Commit-ID: c9a24e2d0c7d33b141167f5fa13f95cf6d35cb1e
Gitweb: https://git.kernel.org/tip/c9a24e2d0c7d33b141167f5fa13f95cf6d35cb1e
Author: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx>
AuthorDate: Fri, 27 Apr 2018 14:54:46 -0700
Committer: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx>
CommitDate: Thu, 12 Jul 2018 14:27:48 -0700
rcu: Make quiescent-state reporting use ->gp_seq
This commit switches the functions reporting quiescent states from
use of ->gpnum to ->gp_seq. In either case, the point is to handle
races where a given grace period ends before a quiescent state can
be reported. Failing to catch these races would result in too-short
grace periods, hence the checking.
Signed-off-by: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx>
---
kernel/rcu/tree.c | 18 +++++++++---------
1 file changed, 9 insertions(+), 9 deletions(-)
diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index 002f85357226..a54587dc13f0 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -2242,7 +2242,7 @@ static void rcu_report_qs_rsp(struct rcu_state *rsp, unsigned long flags)
* must be represented by the same rcu_node structure (which need not be a
* leaf rcu_node structure, though it often will be). The gps parameter
* is the grace-period snapshot, which means that the quiescent states
- * are valid only if rnp->gpnum is equal to gps. That structure's lock
+ * are valid only if rnp->gp_seq is equal to gps. That structure's lock
* must be held upon entry, and it is released before return.
*/
static void
@@ -2257,7 +2257,7 @@ rcu_report_qs_rnp(unsigned long mask, struct rcu_state *rsp,
/* Walk up the rcu_node hierarchy. */
for (;;) {
- if (!(rnp->qsmask & mask) || rnp->gpnum != gps) {
+ if (!(rnp->qsmask & mask) || rnp->gp_seq != gps) {
/*
* Our bit has already been cleared, or the
@@ -2335,8 +2335,8 @@ static void rcu_report_unblock_qs_rnp(struct rcu_state *rsp,
return;
}
- /* Report up the rest of the hierarchy, tracking current ->gpnum. */
- gps = rnp->gpnum;
+ /* Report up the rest of the hierarchy, tracking current ->gp_seq. */
+ gps = rnp->gp_seq;
mask = rnp->grpmask;
raw_spin_unlock_rcu_node(rnp); /* irqs remain disabled. */
raw_spin_lock_rcu_node(rnp_p); /* irqs already disabled. */
@@ -2357,8 +2357,8 @@ rcu_report_qs_rdp(int cpu, struct rcu_state *rsp, struct rcu_data *rdp)
rnp = rdp->mynode;
raw_spin_lock_irqsave_rcu_node(rnp, flags);
- if (rdp->cpu_no_qs.b.norm || rdp->gpnum != rnp->gpnum ||
- rnp->completed == rnp->gpnum || rdp->gpwrap) {
+ if (rdp->cpu_no_qs.b.norm || rdp->gp_seq != rnp->gp_seq ||
+ rdp->gpwrap) {
/*
* The grace period in which this quiescent state was
@@ -2383,7 +2383,7 @@ rcu_report_qs_rdp(int cpu, struct rcu_state *rsp, struct rcu_data *rdp)
*/
needwake = rcu_accelerate_cbs(rsp, rnp, rdp);
- rcu_report_qs_rnp(mask, rsp, rnp, rnp->gpnum, flags);
+ rcu_report_qs_rnp(mask, rsp, rnp, rnp->gp_seq, flags);
/* ^^^ Released rnp->lock */
if (needwake)
rcu_gp_kthread_wake(rsp);
@@ -2688,8 +2688,8 @@ static void force_qs_rnp(struct rcu_state *rsp, int (*f)(struct rcu_data *rsp))
}
}
if (mask != 0) {
- /* Idle/offline CPUs, report (releases rnp->lock. */
- rcu_report_qs_rnp(mask, rsp, rnp, rnp->gpnum, flags);
+ /* Idle/offline CPUs, report (releases rnp->lock). */
+ rcu_report_qs_rnp(mask, rsp, rnp, rnp->gp_seq, flags);
} else {
/* Nothing to do here, so just drop the lock. */
raw_spin_unlock_irqrestore_rcu_node(rnp, flags);
--
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