3.16.61-rc1 review patch. If anyone has any objections, please let me know.
------------------ From: Yoshihiro Shimoda <[email protected]> commit 9ada8c582088d32bd5c071c17213bc6edf37443a upstream. If usb_gadget_giveback_request() is called in usb_ep_queue(), this printer_write() is possible to cause spinlock recursion. So, this patch adds spin_unlock() before calls usb_ep_queue() to avoid it. Signed-off-by: Yoshihiro Shimoda <[email protected]> Signed-off-by: Felipe Balbi <[email protected]> [bwh: Backported to 3.16: adjust filename] Signed-off-by: Ben Hutchings <[email protected]> --- drivers/usb/gadget/printer.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) --- a/drivers/usb/gadget/printer.c +++ b/drivers/usb/gadget/printer.c @@ -587,6 +587,7 @@ printer_write(struct file *fd, const cha size_t size; /* Amount of data in a TX request. */ size_t bytes_copied = 0; struct usb_request *req; + int value; DBG(dev, "printer_write trying to send %d bytes\n", (int)len); @@ -666,7 +667,11 @@ printer_write(struct file *fd, const cha return -EAGAIN; } - if (usb_ep_queue(dev->in_ep, req, GFP_ATOMIC)) { + /* 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_add(&req->list, &dev->tx_reqs); spin_unlock_irqrestore(&dev->lock, flags); mutex_unlock(&dev->lock_printer_io);
