| From: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com> |
| Date: Wed, 13 Sep 2017 15:31:33 +0900 |
| Subject: usb: gadget: function: printer: avoid spinlock recursion |
| |
| 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 <yoshihiro.shimoda.uh@renesas.com> |
| Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com> |
| [bwh: Backported to 3.16: adjust filename] |
| Signed-off-by: Ben Hutchings <ben@decadent.org.uk> |
| --- |
| 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); |