1 files changed, 137 insertions, 56 deletions

diff --git a/kernel/rcutree.h b/kernel/rcutree.h
index 14c040b18ed0..01b2ccda26fb 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)
@@ -79,13 +84,19 @@
  * Dynticks per-CPU state.
  */
 struct rcu_dynticks {
-        int dynticks_nesting;   /* Track nesting level, sort of. */
-        int dynticks;           /* Even value for dynticks-idle, else odd. */
-        int dynticks_nmi;       /* Even value for either dynticks-idle or */
-                                /*  not in nmi handler, else odd.  So this */
-                                /*  remains even for nmi from irq handler. */
+        int dynticks_nesting;   /* Track irq/process nesting level. */
+        int dynticks_nmi_nesting; /* Track NMI nesting level. */
+        atomic_t dynticks;      /* Even value for dynticks-idle, else odd. */
 };
 
+/* RCU's kthread states for tracing. */
+#define RCU_KTHREAD_STOPPED  0
+#define RCU_KTHREAD_RUNNING  1
+#define RCU_KTHREAD_WAITING  2
+#define RCU_KTHREAD_OFFCPU   3
+#define RCU_KTHREAD_YIELDING 4
+#define RCU_KTHREAD_MAX      4
+
 /*
  * Definition for node within the RCU grace-period-detection hierarchy.
  */
@@ -104,10 +115,13 @@ struct rcu_node {
                                 /*  an rcu_data structure, otherwise, each */
                                 /*  bit corresponds to a child rcu_node */
                                 /*  structure. */
-        unsigned long expmask;  /* Groups that have ->blocked_tasks[] */
+        unsigned long expmask;  /* Groups that have ->blkd_tasks */
                                 /*  elements that need to drain to allow the */
                                 /*  current expedited grace period to */
                                 /*  complete (only for TREE_PREEMPT_RCU). */
+        atomic_t wakemask;      /* CPUs whose kthread needs to be awakened. */
+                                /*  Since this has meaning only for leaf */
+                                /*  rcu_node structures, 32 bits suffices. */
         unsigned long qsmaskinit;
                                 /* Per-GP initial value for qsmask & expmask. */
         unsigned long grpmask;  /* Mask to apply to parent qsmask. */
@@ -117,11 +131,62 @@ struct rcu_node {
         u8      grpnum;         /* CPU/group number for next level up. */
         u8      level;          /* root is at level 0. */
         struct rcu_node *parent;
-        struct list_head blocked_tasks[4];
-                                /* Tasks blocked in RCU read-side critsect. */
-                                /*  Grace period number (->gpnum) x blocked */
-                                /*  by tasks on the (x & 0x1) element of the */
-                                /*  blocked_tasks[] array. */
+        struct list_head blkd_tasks;
+                                /* Tasks blocked in RCU read-side critical */
+                                /*  section.  Tasks are placed at the head */
+                                /*  of this list and age towards the tail. */
+        struct list_head *gp_tasks;
+                                /* Pointer to the first task blocking the */
+                                /*  current grace period, or NULL if there */
+                                /*  is no such task. */
+        struct list_head *exp_tasks;
+                                /* Pointer to the first task blocking the */
+                                /*  current expedited grace period, or NULL */
+                                /*  if there is no such task.  If there */
+                                /*  is no current expedited grace period, */
+                                /*  then there can cannot be any such task. */
+#ifdef CONFIG_RCU_BOOST
+        struct list_head *boost_tasks;
+                                /* Pointer to first task that needs to be */
+                                /*  priority boosted, or NULL if no priority */
+                                /*  boosting is needed for this rcu_node */
+                                /*  structure.  If there are no tasks */
+                                /*  queued on this rcu_node structure that */
+                                /*  are blocking the current grace period, */
+                                /*  there can be no such task. */
+        unsigned long boost_time;
+                                /* When to start boosting (jiffies). */
+        struct task_struct *boost_kthread_task;
+                                /* kthread that takes care of priority */
+                                /*  boosting for this rcu_node structure. */
+        unsigned int boost_kthread_status;
+                                /* State of boost_kthread_task for tracing. */
+        unsigned long n_tasks_boosted;
+                                /* Total number of tasks boosted. */
+        unsigned long n_exp_boosts;
+                                /* Number of tasks boosted for expedited GP. */
+        unsigned long n_normal_boosts;
+                                /* Number of tasks boosted for normal GP. */
+        unsigned long n_balk_blkd_tasks;
+                                /* Refused to boost: no blocked tasks. */
+        unsigned long n_balk_exp_gp_tasks;
+                                /* Refused to boost: nothing blocking GP. */
+        unsigned long n_balk_boost_tasks;
+                                /* Refused to boost: already boosting. */
+        unsigned long n_balk_notblocked;
+                                /* Refused to boost: RCU RS CS still running. */
+        unsigned long n_balk_notyet;
+                                /* Refused to boost: not yet time. */
+        unsigned long n_balk_nos;
+                                /* Refused to boost: not sure why, though. */
+                                /*  This can happen due to race conditions. */
+#endif /* #ifdef CONFIG_RCU_BOOST */
+        struct task_struct *node_kthread_task;
+                                /* kthread that takes care of this rcu_node */
+                                /*  structure, for example, awakening the */
+                                /*  per-CPU kthreads as needed. */
+        unsigned int node_kthread_status;
+                                /* State of node_kthread_task for tracing. */
 } ____cacheline_internodealigned_in_smp;
 
