linux-kernel - [PATCH 2/2] input: usbtouchscreen: do not rely on input

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Message-Id: <20180124154713.28962-2-marcus.folkesson@gmail.com>
Date:   Wed, 24 Jan 2018 16:47:13 +0100
From:   Marcus Folkesson <marcus.folkesson@...il.com>
To:     Dmitry Torokhov <dmitry.torokhov@...il.com>
Cc:     Marcus Folkesson <marcus.folkesson@...il.com>,
        linux-input@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH 2/2] input: usbtouchscreen: 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->users || usbtouch->type->irq_always)
		result = usb_submit_urb(usbtouch->irq, GFP_NOIO);

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

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

Signed-off-by: Marcus Folkesson <marcus.folkesson@...il.com>
---
 drivers/input/touchscreen/usbtouchscreen.c | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/drivers/input/touchscreen/usbtouchscreen.c b/drivers/input/touchscreen/usbtouchscreen.c
index e964658203d8..0356ad792e40 100644
--- a/drivers/input/touchscreen/usbtouchscreen.c
+++ b/drivers/input/touchscreen/usbtouchscreen.c
@@ -114,6 +114,7 @@ struct usbtouch_usb {
 	struct input_dev *input;
 	struct usbtouch_device_info *type;
 	struct mutex pm_mutex;  /* serialize access to open/suspend */
+	bool is_open;
 	char name[128];
 	char phys[64];
 	void *priv;
@@ -1466,6 +1467,7 @@ static int usbtouch_open(struct input_dev *input)
 	}
 
 	usbtouch->interface->needs_remote_wakeup = 1;
+	usbtouch->is_open = 1;
 out_put:
 	mutex_unlock(&usbtouch->pm_mutex);
 	usb_autopm_put_interface(usbtouch->interface);
@@ -1481,6 +1483,7 @@ static void usbtouch_close(struct input_dev *input)
 	mutex_lock(&usbtouch->pm_mutex);
 	if (!usbtouch->type->irq_always)
 		usb_kill_urb(usbtouch->irq);
+	usbtouch->is_open = 0;
 	mutex_lock(&usbtouch->pm_mutex);
 
 	r = usb_autopm_get_interface(usbtouch->interface);
@@ -1502,11 +1505,10 @@ static int usbtouch_suspend
 static int usbtouch_resume(struct usb_interface *intf)
 {
 	struct usbtouch_usb *usbtouch = usb_get_intfdata(intf);
-	struct input_dev *input = usbtouch->input;
 	int result = 0;
 
 	mutex_lock(&usbtouch->pm_mutex);
-	if (input->users || usbtouch->type->irq_always)
+	if (usbtouch->is_open || usbtouch->type->irq_always)
 		result = usb_submit_urb(usbtouch->irq, GFP_NOIO);
 	mutex_unlock(&usbtouch->pm_mutex);
 
@@ -1516,7 +1518,6 @@ static int usbtouch_resume(struct usb_interface *intf)
 static int usbtouch_reset_resume(struct usb_interface *intf)
 {
 	struct usbtouch_usb *usbtouch = usb_get_intfdata(intf);
-	struct input_dev *input = usbtouch->input;
 	int err = 0;
 
 	/* reinit the device */
@@ -1532,7 +1533,7 @@ static int usbtouch_reset_resume(struct usb_interface *intf)
 
 	/* restart IO if needed */
 	mutex_lock(&usbtouch->pm_mutex);
-	if (input->users)
+	if (usbtouch->is_open)
 		err = usb_submit_urb(usbtouch->irq, GFP_NOIO);
 	mutex_unlock(&usbtouch->pm_mutex);
 
-- 
2.15.1