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[31.46.245.48]) by smtp.gmail.com with ESMTPSA id l11-20020a170906a40b00b009b64987e1absm2488023ejz.139.2023.10.04.02.39.54 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 04 Oct 2023 02:39:55 -0700 (PDT) Sender: Ingo Molnar Date: Wed, 4 Oct 2023 11:39:53 +0200 From: Ingo Molnar To: Peter Zijlstra Cc: Zhang Qiao , mingo@redhat.com, juri.lelli@redhat.com, vincent.guittot@linaro.org, dietmar.eggemann@arm.com, rostedt@goodmis.org, bsegall@google.com, mgorman@suse.de, bristot@redhat.com, vschneid@redhat.com, linux-kernel@vger.kernel.org Subject: [PATCH] sched/core: Update stale comment in try_to_wake_up() Message-ID: References: <20230731085759.11443-1-zhangqiao22@huawei.com> <20231004093323.GK1539@noisy.programming.kicks-ass.net> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20231004093323.GK1539@noisy.programming.kicks-ass.net> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" * Peter Zijlstra wrote: > On Wed, Oct 04, 2023 at 11:31:26AM +0200, Ingo Molnar wrote: > >=20 > > * Zhang Qiao wrote: > >=20 > > > Since commit 9b3c4ab3045e ("sched,rcu: Rework > > > try_invoke_on_locked_down_task()") renamed > > > try_invoke_on_locked_down_task() to task_call_func(). > > > Now, update some comment about it. > > >=20 > > > Signed-off-by: Zhang Qiao > > > --- > > > kernel/sched/core.c | 2 +- > > > 1 file changed, 1 insertion(+), 1 deletion(-) > > >=20 > > > diff --git a/kernel/sched/core.c b/kernel/sched/core.c > > > index 0d18c3969f90..540ac33ddb80 100644 > > > --- a/kernel/sched/core.c > > > +++ b/kernel/sched/core.c > > > @@ -4186,7 +4186,7 @@ try_to_wake_up(struct task_struct *p, unsigned = int state, int wake_flags) > > > * Pairs with the LOCK+smp_mb__after_spinlock() on rq->lock in > > > * __schedule(). See the comment for smp_mb__after_spinlock(). > > > * > > > - * A similar smb_rmb() lives in try_invoke_on_locked_down_task(). > > > + * A similar smb_rmb() lives in task_call_func(). > >=20 > > Except the matching smp_rmb() doesn't live in task_call_func() anymore,= so=20 > > you now turned a stale comment into a misleading one ... >=20 > It moved, *again*, it's now in __task_needs_rq_lock() :-) Yeah, I know, see: bdf85bec2b1e ("sched/core: Update stale comment in try_to_wake_up()") Thanks, Ingo =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D> From: Ingo Molnar Date: Wed, 4 Oct 2023 11:33:36 +0200 Subject: [PATCH] sched/core: Update stale comment in try_to_wake_up() The following commit: 9b3c4ab3045e ("sched,rcu: Rework try_invoke_on_locked_down_task()") ... renamed try_invoke_on_locked_down_task() to task_call_func(), but forgot to update the comment in try_to_wake_up(). But it turns out that the smp_rmb() doesn't live in task_call_func() either, it was moved to __task_needs_rq_lock() in: 91dabf33ae5d ("sched: Fix race in task_call_func()") Fix that now. Also fix the s/smb/smp typo while at it. Reported-by: Zhang Qiao Signed-off-by: Ingo Molnar Link: https://lore.kernel.org/r/20230731085759.11443-1-zhangqiao22@huawei.c= om --- kernel/sched/core.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 65e10ac34660..f5783cb16791 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -4237,7 +4237,7 @@ int try_to_wake_up(struct task_struct *p, unsigned in= t state, int wake_flags) * Pairs with the LOCK+smp_mb__after_spinlock() on rq->lock in * __schedule(). See the comment for smp_mb__after_spinlock(). * - * A similar smb_rmb() lives in try_invoke_on_locked_down_task(). + * A similar smp_rmb() lives in __task_needs_rq_lock(). */ smp_rmb(); if (READ_ONCE(p->on_rq) && ttwu_runnable(p, wake_flags))