From de72c08660fca1597be0bb0b6536c122ae324645 Mon Sep 17 00:00:00 2001
From: Howard Chu <hyc@symas.com>
Date: Fri, 19 Jul 2013 09:57:33 -0700
Subject: [PATCH] Tweak reader_pid check

Check again after acquiring rmutex. Avoids potential issue with
a duplicate pid coming in between initial check and rmutex.
---
 libraries/liblmdb/mdb.c | 12 +++++++-----
 1 file changed, 7 insertions(+), 5 deletions(-)

diff --git a/libraries/liblmdb/mdb.c b/libraries/liblmdb/mdb.c
index 1e26d16..4d68600 100644
--- a/libraries/liblmdb/mdb.c
+++ b/libraries/liblmdb/mdb.c
@@ -8092,11 +8092,13 @@ int mdb_reader_check(MDB_env *env, int *dead)
 			if (mdb_pid_insert(pids, pid) == 0) {
 				if (mdb_reader_pid(env, Pidcheck, pid)) {
 					LOCK_MUTEX_R(env);
-					for (j=i; j<rdrs; j++)
-						if (mr[j].mr_pid == pid) {
-							mr[j].mr_pid = 0;
-							count++;
-						}
+					if (mdb_reader_pid(env, Pidcheck, pid)) {
+						for (j=i; j<rdrs; j++)
+							if (mr[j].mr_pid == pid) {
+								mr[j].mr_pid = 0;
+								count++;
+							}
+					}
 					UNLOCK_MUTEX_R(env);
 				}
 			}