[PATCH] PCI/MSI: Don't try to mask/unmask an MSI that doesn't have an msi_desc

[Marc Zyngier]

There are a lot of MSI drivers out there that preallocate their
interrupts but not the corresponding MSIs. That's a prettty
naughty behaviour. On a kexec crash, we try to shut down all
the interrupts by calling the disable/mask methods.

On these drivers, pci_msi_mask_irq() is unconditionnaly called,
leading to a crash. You wanted a crash kernel, right?

So let's paper over the issue for the time being by detecting
the NULL msi_desc in msi_set_mask_bit(). Eventually, these drivers
will have to be fixed...

Signed-off-by: Marc Zyngier <marc.zyngier@xxxxxxx>
---
 drivers/pci/msi.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/pci/msi.c b/drivers/pci/msi.c
index e06607167858..a5042cc8f3fc 100644
--- a/drivers/pci/msi.c
+++ b/drivers/pci/msi.c
@@ -227,6 +227,9 @@ static void msi_set_mask_bit(struct irq_data *data, u32 flag)
 {
 	struct msi_desc *desc = irq_data_get_msi_desc(data);
 
+	if (WARN_ONCE(!desc, "NULL MSI descriptor!"))
+		return;
+
 	if (desc->msi_attrib.is_msix) {
 		msix_mask_irq(desc, flag);
 		readl(desc->mask_base);		/* Flush write to device */
-- 
2.14.2


Thanks,

	M.
-- 
Jazz is not dead. It just smells funny...