From: Tariq Toukan <tariqt@mellanox.com>
Date: Tue, 24 Jul 2018 13:53:00 +0300
Subject: net: remove redundant input checks in SIOCSIFTXQLEN case of
 dev_ifsioc
Patch-mainline: v4.19-rc1
Git-commit: 8dd30201ce66f2c81077e06056f4a865e512e854
References: bsc#1109837

The cited patch added a call to dev_change_tx_queue_len in
SIOCSIFTXQLEN case.
This obsoletes the new len comparison check done before the function call.
Remove it here.

For the desicion of keep/remove the negative value check, we examine the
range check in dev_change_tx_queue_len.
On 64-bit we will fail with -ERANGE.  The 32-bit int ifr_qlen will be sign
extended to 64-bits when it is passed into dev_change_tx_queue_len(). And
then for negative values this test triggers:

	if (new_len != (unsigned int)new_len)
		return -ERANGE;

because:
	if (0xffffffffWHATEVER != 0x00000000WHATEVER)

On 32-bit the signed value will be accepted, changing behavior.

Therefore, the negative value check is kept.

Fixes: 3f76df198288 ("net: use dev_change_tx_queue_len() for SIOCSIFTXQLEN")
Signed-off-by: Tariq Toukan <tariqt@mellanox.com>
Reviewed-by: Eran Ben Elisha <eranbe@mellanox.com>
Cc: Cong Wang <xiyou.wangcong@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Acked-by: Thomas Bogendoerfer <tbogendoerfer@suse.de>
---
 net/core/dev_ioctl.c |    7 +------
 1 file changed, 1 insertion(+), 6 deletions(-)

--- a/net/core/dev_ioctl.c
+++ b/net/core/dev_ioctl.c
@@ -303,12 +303,7 @@ static int dev_ifsioc(struct net *net, s
 	case SIOCSIFTXQLEN:
 		if (ifr->ifr_qlen < 0)
 			return -EINVAL;
-		if (dev->tx_queue_len ^ ifr->ifr_qlen) {
-			err = dev_change_tx_queue_len(dev, ifr->ifr_qlen);
-			if (err)
-				return err;
-		}
-		return 0;
+		return dev_change_tx_queue_len(dev, ifr->ifr_qlen);
 
 	case SIOCSIFNAME:
 		ifr->ifr_newname[IFNAMSIZ-1] = '\0';