From c1ae4fcf7d5d85c182e36ff6f7a529f8a84aa372 Mon Sep 17 00:00:00 2001
From: Matt Corallo <git@bluematt.me>
Date: Thu, 5 Jan 2017 15:15:40 -0500
Subject: [PATCH] Avoid holding cs_most_recent_block while calling
 ReadBlockFromDisk

---
 src/net_processing.cpp | 21 +++++++++++++--------
 1 file changed, 13 insertions(+), 8 deletions(-)

diff --git a/src/net_processing.cpp b/src/net_processing.cpp
index fdb70d6578..440696ae55 100644
--- a/src/net_processing.cpp
+++ b/src/net_processing.cpp
@@ -2894,15 +2894,20 @@ bool SendMessages(CNode* pto, CConnman& connman, std::atomic<bool>& interruptMsg
 
                     int nSendFlags = state.fWantsCmpctWitness ? 0 : SERIALIZE_TRANSACTION_NO_WITNESS;
 
-                    LOCK(cs_most_recent_block);
-                    if (most_recent_block_hash == pBestIndex->GetBlockHash()) {
-                        if (state.fWantsCmpctWitness)
-                            connman.PushMessage(pto, msgMaker.Make(nSendFlags, NetMsgType::CMPCTBLOCK, *most_recent_compact_block));
-                        else {
-                            CBlockHeaderAndShortTxIDs cmpctblock(*most_recent_block, state.fWantsCmpctWitness);
-                            connman.PushMessage(pto, msgMaker.Make(nSendFlags, NetMsgType::CMPCTBLOCK, cmpctblock));
+                    bool fGotBlockFromCache = false;
+                    {
+                        LOCK(cs_most_recent_block);
+                        if (most_recent_block_hash == pBestIndex->GetBlockHash()) {
+                            if (state.fWantsCmpctWitness)
+                                connman.PushMessage(pto, msgMaker.Make(nSendFlags, NetMsgType::CMPCTBLOCK, *most_recent_compact_block));
+                            else {
+                                CBlockHeaderAndShortTxIDs cmpctblock(*most_recent_block, state.fWantsCmpctWitness);
+                                connman.PushMessage(pto, msgMaker.Make(nSendFlags, NetMsgType::CMPCTBLOCK, cmpctblock));
+                            }
+                            fGotBlockFromCache = true;
                         }
-                    } else {
+                    }
+                    if (!fGotBlockFromCache) {
                         CBlock block;
                         bool ret = ReadBlockFromDisk(block, pBestIndex, consensusParams);
                         assert(ret);