Re: [PATCH v8 3/8] nvmem: core: take a reference on dev.of_node in nvmem_register()

[<Manikandan.M@microchip.com>]

Hi Michael,

On 10/15/26 2:42 PM, Michael Walle wrote:
> On Wed Oct 14, 2026 at 8:40 AM CEST, Manikandan Muralidharan wrote:
>> nvmem_register() stores config->of_node (or config->dev->of_node)
>> into nvmem->dev.of_node without taking its own reference. Callers
>> that get the node via of_get_compatible_child() etc. and drop their
>> reference right after registering leave nvmem->dev.of_node backed by
>> no reference at all.
>>
>> Take an of_node_get() when assigning nvmem->dev.of_node and release
>> it in nvmem_release(). Existing callers that hold their own get/put
>> pair around the registration call need no changes, since get/put on
>> a device_node is per-holder and independent of core now also holding
>> one.
>>
>> Suggested-by: Michael Walle <mwalle@kernel.org>
>> Signed-off-by: Manikandan Muralidharan <manikandan.m@microchip.com>
> 
> Nice!
> 
> Did you check if any callers are also taking a reference, which
> might not be needed anymore now.
> 

Yes, I checked — none of the callers hold a reference beyond the 
registration call itself. The pattern I verified in each drivers is 
short-lived, the reference is dropped right after 
nvmem_register()/devm_nvmem_register() call.

> Reviewed-by: Michael Walle <mwalle@kernel.org>
> 
> -michael
> 
>> ---
>>   drivers/nvmem/core.c | 5 +++--
>>   1 file changed, 3 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/nvmem/core.c b/drivers/nvmem/core.c
>> index 0556d140170a..98192597b935 100644
>> --- a/drivers/nvmem/core.c
>> +++ b/drivers/nvmem/core.c
>> @@ -541,6 +541,7 @@ static void nvmem_release(struct device *dev)
>>   
>>   	ida_free(&nvmem_ida, nvmem->id);
>>   	gpiod_put(nvmem->wp_gpio);
>> +	of_node_put(nvmem->dev.of_node);
>>   	kfree(nvmem->ops);
>>   	kfree(nvmem);
>>   }
>> @@ -950,9 +951,9 @@ struct nvmem_device *nvmem_register(const struct nvmem_config *config)
>>   	nvmem->keepout = config->keepout;
>>   	nvmem->nkeepout = config->nkeepout;
>>   	if (config->of_node)
>> -		nvmem->dev.of_node = config->of_node;
>> +		nvmem->dev.of_node = of_node_get(config->of_node);
>>   	else
>> -		nvmem->dev.of_node = config->dev->of_node;
>> +		nvmem->dev.of_node = of_node_get(config->dev->of_node);
>>   
>>   	switch (config->id) {
>>   	case NVMEM_DEVID_NONE:
> 


-- 
Thanks and Regards,
Manikandan M.