linux-kernel - Re: [PATCH v2 3/3] gpuvm: remove gem.gpuva.lock_dep

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Message-ID: <20250822115543.62094f53@fedora>
Date: Fri, 22 Aug 2025 11:55:43 +0200
From: Boris Brezillon <boris.brezillon@...labora.com>
To: Alice Ryhl <aliceryhl@...gle.com>
Cc: 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>, Danilo Krummrich
 <dakr@...nel.org>, Daniel Almeida <daniel.almeida@...labora.com>, Steven
 Price <steven.price@....com>, Liviu Dudau <liviu.dudau@....com>, Rob Clark
 <robin.clark@....qualcomm.com>, Rob Herring <robh@...nel.org>, Miguel Ojeda
 <ojeda@...nel.org>, Boqun Feng <boqun.feng@...il.com>, Gary Guo
 <gary@...yguo.net>, "Björn Roy Baron"
 <bjorn3_gh@...tonmail.com>, Benno Lossin <lossin@...nel.org>, Andreas
 Hindborg <a.hindborg@...nel.org>, Trevor Gross <tmgross@...ch.edu>,
 dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
 rust-for-linux@...r.kernel.org
Subject: Re: [PATCH v2 3/3] gpuvm: remove gem.gpuva.lock_dep_map

On Fri, 22 Aug 2025 09:28:26 +0000
Alice Ryhl <aliceryhl@...gle.com> wrote:

> diff --git a/include/drm/drm_gem.h b/include/drm/drm_gem.h
> index 5934d8dc267a65aaf62d2d025869221cd110b325..85a25bbb387c4590678e4ba243b51acd94b008ed 100644
> --- a/include/drm/drm_gem.h
> +++ b/include/drm/drm_gem.h
> @@ -402,17 +402,22 @@ struct drm_gem_object {
>  	 *
>  	 * Provides the list of GPU VAs attached to this GEM object.
>  	 *
> -	 * Drivers should lock list accesses with the GEMs &dma_resv lock
> -	 * (&drm_gem_object.resv) or a custom lock if one is provided. The
> -	 * mutex inside this struct may be used as the custom lock.
> +	 * When DRM_GPUVM_IMMEDIATE_MODE is set, this list is protected by the
> +	 * mutex. Otherwise, the list is protected by the GEMs &dma_resv lock.
> +	 *
> +	 * Note that all entries in this list must agree on whether
> +	 * DRM_GPUVM_IMMEDIATE_MODE is set.
>  	 */
>  	struct {
>  		struct list_head list;
>  
> +		/**
> +		 * @gpuva.lock: Only used when DRM_GPUVM_IMMEDIATE_MODE is set.
> +		 * It should be safe to take this mutex during the fence
> +		 * signalling path, so do not allocate memory while holding
> +		 * this lock.
> +		 */

To follow-up on my comment on patch 1: this makes
drm_gem_object::gpuva::list the only field to not have a proper doc.
This patch is

Reviewed-by: Boris Brezillon <boris.brezillon@...labora.com>

regardless.

Thanks,

Boris