The boot parameter, crossrelease_fullstack, was introduced to control
whether to enable unwind in cross-release or not. Add a Kconfig doing
the same thing.

Suggested-by: Ingo Molnar <mi...@kernel.org>
Signed-off-by: Byungchul Park <byungchul.p...@lge.com>
---
 kernel/locking/lockdep.c |  4 ++++
 lib/Kconfig.debug        | 15 +++++++++++++++
 2 files changed, 19 insertions(+)

diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c
index 160b5d6..db933d0 100644
--- a/kernel/locking/lockdep.c
+++ b/kernel/locking/lockdep.c
@@ -76,7 +76,11 @@
 #define lock_stat 0
 #endif
 
+#ifdef CONFIG_BOOTPARAM_LOCKDEP_CROSSRELEASE_FULLSTACK
+static int crossrelease_fullstack = 1;
+#else
 static int crossrelease_fullstack;
+#endif
 static int __init allow_crossrelease_fullstack(char *str)
 {
        crossrelease_fullstack = 1;
diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index 4bef610..e4b54a5 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -1225,6 +1225,21 @@ config LOCKDEP_COMPLETIONS
         A deadlock caused by wait_for_completion() and complete() can be
         detected by lockdep using crossrelease feature.
 
+config BOOTPARAM_LOCKDEP_CROSSRELEASE_FULLSTACK
+       bool "Enable the boot parameter, crossrelease_fullstack"
+       depends on LOCKDEP_CROSSRELEASE
+       default n
+       help
+        The lockdep "cross-release" feature needs to record stack traces
+        (of calling functions) for all acquisitions, for eventual later
+        use during analysis. By default only a single caller is recorded,
+        because the unwind operation can be very expensive with deeper
+        stack chains.
+
+        However a boot parameter, crossrelease_fullstack, was
+        introduced since sometimes deeper traces are required for full
+        analysis. This option turns on the boot parameter.
+
 config DEBUG_LOCKDEP
        bool "Lock dependency engine debugging"
        depends on DEBUG_KERNEL && LOCKDEP
-- 
1.9.1

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