From: Claudiu Beznea <Claudiu.Beznea@microchip.com>
To: Alexandre Belloni <alexandre.belloni@bootlin.com>,
zhong jiang <zhongjiang@huawei.com>
Cc: <linux-kernel@vger.kernel.org>,
<linux-arm-kernel@lists.infradead.org>, <linux@armlinux.org.uk>
Subject: Re: [PATCH] arm/mach-at91/pm: Do not double put the device node
Date: Thu, 16 Aug 2018 12:32:57 +0300 [thread overview]
Message-ID: <59e252e6-6027-9f52-9ee8-8d0bd32659d2@microchip.com> (raw)
In-Reply-To: <20180814125954.GM943@piout.net>
Hi Alexandre,
On 14.08.2018 15:59, Alexandre Belloni wrote:
> On 14/08/2018 09:54:56+0800, zhong jiang wrote:
>> Device node iterators put the previous value of the index variable,
>> so an explicit put causes a double put.
>>
>
> While for_each_matching_node_and_match will get and put the node
> properly, there is also a call to of_find_device_by_node that will get a
> reference to the node.
>
Looking through of_find_device_by_node() it seems that a put_device() on the
struct device member of the returned struct platform_device has to be called
instead of of_node_put().
of_find_device_by_node() calls bus_find_device():
dev = bus_find_device(&platform_bus_type, NULL, np, of_dev_node_match);
the match function, of_dev_node_match(), is just as follows:
static int of_dev_node_match(struct device *dev, void *data)
{
return dev->of_node == data;
}
but bus_find_device() takes a reference to the struct device returned in case it
founds a match, via get_device():
struct device *bus_find_device(struct bus_type *bus,
struct device *start, void *data,
int (*match)(struct device *dev,
void*data))
{
struct klist_iter i;
struct device *dev;
if (!bus || !bus->p)
return NULL;
klist_iter_init_node(&bus->p->klist_devices, &i,
(start ? &start->p->knode_bus : NULL));
while ((dev = next_device(&i)))
if (match(dev, data) && get_device(dev))
break;
klist_iter_exit(&i);
return dev;
}
So, I think a put_device(&pdev->dev) has to be called in at91_pm_config_ws()
instead of of_node_put(np). My bad!
Thank you,
Claudiu Beznea
>> I detect the issue with the help of Coccinelle.
>>
>> Signed-off-by: zhong jiang <zhongjiang@huawei.com>
>> ---
>> arch/arm/mach-at91/pm.c | 5 +----
>> 1 file changed, 1 insertion(+), 4 deletions(-)
>>
>> diff --git a/arch/arm/mach-at91/pm.c b/arch/arm/mach-at91/pm.c
>> index 32fae4d..a5ec35f 100644
>> --- a/arch/arm/mach-at91/pm.c
>> +++ b/arch/arm/mach-at91/pm.c
>> @@ -143,15 +143,12 @@ static int at91_pm_config_ws(unsigned int pm_mode, bool set)
>>
>> /* Check if enabled on SHDWC. */
>> if (wsi->shdwc_mr_bit && !(val & wsi->shdwc_mr_bit))
>> - goto put_node;
>> + continue;
>>
>> mode |= wsi->pmc_fsmr_bit;
>> if (wsi->set_polarity)
>> polarity |= wsi->pmc_fsmr_bit;
>> }
>> -
>> -put_node:
>> - of_node_put(np);
>> }
>>
>> if (mode) {
>> --
>> 1.7.12.4
>>
>
next prev parent reply other threads:[~2018-08-16 9:33 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-08-14 1:54 [PATCH] arm/mach-at91/pm: Do not double put the device node zhong jiang
2018-08-14 12:59 ` Alexandre Belloni
2018-08-16 9:32 ` Claudiu Beznea [this message]
2018-08-16 10:18 ` zhong jiang
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