[PATCH 4.4 099/163] x86/apic: Handle zero vector gracefully in clear_vector_irq()

From: Greg Kroah-Hartman
Date: Mon May 02 2016 - 20:24:15 EST

4.4-stable review patch. If anyone has any objections, please let me know.


From: Keith Busch <keith.busch@xxxxxxxxx>

commit 1bdb8970392a68489b469c3a330a1adb5ef61beb upstream.

If x86_vector_alloc_irq() fails x86_vector_free_irqs() is invoked to cleanup
the already allocated vectors. This subsequently calls clear_vector_irq().

The failed irq has no vector assigned, which triggers the BUG_ON(!vector) in

We cannot suppress the call to x86_vector_free_irqs() for the failed
interrupt, because the other data related to this irq must be cleaned up as
well. So calling clear_vector_irq() with vector == 0 is legitimate.

Remove the BUG_ON and return if vector is zero,

[ tglx: Massaged changelog ]

Fixes: b5dc8e6c21e7 "x86/irq: Use hierarchical irqdomain to manage CPU interrupt vectors"
Signed-off-by: Keith Busch <keith.busch@xxxxxxxxx>
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

arch/x86/kernel/apic/vector.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

--- a/arch/x86/kernel/apic/vector.c
+++ b/arch/x86/kernel/apic/vector.c
@@ -254,7 +254,8 @@ static void clear_irq_vector(int irq, st
struct irq_desc *desc;
int cpu, vector;

- BUG_ON(!data->cfg.vector);
+ if (!data->cfg.vector)
+ return;

vector = data->cfg.vector;
for_each_cpu_and(cpu, data->domain, cpu_online_mask)