[PATCH] cpumask: limit visibility of FORCE_NR_CPUS

[Yury Norov]

In current form, FORCE_NR_CPUS is visible to all users building their
kernels, even not experts. It is also set in allmodconfig or allyesconfig,
which is not a correct behavior.

Suggested-by: Geert Uytterhoeven <geert@xxxxxxxxxxxxxx>
Suggested-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Yury Norov <yury.norov@xxxxxxxxx>
---
 lib/Kconfig | 31 ++++++++++++++++++++++++-------
 1 file changed, 24 insertions(+), 7 deletions(-)

diff --git a/lib/Kconfig b/lib/Kconfig
index 9bbf8a4b2108..1ada12f5dda6 100644
--- a/lib/Kconfig
+++ b/lib/Kconfig
@@ -528,14 +528,31 @@ config CPUMASK_OFFSTACK
 	  them on the stack.  This is a bit more expensive, but avoids
 	  stack overflow.
 
+choice
+	prompt "Number of CPUs detection method"
+	default UNFORCE_NR_CPUS
+	depends on SMP && EXPERT
+	help
+	  Select between boot-time and compile-time detection of number
+	  of CPUs. If it's possible to provide exact number of CPUs at
+	  compile-time, kernel code may be optimized better.
+	  For general-purpose kernel, choose "boot time" option.
+
+config UNFORCE_NR_CPUS
+	bool "Set number of CPUs at boot time"
+	help
+	  Choose it if you build general-purpose kernel and want to rely
+	  on kernel to detect actual number of CPUs.
+
 config FORCE_NR_CPUS
-       bool "NR_CPUS is set to an actual number of CPUs"
-       depends on SMP
-       help
-         Say Yes if you have NR_CPUS set to an actual number of possible
-         CPUs in your system, not to a default value. This forces the core
-         code to rely on compile-time value and optimize kernel routines
-         better.
+	bool "Set number of CPUs at compile time"
+	help
+	  Choose it if NR_CPUS corresponds to an actual number of
+	  possible CPUs in your system. This forces the core code
+	  to rely on compile-time value and optimize kernel routines
+	  better.
+
+endchoice
 
 config CPU_RMAP
 	bool
-- 
2.34.1