[PATCH 4.20 19/88] genirq: Make sure the initial affinity is not empty

[Greg Kroah-Hartman]

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

------------------

[ Upstream commit bddda606ec76550dd63592e32a6e87e7d32583f7 ]

If all CPUs in the irq_default_affinity mask are offline when an interrupt
is initialized then irq_setup_affinity() can set an empty affinity mask for
a newly allocated interrupt.

Fix this by falling back to cpu_online_mask in case the resulting affinity
mask is zero.

Signed-off-by: Srinivas Ramana <sramana@xxxxxxxxxxxxxx>
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: linux-arm-msm@xxxxxxxxxxxxxxx
Link: https://lkml.kernel.org/r/1545312957-8504-1-git-send-email-sramana@xxxxxxxxxxxxxx
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 kernel/irq/manage.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/kernel/irq/manage.c b/kernel/irq/manage.c
index 9dbdccab3b6a3..5c0ba5ca59308 100644
--- a/kernel/irq/manage.c
+++ b/kernel/irq/manage.c
@@ -393,6 +393,9 @@ int irq_setup_affinity(struct irq_desc *desc)
 	}
 
 	cpumask_and(&mask, cpu_online_mask, set);
+	if (cpumask_empty(&mask))
+		cpumask_copy(&mask, cpu_online_mask);
+
 	if (node != NUMA_NO_NODE) {
 		const struct cpumask *nodemask = cpumask_of_node(node);
 
-- 
2.19.1