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Message-Id: <09954A1D-CB7A-43C6-B30C-4E24731E1FC2@joelfernandes.org>
Date: Fri, 9 Jan 2026 06:20:20 -0500
From: Joel Fernandes <joel@...lfernandes.org>
To: Boqun Feng <boqun.feng@...il.com>
Cc: Frederic Weisbecker <frederic@...nel.org>,
Joel Fernandes <joelagnelf@...dia.com>,
Paul E McKenney <paulmck@...nel.org>, 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 Jan 9, 2026, at 5:32 AM, Boqun Feng <boqun.feng@...il.com> wrote:
>
> On Thu, Jan 08, 2026 at 08:39:11PM -0500, Joel Fernandes wrote:
>>> 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.
>>
>
> We still have time for this merge window, but I see there is still
> reviewing going on for other patches, maybe you could resend these 3
> patches once we reach agreement, and then we can decide which merge
> window. Thoughts?
Yes, or let us drop these 3 for this merge window and since I am doing the next
merge window, I will include these after agreement. I have 3 more patches
as well in this area coming up.
So I will re-send all of them together for nocb.
That will also make it easier for you and Frederic.
If by chance, we conclude review and agreement in time for this window, you could add them too, for now ok to drop nocb ones.
Thanks!
- Joel
>
> Regards,
> Boqun
>
>> ---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
>>
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