linux-kernel - Re: [PATCH 3/6] drm/gpu/xe: Ignore dma_fenc

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Message-ID: <aScvYd0zEXpn87S/@lstrano-desk.jf.intel.com>
Date: Wed, 26 Nov 2025 08:48:33 -0800
From: Matthew Brost <matthew.brost@...el.com>
To: Philipp Stanner <phasta@...nel.org>
CC: Sumit Semwal <sumit.semwal@...aro.org>, Gustavo Padovan
	<gustavo@...ovan.org>, Christian König
	<christian.koenig@....com>, 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>, 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>, <linux-media@...r.kernel.org>,
	<dri-devel@...ts.freedesktop.org>, <linaro-mm-sig@...ts.linaro.org>,
	<linux-kernel@...r.kernel.org>, <amd-gfx@...ts.freedesktop.org>,
	<intel-gfx@...ts.freedesktop.org>, <intel-xe@...ts.freedesktop.org>,
	<rust-for-linux@...r.kernel.org>
Subject: Re: [PATCH 3/6] drm/gpu/xe: Ignore dma_fenc_signal() return code

On Wed, Nov 26, 2025 at 02:19:12PM +0100, Philipp Stanner wrote:
> The return code of dma_fence_signal() is not really useful as there is
> nothing reasonable to do if a fence was already signaled. That return
> code shall be removed from the kernel.
> 
> Ignore dma_fence_signal()'s return code.
> 
> Suggested-by: Christian König <christian.koenig@....com>
> Signed-off-by: Philipp Stanner <phasta@...nel.org>
> ---
>  drivers/gpu/drm/xe/xe_hw_fence.c | 5 ++---
>  1 file changed, 2 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/gpu/drm/xe/xe_hw_fence.c b/drivers/gpu/drm/xe/xe_hw_fence.c
> index b2a0c46dfcd4..959b30dde724 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 +92,9 @@ 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_test_signaled_flag(&fence->dma));
> +			dma_fence_signal_locked(&fence->dma);

If you also want fix Xe to use dma_fence_test_signaled_flag in all
places where we manually check DMA_FENCE_FLAG_SIGNALED_BIT, I'm not
going to complain. Ofc I can also do this in follow if patch when patch
#1 merges too.

Anyways this patch LGTM:
Reviewed-by: Matthew Brost <matthew.brost@...el.com>

>  			dma_fence_put(&fence->dma);
> -			XE_WARN_ON(err);
>  		}
>  		spin_unlock_irqrestore(&irq->lock, flags);
>  		dma_fence_end_signalling(tmp);
> -- 
> 2.49.0
>