Input: wacom - fix runtime PM related deadlock
When runtime PM is enabled by default for input devices, X hangs in
wacom open:
[<ffffffff814a00ea>] mutex_lock+0x1a/0x40
[<ffffffffa02bc94b>] wacom_resume+0x3b/0x90 [wacom]
[<ffffffff81327a32>] usb_resume_interface+0xd2/0x190
[<ffffffff81327b5d>] usb_resume_both+0x6d/0x110
[<ffffffff81327c24>] usb_runtime_resume+0x24/0x40
[<ffffffff8130a2cf>] __pm_runtime_resume+0x26f/0x450
[<ffffffff8130a23a>] __pm_runtime_resume+0x1da/0x450
[<ffffffff8130a53a>] pm_runtime_resume+0x2a/0x50
[<ffffffff81328176>] usb_autopm_get_interface+0x26/0x60
[<ffffffffa02bc626>] wacom_open+0x36/0x90 [wacom]
wacom_open() takes wacom->lock and calls usb_autopm_get_interface(),
which in turn calls wacom_resume() which tries to acquire the lock
again.
The fix is to call usb_autopm_get_interface() first, before we take
the lock.
Since we do not do usb_autopm_put_interface() until wacom_close()
is called runtime PM is effectively disabled for the driver, however
changing it now would risk regressions so the complete fix will
have to wait till the next merge window.
Reported-by: Jiri Slaby <jslaby@suse.cz>
Acked-by: Oliver Neukum <oneukum@suse.de>
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>
diff --git a/drivers/input/tablet/wacom_sys.c b/drivers/input/tablet/wacom_sys.c
index 42ba369..b35876e 100644
--- a/drivers/input/tablet/wacom_sys.c
+++ b/drivers/input/tablet/wacom_sys.c
@@ -103,27 +103,26 @@
static int wacom_open(struct input_dev *dev)
{
struct wacom *wacom = input_get_drvdata(dev);
+ int retval = 0;
+
+ if (usb_autopm_get_interface(wacom->intf) < 0)
+ return -EIO;
mutex_lock(&wacom->lock);
- wacom->irq->dev = wacom->usbdev;
-
- if (usb_autopm_get_interface(wacom->intf) < 0) {
- mutex_unlock(&wacom->lock);
- return -EIO;
- }
-
if (usb_submit_urb(wacom->irq, GFP_KERNEL)) {
- usb_autopm_put_interface(wacom->intf);
- mutex_unlock(&wacom->lock);
- return -EIO;
+ retval = -EIO;
+ goto out;
}
wacom->open = true;
wacom->intf->needs_remote_wakeup = 1;
+out:
mutex_unlock(&wacom->lock);
- return 0;
+ if (retval)
+ usb_autopm_put_interface(wacom->intf);
+ return retval;
}
static void wacom_close(struct input_dev *dev)
@@ -135,6 +134,8 @@
wacom->open = false;
wacom->intf->needs_remote_wakeup = 0;
mutex_unlock(&wacom->lock);
+
+ usb_autopm_put_interface(wacom->intf);
}
static int wacom_parse_hid(struct usb_interface *intf, struct hid_descriptor *hid_desc,