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

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

[Byungchul Park]

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@lge.com>
---
 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.
-- 
1.9.1

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

[Byungchul Park]

+cc david@fromorbit.com
+cc tytso@mit.edu
+cc willy@infradead.org
+cc torvalds@linux-foundation.org
+cc amir73il@gmail.com

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@lge.com>
> ---
>   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

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