[PATCH 05/21] base: Port driver_deferred_probe_check_state() from Linux

[Andrey Smirnov <andrew.smirnov@gmail.com>]

Port driver_deferred_probe_check_state() from Linux by adding on last
pass going through all of the deferred drivers that allows us to
declare all unresolved dependencies as missing.

Signed-off-by: Andrey Smirnov <andrew.smirnov@gmail.com>
---
 drivers/base/driver.c | 73 ++++++++++++++++++++++++++++++++-----------
 include/driver.h      |  2 ++
 2 files changed, 57 insertions(+), 18 deletions(-)

diff --git a/drivers/base/driver.c b/drivers/base/driver.c
index 1fd6bbc01..be735189a 100644
--- a/drivers/base/driver.c
+++ b/drivers/base/driver.c
@@ -46,6 +46,8 @@ EXPORT_SYMBOL(driver_list);
 static LIST_HEAD(active);
 static LIST_HEAD(deferred);
 
+static bool initcalls_done;
+
 struct device_d *get_device_by_name(const char *name)
 {
 	struct device_d *dev;
@@ -259,31 +261,66 @@ EXPORT_SYMBOL(unregister_device);
  * For devices finally left in deferred list -EPROBE_DEFER
  * becomes a fatal error.
  */
-static int device_probe_deferred(void)
+
+/**
+ * driver_deferred_probe_check_state() - Check deferred probe state
+ * @dev: device to check
+ *
+ * Returns -ENODEV if init is done and all built-in drivers have had a chance
+ * to probe (i.e. initcalls are done), -ETIMEDOUT if deferred probe debug
+ * timeout has expired, or -EPROBE_DEFER if none of those conditions are met.
+ *
+ * Drivers or subsystems can opt-in to calling this function instead of directly
+ * returning -EPROBE_DEFER.
+ */
+int driver_deferred_probe_check_state(struct device_d *dev)
+{
+	if (initcalls_done) {
+		dev_warn(dev, "ignoring dependency for device, assuming no driver");
+		return -ENODEV;
+	}
+	return -EPROBE_DEFER;
+}
+
+static bool device_probe_deferred_match_all(void)
 {
 	struct device_d *dev, *tmp;
 	struct driver_d *drv;
-	bool success;
+	bool success = false;
 
-	do {
-		success = false;
+	list_for_each_entry_safe(dev, tmp, &deferred, active) {
+		list_del(&dev->active);
+		INIT_LIST_HEAD(&dev->active);
 
-		if (list_empty(&deferred))
-			return 0;
+		dev_dbg(dev, "re-probe device\n");
+		bus_for_each_driver(dev->bus, drv) {
+			if (match(drv, dev))
+				continue;
+			success = true;
+			break;
+		}
+	}
 
-		list_for_each_entry_safe(dev, tmp, &deferred, active) {
-			list_del(&dev->active);
-			INIT_LIST_HEAD(&dev->active);
+	return success;
+}
 
-			dev_dbg(dev, "re-probe device\n");
-			bus_for_each_driver(dev->bus, drv) {
-				if (match(drv, dev))
-					continue;
-				success = true;
-				break;
-			}
-		}
-	} while (success);
+static int device_probe_deferred(void)
+{
+	struct device_d *dev;
+
+	while (device_probe_deferred_match_all())
+		;
+
+	initcalls_done = true;
+
+	if (list_empty(&deferred))
+		return 0;
+	/*
+	 * Loop over all deferred devices to give various functions
+	 * that call driver_deferred_probe_check_state() a chance to
+	 * finally return -ENODEV as opposed to -EPROBE_DEFER
+	 */
+	device_probe_deferred_match_all();
 
 	list_for_each_entry(dev, &deferred, active)
 		dev_err(dev, "probe permanently deferred\n");
diff --git a/include/driver.h b/include/driver.h
index 3d9970df5..385e410dd 100644
--- a/include/driver.h
+++ b/include/driver.h
@@ -151,6 +151,8 @@ void device_detect_all(void);
  */
 int unregister_device(struct device_d *);
 
+int driver_deferred_probe_check_state(struct device_d *dev);
+
 /* Iterate over a devices children
  */
 #define device_for_each_child(dev, child) \
-- 
2.20.1


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