| Message ID | 20231212174004.11754-3-neeraj.iitr10@gmail.com (mailing list archive) |
|---|---|
| State | Accepted |
| Commit | dee39c0c1e9624f925da4ca0bece46bdc7427257 |
| Headers | show |
| Series | RCU misc fixes for v6.8 | expand |
On Tue, Dec 12, 2023 at 12:40 PM Neeraj Upadhyay (AMD) <neeraj.iitr10@gmail.com> wrote: > > From: Zqiang <qiang.zhang1211@gmail.com> > > If an rcutorture test scenario creates an fqs_task kthread, it will > periodically invoke rcu_force_quiescent_state() in order to start > force-quiescent-state (FQS) operations. However, an FQS operation > will be started even if there is no RCU grace period in progress. > Although testing FQS operations startup when there is no grace period in > progress is necessary, it need not happen all that often. This commit > therefore causes rcu_force_quiescent_state() to take an early exit > if there is no grace period in progress. > > Note that there will still be attempts to start an FQS scan in the > absence of a grace period because the grace period might end right > after the rcu_force_quiescent_state() function's check. In actual > testing, this happens about once every ten minutes, which should > provide adequate testing. > > Signed-off-by: Zqiang <qiang.zhang1211@gmail.com> > Signed-off-by: Paul E. McKenney <paulmck@kernel.org> > Signed-off-by: Neeraj Upadhyay (AMD) <neeraj.iitr10@gmail.com> > --- > kernel/rcu/tree.c | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c > index 3ac3c846105f..1ae851777806 100644 > --- a/kernel/rcu/tree.c > +++ b/kernel/rcu/tree.c > @@ -2338,6 +2338,8 @@ void rcu_force_quiescent_state(void) > struct rcu_node *rnp; > struct rcu_node *rnp_old = NULL; > > + if (!rcu_gp_in_progress()) > + return; Reviewed-by: Joel Fernandes (Google) <joel@joelfernandes.org> (Probably no need to resend with the tag, just update the patch in the PR). Thanks.
diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c index 3ac3c846105f..1ae851777806 100644 --- a/kernel/rcu/tree.c +++ b/kernel/rcu/tree.c @@ -2338,6 +2338,8 @@ void rcu_force_quiescent_state(void) struct rcu_node *rnp; struct rcu_node *rnp_old = NULL; + if (!rcu_gp_in_progress()) + return; /* Funnel through hierarchy to reduce memory contention. */ rnp = raw_cpu_read(rcu_data.mynode); for (; rnp != NULL; rnp = rnp->parent) {