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Thu, 28 May 2026 09:18:46 -0700 (PDT) Received: from gmail.com ([62.197.47.167]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-45edb549addsm14203420f8f.5.2026.05.28.09.18.45 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 28 May 2026 09:18:46 -0700 (PDT) Date: Thu, 28 May 2026 17:18:45 +0100 From: Breno Leitao To: Marco Crivellari Cc: linux-kernel@vger.kernel.org, Tejun Heo , Lai Jiangshan , Frederic Weisbecker , Sebastian Andrzej Siewior , Michal Hocko Subject: Re: [PATCH v3 1/2] workqueue: Add warnings and fallback if system_{unbound}_wq is used Message-ID: References: <20260528160159.471265-1-marco.crivellari@suse.com> <20260528160159.471265-2-marco.crivellari@suse.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: <20260528160159.471265-2-marco.crivellari@suse.com> On Thu, May 28, 2026 at 06:01:58PM +0000, Marco Crivellari wrote: > Currently many users transitioned already to the new introduced workqueue > (system_percpu_wq, system_dfl_wq), but there are new users who still use the > older system_wq and system_unbound_wq. > > This change try to push this transition forward, by warning whether the old > workqueus are used. > > Link: https://lore.kernel.org/all/20250221112003.1dSuoGyc@linutronix.de/ > Suggested-by: Tejun Heo > Signed-off-by: Marco Crivellari > --- > include/linux/workqueue.h | 1 + > kernel/workqueue.c | 12 ++++++++++-- > 2 files changed, 11 insertions(+), 2 deletions(-) > > diff --git a/include/linux/workqueue.h b/include/linux/workqueue.h > index 6177624539b3..a283766a192a 100644 > --- a/include/linux/workqueue.h > +++ b/include/linux/workqueue.h > @@ -409,6 +409,7 @@ enum wq_flags { > __WQ_DRAINING = 1 << 16, /* internal: workqueue is draining */ > __WQ_ORDERED = 1 << 17, /* internal: workqueue is ordered */ > __WQ_LEGACY = 1 << 18, /* internal: create*_workqueue() */ > + __WQ_DEPRECATED = 1 << 19, /* internal: workqueue is deprecated */ > > /* BH wq only allows the following flags */ > __WQ_BH_ALLOWS = WQ_BH | WQ_HIGHPRI | WQ_PERCPU, > diff --git a/kernel/workqueue.c b/kernel/workqueue.c > index 33b721a9af02..0b55f8009eed 100644 > --- a/kernel/workqueue.c > +++ b/kernel/workqueue.c > @@ -2280,6 +2280,14 @@ static void __queue_work(int cpu, struct workqueue_struct *wq, > unsigned int work_flags; > unsigned int req_cpu = cpu; > > + /* > + * NOTE: Check whether the used workqueue is deprecated and warn > + */ > + if (unlikely(wq->flags & __WQ_DEPRECATED)) > + pr_warn_once("workqueue: work func %ps enqueued on deprecated workqueue. " > + "Use system_{percpu|dfl}_wq instead.\n", > + work->func); Silly question, can we make this a build warning?