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input: synaptics_usb: fix deadlock in autosuspend

PATCH New Marcus Folkesson 1 participant 2 messages Jan 20, 2018

Subsystems (2)
HID Input drivers
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Share & tools
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Marcus Folkesson

author
#0 lore raw

PATCH 1/2 input: synaptics_usb: fix deadlock in autosuspend

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 <[email protected]>
---
 drivers/input/mouse/synaptics_usb.c | 22 ++++++++++++++--------
 1 file changed, 14 insertions(+), 8 deletions(-)
drivers/input/mouse/synaptics_usb.c +14 -8
index cb7d15d826d0..2c66913cf5a2 100644
@@ -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;
 }
Signature · 1 line
2.15.1
author
#1 lore raw

PATCH 2/2 input: synaptics_usb: do not rely on input_dev->users

If the device is unused and suspended, a call to open will cause the device to autoresume through the call to usb_autopm_get_interface().

input_dev->users is already incremented by the input subsystem, therefore this expression will always be evaluated to true:

	if ((input_dev->users || (synusb->flags & SYNUSB_IO_ALWAYS)) &&
	    usb_submit_urb(synusb->urb, GFP_NOIO) < 0) {
		retval = -EIO;
	}

The same URB will then be fail when resubmitted in synusb_open().

Introduce synusb->is_open to keep track of the state instead.

Signed-off-by Marcus Folkesson <[email protected]>
---
 drivers/input/mouse/synaptics_usb.c | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)
drivers/input/mouse/synaptics_usb.c +5 -4
index 2c66913cf5a2..e2b726751220 100644
@@ -84,6 +84,7 @@ struct synusb {
 
 	/* serialize access to open/suspend */
 	struct mutex pm_mutex;
+	bool is_open;
 
 	/* input device related data structures */
 	struct input_dev *input;

@@ -266,6 +267,7 @@ static int synusb_open(struct input_dev *dev)
 	}
 
 	synusb->intf->needs_remote_wakeup = 1;
+	synusb->is_open = 1;
 
 out:
 	mutex_unlock(&synusb->pm_mutex);

@@ -283,6 +285,7 @@ static void synusb_close(struct input_dev *dev)
 	mutex_lock(&synusb->pm_mutex);
 	usb_kill_urb(synusb->urb);
 	synusb->intf->needs_remote_wakeup = 0;
+	synusb->is_open = 0;
 	mutex_unlock(&synusb->pm_mutex);
 
 	if (!autopm_error)

@@ -485,12 +488,11 @@ static int synusb_suspend(struct usb_interface *intf, pm_message_t message)
 static int synusb_resume(struct usb_interface *intf)
 {
 	struct synusb *synusb = usb_get_intfdata(intf);
-	struct input_dev *input_dev = synusb->input;
 	int retval = 0;
 
 	mutex_lock(&synusb->pm_mutex);
 
-	if ((input_dev->users || (synusb->flags & SYNUSB_IO_ALWAYS)) &&
+	if ((synusb->is_open || (synusb->flags & SYNUSB_IO_ALWAYS)) &&
 	    usb_submit_urb(synusb->urb, GFP_NOIO) < 0) {
 		retval = -EIO;
 	}

@@ -513,10 +515,9 @@ static int synusb_pre_reset(struct usb_interface *intf)
 static int synusb_post_reset(struct usb_interface *intf)
 {
 	struct synusb *synusb = usb_get_intfdata(intf);
-	struct input_dev *input_dev = synusb->input;
 	int retval = 0;
 
-	if ((input_dev->users || (synusb->flags & SYNUSB_IO_ALWAYS)) &&
+	if ((synusb->is_open || (synusb->flags & SYNUSB_IO_ALWAYS)) &&
 	    usb_submit_urb(synusb->urb, GFP_NOIO) < 0) {
 		retval = -EIO;
 	}
Signature · 1 line
2.15.1