[PATCH 5/6] m68k/irq: Add empty irq_eoi callback to auto/user IRQ chips

[Kuan-Wei Chiu <visitorckw@gmail.com>]

When an irq_chip lacks an irq_eoi callback, chained_irq_enter() falls
back to invoking chip->irq_mask(). On auto_irq_chip and user_irq_chip,
this leads to a NULL pointer dereference because autovector interrupts
are masked via the CPU SR rather than dedicated mask registers.

Add a no-op m68k_irq_eoi() callback to auto_irq_chip and user_irq_chip
so chained interrupt handlers can safely attach to these chips.

Signed-off-by: Kuan-Wei Chiu <visitorckw@gmail.com>
---
 arch/m68k/kernel/ints.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/arch/m68k/kernel/ints.c b/arch/m68k/kernel/ints.c
index cf2b13488476..731d04ac95bd 100644
--- a/arch/m68k/kernel/ints.c
+++ b/arch/m68k/kernel/ints.c
@@ -33,16 +33,22 @@ extern u16 user_irqvec_fixup[];
 
 static int m68k_first_user_vec;
 
+static void m68k_irq_eoi(struct irq_data *data)
+{
+}
+
 static struct irq_chip auto_irq_chip = {
 	.name		= "auto",
 	.irq_startup	= m68k_irq_startup,
 	.irq_shutdown	= m68k_irq_shutdown,
+	.irq_eoi	= m68k_irq_eoi,
 };
 
 static struct irq_chip user_irq_chip = {
 	.name		= "user",
 	.irq_startup	= m68k_irq_startup,
 	.irq_shutdown	= m68k_irq_shutdown,
+	.irq_eoi	= m68k_irq_eoi,
 };
 
 /*
-- 
2.55.0.979.g7e5102b832-goog