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Subject[PATCH v2 tip/core/rcu 17/39] srcu: Move rcu_seq_start() and friends to rcu.h
Date
This commit moves rcu_seq_start(), rcu_seq_end(), rcu_seq_snap(),
and rcu_seq_done() from kernel/rcu/tree.c to kernel/rcu/rcu.h.
This will allow SRCU to use these functions, which in turn will
allow SRCU to move from a single global callback queue to a
per-CPU callback queue.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
---
kernel/rcu/rcu.h | 40 ++++++++++++++++++++++++++++++++++++++++
kernel/rcu/tree.c | 35 -----------------------------------
2 files changed, 40 insertions(+), 35 deletions(-)

diff --git a/kernel/rcu/rcu.h b/kernel/rcu/rcu.h
index 8700a81daf56..91e0bf31f6ce 100644
--- a/kernel/rcu/rcu.h
+++ b/kernel/rcu/rcu.h
@@ -56,6 +56,46 @@
#define DYNTICK_TASK_EXIT_IDLE (DYNTICK_TASK_NEST_VALUE + \
DYNTICK_TASK_FLAG)

+
+/*
+ * Grace-period counter management.
+ */
+
+/* Adjust sequence number for start of update-side operation. */
+static inline void rcu_seq_start(unsigned long *sp)
+{
+ WRITE_ONCE(*sp, *sp + 1);
+ smp_mb(); /* Ensure update-side operation after counter increment. */
+ WARN_ON_ONCE(!(*sp & 0x1));
+}
+
+/* Adjust sequence number for end of update-side operation. */
+static inline void rcu_seq_end(unsigned long *sp)
+{
+ smp_mb(); /* Ensure update-side operation before counter increment. */
+ WRITE_ONCE(*sp, *sp + 1);
+ WARN_ON_ONCE(*sp & 0x1);
+}
+
+/* Take a snapshot of the update side's sequence number. */
+static inline unsigned long rcu_seq_snap(unsigned long *sp)
+{
+ unsigned long s;
+
+ s = (READ_ONCE(*sp) + 3) & ~0x1;
+ smp_mb(); /* Above access must not bleed into critical section. */
+ return s;
+}
+
+/*
+ * Given a snapshot from rcu_seq_snap(), determine whether or not a
+ * full update-side operation has occurred.
+ */
+static inline bool rcu_seq_done(unsigned long *sp, unsigned long s)
+{
+ return ULONG_CMP_GE(READ_ONCE(*sp), s);
+}
+
/*
* debug_rcu_head_queue()/debug_rcu_head_unqueue() are used internally
* by call_rcu() and rcu callback execution, and are therefore not part of the
diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index 03a1e3e09e82..a3eff40a6c17 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -3409,41 +3409,6 @@ void cond_synchronize_sched(unsigned long oldstate)
}
EXPORT_SYMBOL_GPL(cond_synchronize_sched);

-/* Adjust sequence number for start of update-side operation. */
-static void rcu_seq_start(unsigned long *sp)
-{
- WRITE_ONCE(*sp, *sp + 1);
- smp_mb(); /* Ensure update-side operation after counter increment. */
- WARN_ON_ONCE(!(*sp & 0x1));
-}
-
-/* Adjust sequence number for end of update-side operation. */
-static void rcu_seq_end(unsigned long *sp)
-{
- smp_mb(); /* Ensure update-side operation before counter increment. */
- WRITE_ONCE(*sp, *sp + 1);
- WARN_ON_ONCE(*sp & 0x1);
-}
-
-/* Take a snapshot of the update side's sequence number. */
-static unsigned long rcu_seq_snap(unsigned long *sp)
-{
- unsigned long s;
-
- s = (READ_ONCE(*sp) + 3) & ~0x1;
- smp_mb(); /* Above access must not bleed into critical section. */
- return s;
-}
-
-/*
- * Given a snapshot from rcu_seq_snap(), determine whether or not a
- * full update-side operation has occurred.
- */
-static bool rcu_seq_done(unsigned long *sp, unsigned long s)
-{
- return ULONG_CMP_GE(READ_ONCE(*sp), s);
-}
-
/*
* Check to see if there is any immediate RCU-related work to be done
* by the current CPU, for the specified type of RCU, returning 1 if so.
--
2.5.2
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