*
* 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
#include <linux/percpu.h>
#include <linux/cpumask.h>
#include <linux/seqlock.h>
+#include <linux/lockdep.h>
/**
* struct rcu_head - callback structure for use with RCU
long completed; /* Number of the last completed batch */
int next_pending; /* Is the next batch already waiting? */
+ int signaled;
+
spinlock_t lock ____cacheline_internodealigned_in_smp;
cpumask_t cpumask; /* CPUs that need to switch in order */
/* for current batch to proceed. */
long blimit; /* Upper limit on a processed batch */
int cpu;
struct rcu_head barrier;
-#ifdef CONFIG_SMP
- long last_rs_qlen; /* qlen during the last resched */
-#endif
};
DECLARE_PER_CPU(struct rcu_data, rcu_data);
extern int rcu_pending(int cpu);
extern int rcu_needs_cpu(int 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, _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()
+#define rcu_read_lock() \
+ do { \
+ preempt_disable(); \
+ __acquire(RCU); \
+ rcu_read_acquire(); \
+ } while(0)
/**
* 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()
+#define rcu_read_unlock() \
+ do { \
+ rcu_read_release(); \
+ __release(RCU); \
+ preempt_enable(); \
+ } while(0)
/*
* So where is rcu_write_lock()? It does not exist, as there is no
* can use just rcu_read_lock().
*
*/
-#define rcu_read_lock_bh() local_bh_disable()
+#define rcu_read_lock_bh() \
+ do { \
+ local_bh_disable(); \
+ __acquire(RCU_BH); \
+ rcu_read_acquire(); \
+ } while(0)
/*
* 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()
+#define rcu_read_unlock_bh() \
+ do { \
+ rcu_read_release(); \
+ __release(RCU_BH); \
+ local_bh_enable(); \
+ } while(0)
+
+/*
+ * Prevent the compiler from merging or refetching accesses. The compiler
+ * is also forbidden from reordering successive instances of ACCESS_ONCE(),
+ * but only when the compiler is aware of some particular ordering. One way
+ * to make the compiler aware of ordering is to put the two invocations of
+ * ACCESS_ONCE() in different C statements.
+ *
+ * This macro does absolutely -nothing- to prevent the CPU from reordering,
+ * merging, or refetching absolutely anything at any time.
+ */
+#define ACCESS_ONCE(x) (*(volatile typeof(x) *)&(x))
/**
* 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); \
})
extern void FASTCALL(call_rcu_bh(struct rcu_head *head,
void (*func)(struct rcu_head *head)));
extern void synchronize_rcu(void);
-void synchronize_idle(void);
extern void rcu_barrier(void);
#endif /* __KERNEL__ */