Re: [PATCH] dma: zynqmp_dma: Initialize descriptor list after freeing during reset

Vinod Koul
2020-05-04T05:16:34Z

On 02-05-20, 15:00, Rafał Hibner wrote:
> Hello Vinod,
>
> On 02.05.2020 14:32, Vinod Koul wrote:
> > Would it not be better to use list_del_init() where we delete it rather
> > than do the init here?
> >
>
> It is not a problem of list element itself not being initialized.
> The problem is that during fault conditions (zynqmp_dma_reset) all
> elements are moved to free list. List head however is not reinitialized.
>
> In normal flow elements are removed by list_del and resubmitted to
> free list with zynqmp_dma_free_descriptor.
>
> static void zynqmp_dma_chan_desc_cleanup(struct zynqmp_dma_chan *chan)
> {
>     ...
>     list_for_each_entry_safe(desc, next, &chan->done_list, node) {
>         ...
>         list_del(&desc->node);
>         ...
>         zynqmp_dma_free_descriptor(chan, desc);
>     }
> }
>
> The zynqmp_dma_free_descriptor does not delete elements from the
> list by itself.
> I am not he author of this driver so I fixed it by
> doing non intrusive changes.
>
> Anyways, I do not see how using list_del_init would fix the bug.

Looking at this, i think it would make sense to do list_splice_init()
before we send the list to be freed.

Radhey/Appana are cced, they should test this.

--
~Vinod