fix race conditionmuchsync-5

4 files changed, 12 insertions, 3 deletions

diff --git a/NEWS b/NEWS
index 1e5e9fe..3079eef 100644
--- a/NEWS
+++ b/NEWS
@@ -1,3 +1,9 @@
+
+* Changes in release 5
+
+Fixed a race condition that could cause a core dump on fast networks
+when flow-control logic kicked in.
+
 * Changes in release 4
 
 Updated for GCC 7 header changes (thanks Toke Høiland-Jørgensen).
diff --git a/configure.ac b/configure.ac
index 0af6eaa..9533bff 100644
--- a/configure.ac
+++ b/configure.ac
@@ -2,7 +2,7 @@
 # Process this file with autoconf to produce a configure script.
 
 AC_PREREQ([2.69])
-AC_INIT(muchsync, 4)
+AC_INIT(muchsync, 5)
 AM_INIT_AUTOMAKE([-Wall])
 AC_CONFIG_SRCDIR([configure.ac])
 AC_CONFIG_MACRO_DIR([m4])
diff --git a/infinibuf.cc b/infinibuf.cc
index b7640aa..e7ef5f8 100644
--- a/infinibuf.cc
+++ b/infinibuf.cc
@@ -178,6 +178,7 @@ infinibuf::input_loop(shared_ptr<infinibuf> ib, int fd)
       else if (res == 0)
 	return;
       // Don't even bother checking flow control if less than 1MB allocated
+      lock_guard<infinibuf> lk (*ib);
       if (ib->buffer_size() >= 100000)
 	ib->pwait();
     }
diff --git a/infinibuf.h b/infinibuf.h
index 1fd4788..2713ddf 100644
--- a/infinibuf.h
+++ b/infinibuf.h
@@ -184,9 +184,11 @@ public:
   }
   void pwait() override {
     if (max_buf_size_ && buffer_size() > max_buf_size_) {
-      std::unique_lock<std::mutex> ul (m_, std::adopt_lock);
-      if (max_buf_size_ && buffer_size() > max_buf_size_)
+      if (max_buf_size_ && buffer_size() > max_buf_size_) {
+	std::unique_lock<std::mutex> ul (m_, std::adopt_lock);
 	flow_ctrl_cv_.wait(ul);
+	ul.release();
+      }
     }
   }
 };