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

Marcus Folkesson
2018-02-28T13:38:23Z

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>
---
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