/*
- * Read-Copy Update mechanism for mutual exclusion
+ * Read-Copy Update mechanism for mutual exclusion
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
*
- * Copyright (C) IBM Corporation, 2001
+ * Copyright IBM Corporation, 2001
*
* Author: Dipankar Sarma <dipankar@in.ibm.com>
- *
- * Based on the original work by Paul McKenney <paul.mckenney@us.ibm.com>
+ *
+ * Based on the original work by Paul McKenney <paulmck@us.ibm.com>
* and inputs from Rusty Russell, Andrea Arcangeli and Andi Kleen.
* Papers:
* http://www.rdrop.com/users/paulmck/paper/rclockpdcsproof.pdf
* http://lse.sourceforge.net/locking/rclock_OLS.2001.05.01c.sc.pdf (OLS2001)
*
* For detailed explanation of Read-Copy Update mechanism see -
- * http://lse.sourceforge.net/locking/rcupdate.html
+ * http://lse.sourceforge.net/locking/rcupdate.html
*
*/
#ifndef __LINUX_RCUPDATE_H
#define __LINUX_RCUPDATE_H
-#ifdef __KERNEL__
-
#include <linux/cache.h>
#include <linux/spinlock.h>
#include <linux/threads.h>
-#include <linux/percpu.h>
#include <linux/cpumask.h>
#include <linux/seqlock.h>
+#include <linux/lockdep.h>
+#include <linux/completion.h>
/**
* struct rcu_head - callback structure for use with RCU
void (*func)(struct rcu_head *head);
};
-#define RCU_HEAD_INIT { .next = NULL, .func = NULL }
+/* Exported common interfaces */
+extern void synchronize_rcu_bh(void);
+extern void synchronize_sched(void);
+extern void rcu_barrier(void);
+extern void rcu_barrier_bh(void);
+extern void rcu_barrier_sched(void);
+extern void synchronize_sched_expedited(void);
+extern int sched_expedited_torture_stats(char *page);
+
+/* Internal to kernel */
+extern void rcu_init(void);
+
+#if defined(CONFIG_TREE_RCU) || defined(CONFIG_TREE_PREEMPT_RCU)
+#include <linux/rcutree.h>
+#elif defined(CONFIG_TINY_RCU)
+#include <linux/rcutiny.h>
+#else
+#error "Unknown RCU implementation specified to kernel configuration"
+#endif
+
+#define RCU_HEAD_INIT { .next = NULL, .func = NULL }
#define RCU_HEAD(head) struct rcu_head head = RCU_HEAD_INIT
#define INIT_RCU_HEAD(ptr) do { \
(ptr)->next = NULL; (ptr)->func = NULL; \
} while (0)
-
-
-/* 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? */
-} ____cacheline_internodealigned_in_smp;
-
-/* Is batch a before batch b ? */
-static inline int rcu_batch_before(long a, long b)
-{
- return (a - b) < 0;
-}
-
-/* Is batch a after batch b ? */
-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
- */
-struct rcu_data {
- /* 1) quiescent state handling : */
- long quiescbatch; /* Batch # for grace period */
- int passed_quiesc; /* User-mode/idle loop etc. */
- int qs_pending; /* core waits for quiesc state */
-
- /* 2) batch handling */
- long batch; /* Batch # for current RCU batch */
- struct rcu_head *nxtlist;
- struct rcu_head **nxttail;
- long count; /* # of queued items */
- struct rcu_head *curlist;
- struct rcu_head **curtail;
- struct rcu_head *donelist;
- struct rcu_head **donetail;
- int cpu;
- struct rcu_head barrier;
-};
-
-DECLARE_PER_CPU(struct rcu_data, rcu_data);
-DECLARE_PER_CPU(struct rcu_data, rcu_bh_data);
-extern struct rcu_ctrlblk rcu_ctrlblk;
-extern struct rcu_ctrlblk rcu_bh_ctrlblk;
-
-/*
- * Increment the quiescent state counter.
- * The counter is a bit degenerated: We do not need to know
- * how many quiescent states passed, just if there was at least
- * one since the start of the grace period. Thus just a flag.
