[tip: locking/core] locking: Enable RT_MUTEXES by default on PREEMPT_RT.

[tip-bot2 for Sebastian Andrzej Siewior]

The following commit has been merged into the locking/core branch of tip:

Commit-ID:     1c6f9ec0095459b5120a1cb059d442f56d3cb6e7
Gitweb:        https://git.kernel.org/tip/1c6f9ec0095459b5120a1cb059d442f56d3cb6e7
Author:        Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx>
AuthorDate:    Tue, 08 Feb 2022 18:21:10 +01:00
Committer:     Peter Zijlstra <peterz@xxxxxxxxxxxxx>
CommitterDate: Fri, 11 Feb 2022 12:13:56 +01:00

locking: Enable RT_MUTEXES by default on PREEMPT_RT.

The CONFIG_RT_MUTEXES option is enabled by CONFIG_FUTEX and CONFIG_I2C.
If both are disabled then a CONFIG_PREEMPT_RT build fails to compile.
It is not possible to have a PREEMPT_RT kernel without RT_MUTEX support
because RT_MUTEX based locking is always used.

Enable CONFIG_RT_MUTEXES by default on PREEMPT_RT builds.

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx>
Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Link: https://lkml.kernel.org/r/YgKmhjkcuqWXdUjQ@xxxxxxxxxxxxx
---
 init/Kconfig | 1 +
 1 file changed, 1 insertion(+)

diff --git a/init/Kconfig b/init/Kconfig
index e9119bf..beb5b86 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -2054,6 +2054,7 @@ source "arch/Kconfig"
 
 config RT_MUTEXES
 	bool
+	default y if PREEMPT_RT
 
 config BASE_SMALL
 	int