[RESEND PATCH 3/6] input: pagasus_notetaker: fix deadlock in autosuspend

Marcus Folkesson
2018-02-28T13:38:20Z

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

input_dev->mutex used in pegasus_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/tablet/pegasus_notetaker.c | 25 +++++++++++++++++++------
1 file changed, 19 insertions(+), 6 deletions(-)

diff --git a/drivers/input/tablet/pegasus_notetaker.c b/drivers/input/tablet/pegasus_notetaker.c
index 47de5a81172f..9ab1ed5e20e7 100644
--- a/drivers/input/tablet/pegasus_notetaker.c
+++ b/drivers/input/tablet/pegasus_notetaker.c
@@ -41,6 +41,7 @@
#include <linux/usb/input.h>
#include <linux/slab.h>
#include <linux/workqueue.h>
+#include <linux/mutex.h>

/* USB HID defines */
#define USB_REQ_GET_REPORT 0x01
@@ -76,6 +77,10 @@ struct pegasus {
struct usb_device *usbdev;
struct usb_interface *intf;
struct urb *irq;
+
+ /* serialize access to open/suspend */
+ struct mutex pm_mutex;
+
char name[128];
char phys[64];
struct work_struct init;
@@ -216,6 +221,7 @@ static int pegasus_open(struct input_dev *dev)
if (error)
return error;

+ mutex_lock(&pegasus->pm_mutex);
pegasus->irq->dev = pegasus->usbdev;
if (usb_submit_urb(pegasus->irq, GFP_KERNEL)) {
error = -EIO;
@@ -226,12 +232,14 @@ static int pegasus_open(struct input_dev *dev)
if (error)
goto err_kill_urb;

+ mutex_unlock(&pegasus->pm_mutex);
return 0;

err_kill_urb:
usb_kill_urb(pegasus->irq);
cancel_work_sync(&pegasus->init);
err_autopm_put:
+ mutex_unlock(&pegasus->pm_mutex);
usb_autopm_put_interface(pegasus->intf);
return error;
}
@@ -240,8 +248,11 @@ static void pegasus_close(struct input_dev *dev)
{
struct pegasus *pegasus = input_get_drvdata(dev);

+ mutex_lock(&pegasus->pm_mutex);
usb_kill_urb(pegasus->irq);
cancel_work_sync(&pegasus->init);
+ mutex_unlock(&pegasus->pm_mutex);
+
usb_autopm_put_interface(pegasus->intf);
}

@@ -274,6 +285,8 @@ static int pegasus_probe(struct usb_interface *intf,
goto err_free_mem;
}

+ mutex_init(&pegasus->pm_mutex);
+
pegasus->usbdev = dev;
pegasus->dev = input_dev;
pegasus->intf = intf;
@@ -388,10 +401,10 @@ static int pegasus_suspend(struct usb_interface *intf, pm_message_t message)
{
struct pegasus *pegasus = usb_get_intfdata(intf);

- mutex_lock(&pegasus->dev->mutex);
+ mutex_lock(&pegasus->pm_mutex);
usb_kill_urb(pegasus->irq);
cancel_work_sync(&pegasus->init);
- mutex_unlock(&pegasus->dev->mutex);
+ mutex_unlock(&pegasus->pm_mutex);

return 0;
}
@@ -401,10 +414,10 @@ static int pegasus_resume(struct usb_interface *intf)
struct pegasus *pegasus = usb_get_intfdata(intf);
int retval = 0;

- mutex_lock(&pegasus->dev->mutex);
+ mutex_lock(&pegasus->pm_mutex);
if (pegasus->dev->users && usb_submit_urb(pegasus->irq, GFP_NOIO) < 0)
retval = -EIO;
- mutex_unlock(&pegasus->dev->mutex);
+ mutex_unlock(&pegasus->pm_mutex);

return retval;
}
@@ -414,14 +427,14 @@ static int pegasus_reset_resume(struct usb_interface *intf)
struct pegasus *pegasus = usb_get_intfdata(intf);
int retval = 0;

- mutex_lock(&pegasus->dev->mutex);
+ mutex_lock(&pegasus->pm_mutex);
if (pegasus->dev->users) {
retval = pegasus_set_mode(pegasus, PEN_MODE_XY,
NOTETAKER_LED_MOUSE);
if (!retval && usb_submit_urb(pegasus->irq, GFP_NOIO) < 0)
retval = -EIO;
}
- mutex_unlock(&pegasus->dev->mutex);
+ mutex_unlock(&pegasus->pm_mutex);

return retval;
}
--
2.16.2