VServer 1.9.2 (patch-2.6.8.1-vs1.9.2.diff)

[linux-2.6.git] / include / linux / rcupdate.h

diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h
index 58048ab..10c4b8f 100644 (file)
--- a/include/linux/rcupdate.h
+++ b/include/linux/rcupdate.h
@@ -36,41 +36,37 @@
 #ifdef __KERNEL__
 
 #include <linux/cache.h>
-#include <linux/list.h>
 #include <linux/spinlock.h>
 #include <linux/threads.h>
 #include <linux/percpu.h>
 #include <linux/cpumask.h>
+#include <linux/seqlock.h>
 
 /**
  * struct rcu_head - callback structure for use with RCU
- * @list: list_head to queue the update requests
+ * @next: next update requests in a list
  * @func: actual update function to call after the grace period.
- * @arg: argument to be passed to the actual update function.
  */
 struct rcu_head {
-       struct list_head list;
-       void (*func)(void *obj);
-       void *arg;
+       struct rcu_head *next;
+       void (*func)(struct rcu_head *head);
 };
 
-#define RCU_HEAD_INIT(head) \
-               { .list = LIST_HEAD_INIT(head.list), .func = NULL, .arg = NULL }
+#define RCU_HEAD_INIT(head) { .next = NULL, .func = NULL }
 #define RCU_HEAD(head) struct rcu_head head = RCU_HEAD_INIT(head)
 #define INIT_RCU_HEAD(ptr) do { \
-       INIT_LIST_HEAD(&(ptr)->list); (ptr)->func = NULL; (ptr)->arg = NULL; \
+       (ptr)->next = NULL; (ptr)->func = NULL; \
 } while (0)
 
 
 
-/* Control variables for rcupdate callback mechanism. */
+/* Global control variables for rcupdate callback mechanism. */
 struct rcu_ctrlblk {
-       spinlock_t      mutex;          /* Guard this struct                  */
-       long            curbatch;       /* Current batch number.              */
-       long            maxbatch;       /* Max requested batch number.        */
-       cpumask_t       rcu_cpu_mask;   /* CPUs that need to switch in order  */
-                                       /* for current batch to proceed.      */
-};
+       long    cur;            /* Current batch number.                      */
+       long    completed;      /* Number of the last completed batch         */
+       int     next_pending;   /* Is the next batch already waiting?         */
+       seqcount_t lock;        /* For atomic reads of cur and next_pending.  */
+} ____cacheline_maxaligned_in_smp;
 
 /* Is batch a before batch b ? */
 static inline int rcu_batch_before(long a, long b)
@@ -90,35 +86,51 @@ static inline int rcu_batch_after(long a, long b)
  * curlist - current batch for which quiescent cycle started if any
  */
 struct rcu_data {
+       /* 1) quiescent state handling : */
+        long           quiescbatch;     /* Batch # for grace period */
        long            qsctr;           /* User-mode/idle loop etc. */
         long            last_qsctr;     /* value of qsctr at beginning */
                                          /* of rcu grace period */
+       int             qs_pending;      /* core waits for quiesc state */
+
+       /* 2) batch handling */
         long           batch;           /* Batch # for current RCU batch */
-        struct list_head  nxtlist;
-        struct list_head  curlist;
+        struct rcu_head *nxtlist;
+       struct rcu_head **nxttail;
+        struct rcu_head *curlist;
 };
 
 DECLARE_PER_CPU(struct rcu_data, rcu_data);
 extern struct rcu_ctrlblk rcu_ctrlblk;
 
+#define RCU_quiescbatch(cpu)   (per_cpu(rcu_data, (cpu)).quiescbatch)
 #define RCU_qsctr(cpu)                 (per_cpu(rcu_data, (cpu)).qsctr)
 #define RCU_last_qsctr(cpu)    (per_cpu(rcu_data, (cpu)).last_qsctr)
+#define RCU_qs_pending(cpu)    (per_cpu(rcu_data, (cpu)).qs_pending)
 #define RCU_batch(cpu)                 (per_cpu(rcu_data, (cpu)).batch)
 #define RCU_nxtlist(cpu)       (per_cpu(rcu_data, (cpu)).nxtlist)
 #define RCU_curlist(cpu)       (per_cpu(rcu_data, (cpu)).curlist)
-
-#define RCU_QSCTR_INVALID      0
+#define RCU_nxttail(cpu)       (per_cpu(rcu_data, (cpu)).nxttail)
 
 static inline int rcu_pending(int cpu) 
 {
-       if ((!list_empty(&RCU_curlist(cpu)) &&
-            rcu_batch_before(RCU_batch(cpu), rcu_ctrlblk.curbatch)) ||
-           (list_empty(&RCU_curlist(cpu)) &&
-                        !list_empty(&RCU_nxtlist(cpu))) ||
-           cpu_isset(cpu, rcu_ctrlblk.rcu_cpu_mask))
+       /* This cpu has pending rcu entries and the grace period
+        * for them has completed.
+        */
+       if (RCU_curlist(cpu) &&
+                 !rcu_batch_before(rcu_ctrlblk.completed,RCU_batch(cpu)))
+               return 1;
+
+       /* This cpu has no pending entries, but there are new entries */
+       if (!RCU_curlist(cpu) && RCU_nxtlist(cpu))
+               return 1;
+
+       /* The rcu core waits for a quiescent state from the cpu */
+       if (RCU_quiescbatch(cpu) != rcu_ctrlblk.cur || RCU_qs_pending(cpu))
                return 1;
-       else
-               return 0;
+
+       /* nothing to do */
+       return 0;
 }
 
 #define rcu_read_lock()                preempt_disable()
@@ -126,10 +138,11 @@ static inline int rcu_pending(int cpu)
 
 extern void rcu_init(void);
 extern void rcu_check_callbacks(int cpu, int user);
+extern void rcu_restart_cpu(int cpu);
 
 /* Exported interfaces */
 extern void FASTCALL(call_rcu(struct rcu_head *head, 
-                          void (*func)(void *arg), void *arg));
+                               void (*func)(struct rcu_head *head)));
 extern void synchronize_kernel(void);
 
 #endif /* __KERNEL__ */