06.04.2020 18:41, Sowjanya Komatineni пишет:
>
> On 4/5/20 2:11 PM, Dmitry Osipenko wrote:
>> External email: Use caution opening links or attachments
>>
>>
>> 04.04.2020 04:25, Sowjanya Komatineni пишет:
>> ...
>>> +static int tegra_vi_tpg_channels_alloc(struct tegra_vi *vi)
>>> +{
>>> + struct tegra_vi_channel *chan, *tmp;
>>> + unsigned int port_num;
>>> + unsigned int nchannels = vi->soc->vi_max_channels;
>>> + int ret = 0;
>>> +
>>> + for (port_num = 0; port_num < nchannels; port_num++) {
>>> + /*
>>> + * Do not use devm_kzalloc as memory is freed immediately
>>> + * when device instance is unbound but application
>>> might still
>>> + * be holding the device node open. Channel memory
>>> allocated
>>> + * with kzalloc is freed during video device release
>>> callback.
>>> + */
>>> + chan = kzalloc(sizeof(*chan), GFP_KERNEL);
>> Why anyone would want to unbind this driver in practice?
>>
>> I think it should make more sense to set suppress_bind_attrs=true.
>
> From the previous feedback of patch series, we need to support
> unbind/bind and looks like this driver should also support to built as a
> module.
If module unloading is also affected, then perhaps you should use
get/put_device() to not allow freeing the resources until they're still
in-use.
I suppose that it should be up to the V4L core to keep the device alive
while needed, rather than to put the burden to the individual drivers.
