From 45705f4983bc0fc7155ad092428cb9e2157012a9 Mon Sep 17 00:00:00 2001
From: Andrew Morton <akpm@osdl.org>
Date: Fri, 31 Mar 2006 02:09:36 -0800
Subject: [PATCH] --- yaml --- r: 24959 b: refs/heads/master c:
 c08e49611a8b4e38a75bf217e1029a48faf10b82 h: refs/heads/master i:   24957:
 7ea0f563487f5acd2572fc49f5eec84ecb7ddd37   24955:
 bb736eb9f72fd274f569d11e76415385050c9247   24951:
 7c07c0df47386f27ade60cc92fbca7c3f2bbac9e   24943:
 ba2e061f082083353b810009c3905619255c9b95   24927:
 cb18bfd508cb5e2ac49edfdb30fee83db1b071c2   24895:
 aed9b2c133fda3b9cd3e687859a1d77cfe873563   24831:
 f349d84973f205a3dc6ba070b5932a9fa98733ef v: v3

---
 [refs]                |  2 +-
 trunk/net/core/sock.c | 16 +++++++++++++++-
 2 files changed, 16 insertions(+), 2 deletions(-)

diff --git a/[refs] b/[refs]
index a48fc0842297..91cb5805b0b2 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 56079431b6ba163df8ba26b3eccc82379f0c0ce4
+refs/heads/master: c08e49611a8b4e38a75bf217e1029a48faf10b82
diff --git a/trunk/net/core/sock.c b/trunk/net/core/sock.c
index a96ea7dd0fc1..ed2afdb9ea2d 100644
--- a/trunk/net/core/sock.c
+++ b/trunk/net/core/sock.c
@@ -385,7 +385,21 @@ int sock_setsockopt(struct socket *sock, int level, int optname,
 				val = sysctl_rmem_max;
 set_rcvbuf:
 			sk->sk_userlocks |= SOCK_RCVBUF_LOCK;
-			/* FIXME: is this lower bound the right one? */
+			/*
+			 * We double it on the way in to account for
+			 * "struct sk_buff" etc. overhead.   Applications
+			 * assume that the SO_RCVBUF setting they make will
+			 * allow that much actual data to be received on that
+			 * socket.
+			 *
+			 * Applications are unaware that "struct sk_buff" and
+			 * other overheads allocate from the receive buffer
+			 * during socket buffer allocation.
+			 *
+			 * And after considering the possible alternatives,
+			 * returning the value we actually used in getsockopt
+			 * is the most desirable behavior.
+			 */
 			if ((val * 2) < SOCK_MIN_RCVBUF)
 				sk->sk_rcvbuf = SOCK_MIN_RCVBUF;
 			else