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.

Fixes c17a7476e4c4 ("HID: core: rewrite the hid-generic automatic unbind")

Cc: sta...@vger.kernel.org # v4.17
Signed-off-by: Benjamin Tissoires <benjamin.tissoi...@redhat.com>
---

Hi Mario,

can you please test this on your faulty XPS?
I think it'll fix the issue, but I can not reproduce, so better wait for
your confirmation.

Jiri, ideally I would love to see this in v4.17 final, but Mario seems
to be on PTO until next week. I guess we'll just push this in v4.17.1
then. Also, if you can double check that it makes sense, that would be
nice :)

Cheers,
Benjamin

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

diff --git a/drivers/hid/hid-core.c b/drivers/hid/hid-core.c
index 2f7367b1de00..7afed0c0f9e5 100644
--- a/drivers/hid/hid-core.c
+++ b/drivers/hid/hid-core.c
@@ -1960,6 +1960,8 @@ 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) {
@@ -2223,7 +2225,8 @@ 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;
diff --git a/include/linux/hid.h b/include/linux/hid.h
index ee2510019033..aee281522c6d 100644
--- a/include/linux/hid.h
+++ b/include/linux/hid.h
@@ -517,6 +517,7 @@ 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;
@@ -585,7 +586,7 @@ 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 */
-- 
2.14.3

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