PCI: xgene-msi: Fix race in installing chained irq handler

Fix a race where a pending interrupt could be received and the handler
called before the handler's data has been setup, by converting to
irq_set_chained_handler_and_data().

See also 2cf5a03cb29d ("PCI/keystone: Fix race in installing chained IRQ
handler").

Based on the mail discussion, it seems ok to drop the error handling.

Link: https://lore.kernel.org/r/20210115212435.19940-3-martin@kaiser.cx
Signed-off-by: Martin Kaiser <martin@kaiser.cx>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>

diff --git a/drivers/pci/controller/pci-xgene-msi.c b/drivers/pci/controller/pci-xgene-msi.c
index 2470782..1c34c89 100644 (file)
--- a/drivers/pci/controller/pci-xgene-msi.c
+++ b/drivers/pci/controller/pci-xgene-msi.c
@@ -384,13 +384,9 @@ static int xgene_msi_hwirq_alloc(unsigned int cpu)
                if (!msi_group->gic_irq)
                        continue;
 
-               irq_set_chained_handler(msi_group->gic_irq,
-                                       xgene_msi_isr);
-               err = irq_set_handler_data(msi_group->gic_irq, msi_group);
-               if (err) {
-                       pr_err("failed to register GIC IRQ handler\n");
-                       return -EINVAL;
-               }
+               irq_set_chained_handler_and_data(msi_group->gic_irq,
+                       xgene_msi_isr, msi_group);
+
                /*
                 * Statically allocate MSI GIC IRQs to each CPU core.
                 * With 8-core X-Gene v1, 2 MSI GIC IRQs are allocated