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usb: gadget: function: printer: avoid wrong list handling in printer_write()

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When printer_write() calls usb_ep_queue(), a udc driver (e.g.
renesas_usbhs driver) may call usb_gadget_giveback_request() in
the udc .queue ops immediately. Then, printer_write() calls
list_add(&req->list, &dev->tx_reqs_active) wrongly. After that,
if we do unbind the printer driver, WARN_ON() happens in
printer_func_unbind() because the list entry is not removed.

So, this patch moves list_add(&req->list, &dev->tx_reqs_active)
calling before usb_ep_queue().

Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
Acked-by: Felipe Balbi <felipe.balbi@linux.intel.com>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Yoshihiro Shimoda 2018-05-21 20:18:07 +09:00 committed by Greg Kroah-Hartman
parent c97a8cc17f
commit 4a014a7339
1 changed files with 3 additions and 3 deletions
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6
drivers/usb/gadget/function/f_printer.c
View file

@ -631,19 +631,19 @@ printer_write(struct file *fd, const char __user *buf, size_t len, loff_t *ptr)
return -EAGAIN;
}
list_add(&req->list, &dev->tx_reqs_active);
/* here, we unlock, and only unlock, to avoid deadlock. */
spin_unlock(&dev->lock);
value = usb_ep_queue(dev->in_ep, req, GFP_ATOMIC);
spin_lock(&dev->lock);
if (value) {
list_del(&req->list);
list_add(&req->list, &dev->tx_reqs);
spin_unlock_irqrestore(&dev->lock, flags);
mutex_unlock(&dev->lock_printer_io);
return -EAGAIN;
}
list_add(&req->list, &dev->tx_reqs_active);
}
spin_unlock_irqrestore(&dev->lock, flags);