diff mbox series

[4/5,V4] PCI: only return true when dev io state is really changed

Message ID 20200928040651.24937-5-haifeng.zhao@intel.com
State New
Headers show
Series Fix DPC hotplug race and enhance error handling | expand

Commit Message

Ethan Zhao Sept. 28, 2020, 4:06 a.m. UTC
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>
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(-)

Comments

Andy Shevchenko Sept. 28, 2020, 8:46 a.m. UTC | #1
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
>
diff mbox series

Patch

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)