linux-kernel - Re: [PATCH 10/10] drm/qxl: add lock asserts to qxl_bo_kmap_locked + qxl_bo_kunmap

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Message-ID: <f61561a4-f6c7-9237-cd10-1c69016e6e45@suse.de>
Date:   Tue, 16 Feb 2021 14:30:38 +0100
From:   Thomas Zimmermann <tzimmermann@...e.de>
To:     Gerd Hoffmann <kraxel@...hat.com>, dri-devel@...ts.freedesktop.org
Cc:     David Airlie <airlied@...ux.ie>,
        open list <linux-kernel@...r.kernel.org>,
        "open list:DRM DRIVER FOR QXL VIRTUAL GPU" 
        <virtualization@...ts.linux-foundation.org>,
        "open list:DRM DRIVER FOR QXL VIRTUAL GPU" 
        <spice-devel@...ts.freedesktop.org>,
        Dave Airlie <airlied@...hat.com>
Subject: Re: [PATCH 10/10] drm/qxl: add lock asserts to qxl_bo_kmap_locked +
 qxl_bo_kunmap_locked

Hi

Am 16.02.21 um 12:37 schrieb Gerd Hoffmann:
> Try avoid re-introducing locking bugs.
> 
> Signed-off-by: Gerd Hoffmann <kraxel@...hat.com>

Acked-by: Thomas Zimmermann <tzimmermann@...e.de>

IMHO this should eventually be done in the rsp TTM functions. But so 
far, I'd expect this to break some drivers.

Best regards
Thomas

> ---
>   drivers/gpu/drm/qxl/qxl_object.c | 4 ++++
>   1 file changed, 4 insertions(+)
> 
> diff --git a/drivers/gpu/drm/qxl/qxl_object.c b/drivers/gpu/drm/qxl/qxl_object.c
> index 22748b9566af..90d5e5b7f927 100644
> --- a/drivers/gpu/drm/qxl/qxl_object.c
> +++ b/drivers/gpu/drm/qxl/qxl_object.c
> @@ -162,6 +162,8 @@ int qxl_bo_kmap_locked(struct qxl_bo *bo, struct dma_buf_map *map)
>   {
>   	int r;
>   
> +	dma_resv_assert_held(bo->tbo.base.resv);
> +
>   	if (bo->kptr) {
>   		bo->map_count++;
>   		goto out;
> @@ -236,6 +238,8 @@ void *qxl_bo_kmap_atomic_page(struct qxl_device *qdev,
>   
>   void qxl_bo_kunmap_locked(struct qxl_bo *bo)
>   {
> +	dma_resv_assert_held(bo->tbo.base.resv);
> +
>   	if (bo->kptr == NULL)
>   		return;
>   	bo->map_count--;
> 

-- 
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Maxfeldstr. 5, 90409 Nürnberg, Germany
(HRB 36809, AG Nürnberg)
Geschäftsführer: Felix Imendörffer



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