messages/MOSDPing: initialize MOSDPing padding

This memory must be initialized or else valgrind will be very unhappy.

Avoid the cost of zeroing (or even allocating) the buffer for normal
padding values by (re)using a static zero buffer.

Fixes: http://tracker.ceph.com/issues/20323
Signed-off-by: Sage Weil <sage@redhat.com>
(cherry picked from commit 9beaf5efd74daa8c15e50b42583264d1252a85f5)

diff --git a/src/messages/MOSDPing.h b/src/messages/MOSDPing.h
index 61310b3534f175c41c6b260a7d05bcd511374e7e..cf211ed9795c0954931dac7681313b2900032591 100644 (file)
--- a/src/messages/MOSDPing.h
+++ b/src/messages/MOSDPing.h
@@ -99,10 +99,22 @@ public:
     ::encode(op, payload);
     ::encode(peer_stat, payload);
     ::encode(stamp, payload);
-    bufferptr size_bp(MAX(min_message_size - payload.length(), 0));
-    bufferlist size_bl;;
-    size_bl.push_back(size_bp);
-    ::encode(size_bl, payload);
+
+    bufferlist pad;
+    size_t s = MAX(min_message_size - payload.length(), 0);
+    // this should be big enough for normal min_message padding sizes. since
+    // we are targetting jumbo ethernet frames around 9000 bytes, 16k should
+    // be more than sufficient!  the compiler will statically zero this so
+    // that at runtime we are only adding a bufferptr reference to it.
+    static char zeros[16384] = {};
+    while (s > sizeof(zeros)) {
+      pad.append(buffer::create_static(sizeof(zeros), zeros));
+      s -= sizeof(zeros);
+    }
+    if (s) {
+      pad.append(buffer::create_static(s, zeros));
+    }
+    ::encode(pad, payload);
   }
 
   const char *get_type_name() const { return "osd_ping"; }