- */
-static inline void rcu_qsctr_inc(int cpu)
-{
- struct rcu_data *rdp = &per_cpu(rcu_data, cpu);
- rdp->passed_quiesc = 1;
-}
-static inline void rcu_bh_qsctr_inc(int cpu)
-{
- struct rcu_data *rdp = &per_cpu(rcu_bh_data, cpu);
- rdp->passed_quiesc = 1;
-}
-
-static inline int __rcu_pending(struct rcu_ctrlblk *rcp,
- struct rcu_data *rdp)
-{
- /* This cpu has pending rcu entries and the grace period
- * for them has completed.
- */
- if (rdp->curlist && !rcu_batch_before(rcp->completed, rdp->batch))
- return 1;
-
- /* This cpu has no pending entries, but there are new entries */
- if (!rdp->curlist && rdp->nxtlist)
- return 1;
-
- /* This cpu has finished callbacks to invoke */
- if (rdp->donelist)
- return 1;
-
- /* The rcu core waits for a quiescent state from the cpu */
- if (rdp->quiescbatch != rcp->cur || rdp->qs_pending)
- return 1;
-
- /* nothing to do */
- return 0;
-}
-
-static inline int rcu_pending(int cpu)
-{
- return __rcu_pending(&rcu_ctrlblk, &per_cpu(rcu_data, cpu)) ||
- __rcu_pending(&rcu_bh_ctrlblk, &per_cpu(rcu_bh_data, cpu));
-}
+#ifdef CONFIG_DEBUG_LOCK_ALLOC
+extern struct lockdep_map rcu_lock_map;
+# define rcu_read_acquire() \
+ lock_acquire(&rcu_lock_map, 0, 0, 2, 1, NULL, _THIS_IP_)
+# define rcu_read_release() lock_release(&rcu_lock_map, 1, _THIS_IP_)
+#else
+# define rcu_read_acquire() do { } while (0)
+# define rcu_read_release() do { } while (0)
+#endif
/**
* rcu_read_lock - mark the beginning of an RCU read-side critical section.
*
* It is illegal to block while in an RCU read-side critical section.
*/
-#define rcu_read_lock() preempt_disable()
-
-/**
- * rcu_read_unlock - marks the end of an RCU read-side critical section.
- *
- * See rcu_read_lock() for more information.
- */
-#define rcu_read_unlock() preempt_enable()
+static inline void rcu_read_lock(void)
+{
+ __rcu_read_lock();
+ __acquire(RCU);
+ rcu_read_acquire();
+}
/*
* So where is rcu_write_lock()? It does not exist, as there is no
*/
/**
+ * rcu_read_unlock - marks the end of an RCU read-side critical section.
+ *
+ * See rcu_read_lock() for more information.
+ */
+static inline void rcu_read_unlock(void)
+{
+ rcu_read_release();
+ __release(RCU);
+ __rcu_read_unlock();
+}
+
+/**
* rcu_read_lock_bh - mark the beginning of a softirq-only RCU critical section
*
* This is equivalent of rcu_read_lock(), but to be used when updates
* can use just rcu_read_lock().
*
*/
-#define rcu_read_lock_bh() local_bh_disable()
+static inline void rcu_read_lock_bh(void)
+{
+ __rcu_read_lock_bh();
+ __acquire(RCU_BH);
+ rcu_read_acquire();
+}
/*
* rcu_read_unlock_bh - marks the end of a softirq-only RCU critical section
*
* See rcu_read_lock_bh() for more information.
*/
-#define rcu_read_unlock_bh() local_bh_enable()
+static inline void rcu_read_unlock_bh(void)
+{
+ rcu_read_release();
+ __release(RCU_BH);
+ __rcu_read_unlock_bh();
+}
+
+/**
+ * rcu_read_lock_sched - mark the beginning of a RCU-classic critical section
+ *
+ * Should be used with either
+ * - synchronize_sched()
+ * or
+ * - call_rcu_sched() and rcu_barrier_sched()
+ * on the write-side to insure proper synchronization.
+ */
+static inline void rcu_read_lock_sched(void)
+{
+ preempt_disable();
+ __acquire(RCU_SCHED);
+ rcu_read_acquire();
+}
+
+/* Used by lockdep and tracing: cannot be traced, cannot call lockdep. */
+static inline notrace void rcu_read_lock_sched_notrace(void)
+{
+ preempt_disable_notrace();
+ __acquire(RCU_SCHED);
+}
+
+/*
+ * rcu_read_unlock_sched - marks the end of a RCU-classic critical section
+ *
+ * See rcu_read_lock_sched for more information.
