On Wed, Apr 10, 2019 at 10:44:03AM +0100, Robin Murphy wrote:
> Hi Dan,
>
> On 10/04/2019 10:34, Dan Carpenter wrote:
> > Hello Jean-Philippe Brucker,
> >
> > This is a semi-automatic email about new static checker warnings.
> >
> > The patch fac83d29d954: "iommu/io-pgtable-arm: Fix pgtable allocation
> > in selftest" from Jun 18, 2018, leads to the following Smatch
> > complaint:
> >
> > drivers/iommu/io-pgtable-arm.c:246 __arm_lpae_alloc_pages()
> > error: we previously assumed 'dev' could be null (see line 239)
> >
> > drivers/iommu/io-pgtable-arm.c
> > 238 VM_BUG_ON((gfp & __GFP_HIGHMEM));
> > 239 p = alloc_pages_node(dev ? dev_to_node(dev) :
> > NUMA_NO_NODE,
> > ^^^
> > We added a NULL check here
> >
> > 240 gfp | __GFP_ZERO, order);
> > 241 if (!p)
> > 242 return NULL;
> > 243
> > 244 pages = page_address(p);
> > 245 if (!(cfg->quirks & IO_PGTABLE_QUIRK_NO_DMA)) {
>
> The selftests *should* always set this quirk such that they never get to the
> DMA mapping calls (that was one of the reasons for implementing things that
> way) - I guess that might be a bit too sneaky for Smatch, but I can take a
> look to double-check that the flow is working correctly such that this
> really is a false-positive.
Ah, thanks.
I have a plan for fixing these false positives caused by not tracking
bit masks. It's not that complicated to fix, it just takes time to
write the code.
regards,
dan carpenter
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