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>

diff --git a/src/messages/MOSDPing.h b/src/messages/MOSDPing.h
index 7a8bf2f986f01c0f7b1d8949e63cf4a0b903d13d..22d24d6aae7a0b9b5be7c4b10f011265a40f4477 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 override { return "osd_ping"; }