From: Willem de Bruijn <willemb@google.com>
Date: Wed, 9 Aug 2017 23:09:44 +0000 (-0400)
Subject: sock: fix zerocopy_success regression with msg_zerocopy
X-Git-Tag: v4.14-rc1~130^2~310^2
X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=0a4a060bb204c47825eb4f7c27f66fc7ee85d508;p=platform%2Fkernel%2Flinux-exynos.git

sock: fix zerocopy_success regression with msg_zerocopy

Do not use uarg->zerocopy outside msg_zerocopy. In other paths the
field is not explicitly initialized and aliases another field.

Those paths have only one reference so do not need this intermediate
variable. Call uarg->callback directly.

Fixes: 1f8b977ab32d ("sock: enable MSG_ZEROCOPY")
Signed-off-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
---

diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index 8c0708d..7594e19 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -1273,8 +1273,13 @@ static inline void skb_zcopy_clear(struct sk_buff *skb, bool zerocopy)
 	struct ubuf_info *uarg = skb_zcopy(skb);
 
 	if (uarg) {
-		uarg->zerocopy = uarg->zerocopy && zerocopy;
-		sock_zerocopy_put(uarg);
+		if (uarg->callback == sock_zerocopy_callback) {
+			uarg->zerocopy = uarg->zerocopy && zerocopy;
+			sock_zerocopy_put(uarg);
+		} else {
+			uarg->callback(uarg, zerocopy);
+		}
+
 		skb_shinfo(skb)->tx_flags &= ~SKBTX_ZEROCOPY_FRAG;
 	}
 }