}
EXPORT_SYMBOL_GPL(pm_runtime_autosuspend_expiration);
+static int dev_memalloc_noio(struct device *dev, void *data)
+{
+ return dev->power.memalloc_noio;
+}
+
+/*
+ * pm_runtime_set_memalloc_noio - Set a device's memalloc_noio flag.
+ * @dev: Device to handle.
+ * @enable: True for setting the flag and False for clearing the flag.
+ *
+ * Set the flag for all devices in the path from the device to the
+ * root device in the device tree if @enable is true, otherwise clear
+ * the flag for devices in the path whose siblings don't set the flag.
+ *
+ * The function should only be called by block device, or network
+ * device driver for solving the deadlock problem during runtime
+ * resume/suspend:
+ *
+ * If memory allocation with GFP_KERNEL is called inside runtime
+ * resume/suspend callback of any one of its ancestors(or the
+ * block device itself), the deadlock may be triggered inside the
+ * memory allocation since it might not complete until the block
+ * device becomes active and the involed page I/O finishes. The
+ * situation is pointed out first by Alan Stern. Network device
+ * are involved in iSCSI kind of situation.
+ *
+ * The lock of dev_hotplug_mutex is held in the function for handling
+ * hotplug race because pm_runtime_set_memalloc_noio() may be called
+ * in async probe().
+ *
+ * The function should be called between device_add() and device_del()
+ * on the affected device(block/network device).
+ */
+void pm_runtime_set_memalloc_noio(struct device *dev, bool enable)
+{
+ static DEFINE_MUTEX(dev_hotplug_mutex);
+
+ mutex_lock(&dev_hotplug_mutex);
+ for (;;) {
+ bool enabled;
+
+ /* hold power lock since bitfield is not SMP-safe. */
+ spin_lock_irq(&dev->power.lock);
+ enabled = dev->power.memalloc_noio;
+ dev->power.memalloc_noio = enable;
+ spin_unlock_irq(&dev->power.lock);
+
+ /*
+ * not need to enable ancestors any more if the device
+ * has been enabled.
+ */
+ if (enabled && enable)
+ break;
+
+ dev = dev->parent;
+
+ /*
+ * clear flag of the parent device only if all the
+ * children don't set the flag because ancestor's
+ * flag was set by any one of the descendants.
+ */
+ if (!dev || (!enable &&
+ device_for_each_child(dev, NULL,
+ dev_memalloc_noio)))
+ break;
+ }
+ mutex_unlock(&dev_hotplug_mutex);
+}
+EXPORT_SYMBOL_GPL(pm_runtime_set_memalloc_noio);
+
/**
* rpm_check_suspend_allowed - Test whether a device may be suspended.
* @dev: Device to test.
if (!cb)
return -ENOSYS;
- retval = __rpm_callback(cb, dev);
+ if (dev->power.memalloc_noio) {
+ unsigned int noio_flag;
+
+ /*
+ * Deadlock might be caused if memory allocation with
+ * GFP_KERNEL happens inside runtime_suspend and
+ * runtime_resume callbacks of one block device's
+ * ancestor or the block device itself. Network
+ * device might be thought as part of iSCSI block
+ * device, so network device and its ancestor should
+ * be marked as memalloc_noio too.
+ */
+ noio_flag = memalloc_noio_save();
+ retval = __rpm_callback(cb, dev);
+ memalloc_noio_restore(noio_flag);
+ } else {
+ retval = __rpm_callback(cb, dev);
+ }
dev->power.runtime_error = retval;
return retval != -EACCES ? retval : -EIO;