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Subject[tip:locking/core] locking/lockdep: Introduce CONFIG_BOOTPARAM_LOCKDEP_CROSSRELEASE_FULLSTACK=y
Commit-ID:  e121d64e16484d4a5eba94cd2fa9eb3848b7c9c2
Gitweb: https://git.kernel.org/tip/e121d64e16484d4a5eba94cd2fa9eb3848b7c9c2
Author: Byungchul Park <byungchul.park@lge.com>
AuthorDate: Wed, 25 Oct 2017 17:56:02 +0900
Committer: Ingo Molnar <mingo@kernel.org>
CommitDate: Wed, 25 Oct 2017 12:19:02 +0200

locking/lockdep: Introduce CONFIG_BOOTPARAM_LOCKDEP_CROSSRELEASE_FULLSTACK=y

Add a Kconfig knob that enables the lockdep "crossrelease_fullstack" boot parameter.

Suggested-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Byungchul Park <byungchul.park@lge.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: amir73il@gmail.com
Cc: axboe@kernel.dk
Cc: darrick.wong@oracle.com
Cc: david@fromorbit.com
Cc: hch@infradead.org
Cc: idryomov@gmail.com
Cc: johan@kernel.org
Cc: johannes.berg@intel.com
Cc: kernel-team@lge.com
Cc: linux-block@vger.kernel.org
Cc: linux-fsdevel@vger.kernel.org
Cc: linux-mm@kvack.org
Cc: linux-xfs@vger.kernel.org
Cc: oleg@redhat.com
Cc: tj@kernel.org
Link: http://lkml.kernel.org/r/1508921765-15396-7-git-send-email-byungchul.park@lge.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
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 @@ module_param(lock_stat, int, 0644);
#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 c1e720a..2b439a5 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -1179,6 +1179,21 @@ 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
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