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>
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@@ -119,8 +119,8 @@ module_param(dump_tree, bool, 0444);
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/* Control rcu_node-tree auto-balancing at boot time. */
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static bool rcu_fanout_exact;
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module_param(rcu_fanout_exact, bool, 0444);
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/* Increase (but not decrease) the CONFIG_RCU_FANOUT_LEAF at boot time. */
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static int rcu_fanout_leaf = CONFIG_RCU_FANOUT_LEAF;
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/* Increase (but not decrease) the RCU_FANOUT_LEAF at boot time. */
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static int rcu_fanout_leaf = RCU_FANOUT_LEAF;
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module_param(rcu_fanout_leaf, int, 0444);
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int rcu_num_lvls __read_mostly = RCU_NUM_LVLS;
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static int num_rcu_lvl[] = { /* Number of rcu_nodes at specified level. */
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@@ -4097,7 +4097,7 @@ static void __init rcu_init_geometry(void)
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jiffies_till_next_fqs = d;
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/* If the compile-time values are accurate, just leave. */
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if (rcu_fanout_leaf == CONFIG_RCU_FANOUT_LEAF &&
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if (rcu_fanout_leaf == RCU_FANOUT_LEAF &&
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nr_cpu_ids == NR_CPUS)
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return;
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pr_info("RCU: Adjusting geometry for rcu_fanout_leaf=%d, nr_cpu_ids=%d\n",
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@@ -4121,7 +4121,7 @@ static void __init rcu_init_geometry(void)
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* the configured number of CPUs. Complain and fall back to the
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* compile-time values if these limits are exceeded.
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*/
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if (rcu_fanout_leaf < CONFIG_RCU_FANOUT_LEAF ||
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if (rcu_fanout_leaf < RCU_FANOUT_LEAF ||
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rcu_fanout_leaf > sizeof(unsigned long) * 8 ||
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n > rcu_capacity[MAX_RCU_LVLS]) {
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WARN_ON(1);
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