On 10/20/2018 07:19 PM, Bjorn Helgaas wrote:
On Fri, Oct 19, 2018 at 03:21:05PM +0200, Jean Delvare wrote:
Later in this function, pm is dereferenced again. It happens twice in
the "if (error)" condition where it is currently safe (error can't be
non-zero if pm->runtime_suspend() has not been called, and obviously
pm->runtime_suspend() can't have been called if pm was NULL). However
it also happens later without the condition:
if (!pci_dev->state_saved && pci_dev->current_state != PCI_D0
&& pci_dev->current_state != PCI_UNKNOWN) {
WARN_ONCE(pci_dev->current_state != prev,
"PCI PM: State of device not saved by %pF\n",
pm->runtime_suspend);
return 0;
}
I am no expert of the PM framework but is there no risk to dereference
NULL at this point? Or even if pm is non-NULL, pm->runtime_suspend may
be NULL, leading to a confusing warning message?
Thanks for spotting this! I don't have any excuse why I was so
completely blind.
More generally, I would feel better if instead of initializing error to
0, we would move under the "if (pm && pm->runtime_suspend)" condition
everything that must not be run if pm->runtime_suspend is not defined.
That would make the possible code flows a lot clearer.
I agree, this isn't good. Even if it's safe (and I don't think that
second spot is safe), it's too hard to analyze. I'm going to drop
this for now.
Thanks. I'll cook a better version.
--
Jarkko
