From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933390AbbDUT5P (ORCPT ); Tue, 21 Apr 2015 15:57:15 -0400 Received: from e33.co.us.ibm.com ([32.97.110.151]:43322 "EHLO e33.co.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933105AbbDUT4E (ORCPT ); Tue, 21 Apr 2015 15:56:04 -0400 From: "Paul E. McKenney" To: linux-kernel@vger.kernel.org Cc: mingo@kernel.org, laijs@cn.fujitsu.com, dipankar@in.ibm.com, akpm@linux-foundation.org, mathieu.desnoyers@efficios.com, josh@joshtriplett.org, tglx@linutronix.de, peterz@infradead.org, rostedt@goodmis.org, dhowells@redhat.com, edumazet@google.com, dvhart@linux.intel.com, fweisbec@gmail.com, oleg@redhat.com, bobby.prani@gmail.com, "Paul E. McKenney" Subject: [PATCH tip/core/rcu 10/12] rcu: Make RCU able to tolerate undefined CONFIG_RCU_FANOUT Date: Tue, 21 Apr 2015 12:55:51 -0700 Message-Id: <1429646153-20677-10-git-send-email-paulmck@linux.vnet.ibm.com> X-Mailer: git-send-email 1.8.1.5 In-Reply-To: <1429646153-20677-1-git-send-email-paulmck@linux.vnet.ibm.com> References: <20150421195529.GA17864@linux.vnet.ibm.com> <1429646153-20677-1-git-send-email-paulmck@linux.vnet.ibm.com> X-TM-AS-MML: disable X-Content-Scanned: Fidelis XPS MAILER x-cbid: 15042119-0009-0000-0000-00000A4456A4 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: "Paul E. McKenney" 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 Signed-off-by: Paul E. McKenney --- 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 35559e07db18..efb098ac159d 100644 --- a/init/Kconfig +++ b/init/Kconfig @@ -581,7 +581,7 @@ 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 c8b3700918e6..6fb8e2f0ec19 100644 --- a/kernel/rcu/tree.c +++ b/kernel/rcu/tree.c @@ -3952,7 +3952,7 @@ 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; @@ -4083,7 +4083,7 @@ 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 f12fe832dbd3..ecb259273139 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 074689cedda9..2e52502bfc95 100644 --- a/kernel/rcu/tree_plugin.h +++ b/kernel/rcu/tree_plugin.h @@ -70,10 +70,10 @@ 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