From 7181624aaa3ccdc83ab87edd795ed5cd3f2f124b Mon Sep 17 00:00:00 2001
From: Jeff Roberson <jeff@FreeBSD.org>
Date: Thu, 30 May 2002 05:55:22 +0000
Subject: [PATCH] Record the file, line, and pid of the last successful shared
 lock holder. This is useful as a last effort in debugging file system
 deadlocks.  This is enabled via 'options DEBUG_LOCKS'

---
 sys/kern/kern_lock.c | 6 ++++++
 sys/sys/lockmgr.h    | 5 +++++
 2 files changed, 11 insertions(+)

diff --git a/sys/kern/kern_lock.c b/sys/kern/kern_lock.c
index fddfd26b69c..5189bb71567 100644
--- a/sys/kern/kern_lock.c
+++ b/sys/kern/kern_lock.c
@@ -259,6 +259,12 @@ debuglockmgr(lkp, flags, interlkp, td, name, file, line)
 			if (error)
 				break;
 			sharelock(lkp, 1);
+#if defined(DEBUG_LOCKS)
+			lkp->lk_slockholder = pid;
+			lkp->lk_sfilename = file;
+			lkp->lk_slineno = line;
+			lkp->lk_slockername = name;
+#endif
 			break;
 		}
 		/*
diff --git a/sys/sys/lockmgr.h b/sys/sys/lockmgr.h
index 9ba18847c70..b5bb25175d2 100644
--- a/sys/sys/lockmgr.h
+++ b/sys/sys/lockmgr.h
@@ -62,6 +62,11 @@ struct lock {
 	const char *lk_filename;
 	const char *lk_lockername;
 	int     lk_lineno;
+
+	pid_t	lk_slockholder;
+	const char *lk_sfilename;
+	const char *lk_slockername;
+	int     lk_slineno;
 #endif
 };
 /*