[PATCH] tty: replace use of system_unbound_wq with system_dfl_wq

[PATCH] tty: replace use of system_unbound_wq with system_dfl_wq

[Marco Crivellari]

Currently if a user enqueue a work item using schedule_delayed_work() the
used wq is "system_wq" (per-cpu wq) while queue_delayed_work() use
WORK_CPU_UNBOUND (used when a cpu is not specified). The same applies to
schedule_work() that is using system_wq and queue_work(), that makes use
again of WORK_CPU_UNBOUND.

This lack of consistentcy cannot be addressed without refactoring the API.

This patch continues the effort to refactor worqueue APIs, which has begun
with the change introducing new workqueues and a new alloc_workqueue flag:

commit 128ea9f6ccfb ("workqueue: Add system_percpu_wq and system_dfl_wq")
commit 930c2ea566af ("workqueue: Add new WQ_PERCPU flag")

system_dfl_wq should be the default workqueue so as not to enforce
locality constraints for random work whenever it's not required.

The old system_unbound_wq will be kept for a few release cycles.

Suggested-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Marco Crivellari <marco.crivellari@suse.com>
---
 drivers/tty/serial/8250/8250_dw.c | 4 ++--
 drivers/tty/tty_buffer.c          | 8 ++++----
 2 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/drivers/tty/serial/8250/8250_dw.c b/drivers/tty/serial/8250/8250_dw.c
index 710ae4d40aec..27af83f0ff46 100644
--- a/drivers/tty/serial/8250/8250_dw.c
+++ b/drivers/tty/serial/8250/8250_dw.c
@@ -361,7 +361,7 @@ static int dw8250_clk_notifier_cb(struct notifier_block *nb,
 	 * deferred event handling complication.
 	 */
 	if (event == POST_RATE_CHANGE) {
-		queue_work(system_unbound_wq, &d->clk_work);
+		queue_work(system_dfl_wq, &d->clk_work);
 		return NOTIFY_OK;
 	}
 
@@ -680,7 +680,7 @@ static int dw8250_probe(struct platform_device *pdev)
 		err = clk_notifier_register(data->clk, &data->clk_notifier);
 		if (err)
 			return dev_err_probe(dev, err, "Failed to set the clock notifier\n");
-		queue_work(system_unbound_wq, &data->clk_work);
+		queue_work(system_dfl_wq, &data->clk_work);
 	}
 
 	platform_set_drvdata(pdev, data);
diff --git a/drivers/tty/tty_buffer.c b/drivers/tty/tty_buffer.c
index 67271fc0b223..1a5673acd9b1 100644
--- a/drivers/tty/tty_buffer.c
+++ b/drivers/tty/tty_buffer.c
@@ -76,7 +76,7 @@ void tty_buffer_unlock_exclusive(struct tty_port *port)
 	mutex_unlock(&buf->lock);
 
 	if (restart)
-		queue_work(system_unbound_wq, &buf->work);
+		queue_work(system_dfl_wq, &buf->work);
 }
 EXPORT_SYMBOL_GPL(tty_buffer_unlock_exclusive);
 
@@ -530,7 +530,7 @@ void tty_flip_buffer_push(struct tty_port *port)
 	struct tty_bufhead *buf = &port->buf;
 
 	tty_flip_buffer_commit(buf->tail);
-	queue_work(system_unbound_wq, &buf->work);
+	queue_work(system_dfl_wq, &buf->work);
 }
 EXPORT_SYMBOL(tty_flip_buffer_push);
 
@@ -560,7 +560,7 @@ int tty_insert_flip_string_and_push_buffer(struct tty_port *port,
 		tty_flip_buffer_commit(buf->tail);
 	spin_unlock_irqrestore(&port->lock, flags);
 
-	queue_work(system_unbound_wq, &buf->work);
+	queue_work(system_dfl_wq, &buf->work);
 
 	return size;
 }
@@ -613,7 +613,7 @@ void tty_buffer_set_lock_subclass(struct tty_port *port)
 
 bool tty_buffer_restart_work(struct tty_port *port)
 {
-	return queue_work(system_unbound_wq, &port->buf.work);
+	return queue_work(system_dfl_wq, &port->buf.work);
 }
 
 bool tty_buffer_cancel_work(struct tty_port *port)
-- 
2.51.1

Re: [PATCH] tty: replace use of system_unbound_wq with system_dfl_wq

[Marco Crivellari]

On Tue, Nov 4, 2025 at 11:54 AM Marco Crivellari
<marco.crivellari@suse.com> wrote:
>  drivers/tty/serial/8250/8250_dw.c | 4 ++--
>  drivers/tty/tty_buffer.c          | 8 ++++----
>  2 files changed, 6 insertions(+), 6 deletions(-)

Gentle ping.

Thanks!

-- 

Marco Crivellari

L3 Support Engineer

Re: [PATCH] tty: replace use of system_unbound_wq with system_dfl_wq

[Greg Kroah-Hartman]

On Wed, Dec 24, 2025 at 03:54:01PM +0100, Marco Crivellari wrote:
> On Tue, Nov 4, 2025 at 11:54 AM Marco Crivellari
> <marco.crivellari@suse.com> wrote:
> >  drivers/tty/serial/8250/8250_dw.c | 4 ++--
> >  drivers/tty/tty_buffer.c          | 8 ++++----
> >  2 files changed, 6 insertions(+), 6 deletions(-)
> 
> Gentle ping.

This isn't in my queue anymore, are you sure I didn't apply it (sorry,
don't have access to my devel tree at the moment...)

if not, can you resend it?

thanks,

greg k-h

Re: [PATCH] tty: replace use of system_unbound_wq with system_dfl_wq

[Marco Crivellari]

On Sun, Jan 11, 2026 at 11:26 AM Greg Kroah-Hartman
<gregkh@linuxfoundation.org> wrote:
> [...]
> This isn't in my queue anymore, are you sure I didn't apply it (sorry,
> don't have access to my devel tree at the moment...)
>
> if not, can you resend it?
>
> thanks,

Hi Greg,

I checked, it is already applied!
Sorry for the noise.

Thanks!

-- 

Marco Crivellari

L3 Support Engineer