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

Marcus Folkesson
2018-02-28T13:38:18Z

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>
---
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