3.16.61-rc1 review patch. If anyone has any objections, please let me know.
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From: Yoshihiro Shimoda yoshihiro.shimoda.uh@renesas.com
commit 4a014a7339f441b0851ce012f469c0fadac61c81 upstream.
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 Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org [bwh: Backported to 3.16: adjust filename] Signed-off-by: Ben Hutchings ben@decadent.org.uk --- drivers/usb/gadget/printer.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-)
--- a/drivers/usb/gadget/printer.c +++ b/drivers/usb/gadget/printer.c @@ -667,19 +667,19 @@ printer_write(struct file *fd, const cha 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);