Re: [PATCH] locking/lockdep: Make CONFIG_LOCKDEP_CROSSRELEASE and CONFIG_LOCKDEP_COMPLETIONS optional

From: Byungchul Park
Date: Tue Dec 12 2017 - 02:15:38 EST


+cc david@xxxxxxxxxxxxx
+cc tytso@xxxxxxx
+cc willy@xxxxxxxxxxxxx
+cc torvalds@xxxxxxxxxxxxxxxxxxxx
+cc amir73il@xxxxxxxxx

On 12/12/2017 4:11 PM, Byungchul Park wrote:
At the moment, it's rather premature to enable
CONFIG_LOCKDEP_CROSSRELEASE and CONFIG_LOCKDEP_COMPLETIONS by default,
because we face a lot of false positives for now since all locks and
waiters are not classified properly yet.

Until most of them get annotated properly, it'd be better to be optional.

Signed-off-by: Byungchul Park <byungchul.park@xxxxxxx>
---
lib/Kconfig.debug | 11 +++++++----
1 file changed, 7 insertions(+), 4 deletions(-)

diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index 2689b7c..bc099f1 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -1092,8 +1092,6 @@ config PROVE_LOCKING
select DEBUG_MUTEXES
select DEBUG_RT_MUTEXES if RT_MUTEXES
select DEBUG_LOCK_ALLOC
- select LOCKDEP_CROSSRELEASE
- select LOCKDEP_COMPLETIONS
select TRACE_IRQFLAGS
default n
help
@@ -1164,7 +1162,9 @@ config LOCK_STAT
(CONFIG_LOCKDEP defines "acquire" and "release" events.)
config LOCKDEP_CROSSRELEASE
- bool
+ bool "Lock debugging: enable cross-locking checks in lockdep"
+ depends on PROVE_LOCKING
+ default n
help
This makes lockdep work for crosslock which is a lock allowed to
be released in a different context from the acquisition context.
@@ -1174,7 +1174,10 @@ config LOCKDEP_CROSSRELEASE
detector, lockdep.
config LOCKDEP_COMPLETIONS
- bool
+ bool "Lock debugging: allow completions to use deadlock detector"
+ depends on PROVE_LOCKING
+ select LOCKDEP_CROSSRELEASE
+ default n
help
A deadlock caused by wait_for_completion() and complete() can be
detected by lockdep using crossrelease feature.


--
Thanks,
Byungchul