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

[Marcus Folkesson]

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

input_dev->mutex used in synusb_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/mouse/synaptics_usb.c | 22 ++++++++++++++--------
 1 file changed, 14 insertions(+), 8 deletions(-)

diff --git a/drivers/input/mouse/synaptics_usb.c 
b/drivers/input/mouse/synaptics_usb.c
index cb7d15d826d0..2c66913cf5a2 100644
--- a/drivers/input/mouse/synaptics_usb.c
+++ b/drivers/input/mouse/synaptics_usb.c
@@ -82,6 +82,9 @@ struct synusb {
        struct urb *urb;
        unsigned char *data;
 
+       /* serialize access to open/suspend */
+       struct mutex pm_mutex;
+
        /* input device related data structures */
        struct input_dev *input;
        char name[128];
@@ -252,6 +255,7 @@ static int synusb_open(struct input_dev *dev)
                return retval;
        }
 
+       mutex_lock(&synusb->pm_mutex);
        retval = usb_submit_urb(synusb->urb, GFP_KERNEL);
        if (retval) {
                dev_err(&synusb->intf->dev,
@@ -264,6 +268,7 @@ static int synusb_open(struct input_dev *dev)
        synusb->intf->needs_remote_wakeup = 1;
 
 out:
+       mutex_unlock(&synusb->pm_mutex);
        usb_autopm_put_interface(synusb->intf);
        return retval;
 }
@@ -275,8 +280,10 @@ static void synusb_close(struct input_dev *dev)
 
        autopm_error = usb_autopm_get_interface(synusb->intf);
 
+       mutex_lock(&synusb->pm_mutex);
        usb_kill_urb(synusb->urb);
        synusb->intf->needs_remote_wakeup = 0;
+       mutex_unlock(&synusb->pm_mutex);
 
        if (!autopm_error)
                usb_autopm_put_interface(synusb->intf);
@@ -315,6 +322,7 @@ static int synusb_probe(struct usb_interface *intf,
        synusb->udev = udev;
        synusb->intf = intf;
        synusb->input = input_dev;
+       mutex_init(&synusb->pm_mutex);
 
        synusb->flags = id->driver_info;
        if (synusb->flags & SYNUSB_COMBO) {
@@ -466,11 +474,10 @@ static void synusb_disconnect(struct usb_interface *intf)
 static int synusb_suspend(struct usb_interface *intf, pm_message_t message)
 {
        struct synusb *synusb = usb_get_intfdata(intf);
-       struct input_dev *input_dev = synusb->input;
 
-       mutex_lock(&input_dev->mutex);
+       mutex_lock(&synusb->pm_mutex);
        usb_kill_urb(synusb->urb);
-       mutex_unlock(&input_dev->mutex);
+       mutex_unlock(&synusb->pm_mutex);
 
        return 0;
 }
@@ -481,14 +488,14 @@ static int synusb_resume(struct usb_interface *intf)
        struct input_dev *input_dev = synusb->input;
        int retval = 0;
 
-       mutex_lock(&input_dev->mutex);
+       mutex_lock(&synusb->pm_mutex);
 
        if ((input_dev->users || (synusb->flags & SYNUSB_IO_ALWAYS)) &&
            usb_submit_urb(synusb->urb, GFP_NOIO) < 0) {
                retval = -EIO;
        }
 
-       mutex_unlock(&input_dev->mutex);
+       mutex_unlock(&synusb->pm_mutex);
 
        return retval;
 }
@@ -496,9 +503,8 @@ static int synusb_resume(struct usb_interface *intf)
 static int synusb_pre_reset(struct usb_interface *intf)
 {
        struct synusb *synusb = usb_get_intfdata(intf);
-       struct input_dev *input_dev = synusb->input;
 
-       mutex_lock(&input_dev->mutex);
+       mutex_lock(&synusb->pm_mutex);
        usb_kill_urb(synusb->urb);
 
        return 0;
@@ -515,7 +521,7 @@ static int synusb_post_reset(struct usb_interface *intf)
                retval = -EIO;
        }
 
-       mutex_unlock(&input_dev->mutex);
+       mutex_unlock(&synusb->pm_mutex);
 
        return retval;
 }
-- 
2.15.1