[PATCH v2] irqdomain: potential Oops in irq_domain_push_irq()

[Dan Carpenter]

This code generates a Smatch warning:

    kernel/irq/irqdomain.c:1511 irq_domain_push_irq()
    warn: variable dereferenced before check 'root_irq_data' (see line 1508)

irq_get_irq_data() does sometimes return NULL pointers so it does look
like this code could Oops.  I've moved the check for NULL earlier to
fix this bug.

Signed-off-by: Dan Carpenter <dan.carpen...@oracle.com>
---
v2: redo the commit message

diff --git a/kernel/irq/irqdomain.c b/kernel/irq/irqdomain.c
index b9c688944429..e84b7056bb08 100644
--- a/kernel/irq/irqdomain.c
+++ b/kernel/irq/irqdomain.c
@@ -1505,10 +1505,10 @@ int irq_domain_push_irq(struct irq_domain *domain, int 
virq, void *arg)
        if (WARN_ON(!irq_domain_is_hierarchy(domain)))
                return -EINVAL;
 
-       if (domain->parent != root_irq_data->domain)
+       if (!root_irq_data)
                return -EINVAL;
 
-       if (!root_irq_data)
+       if (domain->parent != root_irq_data->domain)
                return -EINVAL;
 
        child_irq_data = kzalloc_node(sizeof(*child_irq_data), GFP_KERNEL,