[PATCH 18/39] fbdev: defio: assert FBINFO_VIRTFB, drop VM_IO, add VM_MIXEDMAP

[Thomas Zimmermann]

Am 08.09.26 um 22:01 schrieb Lorenzo Stoakes (ARM):
> Currently all drivers which use defio allocate system memory. All of them
> also set FBINFO_VIRTFB, other than ssd1307fb, however this driver allocates
> system RAM, so simply failed to set this flag when it ought to.
>
> This patch sets FBINFO_VIRTFB on ssd1307fb probe, then drops setting VM_IO
> in fb_deferred_io_mmap() and instead requires FBINFO_VIRTFB to be set,
> erroring out with a kernel warning if not.
>
> The logic requires a page from the driver and since commit 1ecbc7dd2902
> ("fbdev/deferred-io: Always call get_page() for framebuffer pages") has
> always required it to be refcounted, so this was implicitly already the
> case.
>
> Finally this patch sets VM_MIXEDMAP, as the logic is mapping
> kernel-allocated memory so this is appropriate.
>
> Signed-off-by: Lorenzo Stoakes (ARM) <ljs at kernel.org>

Reviewed-by: Thomas Zimmermann <tzimmermann at suse.de>

> ---
>   drivers/video/fbdev/core/fb_defio.c | 6 +++---
>   drivers/video/fbdev/ssd1307fb.c     | 2 ++
>   2 files changed, 5 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/video/fbdev/core/fb_defio.c b/drivers/video/fbdev/core/fb_defio.c
> index fd00b86e1ae6..fb359ecc3966 100644
> --- a/drivers/video/fbdev/core/fb_defio.c
> +++ b/drivers/video/fbdev/core/fb_defio.c
> @@ -366,13 +366,13 @@ int fb_deferred_io_mmap(struct fb_info *info, struct vm_area_struct *vma)
>   {
>   	vma->vm_page_prot = pgprot_decrypted(vma->vm_page_prot);
>   
> +	if (WARN_ON_ONCE(!(info->flags & FBINFO_VIRTFB)))
> +		return -EINVAL;
>   	if (!try_module_get(THIS_MODULE))
>   		return -EINVAL;
>   
>   	vma->vm_ops = &fb_deferred_io_vm_ops;
> -	vm_flags_set(vma, VM_DONTEXPAND | VM_DONTDUMP);
> -	if (!(info->flags & FBINFO_VIRTFB))
> -		vm_flags_set(vma, VM_IO);
> +	vm_flags_set(vma, VM_MIXEDMAP | VM_DONTEXPAND | VM_DONTDUMP);
>   	vma->vm_private_data = info->fbdefio_state;
>   
>   	fb_deferred_io_state_get(info->fbdefio_state); /* released in vma->vm_ops->close() */
> diff --git a/drivers/video/fbdev/ssd1307fb.c b/drivers/video/fbdev/ssd1307fb.c
> index c4fdecafd856..958514a35433 100644
> --- a/drivers/video/fbdev/ssd1307fb.c
> +++ b/drivers/video/fbdev/ssd1307fb.c
> @@ -763,6 +763,8 @@ static int ssd1307fb_probe(struct i2c_client *client)
>   	info->fix.smem_start = __pa(vmem);
>   	info->fix.smem_len = vmem_size;
>   
> +	info->flags = FBINFO_VIRTFB;
> +
>   	fb_deferred_io_init(info);
>   
>   	i2c_set_clientdata(client, info);
>

-- 
--
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Frankenstr. 146, 90461 Nürnberg, Germany, www.suse.com
GF: Jochen Jaser, Andrew McDonald, (HRB 36809, AG Nürnberg)