--- sys/netinet/tcp_syncache.c	(revision 50)
+++ sys/netinet/tcp_syncache.c	(working copy)
@@ -97,6 +97,11 @@ 
 
 #include <security/mac/mac_framework.h>
 
+#include <sys/param.h>
+#include <sys/stack.h>
+#include <sys/types.h>
+#include <sys/sbuf.h>
+
 static VNET_DEFINE(int, tcp_syncookies) = 1;
 #define	V_tcp_syncookies		VNET(tcp_syncookies)
 SYSCTL_VNET_INT(_net_inet_tcp, OID_AUTO, syncookies, CTLFLAG_RW,
@@ -200,6 +205,11 @@ 
 #define	SCH_UNLOCK(sch)		mtx_unlock(&(sch)->sch_mtx)
 #define	SCH_LOCK_ASSERT(sch)	mtx_assert(&(sch)->sch_mtx, MA_OWNED)
 
+struct stack *st;
+struct mtx st_mtx;
+struct sbuf st_sb;
+char st_trace[65536];
+
 /*
  * Requires the syncache entry to be already removed from the bucket list.
  */
@@ -223,6 +233,10 @@ 
 {
 	int i;
 
+	st = stack_create();
+	mtx_init(&st_mtx, "tcp_sc_stack", NULL, MTX_DEF);
+	sbuf_new(&st_sb, st_trace, sizeof(st_trace), SBUF_FIXEDLEN);
+
 	V_tcp_syncache.cache_count = 0;
 	V_tcp_syncache.hashsize = TCP_SYNCACHE_HASHSIZE;
 	V_tcp_syncache.bucket_limit = TCP_SYNCACHE_BUCKETLIMIT;
@@ -277,6 +291,10 @@ 
 	struct syncache *sc, *nsc;
 	int i;
 
+	sbuf_delete(&st_sb);
+	mtx_destroy(&st_mtx);
+	stack_destroy(st);
+
 	/* Cleanup hash buckets: stop timers, free entries, destroy locks. */
 	for (i = 0; i < V_tcp_syncache.hashsize; i++) {
 
@@ -949,11 +967,27 @@ 
 
 	*lsop = syncache_socket(sc, *lsop, m);
 
-	if (*lsop == NULL)
+	if (*lsop == NULL) {
+		if ((s = tcp_log_addrs(inc, th, NULL, NULL)))
+			log(LOG_DEBUG, "%s; %s: SEQ %u, ACK %u, syncache_socket() "
+			    "failed\n", s, __func__, th->th_seq, th->th_ack);
 		TCPSTAT_INC(tcps_sc_aborted);
-	else
+        }
+	else {
+		if ((s = tcp_log_addrs(inc, th, NULL, NULL)))
+			log(LOG_DEBUG, "%s; %s: SEQ %u, ACK %u, syncache_socket() "
+			    "succeed\n", s, __func__, th->th_seq, th->th_ack);
 		TCPSTAT_INC(tcps_sc_completed);
+	}
 
+	mtx_lock(&st_mtx);
+	stack_save(st);
+	stack_sbuf_print(&st_sb, st);
+	sbuf_finish(&st_sb);
+	log(LOG_DEBUG, "%s", sbuf_data(&st_sb));
+	sbuf_clear(&st_sb);
+	mtx_unlock(&st_mtx);
+
 /* how do we find the inp for the new socket? */
 	if (sc != &scs)
 		syncache_free(sc);