[M/N] [PATCH] wifi: iwlwifi: pcie: rescan bus if no parent

[Kai-Heng Feng]

From: Johannes Berg <johannes.berg at intel.com>

BugLink: https://bugs.launchpad.net/bugs/2046217

If the bus has no parent due to the topology, the device rescan
(after some kind of reset was detected) wouldn't work. On the
other hand, some platforms appear to require scanning the parent,
though it's not clear why.

However if there's no parent, then we skip the rescan, which isn't a
good idea. Change the code to go to the parent only if that exists,
and rescan the bus itself where it doesn't.

Signed-off-by: Johannes Berg <johannes.berg at intel.com>
Signed-off-by: Gregory Greenman <gregory.greenman at intel.com>
Link: https://lore.kernel.org/r/20230913145231.f7795a1ccdab.I2b84810a743469a1bcabf3628262cf54311593f4@changeid
Signed-off-by: Johannes Berg <johannes.berg at intel.com>
(cherry picked from commit 111ed1eb175754a9ef11811240329ca40db2072f)
Signed-off-by: Kai-Heng Feng <kai.heng.feng at canonical.com>
---
 drivers/net/wireless/intel/iwlwifi/pcie/trans.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/drivers/net/wireless/intel/iwlwifi/pcie/trans.c b/drivers/net/wireless/intel/iwlwifi/pcie/trans.c
index 583d1011963e..86f6cb5af691 100644
--- a/drivers/net/wireless/intel/iwlwifi/pcie/trans.c
+++ b/drivers/net/wireless/intel/iwlwifi/pcie/trans.c
@@ -2113,8 +2113,11 @@ static void iwl_trans_pcie_removal_wk(struct work_struct *wk)
 	pci_lock_rescan_remove();
 	pci_dev_put(pdev);
 	pci_stop_and_remove_bus_device(pdev);
-	if (removal->rescan)
-		pci_rescan_bus(bus->parent);
+	if (removal->rescan && bus) {
+		if (bus->parent)
+			bus = bus->parent;
+		pci_rescan_bus(bus);
+	}
 	pci_unlock_rescan_remove();
 
 	kfree(removal);
-- 
2.34.1