[PATCH 1/2] input: pagasus_notetaker: fix deadlock in autosuspend

[Marcus Folkesson]

usb_autopm_get_interface() that is called in pegasus_open() does an
autoresume if the device is suspended.

input_dev->mutex used in pegasus_resume() is in this case already
taken by the input subsystem and will cause a deadlock.

Signed-off-by: Marcus Folkesson <marcus.folkes...@gmail.com>
---
 drivers/input/tablet/pegasus_notetaker.c | 25 +++++++++++++++++++------
 1 file changed, 19 insertions(+), 6 deletions(-)

diff --git a/drivers/input/tablet/pegasus_notetaker.c 
b/drivers/input/tablet/pegasus_notetaker.c
index 47de5a81172f..9ab1ed5e20e7 100644
--- a/drivers/input/tablet/pegasus_notetaker.c
+++ b/drivers/input/tablet/pegasus_notetaker.c
@@ -41,6 +41,7 @@
 #include <linux/usb/input.h>
 #include <linux/slab.h>
 #include <linux/workqueue.h>
+#include <linux/mutex.h>
 
 /* USB HID defines */
 #define USB_REQ_GET_REPORT             0x01
@@ -76,6 +77,10 @@ struct pegasus {
        struct usb_device *usbdev;
        struct usb_interface *intf;
        struct urb *irq;
+
+       /* serialize access to open/suspend */
+       struct mutex pm_mutex;
+
        char name[128];
        char phys[64];
        struct work_struct init;
@@ -216,6 +221,7 @@ static int pegasus_open(struct input_dev *dev)
        if (error)
                return error;
 
+       mutex_lock(&pegasus->pm_mutex);
        pegasus->irq->dev = pegasus->usbdev;
        if (usb_submit_urb(pegasus->irq, GFP_KERNEL)) {
                error = -EIO;
@@ -226,12 +232,14 @@ static int pegasus_open(struct input_dev *dev)
        if (error)
                goto err_kill_urb;
 
+       mutex_unlock(&pegasus->pm_mutex);
        return 0;
 
 err_kill_urb:
        usb_kill_urb(pegasus->irq);
        cancel_work_sync(&pegasus->init);
 err_autopm_put:
+       mutex_unlock(&pegasus->pm_mutex);
        usb_autopm_put_interface(pegasus->intf);
        return error;
 }
@@ -240,8 +248,11 @@ static void pegasus_close(struct input_dev *dev)
 {
        struct pegasus *pegasus = input_get_drvdata(dev);
 
+       mutex_lock(&pegasus->pm_mutex);
        usb_kill_urb(pegasus->irq);
        cancel_work_sync(&pegasus->init);
+       mutex_unlock(&pegasus->pm_mutex);
+
        usb_autopm_put_interface(pegasus->intf);
 }
 
@@ -274,6 +285,8 @@ static int pegasus_probe(struct usb_interface *intf,
                goto err_free_mem;
        }
 
+       mutex_init(&pegasus->pm_mutex);
+
        pegasus->usbdev = dev;
        pegasus->dev = input_dev;
        pegasus->intf = intf;
@@ -388,10 +401,10 @@ static int pegasus_suspend(struct usb_interface *intf, 
pm_message_t message)
 {
        struct pegasus *pegasus = usb_get_intfdata(intf);
 
-       mutex_lock(&pegasus->dev->mutex);
+       mutex_lock(&pegasus->pm_mutex);
        usb_kill_urb(pegasus->irq);
        cancel_work_sync(&pegasus->init);
-       mutex_unlock(&pegasus->dev->mutex);
+       mutex_unlock(&pegasus->pm_mutex);
 
        return 0;
 }
@@ -401,10 +414,10 @@ static int pegasus_resume(struct usb_interface *intf)
        struct pegasus *pegasus = usb_get_intfdata(intf);
        int retval = 0;
 
-       mutex_lock(&pegasus->dev->mutex);
+       mutex_lock(&pegasus->pm_mutex);
        if (pegasus->dev->users && usb_submit_urb(pegasus->irq, GFP_NOIO) < 0)
                retval = -EIO;
-       mutex_unlock(&pegasus->dev->mutex);
+       mutex_unlock(&pegasus->pm_mutex);
 
        return retval;
 }
@@ -414,14 +427,14 @@ static int pegasus_reset_resume(struct usb_interface 
*intf)
        struct pegasus *pegasus = usb_get_intfdata(intf);
        int retval = 0;
 
-       mutex_lock(&pegasus->dev->mutex);
+       mutex_lock(&pegasus->pm_mutex);
        if (pegasus->dev->users) {
                retval = pegasus_set_mode(pegasus, PEN_MODE_XY,
                                          NOTETAKER_LED_MOUSE);
                if (!retval && usb_submit_urb(pegasus->irq, GFP_NOIO) < 0)
                        retval = -EIO;
        }
-       mutex_unlock(&pegasus->dev->mutex);
+       mutex_unlock(&pegasus->pm_mutex);
 
        return retval;
 }
-- 
2.15.1