Commit-ID: 09e2db37ec6d22bc27e2ba94ab4889541567f52e
Gitweb: http://git.kernel.org/tip/09e2db37ec6d22bc27e2ba94ab4889541567f52e
Author: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx>
AuthorDate: Sun, 18 Dec 2016 13:31:02 -0800
Committer: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx>
CommitDate: Mon, 23 Jan 2017 11:37:13 -0800
rcu: Add comment headers to expedited-grace-period counter functions
These functions (rcu_exp_gp_seq_start(), rcu_exp_gp_seq_end(),
rcu_exp_gp_seq_snap(), and rcu_exp_gp_seq_done() seemed too obvious
to comment when written, but not so much when being documented.
This commit therefore adds header comments to each of them.
Signed-off-by: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx>
Reviewed-by: Josh Triplett <josh@xxxxxxxxxxxxxxxx>
---
kernel/rcu/tree_exp.h | 18 +++++++++++++++++-
1 file changed, 17 insertions(+), 1 deletion(-)
diff --git a/kernel/rcu/tree_exp.h b/kernel/rcu/tree_exp.h
index e59e184..303df97 100644
--- a/kernel/rcu/tree_exp.h
+++ b/kernel/rcu/tree_exp.h
@@ -20,16 +20,26 @@
* Authors: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx>
*/
-/* Wrapper functions for expedited grace periods. */
+/*
+ * Record the start of an expedited grace period.
+ */
static void rcu_exp_gp_seq_start(struct rcu_state *rsp)
{
rcu_seq_start(&rsp->expedited_sequence);
}
+
+/*
+ * Record the end of an expedited grace period.
+ */
static void rcu_exp_gp_seq_end(struct rcu_state *rsp)
{
rcu_seq_end(&rsp->expedited_sequence);
smp_mb(); /* Ensure that consecutive grace periods serialize. */
}
+
+/*
+ * Take a snapshot of the expedited-grace-period counter.
+ */
static unsigned long rcu_exp_gp_seq_snap(struct rcu_state *rsp)
{
unsigned long s;
@@ -39,6 +49,12 @@ static unsigned long rcu_exp_gp_seq_snap(struct rcu_state *rsp)
trace_rcu_exp_grace_period(rsp->name, s, TPS("snap"));
return s;
}
+
+/*
+ * Given a counter snapshot from rcu_exp_gp_seq_snap(), return true
+ * if a full expedited grace period has elapsed since that snapshot
+ * was taken.
+ */
static bool rcu_exp_gp_seq_done(struct rcu_state *rsp, unsigned long s)
{
return rcu_seq_done(&rsp->expedited_sequence, s);
--
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