Linus,
Please pull the latest core-urgent-for-linus git tree from:
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git
core-urgent-for-linus
# HEAD: 651bc1a474ad5f3a94587117cf509d7fa9247f69 Merge branch 'rcu/urgent'
of git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu into
core/urgent
A boot hang fix for the offloaded callback RCU model
(RCU_NOCB_CPU=y && (TREE_CPU=y || TREE_PREEMPT_RC))
in certain bootup scenarios.
Thanks,
Ingo
------------------>
Pranith Kumar (1):
rcu: Make nocb leader kthreads process pending callbacks after spawning
kernel/rcu/tree.h | 2 +-
kernel/rcu/tree_plugin.h | 22 +++++++++++-----------
2 files changed, 12 insertions(+), 12 deletions(-)
diff --git a/kernel/rcu/tree.h b/kernel/rcu/tree.h
index 71e64c718f75..6a86eb7bac45 100644
--- a/kernel/rcu/tree.h
+++ b/kernel/rcu/tree.h
@@ -358,7 +358,7 @@ struct rcu_data {
struct rcu_head **nocb_gp_tail;
long nocb_gp_count;
long nocb_gp_count_lazy;
- bool nocb_leader_wake; /* Is the nocb leader thread awake? */
+ bool nocb_leader_sleep; /* Is the nocb leader thread asleep? */
struct rcu_data *nocb_next_follower;
/* Next follower in wakeup chain. */
diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h
index 00dc411e9676..a7997e272564 100644
--- a/kernel/rcu/tree_plugin.h
+++ b/kernel/rcu/tree_plugin.h
@@ -2074,9 +2074,9 @@ static void wake_nocb_leader(struct rcu_data *rdp, bool
force)
if (!ACCESS_ONCE(rdp_leader->nocb_kthread))
return;
- if (!ACCESS_ONCE(rdp_leader->nocb_leader_wake) || force) {
+ if (ACCESS_ONCE(rdp_leader->nocb_leader_sleep) || force) {
/* Prior xchg orders against prior callback enqueue. */
- ACCESS_ONCE(rdp_leader->nocb_leader_wake) = true;
+ ACCESS_ONCE(rdp_leader->nocb_leader_sleep) = false;
wake_up(&rdp_leader->nocb_wq);
}
}
@@ -2253,7 +2253,7 @@ static void nocb_leader_wait(struct rcu_data *my_rdp)
if (!rcu_nocb_poll) {
trace_rcu_nocb_wake(my_rdp->rsp->name, my_rdp->cpu, "Sleep");
wait_event_interruptible(my_rdp->nocb_wq,
- ACCESS_ONCE(my_rdp->nocb_leader_wake));
+ !ACCESS_ONCE(my_rdp->nocb_leader_sleep));
/* Memory barrier handled by smp_mb() calls below and repoll. */
} else if (firsttime) {
firsttime = false; /* Don't drown trace log with "Poll"! */
@@ -2292,12 +2292,12 @@ static void nocb_leader_wait(struct rcu_data *my_rdp)
schedule_timeout_interruptible(1);
/* Rescan in case we were a victim of memory ordering. */
- my_rdp->nocb_leader_wake = false;
- smp_mb(); /* Ensure _wake false before scan. */
+ my_rdp->nocb_leader_sleep = true;
+ smp_mb(); /* Ensure _sleep true before scan. */
for (rdp = my_rdp; rdp; rdp = rdp->nocb_next_follower)
if (ACCESS_ONCE(rdp->nocb_head)) {
/* Found CB, so short-circuit next wait. */
- my_rdp->nocb_leader_wake = true;
+ my_rdp->nocb_leader_sleep = false;
break;
}
goto wait_again;
@@ -2307,17 +2307,17 @@ static void nocb_leader_wait(struct rcu_data *my_rdp)
rcu_nocb_wait_gp(my_rdp);
/*
- * We left ->nocb_leader_wake set to reduce cache thrashing.
- * We clear it now, but recheck for new callbacks while
+ * We left ->nocb_leader_sleep unset to reduce cache thrashing.
+ * We set it now, but recheck for new callbacks while
* traversing our follower list.
*/
- my_rdp->nocb_leader_wake = false;
- smp_mb(); /* Ensure _wake false before scan of ->nocb_head. */
+ my_rdp->nocb_leader_sleep = true;
+ smp_mb(); /* Ensure _sleep true before scan of ->nocb_head. */
/* Each pass through the following loop wakes a follower, if needed. */
for (rdp = my_rdp; rdp; rdp = rdp->nocb_next_follower) {
if (ACCESS_ONCE(rdp->nocb_head))
- my_rdp->nocb_leader_wake = true; /* No need to wait. */
+ my_rdp->nocb_leader_sleep = false;/* No need to sleep.*/
if (!rdp->nocb_gp_head)
continue; /* No CBs, so no need to wake follower. */
--
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