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Commit 7f1dc313 authored by Oliver Neukum's avatar Oliver Neukum Committed by Greg Kroah-Hartman
Browse files

USB: CDC WDM driver doesn't support non-blocking reads 



support for O_NONBLOCK in read and write path
by simply not waiting for data in read or availability
of the write urb in write but returning -EAGAIN

Signed-off-by: default avatarOliver Neukum <oliver@neukum.org>
Tested-by: default avatarMarcel Holtmann <marcel@holtmann.org>
Cc: stable <stable@kernel.org>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@suse.de>
parent ce60c488

drivers/usb/class/cdc-wdm.c

+24 −6
Original line number Diff line number Diff line
@@ -313,8 +313,13 @@ static ssize_t wdm_write 
	r = usb_autopm_get_interface(desc->intf);

	if (r < 0)

		goto outnp;



	if (!file->f_flags && O_NONBLOCK)

		r = wait_event_interruptible(desc->wait, !test_bit(WDM_IN_USE,

								&desc->flags));

	else

		if (test_bit(WDM_IN_USE, &desc->flags))

			r = -EAGAIN;

	if (r < 0)

		goto out;
@@ -377,7 +382,7 @@ static ssize_t wdm_write 
static ssize_t wdm_read

(struct file *file, char __user *buffer, size_t count, loff_t *ppos)

{

	int rv, cntr;

	int rv, cntr = 0;

	int i = 0;

	struct wdm_device *desc = file->private_data;
@@ -389,10 +394,23 @@ static ssize_t wdm_read 
	if (desc->length == 0) {

		desc->read = 0;

retry:

		if (test_bit(WDM_DISCONNECTING, &desc->flags)) {

			rv = -ENODEV;

			goto err;

		}

		i++;

		if (file->f_flags & O_NONBLOCK) {

			if (!test_bit(WDM_READ, &desc->flags)) {

				rv = cntr ? cntr : -EAGAIN;

				goto err;

			}

			rv = 0;

		} else {

			rv = wait_event_interruptible(desc->wait,

				test_bit(WDM_READ, &desc->flags));

		}



		/* may have happened while we slept */

		if (test_bit(WDM_DISCONNECTING, &desc->flags)) {

			rv = -ENODEV;

			goto err;
@@ -448,7 +466,7 @@ static ssize_t wdm_read 


err:

	mutex_unlock(&desc->rlock);

	if (rv < 0)

	if (rv < 0 && rv != -EAGAIN)

		dev_err(&desc->intf->dev, "wdm_read: exit error\n");

	return rv;

}