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SubjectRe: [PATCH 4/5 V4] PCI: only return true when dev io state is really changed
On Mon, Sep 28, 2020 at 7:13 AM Ethan Zhao <haifeng.zhao@intel.com> 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.
>

This one looks good (more or less) now.
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>

> 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>
> Reviewed-by: Alexandru Gagniuc <mr.nuke.me@gmail.com>
> ---
> Changnes:
> V2: revise description and code according to suggestion from Andy.
> V3: change code to simpler.
> V4: no change.
> V5: no change.
>
> drivers/pci/pci.h | 37 +++++--------------------------------
> 1 file changed, 5 insertions(+), 32 deletions(-)
>
> diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h
> index fa12f7cbc1a0..a2c1c7d5f494 100644
> --- a/drivers/pci/pci.h
> +++ b/drivers/pci/pci.h
> @@ -359,39 +359,12 @@ struct pci_sriov {
> static inline bool pci_dev_set_io_state(struct pci_dev *dev,
> pci_channel_state_t new)
> {
> - 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)
> - dev->error_state = new;
> - return changed;
> + if (dev->error_state == new)
> + return false;
> +
> + dev->error_state = new;
> + return true;
> }
>
> static inline int pci_dev_set_disconnected(struct pci_dev *dev, void *unused)
> --
> 2.18.4
>


--
With Best Regards,
Andy Shevchenko

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