On Fri, Mar 12, 2021 at 02:11:03PM -0800, Kuppuswamy, Sathyanarayanan wrote:
> On 3/12/21 1:33 PM, Bjorn Helgaas wrote:
> > On Mon, Mar 08, 2021 at 10:34:10PM -0800,
> > sathyanarayanan.kuppusw...@linux.intel.com wrote:
> > > From: Kuppuswamy Sathyanarayanan
> > > <sathyanarayanan.kuppusw...@linux.intel.com>
> > > +bool is_dpc_reset_active(struct pci_dev *dev)
> > > +{
> > > + struct pci_host_bridge *host = pci_find_host_bridge(dev->bus);
> > > + u16 status;
> > > +
> > > + if (!dev->dpc_cap)
> > > + return false;
> > > +
> > > + /*
> > > + * If DPC is owned by firmware and EDR is not supported, there is
> > > + * no race between hotplug and DPC recovery handler. So return
> > > + * false.
> > > + */
> > > + if (!host->native_dpc && !IS_ENABLED(CONFIG_PCIE_EDR))
> > > + return false;
> > > +
> > > + if (atomic_read_acquire(&dev->dpc_reset_active))
> > > + return true;
> > > +
> > > + pci_read_config_word(dev, dev->dpc_cap + PCI_EXP_DPC_STATUS, &status);
> > > +
> > > + return !!(status & PCI_EXP_DPC_STATUS_TRIGGER);
> >
> > I know it's somewhat common in drivers/pci/, but I'm not really a
> > big fan of "!!".
> I can change it to use ternary operator.
> (status & PCI_EXP_DPC_STATUS_TRIGGER) ? true : false;
Ternary isn't terrible, but what's wrong with:
if (status & PCI_EXP_DPC_STATUS_TRIGGER)
return true;
return false;
which matches the style of the rest of the function.
Looking at this again, we return "true" if either dpc_reset_active or
PCI_EXP_DPC_STATUS_TRIGGER. I haven't worked this all out, but that
pattern feels racy. I guess the thought is that if
PCI_EXP_DPC_STATUS_TRIGGER is set, dpc_reset_link() will be invoked
soon and we don't want to interfere?
