rcu: Drive configuration directly from SMP and PREEMPT

This commit eliminates the possibility of running TREE_PREEMPT_RCU
when SMP=n and of running TINY_RCU when PREEMPT=y.  People who really
want these combinations can hand-edit init/Kconfig, but eliminating
them as choices for production systems reduces the amount of testing
required.  It will also allow cutting out a few #ifdefs.

Note that running TREE_RCU and TINY_RCU on single-CPU systems using
SMP-built kernels is still supported.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>

1 files changed, 3 insertions, 3 deletions

diff --git a/init/Kconfig b/init/Kconfig
index d62778390e55..dc7e27bf89a8 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -391,7 +391,7 @@ config TREE_RCU
 
 config TREE_PREEMPT_RCU
         bool "Preemptible tree-based hierarchical RCU"
-        depends on PREEMPT
+        depends on PREEMPT && SMP
         help
           This option selects the RCU implementation that is
           designed for very large SMP systems with hundreds or
@@ -401,7 +401,7 @@ config TREE_PREEMPT_RCU
 
 config TINY_RCU
         bool "UP-only small-memory-footprint RCU"
-        depends on !SMP
+        depends on !PREEMPT && !SMP
         help
           This option selects the RCU implementation that is
           designed for UP systems from which real-time response
@@ -410,7 +410,7 @@ config TINY_RCU
 
 config TINY_PREEMPT_RCU
         bool "Preemptible UP-only small-memory-footprint RCU"
-        depends on !SMP && PREEMPT
+        depends on PREEMPT && !SMP
         help
           This option selects the RCU implementation that is designed
           for real-time UP systems.  This option greatly reduces the