 /*
@@ -170,7 +235,7 @@ struct rcu_data {
         bool            passed_quiesc;  /* User-mode/idle loop etc. */
         bool            qs_pending;     /* Core waits for quiesc state. */
         bool            beenonline;     /* CPU online at least once. */
-        bool            preemptable;    /* Preemptable RCU? */
+        bool            preemptible;    /* Preemptible RCU? */
         struct rcu_node *mynode;        /* This CPU's leaf of hierarchy */
         unsigned long grpmask;          /* Mask to apply to leaf qsmask. */
 
@@ -202,6 +267,9 @@ struct rcu_data {
         long            qlen;           /* # of queued callbacks */
         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 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 */
@@ -210,7 +278,6 @@ struct rcu_data {
         /* 3) dynticks interface. */
         struct rcu_dynticks *dynticks;  /* Shared per-CPU dynticks state. */
         int dynticks_snap;              /* Per-GP tracking for dynticks. */
-        int dynticks_nmi_snap;          /* Per-GP tracking for dynticks_nmi. */
 #endif /* #ifdef CONFIG_NO_HZ */
 
         /* 4) reasons this CPU needed to be kicked by force_quiescent_state */
@@ -246,7 +313,6 @@ struct rcu_data {
 #endif /* #else #ifdef CONFIG_NO_HZ */
 
 #define RCU_JIFFIES_TILL_FORCE_QS        3      /* for rsp->jiffies_force_qs */
-#ifdef CONFIG_RCU_CPU_STALL_DETECTOR
 
 #ifdef CONFIG_PROVE_RCU
 #define RCU_STALL_DELAY_DELTA          (5 * HZ)
@@ -254,19 +320,26 @@ struct rcu_data {
 #define RCU_STALL_DELAY_DELTA          0
 #endif
 
-#define RCU_SECONDS_TILL_STALL_CHECK   (10 * HZ + RCU_STALL_DELAY_DELTA)
+#define RCU_SECONDS_TILL_STALL_CHECK   (CONFIG_RCU_CPU_STALL_TIMEOUT * HZ + \
+                                        RCU_STALL_DELAY_DELTA)
                                                 /* for rsp->jiffies_stall */
-#define RCU_SECONDS_TILL_STALL_RECHECK (30 * HZ + RCU_STALL_DELAY_DELTA)
+#define RCU_SECONDS_TILL_STALL_RECHECK (3 * RCU_SECONDS_TILL_STALL_CHECK + 30)
                                                 /* for rsp->jiffies_stall */
 #define RCU_STALL_RAT_DELAY             2       /* Allow other CPUs time */
                                                 /*  to take at least one */
                                                 /*  scheduling clock irq */
                                                 /*  before ratting on them. */
 
-#endif /* #ifdef CONFIG_RCU_CPU_STALL_DETECTOR */
-
-#define ULONG_CMP_GE(a, b)      (ULONG_MAX / 2 >= (a) - (b))
-#define ULONG_CMP_LT(a, b)      (ULONG_MAX / 2 < (a) - (b))
+#define rcu_wait(cond)                                                  \
+do {                                                                    \
+        for (;;) {                                                      \
+                set_current_state(TASK_INTERRUPTIBLE);                  \
+                if (cond)                                               \
+                        break;                                          \
+                schedule();                                             \
+        }                                                               \
+        __set_current_state(TASK_RUNNING);                              \
+} while (0)
 
