rcu: Convert CONFIG_RCU_FANOUT_EXACT to boot parameter
The CONFIG_RCU_FANOUT_EXACT Kconfig parameter is used primarily (and
perhaps only) by rcutorture to verify that RCU works correctly in specific
rcu_node combining-tree configurations. It therefore does not make
much sense have this as a question to people attempting to configure
their kernels. So this commit creates an rcutree.rcu_fanout_exact=
boot parameter that rcutorture can use, and eliminates the original
CONFIG_RCU_FANOUT_EXACT Kconfig parameter.
Reported-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Pranith Kumar <bobby.prani@gmail.com>
diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h
index 58b1ebd..eb460ec 100644
--- a/kernel/rcu/tree_plugin.h
+++ b/kernel/rcu/tree_plugin.h
@@ -64,7 +64,7 @@
(!IS_ENABLED(CONFIG_64BIT) && CONFIG_RCU_FANOUT != 32))
pr_info("\tCONFIG_RCU_FANOUT set to non-default value of %d\n",
CONFIG_RCU_FANOUT);
- if (IS_ENABLED(CONFIG_RCU_FANOUT_EXACT))
+ if (rcu_fanout_exact)
pr_info("\tHierarchical RCU autobalancing is disabled.\n");
if (IS_ENABLED(CONFIG_RCU_FAST_NO_HZ))
pr_info("\tRCU dyntick-idle grace-period acceleration is enabled.\n");