linux-kernel - [PATCH 4.17 44/56] HID: core: allow concurrent registration of drivers

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Date:   Tue, 10 Jul 2018 20:25:26 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org,
        Mario Limonciello <mario.limonciello@...l.com>,
        Benjamin Tissoires <benjamin.tissoires@...hat.com>,
        Jiri Kosina <jkosina@...e.cz>
Subject: [PATCH 4.17 44/56] HID: core: allow concurrent registration of drivers

4.17-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Benjamin Tissoires <benjamin.tissoires@...hat.com>

commit 8f732850df1b2b4d8d719f7e606dfb3050e7ea11 upstream.

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@...e.cz: reformat changelog a bit]
Fixes c17a7476e4c4 ("HID: core: rewrite the hid-generic automatic unbind")
Cc: stable@...r.kernel.org # v4.17
Tested-by: Mario Limonciello <mario.limonciello@...l.com>
Signed-off-by: Benjamin Tissoires <benjamin.tissoires@...hat.com>
Signed-off-by: Jiri Kosina <jkosina@...e.cz>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 drivers/hid/hid-core.c |    5 ++++-
 include/linux/hid.h    |    3 ++-
 2 files changed, 6 insertions(+), 2 deletions(-)

--- a/drivers/hid/hid-core.c
+++ b/drivers/hid/hid-core.c
@@ -1942,6 +1942,8 @@ static int hid_device_probe(struct devic
 	}
 	hdev->io_started = false;
 
+	clear_bit(ffs(HID_STAT_REPROBED), &hdev->status);
+
 	if (!hdev->driver) {
 		id = hid_match_device(hdev, hdrv);
 		if (id == NULL) {
@@ -2205,7 +2207,8 @@ static int __hid_bus_reprobe_drivers(str
 	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;
--- a/include/linux/hid.h
+++ b/include/linux/hid.h
@@ -502,6 +502,7 @@ struct hid_output_fifo {
 
 #define HID_STAT_ADDED		BIT(0)
 #define HID_STAT_PARSED		BIT(1)
+#define HID_STAT_REPROBED	BIT(3)
 
 struct hid_input {
 	struct list_head list;
@@ -568,7 +569,7 @@ struct hid_device {							/* device repo
 	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 */