Re: [PATCH] drm/shmem-helpers: Simplify dma-buf importing

From: Boris Brezillon <boris.brezillon@collabora.com>
To: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: Thomas Zimmermann <tzimmermann@suse.de>,
	Gerd Hoffmann <kraxel@redhat.com>,
	DRI Development <dri-devel@lists.freedesktop.org>
Subject: Re: [PATCH] drm/shmem-helpers: Simplify dma-buf importing
Date: Fri, 29 May 2020 15:34:28 +0200	[thread overview]
Message-ID: <20200529153428.50688049@collabora.com> (raw)
In-Reply-To: <20200520180232.956489-1-daniel.vetter@ffwll.ch>

Hi Daniel,

On Wed, 20 May 2020 20:02:32 +0200
Daniel Vetter <daniel.vetter@ffwll.ch> wrote:

> - Ditch the ->pages array
> - Make it a private gem bo, which means no shmem object, which means
>   fireworks if anyone calls drm_gem_object_get_pages. But we've just
>   made sure that's all covered.
> 
> v2: Rebase
> 
> Acked-by: Thomas Zimmermann <tzimmermann@suse.de>
> Cc: Gerd Hoffmann <kraxel@redhat.com>
> Cc: Rob Herring <robh@kernel.org>
> Cc: Noralf Trønnes <noralf@tronnes.org>
> Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>

I see a bunch of

[   38.261313] ------------[ cut here ]------------
[   38.261740] WARNING: CPU: 4 PID: 2945 at drivers/gpu/drm/drm_gem_shmem_helper.c:137 drm_gem_shmem_free_object+0xb4/0xe0
[   38.262676] Modules linked in:
[   38.262949] CPU: 4 PID: 2945 Comm: Xwayland Not tainted 5.7.0-rc1-00111-g9c7e526c43d0 #520
[   38.263667] Hardware name: Radxa ROCK Pi 4 (DT)
[   38.264062] pstate: 60000005 (nZCv daif -PAN -UAO)
[   38.264482] pc : drm_gem_shmem_free_object+0xb4/0xe0
[   38.264916] lr : drm_gem_shmem_free_object+0x38/0xe0
[   38.265348] sp : ffff800011cebbb0
[   38.265639] x29: ffff800011cebbb0 x28: ffff800011cebd88 
[   38.266102] x27: 0000000000000000 x26: ffff000072a1f400 
[   38.266566] x25: 0000000000000009 x24: ffff000072a1f400 
[   38.267029] x23: 0000000000000002 x22: ffff000079409080 
[   38.267492] x21: ffff000079409280 x20: ffff00006c304800 
[   38.267955] x19: ffff00006c304800 x18: 0000000000000000 
[   38.268417] x17: 0000000000000000 x16: 0000000000000000 
[   38.268880] x15: 0000000000000000 x14: 0000000000000000 
[   38.269343] x13: 0001000000000000 x12: 0000000000000008 
[   38.269806] x11: 000000000000ffff x10: 0000000000000000 
[   38.270269] x9 : 0000000000000001 x8 : 0000000000210d00 
[   38.270732] x7 : 0000000000000001 x6 : ffff800011307980 
[   38.271195] x5 : ffff00006641c240 x4 : ffff00006ee1b400 
[   38.271656] x3 : 0000000000000004 x2 : aafbc6f338cf6000 
[   38.272119] x1 : 0000000000000000 x0 : 00000000ffffffff 
[   38.272583] Call trace:
[   38.272799]  drm_gem_shmem_free_object+0xb4/0xe0
[   38.273203]  panfrost_gem_free_object+0xf0/0x128
[   38.273608]  drm_gem_object_free+0x18/0x40
[   38.273967]  drm_gem_object_handle_put_unlocked+0xe4/0xe8
[   38.274439]  drm_gem_object_release_handle+0x6c/0x98
[   38.274872]  drm_gem_handle_delete+0x84/0x140
[   38.275253]  drm_gem_close_ioctl+0x2c/0x40
[   38.275612]  drm_ioctl_kernel+0xb8/0x108
[   38.275954]  drm_ioctl+0x214/0x450
[   38.276255]  ksys_ioctl+0xa0/0xe0
[   38.276546]  __arm64_sys_ioctl+0x1c/0x28
[   38.276891]  el0_svc_common.constprop.0+0x68/0x160
[   38.277310]  do_el0_svc+0x20/0x80
[   38.277602]  el0_sync_handler+0x10c/0x178
[   38.277952]  el0_sync+0x140/0x180
[   38.278242] ---[ end trace db5754ef8b213ce5 ]---

after applying that patch. Didn't have time to dig through it, unfortunately.

