HID: core: allow concurrent registration of drivers

Detected on the Dell XPS 9365.

The laptop has 2 devices that benefit from the hid-generic auto-unbinding.
When those 2 devices are presented to the userspace, udev loads both wacom and
hid-multitouch. When this happens, the code in __hid_bus_reprobe_drivers() is
called concurrently and the second device gets reprobed twice.

An other bug in the power_supply subsystem prevent to remove the wacom driver
if it just finished its initialization, which basically kills the wacom node.

[jkosina@suse.cz: reformat changelog a bit]
Fixes c17a747 ("HID: core: rewrite the hid-generic automatic unbind")
Cc: stable@vger.kernel.org # v4.17
Tested-by: Mario Limonciello <mario.limonciello@dell.com>
Signed-off-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>

drivers/hid/hid-core.c

@@ -1949,6 +1949,8 @@ static int hid_device_probe(struct device *dev)
 	}
 	hdev->io_started = false;
 
+	clear_bit(ffs(HID_STAT_REPROBED), &hdev->status);
+
 	if (!hdev->driver) {
 		id = hid_match_device(hdev, hdrv);
 		if (id == NULL) {
@@ -2212,7 +2214,8 @@ static int __hid_bus_reprobe_drivers(struct device *dev, void *data)
 	struct hid_device *hdev = to_hid_device(dev);
 
 	if (hdev->driver == hdrv &&
-	    !hdrv->match(hdev, hid_ignore_special_drivers))
+	    !hdrv->match(hdev, hid_ignore_special_drivers) &&
+	    !test_and_set_bit(ffs(HID_STAT_REPROBED), &hdev->status))
 		return device_reprobe(dev);
 
 	return 0;

include/linux/hid.h

@@ -511,6 +511,7 @@ struct hid_output_fifo {
 #define HID_STAT_ADDED		BIT(0)
 #define HID_STAT_PARSED		BIT(1)
 #define HID_STAT_DUP_DETECTED	BIT(2)
+#define HID_STAT_REPROBED	BIT(3)
 
 struct hid_input {
 	struct list_head list;
@@ -579,7 +580,7 @@ struct hid_device {							/* device report descriptor */
 	bool battery_avoid_query;
 #endif
 
-	unsigned int status;						/* see STAT flags above */
+	unsigned long status;						/* see STAT flags above */
 	unsigned claimed;						/* Claimed by hidinput, hiddev? */
 	unsigned quirks;						/* Various quirks the device can pull on us */
 	bool io_started;						/* If IO has started */