patch "usb: gadget: function: printer: avoid wrong list handling in" added to usb-next

[<gregkh@linuxfoundation.org>]

This is a note to let you know that I've just added the patch titled

    usb: gadget: function: printer: avoid wrong list handling in

to my usb git tree which can be found at
    git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb.git
in the usb-next branch.

The patch will show up in the next release of the linux-next tree
(usually sometime within the next 24 hours during the week.)

The patch will also be merged in the next major kernel release
during the merge window.

If you have any questions about this process, please let me know.


>From 4a014a7339f441b0851ce012f469c0fadac61c81 Mon Sep 17 00:00:00 2001
From: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
Date: Mon, 21 May 2018 20:18:07 +0900
Subject: 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 <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>
---
 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);
-- 
2.17.0