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[36.225.83.234]) by smtp.gmail.com with ESMTPSA id 98e67ed59e1d1-3614189343esm22743994a91.6.2026.04.24.03.21.38 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 24 Apr 2026 03:21:42 -0700 (PDT) Date: Fri, 24 Apr 2026 18:21:37 +0800 From: Cheng-Yang Chou To: Richard Cheng Cc: tj@kernel.org, void@manifault.com, arighi@nvidia.com, changwoo@igalia.com, mingo@redhat.com, peterz@infradead.org, juri.lelli@redhat.com, vincent.guittot@linaro.org, dietmar.eggemann@arm.com, rostedt@goodmis.org, bsegall@google.com, mgorman@suse.de, vschneid@redhat.com, kprateek.nayak@amd.com, sched-ext@lists.linux.dev, linux-kernel@vger.kernel.org, newtonl@nvidia.com, kristinc@nvidia.com, kaihengf@nvidia.com, kobak@nvidia.com, jserv@ccns.ncku.edu.tw, chia7712@gmail.com Subject: Re: [PATCH v2] sched_ext: sync disable_irq_work in bpf_scx_unreg() Message-ID: <20260424181151.Ge109@cchengyang.duckdns.org> References: <20260424100221.32407-1-icheng@nvidia.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260424100221.32407-1-icheng@nvidia.com> Hi Richard, On Fri, Apr 24, 2026 at 06:02:21PM +0800, Richard Cheng wrote: [...] > --- > kernel/sched/ext.c | 20 +++++++++++++++++--- > 1 file changed, 17 insertions(+), 3 deletions(-) > > diff --git a/kernel/sched/ext.c b/kernel/sched/ext.c > index 012ca8bd70fb..ff42ac197bfd 100644 > --- a/kernel/sched/ext.c > +++ b/kernel/sched/ext.c > @@ -5921,6 +5921,20 @@ static void scx_disable(struct scx_sched *sch, enum scx_exit_kind kind) > irq_work_queue(&sch->disable_irq_work); > } > > +/** > + * scx_flush_disable_work - flush the disable work and wait for it to finish > + * @sch: the scheduler Not to be picky here, but I think '@sch: the scheduler' is a bit vague. Since nearly every 'sch' in ext.c is a scheduler instance, maybe '@sch: sched to be flushed' would be more descriptive? You can check more specific comments for 'sch' elsewhere in ext.c as well. WDYT, thanks! > + * > + * sch->disable_work might still not queued, causing kthread_flush_work() > + * as a noop. Syncing the irq_work first is required to guarantee the > + * kthread work has been queued before waiting for it. > + */ > +static void scx_flush_disable_work(struct scx_sched *sch) > +{ > + irq_work_sync(&sch->disable_irq_work); > + kthread_flush_work(&sch->disable_work); > +} > + > static void dump_newline(struct seq_buf *s) > { > trace_sched_ext_dump(""); > @@ -6821,7 +6835,7 @@ static void scx_root_enable_workfn(struct kthread_work *work) > * completion. sch's base reference will be put by bpf_scx_unreg(). > */ > scx_error(sch, "scx_root_enable() failed (%d)", ret); > - kthread_flush_work(&sch->disable_work); > + scx_flush_disable_work(sch); > cmd->ret = 0; > } > > @@ -7088,7 +7102,7 @@ static void scx_sub_enable_workfn(struct kthread_work *work) > percpu_up_write(&scx_fork_rwsem); > err_disable: > mutex_unlock(&scx_enable_mutex); > - kthread_flush_work(&sch->disable_work); > + scx_flush_disable_work(sch); > cmd->ret = 0; > } > > @@ -7349,7 +7363,7 @@ static void bpf_scx_unreg(void *kdata, struct bpf_link *link) > struct scx_sched *sch = rcu_dereference_protected(ops->priv, true); > > scx_disable(sch, SCX_EXIT_UNREG); > - kthread_flush_work(&sch->disable_work); > + scx_flush_disable_work(sch); > RCU_INIT_POINTER(ops->priv, NULL); > kobject_put(&sch->kobj); > } > -- > 2.43.0 > -- Cheers, Cheng-Yang