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SubjectRe: [PATCH] clocksource/drivers/integrator-ap: add missing of_node_put()
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On 25/11/2018 05:25, Frank Lee wrote:
> On Sun, Nov 25, 2018 at 3:49 AM Daniel Lezcano
> <daniel.lezcano@linaro.org> wrote:
>>
>> On 24/11/2018 15:58, Frank Lee wrote:
>>> On Thu, Nov 22, 2018 at 11:23 PM Yangtao Li <tiny.windzz@gmail.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@gmail.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);
>
> Daniel,
>
> OK,I will simplify it like you said.Although I think of_node_put
> should be called
> after we don't use node.

Except I'm missing something, we don't use the alias_node at any time.
The node itself has already a refcount which gives us the guarantee it
is valid.

I agree it can appear a bit strange to put the node right after getting
it but in our case the alias_node is used as an ID, not a pointer, so it
is fine.




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