[RFC PATCH] rcu: config: Remove prompt for RCU implementation

[RFC PATCH] rcu: config: Remove prompt for RCU implementation

[Pranith Kumar]

The RCU implementation which is chosen is dependent on PREEMPT and SMP config
options and is not really a user-selectable choice. The following change will
remove the menu entry and will be derived from the above two options.

Signed-off-by: Pranith Kumar <bobby.prani@gmail.com>
---
 init/Kconfig | 18 ++++++------------
 1 file changed, 6 insertions(+), 12 deletions(-)

diff --git a/init/Kconfig b/init/Kconfig
index 0b37750..7707e4a 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -463,13 +463,9 @@ endmenu # "CPU/Task time and stats accounting"
 
 menu "RCU Subsystem"
 
-choice
-	prompt "RCU Implementation"
-	default TREE_RCU
-
 config TREE_RCU
-	bool "Tree-based hierarchical RCU"
-	depends on !PREEMPT && SMP
+	bool
+	default y if !PREEMPT && SMP
 	help
 	  This option selects the RCU implementation that is
 	  designed for very large SMP system with hundreds or
@@ -477,8 +473,8 @@ config TREE_RCU
 	  smaller systems.
 
 config PREEMPT_RCU
-	bool "Preemptible tree-based hierarchical RCU"
-	depends on PREEMPT
+	bool
+	default y if PREEMPT
 	help
 	  This option selects the RCU implementation that is
 	  designed for very large SMP systems with hundreds or
@@ -489,16 +485,14 @@ config PREEMPT_RCU
 	  Select this option if you are unsure.
 
 config TINY_RCU
-	bool "UP-only small-memory-footprint RCU"
-	depends on !PREEMPT && !SMP
+	bool
+	default y if !PREEMPT && !SMP
 	help
 	  This option selects the RCU implementation that is
 	  designed for UP systems from which real-time response
 	  is not required.  This option greatly reduces the
 	  memory footprint of RCU.
 
-endchoice
-
 config RCU_EXPERT
 	bool "Make expert-level adjustments to RCU configuration"
 	default n
-- 
1.9.1

Re: [RFC PATCH] rcu: config: Remove prompt for RCU implementation

[Paul E. McKenney]

On Tue, Apr 21, 2015 at 05:29:42PM -0400, Pranith Kumar wrote:
> The RCU implementation which is chosen is dependent on PREEMPT and SMP config
> options and is not really a user-selectable choice. The following change will
> remove the menu entry and will be derived from the above two options.
> 
> Signed-off-by: Pranith Kumar <bobby.prani@gmail.com>

Hmmm...  I guess that there isn't much point in calling something a
"choice" when it hasn't really been a choice for quite a few years
now.  I queued this, and have started testing it.

							Thanx, Paul

> ---
>  init/Kconfig | 18 ++++++------------
>  1 file changed, 6 insertions(+), 12 deletions(-)
> 
> diff --git a/init/Kconfig b/init/Kconfig
> index 0b37750..7707e4a 100644
> --- a/init/Kconfig
> +++ b/init/Kconfig
> @@ -463,13 +463,9 @@ endmenu # "CPU/Task time and stats accounting"
> 
>  menu "RCU Subsystem"
> 
> -choice
> -	prompt "RCU Implementation"
> -	default TREE_RCU
> -
>  config TREE_RCU
> -	bool "Tree-based hierarchical RCU"
> -	depends on !PREEMPT && SMP
> +	bool
> +	default y if !PREEMPT && SMP
>  	help
>  	  This option selects the RCU implementation that is
>  	  designed for very large SMP system with hundreds or
> @@ -477,8 +473,8 @@ config TREE_RCU
>  	  smaller systems.
> 
>  config PREEMPT_RCU
> -	bool "Preemptible tree-based hierarchical RCU"
> -	depends on PREEMPT
> +	bool
> +	default y if PREEMPT
>  	help
>  	  This option selects the RCU implementation that is
>  	  designed for very large SMP systems with hundreds or
> @@ -489,16 +485,14 @@ config PREEMPT_RCU
>  	  Select this option if you are unsure.
> 
>  config TINY_RCU
> -	bool "UP-only small-memory-footprint RCU"
> -	depends on !PREEMPT && !SMP
> +	bool
> +	default y if !PREEMPT && !SMP
>  	help
>  	  This option selects the RCU implementation that is
>  	  designed for UP systems from which real-time response
>  	  is not required.  This option greatly reduces the
>  	  memory footprint of RCU.
> 
> -endchoice
> -
>  config RCU_EXPERT
>  	bool "Make expert-level adjustments to RCU configuration"
>  	default n
> -- 
> 1.9.1
>