[PATCH] PCI: plda: Synchronize chained IRQs during deinitialization

[Ali Tariq <alitariq45892@gmail.com>]

During driver unbind or probe failure teardown,
plda_pcie_irq_domain_deinit() unlinks the chained interrupt
handlers for the main, MSI, and INTx interrupts using
irq_set_chained_handler_and_data(). However, this function
only updates the handler pointers and does not wait for any
in-flight interrupt handlers running on other CPUs to finish.

If a PCIe interrupt fires concurrently with the teardown
process, the handler could continue running on another CPU.
If the hardware clocks are disabled shortly after in
host_deinit(), the executing handler will attempt to read
un-clocked PCIe registers, triggering a fatal system bus
fault (external abort) or kernel panic.

Add synchronize_irq() after clearing each chained handler to
guarantee that any executing handlers have fully completed
before proceeding with interrupt domain removal and hardware
deinitialization.

Fixes: 76c911396807 ("PCI: plda: Add host init/deinit and map bus functions")
Signed-off-by: Ali Tariq <alitariq45892@gmail.com>
---
 drivers/pci/controller/plda/pcie-plda-host.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/pci/controller/plda/pcie-plda-host.c b/drivers/pci/controller/plda/pcie-plda-host.c
index f9a34f323ad8..f6759e255c75 100644
--- a/drivers/pci/controller/plda/pcie-plda-host.c
+++ b/drivers/pci/controller/plda/pcie-plda-host.c
@@ -560,8 +560,13 @@ EXPORT_SYMBOL_GPL(plda_pcie_setup_iomems);
 static void plda_pcie_irq_domain_deinit(struct plda_pcie_rp *pcie)
 {
 	irq_set_chained_handler_and_data(pcie->irq, NULL, NULL);
+	synchronize_irq(pcie->irq);
+
 	irq_set_chained_handler_and_data(pcie->msi_irq, NULL, NULL);
+	synchronize_irq(pcie->msi_irq);
+
 	irq_set_chained_handler_and_data(pcie->intx_irq, NULL, NULL);
+	synchronize_irq(pcie->intx_irq);
 
 	irq_domain_remove(pcie->msi.dev_domain);
 
-- 
2.34.1