timer-integrator-ap.c
>> index 76e526f58620..1f04069470bb 100644
>> --- a/drivers/clocksource/timer-integrator-ap.c
>> +++ b/drivers/clocksource/timer-integrator-ap.c
>> @@ -177,7 +177,7 @@ static int __init integrator_ap_timer_init_of(struct device_node *node)
>>  {
>>         const char *path;
>>         void __iomem *base;
>> -       int err;
>> +       int err,rc = 0;
>>         int irq;
>>         struct clk *clk;
>>         unsigned long rate;
>> @@ -210,26 +210,34 @@ static int __init integrator_ap_timer_init_of(struct device_node *node)
>>                                 "arm,timer-secondary", &path);
>>         if (err) {
>>                 pr_warn("Failed to read property\n");
>> -               return err;
>> +               rc = err;
>> +               goto out_put_pri_node;
>>         }
>>
>>
>>         sec_node = of_find_node_by_path(path);
>>
>> -       if (node == pri_node)
>> +       if (node == pri_node){
>>                 /* The primary timer lacks IRQ, use as clocksource */
>> -               return integrator_clocksource_init(rate, base);
>> +               rc = integrator_clocksource_init(rate, base);
>> +               goto out;
>> +       }
>>
>>         if (node == sec_node) {
>>                 /* The secondary timer will drive the clock event */
>>                 irq = irq_of_parse_and_map(node, 0);
>> -               return integrator_clockevent_init(rate, base, irq);
>> +               rc = integrator_clockevent_init(rate, base, irq);
>> +               goto out;
>>         }
>>
>>         pr_info("Timer @%p unused\n", base);
>>         clk_disable_unprepare(clk);
>> +out:
>> +       of_node_put(sec_node);
>> +out_put_pri_node:
>> +       of_node_put(pri_node);
>>
>> -       return 0;
>> +       return rc;
>>  }
>>
>>  TIMER_OF_DECLARE(integrator_ap_timer, "arm,integrator-timer",
>> --
>> 2.17.0
>>
> Hi Daniel：
> 
> How about this?

Hi,

I think there is a simpler fix. The pri_node and the sec_node are used
as an identifier to compare against the current node, we can directly
drop the refcount after getting the node from path as it is not used as
pointer. In addition, a single variable is needed, so we end up with a
fix like that.

	alias_node = of_find_node_by_path(path);
	of_node_put(alias_node);
	if (node == alias_node)
		return integrator_clocksource_init(rate, base);



> 
> Thanks，
> Yangtao
> 


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