3 files changed, 66 insertions, 1 deletions

diff --git a/drivers/base/base.h b/drivers/base/base.h
index 1782f3aa386e..e05db388bd1c 100644
--- a/drivers/base/base.h
+++ b/drivers/base/base.h
@@ -131,6 +131,8 @@ extern void device_remove_groups(struct device *dev,
 extern char *make_class_name(const char *name, struct kobject *kobj);
 
 extern int devres_release_all(struct device *dev);
+extern void device_block_probing(void);
+extern void device_unblock_probing(void);
 
 /* /sys/devices directory */
 extern struct kset *devices_kset;
diff --git a/drivers/base/dd.c b/drivers/base/dd.c
index a641cf3ccad6..b605f734b882 100644
--- a/drivers/base/dd.c
+++ b/drivers/base/dd.c
@@ -55,6 +55,13 @@ static struct workqueue_struct *deferred_wq;
 static atomic_t deferred_trigger_count = ATOMIC_INIT(0);
 
 /*
+ * In some cases, like suspend to RAM or hibernation, It might be reasonable
+ * to prohibit probing of devices as it could be unsafe.
+ * Once defer_all_probes is true all drivers probes will be forcibly deferred.
+ */
+static bool defer_all_probes;
+
+/*
  * deferred_probe_work_func() - Retry probing devices in the active list.
  */
 static void deferred_probe_work_func(struct work_struct *work)
@@ -172,6 +179,30 @@ static void driver_deferred_probe_trigger(void)
 }
 
 /**
+ * device_block_probing() - Block/defere device's probes
+ *
+ *      It will disable probing of devices and defer their probes instead.
+ */
+void device_block_probing(void)
+{
+        defer_all_probes = true;
+        /* sync with probes to avoid races. */
+        wait_for_device_probe();
+}
+
+/**
+ * device_unblock_probing() - Unblock/enable device's probes
+ *
+ *      It will restore normal behavior and trigger re-probing of deferred
+ * devices.
+ */
+void device_unblock_probing(void)
+{
+        defer_all_probes = false;
+        driver_deferred_probe_trigger();
+}
+
+/**
  * deferred_probe_initcall() - Enable probing of deferred devices
  *
  * We don't want to get in the way when the bulk of drivers are getting probed.
@@ -277,9 +308,20 @@ static DECLARE_WAIT_QUEUE_HEAD(probe_waitqueue);
 
 static int really_probe(struct device *dev, struct device_driver *drv)
 {
-        int ret = 0;
+        int ret = -EPROBE_DEFER;
         int local_trigger_count = atomic_read(&deferred_trigger_count);
 
+        if (defer_all_probes) {
+                /*
+                 * Value of defer_all_probes can be set only by
+                 * device_defer_all_probes_enable() which, in turn, will call
+                 * wait_for_device_probe() right after that to avoid any races.
+                 */
+                dev_dbg(dev, "Driver %s force probe deferral\n", drv->name);
+                driver_deferred_probe_add(dev);
+                return ret;
+        }
+
         atomic_inc(&probe_count);
         pr_debug("bus: '%s': %s: probing driver %s with device %s\n",
                  drv->bus->name, __func__, drv->name, dev_name(dev));
@@ -393,6 +435,10 @@ int driver_probe_done(void)
  */
 void wait_for_device_probe(void)
 {
+        /* wait for the deferred probe workqueue to finish */
+        if (driver_deferred_probe_enable)
+                flush_workqueue(deferred_wq);
+
         /* wait for the known devices to complete their probing */
         wait_event(probe_waitqueue, atomic_read(&probe_count) == 0);
         async_synchronize_full();
diff --git a/drivers/base/power/main.c b/drivers/base/power/main.c
index 1710c26ba097..9d626ac08d9c 100644
--- a/drivers/base/power/main.c
+++ b/drivers/base/power/main.c
@@ -963,6 +963,9 @@ void dpm_complete(pm_message_t state)
         }
         list_splice(&list, &dpm_list);
         mutex_unlock(&dpm_list_mtx);
+
+        /* Allow device probing and trigger re-probing of deferred devices */
+        device_unblock_probing();
         trace_suspend_resume(TPS("dpm_complete"), state.event, false);
 }
 
@@ -1624,6 +1627,20 @@ int dpm_prepare(pm_message_t state)
         trace_suspend_resume(TPS("dpm_prepare"), state.event, true);
         might_sleep();
 
+        /*
+         * Give a chance for the known devices to complete their probes, before
+         * disable probing of devices. This sync point is important at least
+         * at boot time + hibernation restore.
+         */
+        wait_for_device_probe();
+        /*
+         * It is unsafe if probing of devices will happen during suspend or
+         * hibernation and system behavior will be unpredictable in this case.
+         * So, let's prohibit device's probing here and defer their probes
+         * instead. The normal behavior will be restored in dpm_complete().
+         */
+        device_block_probing();
+
         mutex_lock(&dpm_list_mtx);
         while (!list_empty(&dpm_list)) {
                 struct device *dev = to_device(dpm_list.next);