1 files changed, 21 insertions, 2 deletions

diff --git a/kernel/irq/manage.c b/kernel/irq/manage.c
index 1cbd572f6ad8..35c70c9e24d8 100644
--- a/kernel/irq/manage.c
+++ b/kernel/irq/manage.c
@@ -732,6 +732,7 @@ static void
 irq_thread_check_affinity(struct irq_desc *desc, struct irqaction *action)
 {
         cpumask_var_t mask;
+        bool valid = true;
 
         if (!test_and_clear_bit(IRQTF_AFFINITY, &action->thread_flags))
                 return;
@@ -746,10 +747,18 @@ irq_thread_check_affinity(struct irq_desc *desc, struct irqaction *action)
         }
 
         raw_spin_lock_irq(&desc->lock);
-        cpumask_copy(mask, desc->irq_data.affinity);
+        /*
+         * This code is triggered unconditionally. Check the affinity
+         * mask pointer. For CPU_MASK_OFFSTACK=n this is optimized out.
+         */
+        if (desc->irq_data.affinity)
+                cpumask_copy(mask, desc->irq_data.affinity);
+        else
+                valid = false;
         raw_spin_unlock_irq(&desc->lock);
 
-        set_cpus_allowed_ptr(current, mask);
+        if (valid)
+                set_cpus_allowed_ptr(current, mask);
         free_cpumask_var(mask);
 }
 #else
@@ -954,6 +963,16 @@ __setup_irq(unsigned int irq, struct irq_desc *desc, struct irqaction *new)
                  */
                 get_task_struct(t);
                 new->thread = t;
+                /*
+                 * Tell the thread to set its affinity. This is
+                 * important for shared interrupt handlers as we do
+                 * not invoke setup_affinity() for the secondary
+                 * handlers as everything is already set up. Even for
+                 * interrupts marked with IRQF_NO_BALANCE this is
+                 * correct as we want the thread to move to the cpu(s)
+                 * on which the requesting code placed the interrupt.
+                 */
+                set_bit(IRQTF_AFFINITY, &new->thread_flags);
         }
 
         if (!alloc_cpumask_var(&mask, GFP_KERNEL)) {