linux-kernel - Re: [PATCH -next 3/8] rcu/nocb: Remove unnecessary WakeOvfIsDeferred wake path

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Message-ID: <20260109013911.GA1102915@joelbox2>
Date: Thu, 8 Jan 2026 20:39:11 -0500
From: Joel Fernandes <joel@...lfernandes.org>
To: Frederic Weisbecker <frederic@...nel.org>
Cc: Joel Fernandes <joelagnelf@...dia.com>,
	"Paul E . McKenney" <paulmck@...nel.org>,
	Boqun Feng <boqun.feng@...il.com>, rcu@...r.kernel.org,
	Neeraj Upadhyay <neeraj.upadhyay@...nel.org>,
	Josh Triplett <josh@...htriplett.org>,
	Uladzislau Rezki <urezki@...il.com>,
	Steven Rostedt <rostedt@...dmis.org>,
	Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
	Lai Jiangshan <jiangshanlai@...il.com>,
	Zqiang <qiang.zhang@...ux.dev>, Shuah Khan <shuah@...nel.org>,
	linux-kernel@...r.kernel.org, linux-kselftest@...r.kernel.org
Subject: Re: [PATCH -next 3/8] rcu/nocb: Remove unnecessary WakeOvfIsDeferred
 wake path

On Thu, Jan 08, 2026 at 04:57:26PM +0100, Frederic Weisbecker wrote:
> Le Thu, Jan 01, 2026 at 11:34:12AM -0500, Joel Fernandes a écrit :
> > @@ -974,8 +959,7 @@ static bool do_nocb_deferred_wakeup_common(struct rcu_data *rdp_gp,
> >  		return false;
> >  	}
> >  
> > -	ndw = rdp_gp->nocb_defer_wakeup;
> > -	ret = __wake_nocb_gp(rdp_gp, rdp, ndw == RCU_NOCB_WAKE_FORCE, flags);
> > +	ret = __wake_nocb_gp(rdp_gp, rdp, false, flags);
> 
> The force parameter can now be removed, right? (same applies to wake_nocb_gp()).
> 
> Other than that:
> 
> Reviewed-by: Frederic Weisbecker <frederic@...nel.org>

Ah true! Thanks, so the following hunk needs to be squashed into the patch
then, with the review tag. Boqun, if you want to do that please do, or I can
send it again for the next merge window.

---8<-----------------------

From: "Joel Fernandes" <joelagnelf@...dia.com>
Subject: [PATCH] fixup! rcu/nocb: Remove unnecessary WakeOvfIsDeferred wake
 path

Signed-off-by: Joel Fernandes <joelagnelf@...dia.com>
---
 kernel/rcu/tree.c      |  2 +-
 kernel/rcu/tree.h      |  2 +-
 kernel/rcu/tree_nocb.h | 14 +++++++-------
 3 files changed, 9 insertions(+), 9 deletions(-)

diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index 293bbd9ac3f4..2921ffb19939 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -3769,7 +3769,7 @@ static void rcu_barrier_entrain(struct rcu_data *rdp)
 	}
 	rcu_nocb_unlock(rdp);
 	if (wake_nocb)
-		wake_nocb_gp(rdp, false);
+		wake_nocb_gp(rdp);
 	smp_store_release(&rdp->barrier_seq_snap, gseq);
 }
 
diff --git a/kernel/rcu/tree.h b/kernel/rcu/tree.h
index 653fb4ba5852..7dfc57e9adb1 100644
--- a/kernel/rcu/tree.h
+++ b/kernel/rcu/tree.h
@@ -499,7 +499,7 @@ static void zero_cpu_stall_ticks(struct rcu_data *rdp);
 static struct swait_queue_head *rcu_nocb_gp_get(struct rcu_node *rnp);
 static void rcu_nocb_gp_cleanup(struct swait_queue_head *sq);
 static void rcu_init_one_nocb(struct rcu_node *rnp);
-static bool wake_nocb_gp(struct rcu_data *rdp, bool force);
+static bool wake_nocb_gp(struct rcu_data *rdp);
 static bool rcu_nocb_flush_bypass(struct rcu_data *rdp, struct rcu_head *rhp,
 				  unsigned long j, bool lazy);
 static void call_rcu_nocb(struct rcu_data *rdp, struct rcu_head *head,
diff --git a/kernel/rcu/tree_nocb.h b/kernel/rcu/tree_nocb.h
index daff2756cd90..c6f1ddecc2d8 100644
--- a/kernel/rcu/tree_nocb.h
+++ b/kernel/rcu/tree_nocb.h
@@ -192,7 +192,7 @@ static void rcu_init_one_nocb(struct rcu_node *rnp)
 
 static bool __wake_nocb_gp(struct rcu_data *rdp_gp,
 			   struct rcu_data *rdp,
-			   bool force, unsigned long flags)
+			   unsigned long flags)
 	__releases(rdp_gp->nocb_gp_lock)
 {
 	bool needwake = false;
@@ -225,13 +225,13 @@ static bool __wake_nocb_gp(struct rcu_data *rdp_gp,
 /*
  * Kick the GP kthread for this NOCB group.
  */
-static bool wake_nocb_gp(struct rcu_data *rdp, bool force)
+static bool wake_nocb_gp(struct rcu_data *rdp)
 {
 	unsigned long flags;
 	struct rcu_data *rdp_gp = rdp->nocb_gp_rdp;
 
 	raw_spin_lock_irqsave(&rdp_gp->nocb_gp_lock, flags);
-	return __wake_nocb_gp(rdp_gp, rdp, force, flags);
+	return __wake_nocb_gp(rdp_gp, rdp, flags);
 }
 
 #ifdef CONFIG_RCU_LAZY
@@ -553,7 +553,7 @@ static void __call_rcu_nocb_wake(struct rcu_data *rdp, bool was_alldone,
 					   TPS("WakeLazy"));
 		} else if (!irqs_disabled_flags(flags)) {
 			/* ... if queue was empty ... */
-			wake_nocb_gp(rdp, false);
+			wake_nocb_gp(rdp);
 			trace_rcu_nocb_wake(rcu_state.name, rdp->cpu,
 					    TPS("WakeEmpty"));
 		} else {
@@ -959,7 +959,7 @@ static bool do_nocb_deferred_wakeup_common(struct rcu_data *rdp_gp,
 		return false;
 	}
 
-	ret = __wake_nocb_gp(rdp_gp, rdp, false, flags);
+	ret = __wake_nocb_gp(rdp_gp, rdp, flags);
 	trace_rcu_nocb_wake(rcu_state.name, rdp->cpu, TPS("DeferredWake"));
 
 	return ret;
@@ -1255,7 +1255,7 @@ lazy_rcu_shrink_scan(struct shrinker *shrink, struct shrink_control *sc)
 		}
 		rcu_nocb_try_flush_bypass(rdp, jiffies);
 		rcu_nocb_unlock_irqrestore(rdp, flags);
-		wake_nocb_gp(rdp, false);
+		wake_nocb_gp(rdp);
 		sc->nr_to_scan -= _count;
 		count += _count;
 		if (sc->nr_to_scan <= 0)
@@ -1640,7 +1640,7 @@ static void rcu_init_one_nocb(struct rcu_node *rnp)
 {
 }
 
-static bool wake_nocb_gp(struct rcu_data *rdp, bool force)
+static bool wake_nocb_gp(struct rcu_data *rdp)
 {
 	return false;
 }
-- 
2.34.1