[master] 1732352 If the OC doesn't have a boc, don't lock unnecessarily lock the OH

[Martin Blix Grydeland]

commit 17323520af6afc72261fc43bdd7ded803497f8d6
Author: Martin Blix Grydeland <martin at varnish-software.com>
Date:   Tue Feb 23 14:39:41 2016 +0100

    If the OC doesn't have a boc, don't lock unnecessarily lock the OH
    
    The objcore won't gain a boc in a way that would call for locking the
    OH when checking if it wasn't there in the first place. So if the
    oc->boc is NULL, return early. This saves a mutex lock/unlock in the
    common case.

diff --git a/bin/varnishd/cache/cache_hash.c b/bin/varnishd/cache/cache_hash.c
index c70ef7b..797677b 100644
--- a/bin/varnishd/cache/cache_hash.c
+++ b/bin/varnishd/cache/cache_hash.c
@@ -749,6 +749,8 @@ HSH_RefBoc(const struct objcore *oc)
 	CHECK_OBJ_NOTNULL(oc, OBJCORE_MAGIC);
 	oh = oc->objhead;
 	CHECK_OBJ_NOTNULL(oh, OBJHEAD_MAGIC);
+	if (oc->boc == NULL)
+		return (NULL);
 	Lck_Lock(&oh->mtx);
 	assert(oc->refcnt > 0);
 	boc = oc->boc;