usb: cdc-wdm: avoid hanging on zero length reads
commit73e06865ea
("USB: cdc-wdm: support back-to-back USB_CDC_NOTIFY_RESPONSE_AVAILABLE notifications") implemented queued response handling. This added a new requirement: The read urb must be resubmitted every time we clear the WDM_READ flag if the response counter indicates that the device is waiting for a read. Fix by factoring out the code handling the WMD_READ clearing and possible urb submission, calling it everywhere we clear the flag. Without this fix, the driver ends up in a state where the read urb is inactive, but the response counter is positive after a zero length read. This prevents the read urb from ever being submitted again and the driver appears to be hanging. Fixes:73e06865ea
("USB: cdc-wdm: support back-to-back USB_CDC_NOTIFY_RESPONSE_AVAILABLE notifications") Cc: Greg Suarez <gsuarez@smithmicro.com> Signed-off-by: Bjørn Mork <bjorn@mork.no> Cc: stable <stable@vger.kernel.org> # 3.13 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Родитель
bee53637e5
Коммит
8dd5cd5395
|
@ -432,6 +432,38 @@ outnl:
|
|||
return rv < 0 ? rv : count;
|
||||
}
|
||||
|
||||
/*
|
||||
* clear WDM_READ flag and possibly submit the read urb if resp_count
|
||||
* is non-zero.
|
||||
*
|
||||
* Called with desc->iuspin locked
|
||||
*/
|
||||
static int clear_wdm_read_flag(struct wdm_device *desc)
|
||||
{
|
||||
int rv = 0;
|
||||
|
||||
clear_bit(WDM_READ, &desc->flags);
|
||||
|
||||
/* submit read urb only if the device is waiting for it */
|
||||
if (!--desc->resp_count)
|
||||
goto out;
|
||||
|
||||
set_bit(WDM_RESPONDING, &desc->flags);
|
||||
spin_unlock_irq(&desc->iuspin);
|
||||
rv = usb_submit_urb(desc->response, GFP_KERNEL);
|
||||
spin_lock_irq(&desc->iuspin);
|
||||
if (rv) {
|
||||
dev_err(&desc->intf->dev,
|
||||
"usb_submit_urb failed with result %d\n", rv);
|
||||
|
||||
/* make sure the next notification trigger a submit */
|
||||
clear_bit(WDM_RESPONDING, &desc->flags);
|
||||
desc->resp_count = 0;
|
||||
}
|
||||
out:
|
||||
return rv;
|
||||
}
|
||||
|
||||
static ssize_t wdm_read
|
||||
(struct file *file, char __user *buffer, size_t count, loff_t *ppos)
|
||||
{
|
||||
|
@ -503,8 +535,10 @@ retry:
|
|||
|
||||
if (!desc->reslength) { /* zero length read */
|
||||
dev_dbg(&desc->intf->dev, "%s: zero length - clearing WDM_READ\n", __func__);
|
||||
clear_bit(WDM_READ, &desc->flags);
|
||||
rv = clear_wdm_read_flag(desc);
|
||||
spin_unlock_irq(&desc->iuspin);
|
||||
if (rv < 0)
|
||||
goto err;
|
||||
goto retry;
|
||||
}
|
||||
cntr = desc->length;
|
||||
|
@ -526,37 +560,9 @@ retry:
|
|||
|
||||
desc->length -= cntr;
|
||||
/* in case we had outstanding data */
|
||||
if (!desc->length) {
|
||||
clear_bit(WDM_READ, &desc->flags);
|
||||
|
||||
if (--desc->resp_count) {
|
||||
set_bit(WDM_RESPONDING, &desc->flags);
|
||||
spin_unlock_irq(&desc->iuspin);
|
||||
|
||||
rv = usb_submit_urb(desc->response, GFP_KERNEL);
|
||||
if (rv) {
|
||||
dev_err(&desc->intf->dev,
|
||||
"%s: usb_submit_urb failed with result %d\n",
|
||||
__func__, rv);
|
||||
spin_lock_irq(&desc->iuspin);
|
||||
clear_bit(WDM_RESPONDING, &desc->flags);
|
||||
spin_unlock_irq(&desc->iuspin);
|
||||
|
||||
if (rv == -ENOMEM) {
|
||||
rv = schedule_work(&desc->rxwork);
|
||||
if (rv)
|
||||
dev_err(&desc->intf->dev, "Cannot schedule work\n");
|
||||
} else {
|
||||
spin_lock_irq(&desc->iuspin);
|
||||
desc->resp_count = 0;
|
||||
spin_unlock_irq(&desc->iuspin);
|
||||
}
|
||||
}
|
||||
} else
|
||||
spin_unlock_irq(&desc->iuspin);
|
||||
} else
|
||||
spin_unlock_irq(&desc->iuspin);
|
||||
|
||||
if (!desc->length)
|
||||
clear_wdm_read_flag(desc);
|
||||
spin_unlock_irq(&desc->iuspin);
|
||||
rv = cntr;
|
||||
|
||||
err:
|
||||
|
|
Загрузка…
Ссылка в новой задаче