Re: [PATCH 4/5] PCI: only return true when dev io state is really changed

Andy Shevchenko
2020-09-25T16:40:35Z

On Thu, Sep 24, 2020 at 10:34:22PM -0400, Ethan Zhao wrote:
> When uncorrectable error happens, AER driver and DPC driver interrupt
> handlers likely call
> pcie_do_recovery()->pci_walk_bus()->report_frozen_detected() with
> pci_channel_io_frozen the same time.

Call chains are better to read if they split like

foo() ->
bar() ->
baz()

> If pci_dev_set_io_state() return true even if the original state is
> pci_channel_io_frozen, that will cause AER or DPC handler re-enter
> the error detecting and recovery procedure one after another.
> The result is the recovery flow mixed between AER and DPC.
> So simplify the pci_dev_set_io_state() function to only return true
> when dev->error_state is changed.

...

> + if (dev->error_state != new) {
> dev->error_state = new;
> + changed = true;
> + }
> return changed;

Perhaps
if (dev->error_state == new)
return changed;

dev->error_state = new;
return true;

?