From 7f7a550f983fcf283bbf343ef74efb62fd08082b Mon Sep 17 00:00:00 2001
From: Avi Kivity <avi@cloudius-systems.com>
Date: Mon, 22 Sep 2014 14:26:34 +0300
Subject: [PATCH] net: extend packet by doubling fragment vector size

Avoid quadratic behavior
---
 net/packet.hh | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/net/packet.hh b/net/packet.hh
index 0ac5a792d6..6330bbd48d 100644
--- a/net/packet.hh
+++ b/net/packet.hh
@@ -77,7 +77,9 @@ class packet final {
             if (old->_allocated_frags >= old->_nr_frags + extra_frags) {
                 return std::move(old);
             }
-            auto n = allocate(old->_nr_frags + extra_frags);
+            auto nr = std::max<size_t>(old->_nr_frags + extra_frags,
+                                       2 * old->_nr_frags);
+            auto n = allocate(nr);
             n->_deleter = std::move(old->_deleter);
             n->_len = old->_len;
             n->_nr_frags = old->_nr_frags;