From 4a014a7339f441b0851ce012f469c0fadac61c81 Mon Sep 17 00:00:00 2001 From: Yoshihiro Shimoda Date: Mon, 21 May 2018 20:18:07 +0900 Subject: [PATCH] usb: gadget: function: printer: avoid wrong list handling in printer_write() 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 Acked-by: Felipe Balbi Cc: stable Signed-off-by: Greg Kroah-Hartman --- drivers/usb/gadget/function/f_printer.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/drivers/usb/gadget/function/f_printer.c b/drivers/usb/gadget/function/f_printer.c index d359efe06c76..9c7ed2539ff7 100644 --- a/drivers/usb/gadget/function/f_printer.c +++ b/drivers/usb/gadget/function/f_printer.c @@ -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); -- 2.45.2