1 files changed, 29 insertions, 32 deletions

diff --git a/kernel/rcutree.h b/kernel/rcutree.h
index 91d4170c5c13..e8f057e44e3e 100644
--- a/kernel/rcutree.h
+++ b/kernel/rcutree.h
@@ -31,46 +31,51 @@
 /*
  * Define shape of hierarchy based on NR_CPUS and CONFIG_RCU_FANOUT.
  * In theory, it should be possible to add more levels straightforwardly.
- * In practice, this has not been tested, so there is probably some
- * bug somewhere.
+ * In practice, this did work well going from three levels to four.
+ * Of course, your mileage may vary.
  */
 #define MAX_RCU_LVLS 4
-#define RCU_FANOUT            (CONFIG_RCU_FANOUT)
-#define RCU_FANOUT_SQ         (RCU_FANOUT * RCU_FANOUT)
-#define RCU_FANOUT_CUBE       (RCU_FANOUT_SQ * RCU_FANOUT)
-#define RCU_FANOUT_FOURTH     (RCU_FANOUT_CUBE * RCU_FANOUT)
-
-#if NR_CPUS <= RCU_FANOUT
+#if CONFIG_RCU_FANOUT > 16
+#define RCU_FANOUT_LEAF       16
+#else /* #if CONFIG_RCU_FANOUT > 16 */
+#define RCU_FANOUT_LEAF       (CONFIG_RCU_FANOUT)
+#endif /* #else #if CONFIG_RCU_FANOUT > 16 */
+#define RCU_FANOUT_1          (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)
+
+#if NR_CPUS <= RCU_FANOUT_1
 #  define NUM_RCU_LVLS        1
 #  define NUM_RCU_LVL_0       1
 #  define NUM_RCU_LVL_1       (NR_CPUS)
 #  define NUM_RCU_LVL_2       0
 #  define NUM_RCU_LVL_3       0
 #  define NUM_RCU_LVL_4       0
-#elif NR_CPUS <= RCU_FANOUT_SQ
+#elif NR_CPUS <= RCU_FANOUT_2
 #  define NUM_RCU_LVLS        2
 #  define NUM_RCU_LVL_0       1
-#  define NUM_RCU_LVL_1       DIV_ROUND_UP(NR_CPUS, RCU_FANOUT)
+#  define NUM_RCU_LVL_1       DIV_ROUND_UP(NR_CPUS, RCU_FANOUT_1)
 #  define NUM_RCU_LVL_2       (NR_CPUS)
 #  define NUM_RCU_LVL_3       0
 #  define NUM_RCU_LVL_4       0
-#elif NR_CPUS <= RCU_FANOUT_CUBE
+#elif NR_CPUS <= RCU_FANOUT_3
 #  define NUM_RCU_LVLS        3
 #  define NUM_RCU_LVL_0       1
-#  define NUM_RCU_LVL_1       DIV_ROUND_UP(NR_CPUS, RCU_FANOUT_SQ)
-#  define NUM_RCU_LVL_2       DIV_ROUND_UP(NR_CPUS, RCU_FANOUT)
-#  define NUM_RCU_LVL_3       NR_CPUS
+#  define NUM_RCU_LVL_1       DIV_ROUND_UP(NR_CPUS, RCU_FANOUT_2)
+#  define NUM_RCU_LVL_2       DIV_ROUND_UP(NR_CPUS, RCU_FANOUT_1)
+#  define NUM_RCU_LVL_3       (NR_CPUS)
 #  define NUM_RCU_LVL_4       0
-#elif NR_CPUS <= RCU_FANOUT_FOURTH
+#elif NR_CPUS <= RCU_FANOUT_4
 #  define NUM_RCU_LVLS        4
 #  define NUM_RCU_LVL_0       1
-#  define NUM_RCU_LVL_1       DIV_ROUND_UP(NR_CPUS, RCU_FANOUT_CUBE)
-#  define NUM_RCU_LVL_2       DIV_ROUND_UP(NR_CPUS, RCU_FANOUT_SQ)
-#  define NUM_RCU_LVL_3       DIV_ROUND_UP(NR_CPUS, RCU_FANOUT)
-#  define NUM_RCU_LVL_4       NR_CPUS
+#  define NUM_RCU_LVL_1       DIV_ROUND_UP(NR_CPUS, RCU_FANOUT_3)
+#  define NUM_RCU_LVL_2       DIV_ROUND_UP(NR_CPUS, RCU_FANOUT_2)
+#  define NUM_RCU_LVL_3       DIV_ROUND_UP(NR_CPUS, RCU_FANOUT_1)
+#  define NUM_RCU_LVL_4       (NR_CPUS)
 #else
 # error "CONFIG_RCU_FANOUT insufficient for NR_CPUS"
-#endif /* #if (NR_CPUS) <= RCU_FANOUT */
+#endif /* #if (NR_CPUS) <= RCU_FANOUT_1 */
 
 #define RCU_SUM (NUM_RCU_LVL_0 + NUM_RCU_LVL_1 + NUM_RCU_LVL_2 + NUM_RCU_LVL_3 + NUM_RCU_LVL_4)
 #define NUM_RCU_NODES (RCU_SUM - NR_CPUS)
@@ -203,8 +208,8 @@ struct rcu_data {
         long            qlen_last_fqs_check;
                                         /* qlen at last check for QS forcing */
         unsigned long   n_cbs_invoked;  /* count of RCU cbs invoked. */
-        unsigned long   n_cbs_orphaned; /* RCU cbs sent to orphanage. */
-        unsigned long   n_cbs_adopted;  /* RCU cbs adopted from orphanage. */
+        unsigned long   n_cbs_orphaned; /* RCU cbs orphaned by dying CPU */
+        unsigned long   n_cbs_adopted;  /* RCU cbs adopted from dying CPU */
         unsigned long   n_force_qs_snap;
                                         /* did other CPU force QS recently? */
         long            blimit;         /* Upper limit on a processed batch */
@@ -309,15 +314,7 @@ struct rcu_state {
         /* End of fields guarded by root rcu_node's lock. */
 
         raw_spinlock_t onofflock;               /* exclude on/offline and */
-                                                /*  starting new GP.  Also */
-                                                /*  protects the following */
-                                                /*  orphan_cbs fields. */
-        struct rcu_head *orphan_cbs_list;       /* list of rcu_head structs */
-                                                /*  orphaned by all CPUs in */
-                                                /*  a given leaf rcu_node */
-                                                /*  going offline. */
-        struct rcu_head **orphan_cbs_tail;      /* And tail pointer. */
-        long orphan_qlen;                       /* Number of orphaned cbs. */
+                                                /*  starting new GP. */
         raw_spinlock_t fqslock;                 /* Only one task forcing */
                                                 /*  quiescent states. */
         unsigned long jiffies_force_qs;         /* Time at which to invoke */
@@ -390,7 +387,7 @@ static void rcu_report_exp_rnp(struct rcu_state *rsp, struct rcu_node *rnp);
 static int rcu_preempt_pending(int cpu);
 static int rcu_preempt_needs_cpu(int cpu);
 static void __cpuinit rcu_preempt_init_percpu_data(int cpu);
-static void rcu_preempt_send_cbs_to_orphanage(void);
+static void rcu_preempt_send_cbs_to_online(void);
 static void __init __rcu_init_preempt(void);
 static void rcu_needs_cpu_flush(void);