From: "Paul E. McKenney" <[email protected]> This commit introduces an RCU_FANOUT C-preprocessor macro so that RCU will build even when CONFIG_RCU_FANOUT is undefined. The RCU_FANOUT macro is set to the value of CONFIG_RCU_FANOUT 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 depend on CONFIG_RCU_EXPERT, so that Kconfig users won't be asked about CONFIG_RCU_FANOUT unless they want to be.
Reported-by: Ingo Molnar <[email protected]> Signed-off-by: Paul E. McKenney <[email protected]> Reviewed-by: Pranith Kumar <[email protected]> --- init/Kconfig | 2 +- kernel/rcu/tree.c | 4 ++-- kernel/rcu/tree.h | 17 ++++++++++++++--- kernel/rcu/tree_plugin.h | 6 +++--- 4 files changed, 20 insertions(+), 9 deletions(-) diff --git a/init/Kconfig b/init/Kconfig index ac5386937d37..fd2d4fb517ca 100644 --- a/init/Kconfig +++ b/init/Kconfig @@ -583,7 +583,7 @@ config RCU_FANOUT int "Tree-based hierarchical RCU 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 64 if 64BIT default 32 if !64BIT help diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c index 01719402fe8e..4b27a7c0926f 100644 --- a/kernel/rcu/tree.c +++ b/kernel/rcu/tree.c @@ -3966,7 +3966,7 @@ static void __init rcu_init_levelspread(int *levelspread, const int *levelcnt) if (rcu_fanout_exact) { levelspread[rcu_num_lvls - 1] = rcu_fanout_leaf; for (i = rcu_num_lvls - 2; i >= 0; i--) - levelspread[i] = CONFIG_RCU_FANOUT; + levelspread[i] = RCU_FANOUT; } else { int ccur; int cprv; @@ -4097,7 +4097,7 @@ static void __init rcu_init_geometry(void) */ rcu_capacity[0] = rcu_fanout_leaf; for (i = 1; i < RCU_NUM_LVLS; i++) - rcu_capacity[i] = rcu_capacity[i - 1] * CONFIG_RCU_FANOUT; + rcu_capacity[i] = rcu_capacity[i - 1] * RCU_FANOUT; /* * The tree must be able to accommodate the configured number of CPUs. diff --git a/kernel/rcu/tree.h b/kernel/rcu/tree.h index 5f294267ed20..7ca17b646428 100644 --- a/kernel/rcu/tree.h +++ b/kernel/rcu/tree.h @@ -35,10 +35,21 @@ * In practice, this did work well going from three levels to four. * Of course, your mileage may vary. */ + +#ifdef CONFIG_RCU_FANOUT +#define RCU_FANOUT CONFIG_RCU_FANOUT +#else /* #ifdef CONFIG_RCU_FANOUT */ +# ifdef CONFIG_64BIT +# define RCU_FANOUT 64 +# else +# define RCU_FANOUT 32 +# endif +#endif /* #else #ifdef CONFIG_RCU_FANOUT */ + #define RCU_FANOUT_1 (CONFIG_RCU_FANOUT_LEAF) -#define RCU_FANOUT_2 (RCU_FANOUT_1 * CONFIG_RCU_FANOUT) -#define RCU_FANOUT_3 (RCU_FANOUT_2 * CONFIG_RCU_FANOUT) -#define RCU_FANOUT_4 (RCU_FANOUT_3 * CONFIG_RCU_FANOUT) +#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) #if NR_CPUS <= RCU_FANOUT_1 # define RCU_NUM_LVLS 1 diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h index 3eb1cda880c8..ca0f54cbba0e 100644 --- a/kernel/rcu/tree_plugin.h +++ b/kernel/rcu/tree_plugin.h @@ -60,10 +60,10 @@ static void __init rcu_bootup_announce_oddness(void) { if (IS_ENABLED(CONFIG_RCU_TRACE)) pr_info("\tRCU debugfs-based tracing is enabled.\n"); - if ((IS_ENABLED(CONFIG_64BIT) && CONFIG_RCU_FANOUT != 64) || - (!IS_ENABLED(CONFIG_64BIT) && CONFIG_RCU_FANOUT != 32)) + if ((IS_ENABLED(CONFIG_64BIT) && RCU_FANOUT != 64) || + (!IS_ENABLED(CONFIG_64BIT) && RCU_FANOUT != 32)) pr_info("\tCONFIG_RCU_FANOUT set to non-default value of %d\n", - CONFIG_RCU_FANOUT); + RCU_FANOUT); if (rcu_fanout_exact) pr_info("\tHierarchical RCU autobalancing is disabled.\n"); if (IS_ENABLED(CONFIG_RCU_FAST_NO_HZ)) -- 1.8.1.5 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
