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

Alex G.
2020-09-25T13:56:33Z

Hi Ethan,

On 9/24/20 9:34 PM, 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.
> 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.
>
> Signed-off-by: Ethan Zhao <haifeng.zhao@intel.com>
> Tested-by: Wen jin <wen.jin@intel.com>
> Tested-by: Shanshan Zhang <ShanshanX.Zhang@intel.com>
> ---
> drivers/pci/pci.h | 31 +++----------------------------
> 1 file changed, 3 insertions(+), 28 deletions(-)
>
> diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h
> index fa12f7cbc1a0..d420bb977f3b 100644
> --- a/drivers/pci/pci.h
> +++ b/drivers/pci/pci.h
> @@ -362,35 +362,10 @@ static inline bool pci_dev_set_io_state(struct pci_dev *dev,
> bool changed = false;
>
> device_lock_assert(&dev->dev);
> - switch (new) {
> - case pci_channel_io_perm_failure:
> - switch (dev->error_state) {
> - case pci_channel_io_frozen:
> - case pci_channel_io_normal:
> - case pci_channel_io_perm_failure:
> - changed = true;
> - break;
> - }
> - break;
> - case pci_channel_io_frozen:
> - switch (dev->error_state) {
> - case pci_channel_io_frozen:
> - case pci_channel_io_normal:
> - changed = true;
> - break;
> - }
> - break;
> - case pci_channel_io_normal:
> - switch (dev->error_state) {
> - case pci_channel_io_frozen:
> - case pci_channel_io_normal:
> - changed = true;
> - break;
> - }
> - break;
> - }
> - if (changed)
> + if (dev->error_state != new) {
> dev->error_state = new;
> + changed = true;
> + }
> return changed;
> }

The flow is a lot easier to follow now. Thank you.

Reviewed-by: Alexandru Gagniuc <mr.nuke.me@gmail.com>