From dbaaca9aa5ce36c07a01a157d203071f6332a2af Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Maciej=20=C5=BBenczykowski?= <maze@google.com>
Date: Thu, 1 Jul 2021 04:48:29 -0700
Subject: [PATCH] usb: gadget: f_ncm: remove timer_force_tx field
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Git-commit: dbaaca9aa5ce36c07a01a157d203071f6332a2af
References: git-fixes
Patch-mainline: v5.15-rc1

It is simply not needed.  This field is equivalent to skb being NULL.

Currently with the boolean set to true we call:
  ncm->netdev->netdev_ops->ndo_start_xmit(NULL, ncm->netdev);
which calls u_ether's:
  eth_start_xmit(NULL, ...)
which then calls:
  skb = dev->wrap(dev->port_usb, NULL);
which calls back into f_ncm's:
  ncm_wrap_ntb(..., NULL)

Cc: Brooke Basile <brookebasile@gmail.com>
Cc: "Bryan O'Donoghue" <bryan.odonoghue@linaro.org>
Cc: Felipe Balbi <balbi@kernel.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Lorenzo Colitti <lorenzo@google.com>
Signed-off-by: Maciej Żenczykowski <maze@google.com>
Link: https://lore.kernel.org/r/20210701114834.884597-1-zenczykowski@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Oliver Neukum <oneukum@suse.com>
---
 drivers/usb/gadget/function/f_ncm.c | 12 +++++-------
 1 file changed, 5 insertions(+), 7 deletions(-)

diff --git a/drivers/usb/gadget/function/f_ncm.c b/drivers/usb/gadget/function/f_ncm.c
index 855127249f24..afbe70bc8d6b 100644
--- a/drivers/usb/gadget/function/f_ncm.c
+++ b/drivers/usb/gadget/function/f_ncm.c
@@ -72,7 +72,6 @@ struct f_ncm {
 	struct sk_buff			*skb_tx_data;
 	struct sk_buff			*skb_tx_ndp;
 	u16				ndp_dgram_count;
-	bool				timer_force_tx;
 	struct hrtimer			task_timer;
 	bool				timer_stopping;
 };
@@ -1126,8 +1125,11 @@ static struct sk_buff *ncm_wrap_ntb(struct gether *port,
 		dev_consume_skb_any(skb);
 		skb = NULL;
 
-	} else if (ncm->skb_tx_data && ncm->timer_force_tx) {
-		/* If the tx was requested because of a timeout then send */
+	} else if (ncm->skb_tx_data) {
+		/* If we get here ncm_wrap_ntb() was called with NULL skb,
+		 * because eth_start_xmit() was called with NULL skb by
+		 * ncm_tx_timeout() - hence, this is our signal to flush/send.
+		 */
 		skb2 = package_for_tx(ncm);
 		if (!skb2)
 			goto err;
@@ -1158,8 +1160,6 @@ static enum hrtimer_restart ncm_tx_timeout(struct hrtimer *data)
 
 	/* Only send if data is available. */
 	if (!ncm->timer_stopping && ncm->skb_tx_data) {
-		ncm->timer_force_tx = true;
-
 		/* XXX This allowance of a NULL skb argument to ndo_start_xmit
 		 * XXX is not sane.  The gadget layer should be redesigned so
 		 * XXX that the dev->wrap() invocations to build SKBs is transparent
@@ -1167,8 +1167,6 @@ static enum hrtimer_restart ncm_tx_timeout(struct hrtimer *data)
 		 * XXX interface.
 		 */
 		ncm->netdev->netdev_ops->ndo_start_xmit(NULL, ncm->netdev);
-
-		ncm->timer_force_tx = false;
 	}
 	return HRTIMER_NORESTART;
 }
-- 
2.39.0