+static int default_affinity_read(char *page, char **start, off_t off,
+ int count, int *eof, void *data)
+{
+ int len = cpumask_scnprintf(page, count, irq_default_affinity);
+ if (count - len < 2)
+ return -EINVAL;
+ len += sprintf(page + len, "\n");
+ return len;
+}
+
+static int default_affinity_write(struct file *file, const char __user *buffer,
+ unsigned long count, void *data)
+{
+ unsigned int full_count = count, err;
+ cpumask_t new_value;
+
+ err = cpumask_parse_user(buffer, count, new_value);
+ if (err)
+ return err;
+
+ if (!is_affinity_mask_valid(new_value))
+ return -EINVAL;
+
+ /*
+ * Do not allow disabling IRQs completely - it's a too easy
+ * way to make the system unusable accidentally :-) At least
+ * one online CPU still has to be targeted.
+ */
+ if (!cpus_intersects(new_value, cpu_online_map))
+ return -EINVAL;
+
+ irq_default_affinity = new_value;
+
+ return full_count;
+}