linux-kernel - Re: [PATCH v2 4/8] drm/xe: Use dma_fence_check_and_signal

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Message-ID: <2fc7bb8e-aa0f-47c8-adf8-61e70d8c5689@amd.com>
Date: Wed, 3 Dec 2025 14:14:11 +0100
From: Christian König <christian.koenig@....com>
To: Philipp Stanner <phasta@...nel.org>,
 Sumit Semwal <sumit.semwal@...aro.org>, Gustavo Padovan
 <gustavo@...ovan.org>, Felix Kuehling <Felix.Kuehling@....com>,
 Alex Deucher <alexander.deucher@....com>, David Airlie <airlied@...il.com>,
 Simona Vetter <simona@...ll.ch>, Jani Nikula <jani.nikula@...ux.intel.com>,
 Joonas Lahtinen <joonas.lahtinen@...ux.intel.com>,
 Rodrigo Vivi <rodrigo.vivi@...el.com>, Tvrtko Ursulin
 <tursulin@...ulin.net>, Huang Rui <ray.huang@....com>,
 Matthew Auld <matthew.auld@...el.com>,
 Matthew Brost <matthew.brost@...el.com>,
 Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
 Maxime Ripard <mripard@...nel.org>, Thomas Zimmermann <tzimmermann@...e.de>,
 Lucas De Marchi <lucas.demarchi@...el.com>,
 Thomas Hellström <thomas.hellstrom@...ux.intel.com>
Cc: linux-media@...r.kernel.org, dri-devel@...ts.freedesktop.org,
 linux-kernel@...r.kernel.org, amd-gfx@...ts.freedesktop.org,
 intel-gfx@...ts.freedesktop.org, intel-xe@...ts.freedesktop.org
Subject: Re: [PATCH v2 4/8] drm/xe: Use dma_fence_check_and_signal_locked()

On 12/1/25 11:50, Philipp Stanner wrote:
> Xe is one of the few users utilizing the return code of
> dma_fence_signal() to check whether a fence had already been signaled by
> someone else.
> 
> To clean up and simplify the dma_fence API, the few kernel users relying
> on that behavior shall be ported to an alternative function.
> 
> Replace dma_fence_signal_locked() with
> dma_fence_check_and_signal_locked().
> 
> Signed-off-by: Philipp Stanner <phasta@...nel.org>

Acked-by: Christian König <christian.koenig@....com>

> ---
>  drivers/gpu/drm/xe/xe_hw_fence.c | 4 +---
>  1 file changed, 1 insertion(+), 3 deletions(-)
> 
> diff --git a/drivers/gpu/drm/xe/xe_hw_fence.c b/drivers/gpu/drm/xe/xe_hw_fence.c
> index b2a0c46dfcd4..f6057456e460 100644
> --- a/drivers/gpu/drm/xe/xe_hw_fence.c
> +++ b/drivers/gpu/drm/xe/xe_hw_fence.c
> @@ -85,7 +85,6 @@ void xe_hw_fence_irq_finish(struct xe_hw_fence_irq *irq)
>  {
>  	struct xe_hw_fence *fence, *next;
>  	unsigned long flags;
> -	int err;
>  	bool tmp;
>  
>  	if (XE_WARN_ON(!list_empty(&irq->pending))) {
> @@ -93,9 +92,8 @@ void xe_hw_fence_irq_finish(struct xe_hw_fence_irq *irq)
>  		spin_lock_irqsave(&irq->lock, flags);
>  		list_for_each_entry_safe(fence, next, &irq->pending, irq_link) {
>  			list_del_init(&fence->irq_link);
> -			err = dma_fence_signal_locked(&fence->dma);
> +			XE_WARN_ON(dma_fence_check_and_signal_locked(&fence->dma));
>  			dma_fence_put(&fence->dma);
> -			XE_WARN_ON(err);
>  		}
>  		spin_unlock_irqrestore(&irq->lock, flags);
>  		dma_fence_end_signalling(tmp);