 /*
  * RCU global state, including node hierarchy.  This hierarchy is
@@ -283,7 +356,7 @@ struct rcu_state {
         struct rcu_node *level[NUM_RCU_LVLS];   /* Hierarchy levels. */
         u32 levelcnt[MAX_RCU_LVLS + 1];         /* # nodes in each level. */
         u8 levelspread[NUM_RCU_LVLS];           /* kids/node in each level. */
-        struct rcu_data *rda[NR_CPUS];          /* array of rdp pointers. */
+        struct rcu_data __percpu *rda;          /* pointer of percu rcu_data. */
 
         /* The following fields are guarded by the root rcu_node's lock. */
 
@@ -296,21 +369,14 @@ struct rcu_state {
                                                 /*  period because */
                                                 /*  force_quiescent_state() */
                                                 /*  was running. */
+        u8      boost;                          /* Subject to priority boost. */
         unsigned long gpnum;                    /* Current gp number. */
         unsigned long completed;                /* # of last completed gp. */
 
         /* 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 */
@@ -321,12 +387,12 @@ struct rcu_state {
                                                 /*  due to lock unavailable. */
         unsigned long n_force_qs_ngp;           /* Number of calls leaving */
                                                 /*  due to no GP active. */
-#ifdef CONFIG_RCU_CPU_STALL_DETECTOR
         unsigned long gp_start;                 /* Time at which GP started, */
                                                 /*  but in jiffies. */
         unsigned long jiffies_stall;            /* Time at which to check */
                                                 /*  for CPU stalls. */
-#endif /* #ifdef CONFIG_RCU_CPU_STALL_DETECTOR */
+        unsigned long gp_max;                   /* Maximum GP duration in */
+                                                /*  jiffies. */
         char *name;                             /* Name of structure. */
 };
 
@@ -357,15 +423,15 @@ DECLARE_PER_CPU(struct rcu_data, rcu_preempt_data);
 static void rcu_bootup_announce(void);
 long rcu_batches_completed(void);
 static void rcu_preempt_note_context_switch(int cpu);
-static int rcu_preempted_readers(struct rcu_node *rnp);
+static int rcu_preempt_blocked_readers_cgp(struct rcu_node *rnp);
 #ifdef CONFIG_HOTPLUG_CPU
 static void rcu_report_unblock_qs_rnp(struct rcu_node *rnp,
                                       unsigned long flags);
+static void rcu_stop_cpu_kthread(int cpu);
 #endif /* #ifdef CONFIG_HOTPLUG_CPU */
-#ifdef CONFIG_RCU_CPU_STALL_DETECTOR
 static void rcu_print_detail_task_stall(struct rcu_state *rsp);
 static void rcu_print_task_stall(struct rcu_node *rnp);
-#endif /* #ifdef CONFIG_RCU_CPU_STALL_DETECTOR */
+static void rcu_preempt_stall_reset(void);
 static void rcu_preempt_check_blocked_tasks(struct rcu_node *rnp);
 #ifdef CONFIG_HOTPLUG_CPU
 static int rcu_preempt_offline_tasks(struct rcu_state *rsp,
@@ -382,8 +448,23 @@ 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);
+static void rcu_initiate_boost(struct rcu_node *rnp, unsigned long flags);
+static void rcu_preempt_boost_start_gp(struct rcu_node *rnp);
+static void invoke_rcu_callbacks_kthread(void);
+#ifdef CONFIG_RCU_BOOST
+static void rcu_preempt_do_callbacks(void);
+static void rcu_boost_kthread_setaffinity(struct rcu_node *rnp,
+                                          cpumask_var_t cm);
+static int __cpuinit rcu_spawn_one_boost_kthread(struct rcu_state *rsp,
+                                                 struct rcu_node *rnp,
+                                                 int rnp_index);
+static void invoke_rcu_node_kthread(struct rcu_node *rnp);
+static void rcu_yield(void (*f)(unsigned long), unsigned long arg);
+#endif /* #ifdef CONFIG_RCU_BOOST */
+static void rcu_cpu_kthread_setrt(int cpu, int to_rt);
+static void __cpuinit rcu_prepare_kthreads(int cpu);
 
 #endif /* #ifndef RCU_TREE_NONCORE */