[PATCH] genirq/msi: Do not use pci_msi_[un]mask_irq as default methods

[Marc Zyngier]

When we create a generic MSI domain, that MSI_FLAG_USE_DEF_CHIP_OPS
is set, and that any of .mask or .unmask are NULL in the irq_chip
structure, we set them to pci_msi_[un]mask_irq.

This is a bad idea for at least two reasons:
- PCI_MSI might not be selected, kernel fails to build (yes, this is
  legitimate, at least on arm64!)
- This may not be a PCI/MSI domain at all (platform MSI, for example)

Either way, this looks wrong. Move the overriding of mask/unmask to
the PCI counterpart, and panic is any of these two methods is not
set in the core code (they really should be present).

Signed-off-by: Marc Zyngier <marc.zyngier@xxxxxxx>
---
 drivers/pci/msi.c | 4 ++++
 kernel/irq/msi.c  | 6 +-----
 2 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/drivers/pci/msi.c b/drivers/pci/msi.c
index d449714..4a7da3c 100644
--- a/drivers/pci/msi.c
+++ b/drivers/pci/msi.c
@@ -1243,6 +1243,10 @@ static void pci_msi_domain_update_chip_ops(struct msi_domain_info *info)
 	BUG_ON(!chip);
 	if (!chip->irq_write_msi_msg)
 		chip->irq_write_msi_msg = pci_msi_domain_write_msg;
+	if (!chip->irq_mask)
+		chip->irq_mask = pci_msi_mask_irq;
+	if (!chip->irq_unmask)
+		chip->irq_unmask = pci_msi_unmask_irq;
 }
 
 /**
diff --git a/kernel/irq/msi.c b/kernel/irq/msi.c
index 7e6512b..be9149f 100644
--- a/kernel/irq/msi.c
+++ b/kernel/irq/msi.c
@@ -228,11 +228,7 @@ static void msi_domain_update_chip_ops(struct msi_domain_info *info)
 {
 	struct irq_chip *chip = info->chip;
 
-	BUG_ON(!chip);
-	if (!chip->irq_mask)
-		chip->irq_mask = pci_msi_mask_irq;
-	if (!chip->irq_unmask)
-		chip->irq_unmask = pci_msi_unmask_irq;
+	BUG_ON(!chip || !chip->irq_mask || !chip->irq_unmask);
 	if (!chip->irq_set_affinity)
 		chip->irq_set_affinity = msi_domain_set_affinity;
 }
-- 
2.1.4

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