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authorPaul E. McKenney <paulmck@linux.vnet.ibm.com>2015-04-21 09:12:13 -0700
committerPaul E. McKenney <paulmck@linux.vnet.ibm.com>2015-05-27 12:59:05 -0700
commit47d631af58bb9b2f2dd3d0da8c98a79a5e75c738 (patch)
tree7472330c70684ac02140d2f3796b042b53a4f6dd
parent05c5df31afd1092ca6322094d22aff6351fa67fe (diff)
downloadlinux-47d631af58bb9b2f2dd3d0da8c98a79a5e75c738.tar.bz2
rcu: Make RCU able to tolerate undefined CONFIG_RCU_FANOUT_LEAF
This commit introduces an RCU_FANOUT_LEAF C-preprocessor macro so that RCU will build even when CONFIG_RCU_FANOUT_LEAF is undefined. The RCU_FANOUT_LEAF macro is set to the value of CONFIG_RCU_FANOUT_LEAF when defined, otherwise it is set to 32 for 32-bit systems and 64 for 64-bit systems. This commit then makes CONFIG_RCU_FANOUT_LEAF depend on CONFIG_RCU_EXPERT, so that Kconfig users won't be asked about CONFIG_RCU_FANOUT_LEAF unless they want to be. 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>
-rw-r--r--init/Kconfig2
-rw-r--r--kernel/rcu/tree.c8
-rw-r--r--kernel/rcu/tree.h12
-rw-r--r--kernel/rcu/tree_plugin.h6
4 files changed, 19 insertions, 9 deletions
diff --git a/init/Kconfig b/init/Kconfig
index fd2d4fb517ca..78176001f73b 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -603,7 +603,7 @@ config RCU_FANOUT_LEAF
int "Tree-based hierarchical RCU leaf-level fanout value"
range 2 64 if 64BIT
range 2 32 if !64BIT
- depends on TREE_RCU || PREEMPT_RCU
+ depends on (TREE_RCU || PREEMPT_RCU) && RCU_EXPERT
default 16
help
This option controls the leaf-level fanout of hierarchical
diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index ba3f8d59d948..1edd11298224 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -119,8 +119,8 @@ module_param(dump_tree, bool, 0444);
/* Control rcu_node-tree auto-balancing at boot time. */
static bool rcu_fanout_exact;
module_param(rcu_fanout_exact, bool, 0444);
-/* Increase (but not decrease) the CONFIG_RCU_FANOUT_LEAF at boot time. */
-static int rcu_fanout_leaf = CONFIG_RCU_FANOUT_LEAF;
+/* Increase (but not decrease) the RCU_FANOUT_LEAF at boot time. */
+static int rcu_fanout_leaf = RCU_FANOUT_LEAF;
module_param(rcu_fanout_leaf, int, 0444);
int rcu_num_lvls __read_mostly = RCU_NUM_LVLS;
static int num_rcu_lvl[] = { /* Number of rcu_nodes at specified level. */
@@ -4097,7 +4097,7 @@ static void __init rcu_init_geometry(void)
jiffies_till_next_fqs = d;
/* If the compile-time values are accurate, just leave. */
- if (rcu_fanout_leaf == CONFIG_RCU_FANOUT_LEAF &&
+ if (rcu_fanout_leaf == RCU_FANOUT_LEAF &&
nr_cpu_ids == NR_CPUS)
return;
pr_info("RCU: Adjusting geometry for rcu_fanout_leaf=%d, nr_cpu_ids=%d\n",
@@ -4121,7 +4121,7 @@ static void __init rcu_init_geometry(void)
* the configured number of CPUs. Complain and fall back to the
* compile-time values if these limits are exceeded.
*/
- if (rcu_fanout_leaf < CONFIG_RCU_FANOUT_LEAF ||
+ if (rcu_fanout_leaf < RCU_FANOUT_LEAF ||
rcu_fanout_leaf > sizeof(unsigned long) * 8 ||
n > rcu_capacity[MAX_RCU_LVLS]) {
WARN_ON(1);
diff --git a/kernel/rcu/tree.h b/kernel/rcu/tree.h
index ac3020fff028..7d949c186302 100644
--- a/kernel/rcu/tree.h
+++ b/kernel/rcu/tree.h
@@ -48,7 +48,17 @@
# endif
#endif /* #else #ifdef CONFIG_RCU_FANOUT */
-#define RCU_FANOUT_1 (CONFIG_RCU_FANOUT_LEAF)
+#ifdef CONFIG_RCU_FANOUT_LEAF
+#define RCU_FANOUT_LEAF CONFIG_RCU_FANOUT_LEAF
+#else /* #ifdef CONFIG_RCU_FANOUT_LEAF */
+# ifdef CONFIG_64BIT
+# define RCU_FANOUT_LEAF 64
+# else
+# define RCU_FANOUT_LEAF 32
+# endif
+#endif /* #else #ifdef CONFIG_RCU_FANOUT_LEAF */
+
+#define RCU_FANOUT_1 (RCU_FANOUT_LEAF)
#define RCU_FANOUT_2 (RCU_FANOUT_1 * RCU_FANOUT)
#define RCU_FANOUT_3 (RCU_FANOUT_2 * RCU_FANOUT)
#define RCU_FANOUT_4 (RCU_FANOUT_3 * RCU_FANOUT)
diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h
index d7e505970f24..713503853841 100644
--- a/kernel/rcu/tree_plugin.h
+++ b/kernel/rcu/tree_plugin.h
@@ -76,10 +76,10 @@ static void __init rcu_bootup_announce_oddness(void)
pr_info("\tAdditional per-CPU info printed with stalls.\n");
if (NUM_RCU_LVL_4 != 0)
pr_info("\tFour-level hierarchy is enabled.\n");
- if (CONFIG_RCU_FANOUT_LEAF != 16)
+ if (RCU_FANOUT_LEAF != 16)
pr_info("\tBuild-time adjustment of leaf fanout to %d.\n",
- CONFIG_RCU_FANOUT_LEAF);
- if (rcu_fanout_leaf != CONFIG_RCU_FANOUT_LEAF)
+ RCU_FANOUT_LEAF);
+ if (rcu_fanout_leaf != RCU_FANOUT_LEAF)
pr_info("\tBoot-time adjustment of leaf fanout to %d.\n", rcu_fanout_leaf);
if (nr_cpu_ids != NR_CPUS)
pr_info("\tRCU restricting CPUs from NR_CPUS=%d to nr_cpu_ids=%d.\n", NR_CPUS, nr_cpu_ids);