From f6cd378372bff06093d72f978c0150eeed3ea201 Mon Sep 17 00:00:00 2001 From: Dmitry Torokhov Date: Mon, 4 Oct 2010 21:46:11 -0700 Subject: [PATCH] Input: wacom - fix runtime PM related deadlock When runtime PM is enabled by default for input devices, X hangs in wacom open: [] mutex_lock+0x1a/0x40 [] wacom_resume+0x3b/0x90 [wacom] [] usb_resume_interface+0xd2/0x190 [] usb_resume_both+0x6d/0x110 [] usb_runtime_resume+0x24/0x40 [] __pm_runtime_resume+0x26f/0x450 [] __pm_runtime_resume+0x1da/0x450 [] pm_runtime_resume+0x2a/0x50 [] usb_autopm_get_interface+0x26/0x60 [] 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 Acked-by: Oliver Neukum Signed-off-by: Dmitry Torokhov --- drivers/input/tablet/wacom_sys.c | 23 ++++++++++++----------- 1 file changed, 12 insertions(+), 11 deletions(-) diff --git a/drivers/input/tablet/wacom_sys.c b/drivers/input/tablet/wacom_sys.c index 42ba3691d90..b35876ee690 100644 --- a/drivers/input/tablet/wacom_sys.c +++ b/drivers/input/tablet/wacom_sys.c @@ -103,27 +103,26 @@ static void wacom_sys_irq(struct urb *urb) static int wacom_open(struct input_dev *dev) { struct wacom *wacom = input_get_drvdata(dev); + int retval = 0; - mutex_lock(&wacom->lock); - - wacom->irq->dev = wacom->usbdev; - - if (usb_autopm_get_interface(wacom->intf) < 0) { - mutex_unlock(&wacom->lock); + if (usb_autopm_get_interface(wacom->intf) < 0) return -EIO; - } + + mutex_lock(&wacom->lock); 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 @@ static void wacom_close(struct input_dev *dev) 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, -- 2.39.2