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>
diff --git a/init/Kconfig b/init/Kconfig
index d627783..dc7e27b 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -391,7 +391,7 @@
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 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_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