> ---
>  drivers/gpu/drm/drm_gem_shmem_helper.c | 59 ++++++++++----------------
>  1 file changed, 23 insertions(+), 36 deletions(-)
> 
> diff --git a/drivers/gpu/drm/drm_gem_shmem_helper.c b/drivers/gpu/drm/drm_gem_shmem_helper.c
> index 06cee8e97d27..f6854af206d2 100644
> --- a/drivers/gpu/drm/drm_gem_shmem_helper.c
> +++ b/drivers/gpu/drm/drm_gem_shmem_helper.c
> @@ -35,22 +35,12 @@ static const struct drm_gem_object_funcs drm_gem_shmem_funcs = {
>  	.mmap = drm_gem_shmem_mmap,
>  };
>  
> -/**
> - * drm_gem_shmem_create - Allocate an object with the given size
> - * @dev: DRM device
> - * @size: Size of the object to allocate
> - *
> - * This function creates a shmem GEM object.
> - *
> - * Returns:
> - * A struct drm_gem_shmem_object * on success or an ERR_PTR()-encoded negative
> - * error code on failure.
> - */
> -struct drm_gem_shmem_object *drm_gem_shmem_create(struct drm_device *dev, size_t size)
> +static struct drm_gem_shmem_object *
> +__drm_gem_shmem_create(struct drm_device *dev, size_t size, bool private)
>  {
>  	struct drm_gem_shmem_object *shmem;
>  	struct drm_gem_object *obj;
> -	int ret;
> +	int ret = 0;
>  
>  	size = PAGE_ALIGN(size);
>  
> @@ -64,7 +54,10 @@ struct drm_gem_shmem_object *drm_gem_shmem_create(struct drm_device *dev, size_t
>  	if (!obj->funcs)
>  		obj->funcs = &drm_gem_shmem_funcs;
>  
> -	ret = drm_gem_object_init(dev, obj, size);
> +	if (private)
> +		drm_gem_private_object_init(dev, obj, size);
> +	else
> +		ret = drm_gem_object_init(dev, obj, size);
>  	if (ret)
>  		goto err_free;
>  
> @@ -96,6 +89,21 @@ struct drm_gem_shmem_object *drm_gem_shmem_create(struct drm_device *dev, size_t
>  
>  	return ERR_PTR(ret);
>  }
> +/**
> + * drm_gem_shmem_create - Allocate an object with the given size
> + * @dev: DRM device
> + * @size: Size of the object to allocate
> + *
> + * This function creates a shmem GEM object.
> + *
> + * Returns:
> + * A struct drm_gem_shmem_object * on success or an ERR_PTR()-encoded negative
> + * error code on failure.
> + */
> +struct drm_gem_shmem_object *drm_gem_shmem_create(struct drm_device *dev, size_t size)
> +{
> +	return __drm_gem_shmem_create(dev, size, false);
> +}
>  EXPORT_SYMBOL_GPL(drm_gem_shmem_create);
>  
>  /**
> @@ -115,7 +123,6 @@ void drm_gem_shmem_free_object(struct drm_gem_object *obj)
>  	if (obj->import_attach) {
>  		shmem->pages_use_count--;
>  		drm_prime_gem_destroy(obj, shmem->sgt);
> -		kvfree(shmem->pages);
>  	} else {
>  		if (shmem->sgt) {
>  			dma_unmap_sg(obj->dev->dev, shmem->sgt->sgl,
> @@ -371,7 +378,7 @@ drm_gem_shmem_create_with_handle(struct drm_file *file_priv,
>  	struct drm_gem_shmem_object *shmem;
>  	int ret;
>  
> -	shmem = drm_gem_shmem_create(dev, size);
> +	shmem = __drm_gem_shmem_create(dev, size, true);
>  	if (IS_ERR(shmem))
>  		return shmem;
>  
> @@ -695,36 +702,16 @@ drm_gem_shmem_prime_import_sg_table(struct drm_device *dev,
>  				    struct sg_table *sgt)
>  {
>  	size_t size = PAGE_ALIGN(attach->dmabuf->size);
> -	size_t npages = size >> PAGE_SHIFT;
>  	struct drm_gem_shmem_object *shmem;
> -	int ret;
>  
>  	shmem = drm_gem_shmem_create(dev, size);
>  	if (IS_ERR(shmem))
>  		return ERR_CAST(shmem);
>  
> -	shmem->pages = kvmalloc_array(npages, sizeof(struct page *), GFP_KERNEL);
> -	if (!shmem->pages) {
> -		ret = -ENOMEM;
> -		goto err_free_gem;
> -	}
> -
> -	ret = drm_prime_sg_to_page_addr_arrays(sgt, shmem->pages, NULL, npages);
> -	if (ret < 0)
> -		goto err_free_array;
> -
>  	shmem->sgt = sgt;
> -	shmem->pages_use_count = 1; /* Permanently pinned from our point of view */
>  
>  	DRM_DEBUG_PRIME("size = %zu\n", size);
>  
>  	return &shmem->base;
> -
> -err_free_array:
> -	kvfree(shmem->pages);
> -err_free_gem:
> -	drm_gem_object_put(&shmem->base);
> -
> -	return ERR_PTR(ret);
>  }
>  EXPORT_SYMBOL_GPL(drm_gem_shmem_prime_import_sg_table);

_______________________________________________
dri-devel mailing list
dri-devel@lists.freedesktop.org
https://lists.freedesktop.org/mailman/listinfo/dri-devel