powerpc/irq: Protect irq_radix_revmap_lookup against irq_free_virt

[pandora-kernel.git] / arch / powerpc / kernel / irq.c

diff --git a/arch/powerpc/kernel/irq.c b/arch/powerpc/kernel/irq.c
index ac4d291..6cb3fcd 100644 (file)
--- a/arch/powerpc/kernel/irq.c
+++ b/arch/powerpc/kernel/irq.c
@@ -893,10 +893,13 @@ unsigned int irq_radix_revmap_lookup(struct irq_host *host,
                return irq_find_mapping(host, hwirq);
 
        /*
-        * No rcu_read_lock(ing) needed, the ptr returned can't go under us
-        * as it's referencing an entry in the static irq_map table.
+        * The ptr returned references the static global irq_map.
+        * but freeing an irq can delete nodes along the path to
+        * do the lookup via call_rcu.
         */
+       rcu_read_lock();
        ptr = radix_tree_lookup(&host->revmap_data.tree, hwirq);
+       rcu_read_unlock();
 
        /*
         * If found in radix tree, then fine.