netdev - [PATCH 21/28] net/hyperv: avoid uninitialized variable

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Date:   Tue, 18 Oct 2016 00:16:09 +0200
From:   Arnd Bergmann <arnd@...db.de>
To:     "K. Y. Srinivasan" <kys@...rosoft.com>,
        Haiyang Zhang <haiyangz@...rosoft.com>
Cc:     Linus Torvalds <torvalds@...ux-foundation.org>,
        linux-kernel@...r.kernel.org, Arnd Bergmann <arnd@...db.de>,
        "David S. Miller" <davem@...emloft.net>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        stephen hemminger <stephen@...workplumber.org>,
        "sixiao@...rosoft.com" <sixiao@...rosoft.com>,
        devel@...uxdriverproject.org, netdev@...r.kernel.org
Subject: [PATCH 21/28] net/hyperv: avoid uninitialized variable

The hdr_offset variable is only if we deal with a TCP or UDP packet,
but as the check surrounding its usage tests for skb_is_gso()
instead, the compiler has no idea if the variable is initialized
or not at that point:

drivers/net/hyperv/netvsc_drv.c: In function ‘netvsc_start_xmit’:
drivers/net/hyperv/netvsc_drv.c:494:42: error: ‘hdr_offset’ may be used uninitialized in this function [-Werror=maybe-uninitialized]

This adds an additional check for the transport type, which
tells the compiler that this path cannot happen. Since the
get_net_transport_info() function should always be inlined
here, I don't expect this to result in additional runtime
checks.

Signed-off-by: Arnd Bergmann <arnd@...db.de>
---
 drivers/net/hyperv/netvsc_drv.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/hyperv/netvsc_drv.c b/drivers/net/hyperv/netvsc_drv.c
index f0919bd..5d6e75a 100644
--- a/drivers/net/hyperv/netvsc_drv.c
+++ b/drivers/net/hyperv/netvsc_drv.c
@@ -447,7 +447,7 @@ static int netvsc_start_xmit(struct sk_buff *skb, struct net_device *net)
 	 * Setup the sendside checksum offload only if this is not a
 	 * GSO packet.
 	 */
-	if (skb_is_gso(skb)) {
+	if ((net_trans_info & (INFO_TCP | INFO_UDP)) && skb_is_gso(skb)) {
 		struct ndis_tcp_lso_info *lso_info;
 
 		rndis_msg_size += NDIS_LSO_PPI_SIZE;
-- 
2.9.0