Hi Gustavo, [...] > > This "pcim_iomap_table(dev)[n]" pattern is extremely common. There > > are over 100 calls of pcim_iomap_table(), and > > > > $ git grep "pcim_iomap_table(.*)\[.*\]" | wc -l > > > > says about 75 of them are of this form, where we dereference the > > result before testing it. > > That's true, there are a lot of drivers that don't verify that pointer. > What do you suggest? > 1) To remove the verification so that is aligned with the other drivers > 2) Leave it as is. Or even to add this verification to the other drivers? > > Either way, I will add the pcim_iomap_table(pdev) before this > instruction. [...] A lot of the drivers consume the value from pcim_iomap_table() at a given BAR index directly as-is, some check if the pointer they got back is not NULL, a very few also check if the address at a given index is not NULL. Given that the memory allocation for the table can fail, we ought to check for a NULL pointer. It's a bit worrying that people decided to consume the value it returns directly without any verification. I only found two drivers that perform this additional verification of checking whether the address at a given index is valid, as per: https://lore.kernel.org/linux-pci/YCLFTjZQ2bCfGC+J@rocinante/ Personally, I would opt for (2), and then like you suggested send a separate series to update other drivers so that they also include the this NULL pointer check. But let's wait for Bjorn's take on this, though. Krzysztof
