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| author | Paul E. McKenney <paulmck@linux.vnet.ibm.com> | 2015-04-20 23:27:43 +0200 |
|---|---|---|
| committer | Paul E. McKenney <paulmck@linux.vnet.ibm.com> | 2015-05-27 21:59:05 +0200 |
| commit | 05c5df31afd1092ca6322094d22aff6351fa67fe (patch) | |
| tree | dffce93d8da097a4701bfdafe4c23323371cd899 | |
| parent | rcu: Break dependency of RCU_FANOUT_LEAF on RCU_FANOUT (diff) | |
| download | linux-05c5df31afd1092ca6322094d22aff6351fa67fe.tar.xz linux-05c5df31afd1092ca6322094d22aff6351fa67fe.zip | |
rcu: Make RCU able to tolerate undefined CONFIG_RCU_FANOUT
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 <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/Kconfig | 2 | ||||
| -rw-r--r-- | kernel/rcu/tree.c | 4 | ||||
| -rw-r--r-- | kernel/rcu/tree.h | 18 | ||||
| -rw-r--r-- | kernel/rcu/tree_plugin.h | 6 |
4 files changed, 21 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 1bc14c670641..ba3f8d59d948 100644 --- a/kernel/rcu/tree.c +++ b/kernel/rcu/tree.c @@ -3971,7 +3971,7 @@ static void __init rcu_init_levelspread(struct rcu_state *rsp) if (rcu_fanout_exact) { rsp->levelspread[rcu_num_lvls - 1] = rcu_fanout_leaf; for (i = rcu_num_lvls - 2; i >= 0; i--) - rsp->levelspread[i] = CONFIG_RCU_FANOUT; + rsp->levelspread[i] = RCU_FANOUT; } else { int ccur; int cprv; @@ -4111,7 +4111,7 @@ static void __init rcu_init_geometry(void) rcu_capacity[0] = 1; rcu_capacity[1] = rcu_fanout_leaf; for (i = 2; i <= MAX_RCU_LVLS; i++) - rcu_capacity[i] = rcu_capacity[i - 1] * CONFIG_RCU_FANOUT; + rcu_capacity[i] = rcu_capacity[i - 1] * RCU_FANOUT; /* * The boot-time rcu_fanout_leaf parameter is only permitted diff --git a/kernel/rcu/tree.h b/kernel/rcu/tree.h index a69d3dab2ec4..ac3020fff028 100644 --- a/kernel/rcu/tree.h +++ b/kernel/rcu/tree.h @@ -35,11 +35,23 @@ * In practice, this did work well going from three levels to four. * Of course, your mileage may vary. */ + #define MAX_RCU_LVLS 4 + +#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 eb460ec747ef..d7e505970f24 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)) |