Merge branch 'rcu-v28-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip

* 'rcu-v28-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: (21 commits)
  rcu: RCU-based detection of stalled CPUs for Classic RCU, fix
  rcu: RCU-based detection of stalled CPUs for Classic RCU
  rcu: add rcu_read_lock_sched() / rcu_read_unlock_sched()
  rcu: fix sparse shadowed variable warning
  doc/RCU: fix pseudocode in rcuref.txt
  rcuclassic: fix compiler warning
  rcu: use irq-safe locks
  rcuclassic: fix compilation NG
  rcu: fix locking cleanup fallout
  rcu: remove redundant ACCESS_ONCE definition from rcupreempt.c
  rcu: fix classic RCU locking cleanup lockdep problem
  rcu: trace fix possible mem-leak
  rcu: just rename call_rcu_bh instead of making it a macro
  rcu: remove list_for_each_rcu()
  rcu: fixes to include/linux/rcupreempt.h
  rcu: classic RCU locking and memory-barrier cleanups
  rcu: prevent console flood when one CPU sees another AWOL via RCU
  rcu, debug: detect stalled grace periods, cleanups
  rcu, debug: detect stalled grace periods
  rcu classic: new algorithm for callbacks-processing(v2)
  ...

1 files changed, 27 insertions, 10 deletions

diff --git a/include/linux/rcuclassic.h b/include/linux/rcuclassic.h
index 4ab843622727..5f89b62e6983 100644
--- a/include/linux/rcuclassic.h
+++ b/include/linux/rcuclassic.h
@@ -40,12 +40,21 @@
 #include <linux/cpumask.h>
 #include <linux/seqlock.h>
 
+#ifdef CONFIG_RCU_CPU_STALL_DETECTOR
+#define RCU_SECONDS_TILL_STALL_CHECK    ( 3 * HZ) /* for rcp->jiffies_stall */
+#define RCU_SECONDS_TILL_STALL_RECHECK  (30 * HZ) /* for rcp->jiffies_stall */
+#endif /* #ifdef CONFIG_RCU_CPU_STALL_DETECTOR */
 
 /* Global control variables for rcupdate callback mechanism. */
 struct rcu_ctrlblk {
         long    cur;            /* Current batch number.                      */
         long    completed;      /* Number of the last completed batch         */
-        int     next_pending;   /* Is the next batch already waiting?         */
+        long    pending;        /* Number of the last pending batch           */
+#ifdef CONFIG_RCU_CPU_STALL_DETECTOR
+        unsigned long gp_start; /* Time at which GP started in jiffies. */
+        unsigned long jiffies_stall;
+                                /* Time at which to check for CPU stalls. */
+#endif /* #ifdef CONFIG_RCU_CPU_STALL_DETECTOR */
 
         int     signaled;
 
@@ -66,11 +75,7 @@ static inline int rcu_batch_after(long a, long b)
         return (a - b) > 0;
 }
 
-/*
- * Per-CPU data for Read-Copy UPdate.
- * nxtlist - new callbacks are added here
- * curlist - current batch for which quiescent cycle started if any
- */
+/* Per-CPU data for Read-Copy UPdate. */
 struct rcu_data {
         /* 1) quiescent state handling : */
         long            quiescbatch;     /* Batch # for grace period */
@@ -78,12 +83,24 @@ struct rcu_data {
         int             qs_pending;      /* core waits for quiesc state */
 
         /* 2) batch handling */
-        long            batch;           /* Batch # for current RCU batch */
+        /*
+         * if nxtlist is not NULL, then:
+         * batch:
+         *      The batch # for the last entry of nxtlist
+         * [*nxttail[1], NULL = *nxttail[2]):
+         *      Entries that batch # <= batch
+         * [*nxttail[0], *nxttail[1]):
+         *      Entries that batch # <= batch - 1
+         * [nxtlist, *nxttail[0]):
+         *      Entries that batch # <= batch - 2
+         *      The grace period for these entries has completed, and
+         *      the other grace-period-completed entries may be moved
+         *      here temporarily in rcu_process_callbacks().
+         */
+        long            batch;
         struct rcu_head *nxtlist;
-        struct rcu_head **nxttail;
+        struct rcu_head **nxttail[3];
         long            qlen;            /* # of queued callbacks */
-        struct rcu_head *curlist;
-        struct rcu_head **curtail;
         struct rcu_head *donelist;
         struct rcu_head **donetail;
         long            blimit;          /* Upper limit on a processed batch */