Input: usbtouchscreen - fix deadlock in autosuspend

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

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

Signed-off-by: Marcus Folkesson <marcus.folkesson@gmail.com>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

diff --git a/drivers/input/touchscreen/usbtouchscreen.c b/drivers/input/touchscreen/usbtouchscreen.c
index aa77d24..d15a7e2 100644 (file)
--- a/drivers/input/touchscreen/usbtouchscreen.c
+++ b/drivers/input/touchscreen/usbtouchscreen.c
@@ -54,6 +54,7 @@
 #include <linux/usb.h>
 #include <linux/usb/input.h>
 #include <linux/hid.h>
+#include <linux/mutex.h>
 
 static bool swap_xy;
 module_param(swap_xy, bool, 0644);
@@ -107,6 +108,7 @@ struct usbtouch_usb {
        struct usb_interface *interface;
        struct input_dev *input;
        struct usbtouch_device_info *type;
+       struct mutex pm_mutex;  /* serialize access to open/suspend */
        char name[128];
        char phys[64];
        void *priv;
@@ -1450,6 +1452,7 @@ static int usbtouch_open(struct input_dev *input)
        if (r < 0)
                goto out;
 
+       mutex_lock(&usbtouch->pm_mutex);
        if (!usbtouch->type->irq_always) {
                if (usb_submit_urb(usbtouch->irq, GFP_KERNEL)) {
                        r = -EIO;
@@ -1459,6 +1462,7 @@ static int usbtouch_open(struct input_dev *input)
 
        usbtouch->interface->needs_remote_wakeup = 1;
 out_put:
+       mutex_unlock(&usbtouch->pm_mutex);
        usb_autopm_put_interface(usbtouch->interface);
 out:
        return r;
@@ -1469,8 +1473,11 @@ static void usbtouch_close(struct input_dev *input)
        struct usbtouch_usb *usbtouch = input_get_drvdata(input);
        int r;
 
+       mutex_lock(&usbtouch->pm_mutex);
        if (!usbtouch->type->irq_always)
                usb_kill_urb(usbtouch->irq);
+       mutex_unlock(&usbtouch->pm_mutex);
+
        r = usb_autopm_get_interface(usbtouch->interface);
        usbtouch->interface->needs_remote_wakeup = 0;
        if (!r)
@@ -1493,10 +1500,10 @@ static int usbtouch_resume(struct usb_interface *intf)
        struct input_dev *input = usbtouch->input;
        int result = 0;
 
-       mutex_lock(&input->mutex);
+       mutex_lock(&usbtouch->pm_mutex);
        if (input->users || usbtouch->type->irq_always)
                result = usb_submit_urb(usbtouch->irq, GFP_NOIO);
-       mutex_unlock(&input->mutex);
+       mutex_unlock(&usbtouch->pm_mutex);
 
        return result;
 }
@@ -1519,10 +1526,10 @@ static int usbtouch_reset_resume(struct usb_interface *intf)
        }
 
        /* restart IO if needed */
-       mutex_lock(&input->mutex);
+       mutex_lock(&usbtouch->pm_mutex);
        if (input->users)
                err = usb_submit_urb(usbtouch->irq, GFP_NOIO);
-       mutex_unlock(&input->mutex);
+       mutex_unlock(&usbtouch->pm_mutex);
 
        return err;
 }