4 files changed, 68 insertions, 0 deletions

diff --git a/include/linux/interrupt.h b/include/linux/interrupt.h
index e6d2f4441fda..5137db3317f9 100644
--- a/include/linux/interrupt.h
+++ b/include/linux/interrupt.h
@@ -233,6 +233,7 @@ extern int irq_set_affinity(unsigned int irq, const struct cpumask *cpumask);
 extern int irq_can_set_affinity(unsigned int irq);
 extern int irq_select_affinity(unsigned int irq);
 
+extern int irq_set_affinity_hint(unsigned int irq, const struct cpumask *m);
 #else /* CONFIG_SMP */
 
 static inline int irq_set_affinity(unsigned int irq, const struct cpumask *m)
@@ -247,6 +248,11 @@ static inline int irq_can_set_affinity(unsigned int irq)
 
 static inline int irq_select_affinity(unsigned int irq)  { return 0; }
 
+static inline int irq_set_affinity_hint(unsigned int irq,
+                                        const struct cpumask *m)
+{
+        return -EINVAL;
+}
 #endif /* CONFIG_SMP && CONFIG_GENERIC_HARDIRQS */
 
 #ifdef CONFIG_GENERIC_HARDIRQS
diff --git a/include/linux/irq.h b/include/linux/irq.h
index 707ab122e2e6..c03243ad84b4 100644
--- a/include/linux/irq.h
+++ b/include/linux/irq.h
@@ -195,6 +195,7 @@ struct irq_desc {
         raw_spinlock_t          lock;
 #ifdef CONFIG_SMP
         cpumask_var_t           affinity;
+        const struct cpumask    *affinity_hint;
         unsigned int            node;
 #ifdef CONFIG_GENERIC_PENDING_IRQ
         cpumask_var_t           pending_mask;
diff --git a/kernel/irq/manage.c b/kernel/irq/manage.c
index 444d5a81a209..3164ba7ce151 100644
--- a/kernel/irq/manage.c
+++ b/kernel/irq/manage.c
@@ -138,6 +138,22 @@ int irq_set_affinity(unsigned int irq, const struct cpumask *cpumask)
         return 0;
 }
 
+int irq_set_affinity_hint(unsigned int irq, const struct cpumask *m)
+{
+        struct irq_desc *desc = irq_to_desc(irq);
+        unsigned long flags;
+
+        if (!desc)
+                return -EINVAL;
+
+        raw_spin_lock_irqsave(&desc->lock, flags);
+        desc->affinity_hint = m;
+        raw_spin_unlock_irqrestore(&desc->lock, flags);
+
+        return 0;
+}
+EXPORT_SYMBOL_GPL(irq_set_affinity_hint);
+
 #ifndef CONFIG_AUTO_IRQ_AFFINITY
 /*
  * Generic version of the affinity autoselector.
@@ -906,6 +922,12 @@ static struct irqaction *__free_irq(unsigned int irq, void *dev_id)
                         desc->chip->disable(irq);
         }
 
+#ifdef CONFIG_SMP
+        /* make sure affinity_hint is cleaned up */
+        if (WARN_ON_ONCE(desc->affinity_hint))
+                desc->affinity_hint = NULL;
+#endif
+
         raw_spin_unlock_irqrestore(&desc->lock, flags);
 
         unregister_handler_proc(irq, action);
diff --git a/kernel/irq/proc.c b/kernel/irq/proc.c
index fe92dc5190dd..4f9427a30e14 100644
--- a/kernel/irq/proc.c
+++ b/kernel/irq/proc.c
@@ -32,6 +32,29 @@ static int irq_affinity_proc_show(struct seq_file *m, void *v)
         return 0;
 }
 
+static int irq_affinity_hint_proc_show(struct seq_file *m, void *v)
+{
+        struct irq_desc *desc = irq_to_desc((long)m->private);
+        unsigned long flags;
+        cpumask_var_t mask;
+
+        if (!alloc_cpumask_var(&mask, GFP_KERNEL))
+                return -ENOMEM;
+
+        raw_spin_lock_irqsave(&desc->lock, flags);
+        if (desc->affinity_hint)
+                cpumask_copy(mask, desc->affinity_hint);
+        else
+                cpumask_setall(mask);
+        raw_spin_unlock_irqrestore(&desc->lock, flags);
+
+        seq_cpumask(m, mask);
+        seq_putc(m, '\n');
+        free_cpumask_var(mask);
+
+        return 0;
+}
+
 #ifndef is_affinity_mask_valid
 #define is_affinity_mask_valid(val) 1
 #endif
@@ -84,6 +107,11 @@ static int irq_affinity_proc_open(struct inode *inode, struct file *file)
         return single_open(file, irq_affinity_proc_show, PDE(inode)->data);
 }
 
+static int irq_affinity_hint_proc_open(struct inode *inode, struct file *file)
+{
+        return single_open(file, irq_affinity_hint_proc_show, PDE(inode)->data);
+}
+
 static const struct file_operations irq_affinity_proc_fops = {
         .open           = irq_affinity_proc_open,
         .read           = seq_read,
@@ -92,6 +120,13 @@ static const struct file_operations irq_affinity_proc_fops = {
         .write          = irq_affinity_proc_write,
 };
 
+static const struct file_operations irq_affinity_hint_proc_fops = {
+        .open           = irq_affinity_hint_proc_open,
+        .read           = seq_read,
+        .llseek         = seq_lseek,
+        .release        = single_release,
+};
+
 static int default_affinity_show(struct seq_file *m, void *v)
 {
         seq_cpumask(m, irq_default_affinity);
@@ -252,6 +287,10 @@ void register_irq_proc(unsigned int irq, struct irq_desc *desc)
         proc_create_data("smp_affinity", 0600, desc->dir,
                          &irq_affinity_proc_fops, (void *)(long)irq);
 
+        /* create /proc/irq/<irq>/affinity_hint */
+        proc_create_data("affinity_hint", 0400, desc->dir,
+                         &irq_affinity_hint_proc_fops, (void *)(long)irq);
+
         proc_create_data("node", 0444, desc->dir,
                          &irq_node_proc_fops, (void *)(long)irq);
 #endif