Re: [RESEND PATCH 1/6] input: synaptics_usb: fix deadlock in autosuspend

Dmitry Torokhov
2018-03-17T18:10:52Z

On Wed, Feb 28, 2018 at 02:37:58PM +0100, Marcus Folkesson wrote:
> 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.folkesson@gmail.com>

Applied, thank you.

> ---
> 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;
> }
> --
> 2.16.2
>

--
Dmitry