+ */
+static inline void rcu_read_unlock_sched(void)
+{
+ rcu_read_release();
+ __release(RCU_SCHED);
+ preempt_enable();
+}
+
+/* Used by lockdep and tracing: cannot be traced, cannot call lockdep. */
+static inline notrace void rcu_read_unlock_sched_notrace(void)
+{
+ __release(RCU_SCHED);
+ preempt_enable_notrace();
+}
+
/**
* rcu_dereference - fetch an RCU-protected pointer in an
*/
#define rcu_dereference(p) ({ \
- typeof(p) _________p1 = p; \
+ typeof(p) _________p1 = ACCESS_ONCE(p); \
smp_read_barrier_depends(); \
(_________p1); \
})
* code.
*/
-#define rcu_assign_pointer(p, v) ({ \
- smp_wmb(); \
- (p) = (v); \
- })
+#define rcu_assign_pointer(p, v) \
+ ({ \
+ if (!__builtin_constant_p(v) || \
+ ((v) != NULL)) \
+ smp_wmb(); \
+ (p) = (v); \
+ })
+
+/* Infrastructure to implement the synchronize_() primitives. */
+
+struct rcu_synchronize {
+ struct rcu_head head;
+ struct completion completion;
+};
+
+extern void wakeme_after_rcu(struct rcu_head *head);
/**
- * synchronize_sched - block until all CPUs have exited any non-preemptive
- * kernel code sequences.
- *
- * This means that all preempt_disable code sequences, including NMI and
- * hardware-interrupt handlers, in progress on entry will have completed
- * before this primitive returns. However, this does not guarantee that
- * softirq handlers will have completed, since in some kernels
+ * call_rcu - Queue an RCU callback for invocation after a grace period.
+ * @head: structure to be used for queueing the RCU updates.
+ * @func: actual update function to be invoked after the grace period
*
- * This primitive provides the guarantees made by the (deprecated)
- * synchronize_kernel() API. In contrast, synchronize_rcu() only
- * guarantees that rcu_read_lock() sections will have completed.
+ * The update function will be invoked some time after a full grace
+ * period elapses, in other words after all currently executing RCU
+ * read-side critical sections have completed. RCU read-side critical
+ * sections are delimited by rcu_read_lock() and rcu_read_unlock(),
+ * and may be nested.
*/
-#define synchronize_sched() synchronize_rcu()
+extern void call_rcu(struct rcu_head *head,
+ void (*func)(struct rcu_head *head));
-extern void rcu_init(void);
-extern void rcu_check_callbacks(int cpu, int user);
-extern void rcu_restart_cpu(int cpu);
-extern long rcu_batches_completed(void);
-
-/* Exported interfaces */
-extern void FASTCALL(call_rcu(struct rcu_head *head,
- void (*func)(struct rcu_head *head)));
-extern void FASTCALL(call_rcu_bh(struct rcu_head *head,
- void (*func)(struct rcu_head *head)));
-extern __deprecated_for_modules void synchronize_kernel(void);
-extern void synchronize_rcu(void);
-void synchronize_idle(void);
-extern void rcu_barrier(void);
+/**
+ * call_rcu_bh - Queue an RCU for invocation after a quicker grace period.
+ * @head: structure to be used for queueing the RCU updates.
+ * @func: actual update function to be invoked after the grace period
+ *
+ * The update function will be invoked some time after a full grace
+ * period elapses, in other words after all currently executing RCU
+ * read-side critical sections have completed. call_rcu_bh() assumes
+ * that the read-side critical sections end on completion of a softirq
+ * handler. This means that read-side critical sections in process
+ * context must not be interrupted by softirqs. This interface is to be
+ * used when most of the read-side critical sections are in softirq context.
+ * RCU read-side critical sections are delimited by :
+ * - rcu_read_lock() and rcu_read_unlock(), if in interrupt context.
+ * OR
+ * - rcu_read_lock_bh() and rcu_read_unlock_bh(), if in process context.
+ * These may be nested.
+ */
+extern void call_rcu_bh(struct rcu_head *head,
+ void (*func)(struct rcu_head *head));
-#endif /* __KERNEL__ */
#endif /* __LINUX_RCUPDATE_H */
git://ftp.safe.ca / safe / jmp / linux-2.6 / blobdiff