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From:   Ethan Zhao <haifeng.zhao@intel.com>
To:     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,
        pei.p.jia@intel.com, Ethan Zhao <haifeng.zhao@intel.com>
Subject: [PATCH 4/5] PCI: only return true when dev io state is really changed
Date:   Thu, 24 Sep 2020 22:34:22 -0400
Message-Id: <20200925023423.42675-5-haifeng.zhao@intel.com>
In-Reply-To: <20200925023423.42675-1-haifeng.zhao@intel.com>
References: <20200925023423.42675-1-haifeng.zhao@intel.com>
Precedence: bulk

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;
 }
 
-- 
2.18.4