Re: [qemu] boot failed: Unable to handle kernel NULL pointer dereference at virtual address 0000000000000000

[Vinod Koul <vkoul@kernel.org>]

On 06-07-20, 07:33, Dave Jiang wrote:

> > I don't see anything suspicious in dmaengine drivers, but there is a
> > recent series
> > from Dave Jiang that might explain it. Could you try reverting  commit
> > deb9541f5052 ("dmaengine: check device and channel list for empty")?
> > 
> > I think the broken change is this one:
> > 
> > @@ -819,6 +850,11 @@ struct dma_chan *dma_request_chan(struct device
> > *dev, const char *name)
> > 
> >          /* Try to find the channel via the DMA filter map(s) */
> >          mutex_lock(&dma_list_mutex);
> > +       if (list_empty(&dma_device_list)) {
> > +               mutex_unlock(&dma_list_mutex);
> > +               return NULL;
> > +       }
> > +
> >          list_for_each_entry_safe(d, _d, &dma_device_list, global_node) {
> >                  dma_cap_mask_t mask;
> >                  const struct dma_slave_map *map = dma_filter_match(d,
> > name, dev);
> > 
> > which needs to return an error code like -ENODEV instead of NULL. There
> > may be other changes in the same patch that introduce the same bug
> > elsewhere.
> > 
> >       Arnd
> > 
> 
> Vinod,
> Do you want a diff fix or a revision of the patch for the fix?

Diff fix please

-- 
~Vinod