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Commit 0a56fd9f authored by Hemant Kumar's avatar Hemant Kumar
Browse files

net: rmnet_usb_ctrl: Block poll() after device disconnect 



Driver is setting POLLERR mask event upon device disconnect which
makes poll() non blocking call. This causes userspace client to
continuously poll for read after device disconnect. Hence clear
mask event next time when usespace client calls poll(). This allows
userspace client to get blocked until device connects back. Also
empty rx_list at the time of disconnect to avoid passing stale
data to userspace after device connects back.

CRs-Fixed: 641385
Change-Id: Iac6449c814e4a6016d3a4d5b4f7a27d9fd1dae6c
Signed-off-by: default avatarHemant Kumar <hemantk@codeaurora.org>
parent 5656dbf3

drivers/net/usb/rmnet_usb.h

+1 −0
Original line number Diff line number Diff line
@@ -109,6 +109,7 @@ struct rmnet_ctrl_dev { 
	unsigned long		status;



	bool			claimed;

	bool			poll_err;



	unsigned int		mdm_wait_timeout;

drivers/net/usb/rmnet_usb_ctrl.c

+29 −30
Original line number Diff line number Diff line
@@ -489,10 +489,24 @@ static int rmnet_usb_ctrl_write_cmd(struct rmnet_ctrl_udev *dev, u8 req, 
	return ret;

}



static int rmnet_ctl_open(struct inode *inode, struct file *file)

static void rmnet_usb_ctrl_free_rx_list(struct rmnet_ctrl_dev *dev)

{

	struct ctrl_pkt_list_elem	*list_elem = NULL;

	unsigned long flag;

	struct ctrl_pkt_list_elem *list_elem = NULL;



	spin_lock_irqsave(&dev->rx_lock, flag);

	while (!list_empty(&dev->rx_list)) {

		list_elem = list_first_entry(&dev->rx_list,

				struct ctrl_pkt_list_elem, list);

		list_del(&list_elem->list);

		kfree(list_elem->cpkt.data);

		kfree(list_elem);

	}

	spin_unlock_irqrestore(&dev->rx_lock, flag);

}



static int rmnet_ctl_open(struct inode *inode, struct file *file)

{

	int				retval = 0;

	struct rmnet_ctrl_dev		*dev =

		container_of(inode->i_cdev, struct rmnet_ctrl_dev, cdev);
@@ -528,17 +542,7 @@ static int rmnet_ctl_open(struct inode *inode, struct file *file) 
	}



	/* clear stale data if device close called but channel was ready */

	spin_lock_irqsave(&dev->rx_lock, flag);

	while (!list_empty(&dev->rx_list)) {

		list_elem = list_first_entry(

				&dev->rx_list,

				struct ctrl_pkt_list_elem,

				list);

		list_del(&list_elem->list);

		kfree(list_elem->cpkt.data);

		kfree(list_elem);

	}

	spin_unlock_irqrestore(&dev->rx_lock, flag);

	rmnet_usb_ctrl_free_rx_list(dev);



	set_bit(RMNET_CTRL_DEV_OPEN, &dev->status);
@@ -552,9 +556,7 @@ already_opened: 


static int rmnet_ctl_release(struct inode *inode, struct file *file)

{

	struct ctrl_pkt_list_elem	*list_elem = NULL;

	struct rmnet_ctrl_dev		*dev;

	unsigned long			flag;



	dev = file->private_data;

	if (!dev)
@@ -562,18 +564,6 @@ static int rmnet_ctl_release(struct inode *inode, struct file *file) 


	DBG("%s Called on %s device\n", __func__, dev->name);



	spin_lock_irqsave(&dev->rx_lock, flag);

	while (!list_empty(&dev->rx_list)) {

		list_elem = list_first_entry(

				&dev->rx_list,

				struct ctrl_pkt_list_elem,

				list);

		list_del(&list_elem->list);

		kfree(list_elem->cpkt.data);

		kfree(list_elem);

	}

	spin_unlock_irqrestore(&dev->rx_lock, flag);



	clear_bit(RMNET_CTRL_DEV_OPEN, &dev->status);



	file->private_data = NULL;
@@ -585,20 +575,27 @@ static unsigned int rmnet_ctl_poll(struct file *file, poll_table *wait) 
{

	unsigned int		mask = 0;

	struct rmnet_ctrl_dev	*dev;

	unsigned long		flags;



	dev = file->private_data;

	if (!dev)

		return POLLERR;



	poll_wait(file, &dev->read_wait_queue, wait);

	if (!test_bit(RMNET_CTRL_DEV_READY, &dev->cudev->status)) {

		dev_dbg(dev->devicep, "%s: Device not connected\n",

			__func__);

	if (!dev->poll_err &&

			!test_bit(RMNET_CTRL_DEV_READY, &dev->cudev->status)) {

		dev_dbg(dev->devicep, "%s: Device not connected\n", __func__);

		dev->poll_err = true;

		return POLLERR;

	}



	if (dev->poll_err)

		dev->poll_err = false;



	spin_lock_irqsave(&dev->rx_lock, flags);

	if (!list_empty(&dev->rx_list))

		mask |= POLLIN | POLLRDNORM;

	spin_unlock_irqrestore(&dev->rx_lock, flags);



	return mask;

}
@@ -931,6 +928,7 @@ void rmnet_usb_ctrl_disconnect(struct rmnet_ctrl_udev *dev) 
	if (test_bit(RMNET_CTRL_DEV_MUX_EN, &dev->status)) {

		for (n = 0; n < insts_per_dev; n++) {

			cdev = &ctrl_devs[dev->rdev_num][n];

			rmnet_usb_ctrl_free_rx_list(cdev);

			wake_up(&cdev->read_wait_queue);

			mutex_lock(&cdev->dev_lock);

			cdev->cbits_tolocal = ~ACM_CTRL_CD;
@@ -940,6 +938,7 @@ void rmnet_usb_ctrl_disconnect(struct rmnet_ctrl_udev *dev) 
	} else {

		cdev = &ctrl_devs[dev->rdev_num][dev->ctrldev_id];

		cdev->claimed = false;

		rmnet_usb_ctrl_free_rx_list(cdev);

		wake_up(&cdev->read_wait_queue);

		mutex_lock(&cdev->dev_lock);

		cdev->cbits_tolocal = ~ACM_CTRL_CD;