[PATCH v3 4/8] sparc64: stop IRQ setup when descriptor allocation fails

[Magnus Lindholm <linmag7@gmail.com>]

irq_alloc() returns zero on failure, but build_irq() then configures
IRQ 0, which is reserved for the timer, as a device interrupt.

Halt before publishing the IRQ or changing its descriptor, matching the
existing fatal handler-data allocation path. Returning zero would let
callers continue treating the timer IRQ as a valid device interrupt.

Signed-off-by: Magnus Lindholm <linmag7@gmail.com>
---
 arch/sparc/kernel/irq_64.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/arch/sparc/kernel/irq_64.c b/arch/sparc/kernel/irq_64.c
index 3f55c69d5f3b..4cceeba726ab 100644
--- a/arch/sparc/kernel/irq_64.c
+++ b/arch/sparc/kernel/irq_64.c
@@ -619,6 +619,10 @@ unsigned int build_irq(int inofixup, unsigned long iclr, unsigned long imap)
 	irq = bucket_get_irq(__pa(bucket));
 	if (!irq) {
 		irq = irq_alloc(0, ino);
+		if (!irq) {
+			prom_printf("IRQ: cannot allocate interrupt descriptor.\n");
+			prom_halt();
+		}
 		bucket_set_irq(__pa(bucket), irq);
 		irq_set_chip_and_handler_name(irq, &sun4u_irq,
 					      handle_fasteoi_irq, "IVEC");