netdev - [PATCH 10/11] tcp: Always set options to 0 before calling tcp_established

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Date:	Mon, 30 Sep 2013 13:29:11 -0700
From:	Andi Kleen <andi@...stfloor.org>
To:	linux-kernel@...r.kernel.org
Cc:	Andi Kleen <ak@...ux.intel.com>, netdev@...r.kernel.org
Subject: [PATCH 10/11] tcp: Always set options to 0 before calling tcp_established_options

From: Andi Kleen <ak@...ux.intel.com>

tcp_established_options assumes opts->options is 0 before calling,
as it read modify writes it.

For the tcp_current_mss() case the opts structure is not zeroed,
so this can be done with uninitialized values.

This is ok, because ->options is not read in this path.
But it's still better to avoid the operation on the uninitialized
field. This shuts up a static code analyzer, and presumably
may help the optimizer.

Cc: netdev@...r.kernel.org
Signed-off-by: Andi Kleen <ak@...ux.intel.com>
---
 net/ipv4/tcp_output.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index 7c83cb8..f3ed78d 100644
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -637,6 +637,8 @@ static unsigned int tcp_established_options(struct sock *sk, struct sk_buff *skb
 	unsigned int size = 0;
 	unsigned int eff_sacks;
 
+	opts->options = 0;
+
 #ifdef CONFIG_TCP_MD5SIG
 	*md5 = tp->af_specific->md5_lookup(sk, sk);
 	if (unlikely(*md5)) {
-- 
1.8.3.1

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