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

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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: Oliver Neukum <oliver@neukum.org>
Tested-by: Marcel Holtmann <marcel@holtmann.org>
Cc: stable <stable@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This commit is contained in:
Oliver Neukum 2009-09-09 10:12:48 +02:00 committed by Greg Kroah-Hartman
parent ce60c48871
commit 7f1dc313d0
1 changed files with 24 additions and 6 deletions
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30
drivers/usb/class/cdc-wdm.c
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@ -313,8 +313,13 @@ static ssize_t wdm_write
r = usb_autopm_get_interface(desc->intf);
if (r < 0)
goto outnp;
r = wait_event_interruptible(desc->wait, !test_bit(WDM_IN_USE,
&desc->flags));
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++;
rv = wait_event_interruptible(desc->wait,
test_bit(WDM_READ, &desc->flags));
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;
}