linux-kernel - Re: [PATCH] drm/panthor: disable async work during unplug

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Message-ID: <aQNPjYdp4XOlk0Ej@e110455-lin.cambridge.arm.com>
Date: Thu, 30 Oct 2025 11:44:13 +0000
From: Liviu Dudau <liviu.dudau@....com>
To: Ketil Johnsen <ketil.johnsen@....com>
Cc: Boris Brezillon <boris.brezillon@...labora.com>,
	Steven Price <steven.price@....com>,
	Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
	Maxime Ripard <mripard@...nel.org>,
	Thomas Zimmermann <tzimmermann@...e.de>,
	David Airlie <airlied@...il.com>, Simona Vetter <simona@...ll.ch>,
	dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] drm/panthor: disable async work during unplug

On Wed, Oct 29, 2025 at 12:14:10PM +0100, Ketil Johnsen wrote:
> A previous change, "drm/panthor: Fix UAF race between device unplug and
> FW event processing", fixes a real issue where new work was unexpectedly
> queued after cancellation. This was fixed by a disable instead.
> 
> Apply the same disable logic to other device level async work on device
> unplug as a precaution.
> 
> Signed-off-by: Ketil Johnsen <ketil.johnsen@....com>

Reviewed-by: Liviu Dudau <liviu.dudau@....com>

Best regards,
Liviu

> ---
>  drivers/gpu/drm/panthor/panthor_device.c | 2 +-
>  drivers/gpu/drm/panthor/panthor_fw.c     | 2 +-
>  drivers/gpu/drm/panthor/panthor_sched.c  | 5 ++---
>  3 files changed, 4 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/gpu/drm/panthor/panthor_device.c b/drivers/gpu/drm/panthor/panthor_device.c
> index 962a10e00848e..c4ae78545ef03 100644
> --- a/drivers/gpu/drm/panthor/panthor_device.c
> +++ b/drivers/gpu/drm/panthor/panthor_device.c
> @@ -120,7 +120,7 @@ static void panthor_device_reset_cleanup(struct drm_device *ddev, void *data)
>  {
>  	struct panthor_device *ptdev = container_of(ddev, struct panthor_device, base);
>  
> -	cancel_work_sync(&ptdev->reset.work);
> +	disable_work_sync(&ptdev->reset.work);
>  	destroy_workqueue(ptdev->reset.wq);
>  }
>  
> diff --git a/drivers/gpu/drm/panthor/panthor_fw.c b/drivers/gpu/drm/panthor/panthor_fw.c
> index 9bf06e55eaeea..ceb249da8b336 100644
> --- a/drivers/gpu/drm/panthor/panthor_fw.c
> +++ b/drivers/gpu/drm/panthor/panthor_fw.c
> @@ -1162,7 +1162,7 @@ void panthor_fw_unplug(struct panthor_device *ptdev)
>  {
>  	struct panthor_fw_section *section;
>  
> -	cancel_delayed_work_sync(&ptdev->fw->watchdog.ping_work);
> +	disable_delayed_work_sync(&ptdev->fw->watchdog.ping_work);
>  
>  	if (!IS_ENABLED(CONFIG_PM) || pm_runtime_active(ptdev->base.dev)) {
>  		/* Make sure the IRQ handler cannot be called after that point. */
> diff --git a/drivers/gpu/drm/panthor/panthor_sched.c b/drivers/gpu/drm/panthor/panthor_sched.c
> index b7595beaa0205..278434da8926d 100644
> --- a/drivers/gpu/drm/panthor/panthor_sched.c
> +++ b/drivers/gpu/drm/panthor/panthor_sched.c
> @@ -3879,8 +3879,9 @@ void panthor_sched_unplug(struct panthor_device *ptdev)
>  {
>  	struct panthor_scheduler *sched = ptdev->scheduler;
>  
> -	cancel_delayed_work_sync(&sched->tick_work);
> +	disable_delayed_work_sync(&sched->tick_work);
>  	disable_work_sync(&sched->fw_events_work);
> +	disable_work_sync(&sched->sync_upd_work);
>  
>  	mutex_lock(&sched->lock);
>  	if (sched->pm.has_ref) {
> @@ -3898,8 +3899,6 @@ static void panthor_sched_fini(struct drm_device *ddev, void *res)
>  	if (!sched || !sched->csg_slot_count)
>  		return;
>  
> -	cancel_delayed_work_sync(&sched->tick_work);
> -
>  	if (sched->wq)
>  		destroy_workqueue(sched->wq);
>  
> -- 
> 2.47.2
> 

-- 
====================
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| but they're not |
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