Re: [RESEND PATCH 5/6] input: usbtouchscreen: fix deadlock in autosuspend

Dmitry Torokhov
2018-03-17T18:11:21Z

On Wed, Feb 28, 2018 at 02:38:02PM +0100, Marcus Folkesson wrote:
> 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>

Applied, thank you.

> ---
> drivers/input/touchscreen/usbtouchscreen.c | 15 +++++++++++----
> 1 file changed, 11 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/input/touchscreen/usbtouchscreen.c b/drivers/input/touchscreen/usbtouchscreen.c
> index 2c41107240de..e964658203d8 100644
> --- 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>
>
>
> #define DRIVER_VERSION "v0.6"
> @@ -112,6 +113,7 @@ 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;
> @@ -1455,6 +1457,7 @@ 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;
> @@ -1464,6 +1467,7 @@ 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;
> @@ -1474,8 +1478,11 @@ 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_lock(&usbtouch->pm_mutex);
> +
> r = usb_autopm_get_interface(usbtouch->interface);
> usbtouch->interface->needs_remote_wakeup = 0;
> if (!r)
> @@ -1498,10 +1505,10 @@ 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;
> }
> @@ -1524,10 +1531,10 @@ 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;
> }
> --
> 2.16.2
>

--
Dmitry