diff mbox series

[4/5,V2] PCI: only return true when dev io state is really changed

Message ID 20200927032829.11321-5-haifeng.zhao@intel.com
State New
Headers show
Series Fix DPC hotplug race and enhance error handling | expand

Commit Message

Ethan Zhao Sept. 27, 2020, 3:28 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: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Alexandru Gagniuc <mr.nuke.me@gmail.com>
---
Changes:
 V2: revise doc and code flow according to Andy's suggestion.
 drivers/pci/pci.h | 34 +++++-----------------------------
 1 file changed, 5 insertions(+), 29 deletions(-)

Comments

Joe Perches Sept. 27, 2020, 4:16 a.m. UTC | #1
On Sat, 2020-09-26 at 23:28 -0400, Ethan Zhao wrote:
> simplify the pci_dev_set_io_state() function to only return true
> when dev->error_state is changed.
[]
> diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h
[]
> @@ -362,35 +362,11 @@ static inline bool pci_dev_set_io_state(struct pci_dev *dev,
>  	bool changed = false;
[]
> +	if (dev->error_state == new)
> +		return changed;
> +
> +	dev->error_state = new;
> +	changed = true;
>  	return changed;
>  }

This would be simpler removing the unnecessary
changed automatic

...

	if (dev->error_state == new)
		return false;

	dev->error_state = new;

	return true;
}
Ethan Zhao Sept. 27, 2020, 5:12 a.m. UTC | #2
😊  definitely simpler !

-----Original Message-----
From: Joe Perches <joe@perches.com> 
Sent: Sunday, September 27, 2020 12:17 PM
To: Zhao, Haifeng <haifeng.zhao@intel.com>; bhelgaas@google.com; oohall@gmail.com; ruscur@russell.cc; lukas@wunner.de; andriy.shevchenko@linux.intel.com; stuart.w.hayes@gmail.com; mr.nuke.me@gmail.com; mika.westerberg@linux.intel.com
Cc: linux-pci@vger.kernel.org; linux-kernel@vger.kernel.org; Jia, Pei P <pei.p.jia@intel.com>; ashok.raj@linux.intel.com; Kuppuswamy, Sathyanarayanan <sathyanarayanan.kuppuswamy@intel.com>
Subject: Re: [PATCH 4/5 V2] PCI: only return true when dev io state is really changed

On Sat, 2020-09-26 at 23:28 -0400, Ethan Zhao wrote:
> simplify the pci_dev_set_io_state() function to only return true when 
> dev->error_state is changed.
[]
> diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h
[]
> @@ -362,35 +362,11 @@ static inline bool pci_dev_set_io_state(struct pci_dev *dev,
>  	bool changed = false;
[]
> +	if (dev->error_state == new)
> +		return changed;
> +
> +	dev->error_state = new;
> +	changed = true;
>  	return changed;
>  }

This would be simpler removing the unnecessary changed automatic

...

	if (dev->error_state == new)
		return false;

	dev->error_state = new;

	return true;
}
diff mbox series

Patch

diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h
index fa12f7cbc1a0..387f891ce6a1 100644
--- a/drivers/pci/pci.h
+++ b/drivers/pci/pci.h
@@ -362,35 +362,11 @@  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)
-		dev->error_state = new;
+	if (dev->error_state == new)
+		return changed;
+
+	dev->error_state = new;
+	changed = true;
 	return changed;
 }