[PATCH v5 6/9] locking/lockdep: Introduce CONFIG_BOOTPARAM_LOCKDEP_CROSSRELEASE_FULLSTACK

Byungchul Park
2017-10-25T08:56:02Z

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 <mingo@kernel.org>
Signed-off-by: Byungchul Park <byungchul.park@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