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