Re: [PATCH v16 2/4] dmaengine: tegra: Add tegra gpcdma driver

[Dmitry Osipenko]

17.01.2022 10:02, Akhil R пишет:
>> 10.01.2022 19:05, Akhil R пишет:
>>> +static int tegra_dma_terminate_all(struct dma_chan *dc)
>>> +{
>>> +     struct tegra_dma_channel *tdc = to_tegra_dma_chan(dc);
>>> +     unsigned long flags;
>>> +     LIST_HEAD(head);
>>> +     int err;
>>> +
>>> +     if (tdc->dma_desc) {
>>
>> Needs locking protection against racing with the interrupt handler.
> tegra_dma_stop_client() waits for the in-flight transfer 
> to complete and prevents any additional transfer to start. 
> Wouldn't it manage the race? Do you see any potential issue there?

You should consider interrupt handler like a process running in a
parallel thread. The interrupt handler sets tdc->dma_desc to NULL, hence
you'll get NULL dereference in tegra_dma_stop_client().