Hi Thomas.
On Mon, Aug 18, 2025 at 12:36:39PM +0200, Thomas Zimmermann wrote:
> Depending on rotation settings, fbcon sets different callback
> functions in struct fbcon from within fbcon_set_bitops(). Declare
> the callback functions in the new type struct fbcon_bitops. Then
> only replace the single bitops pointer in struct fbcon.
>
> Keeping callbacks in constant instances of struct fbcon_bitops
> makes it harder to exploit the callbacks. Also makes the code slightly
> easier to maintain.
>
> For tile-based consoles, there's a separate instance of the bitops
> structure.
>
> Signed-off-by: Thomas Zimmermann <tzimmerm...@suse.de>
> ---
> drivers/video/fbdev/core/bitblit.c | 17 ++++---
> drivers/video/fbdev/core/fbcon.c | 67 +++++++++++++++-------------
> drivers/video/fbdev/core/fbcon.h | 7 ++-
> drivers/video/fbdev/core/fbcon_ccw.c | 18 +++++---
> drivers/video/fbdev/core/fbcon_cw.c | 18 +++++---
> drivers/video/fbdev/core/fbcon_ud.c | 18 +++++---
> drivers/video/fbdev/core/tileblit.c | 16 ++++---
> 7 files changed, 94 insertions(+), 67 deletions(-)
>
> diff --git a/drivers/video/fbdev/core/bitblit.c
> b/drivers/video/fbdev/core/bitblit.c
> index a2202cae0691..267bd1635a41 100644
> --- a/drivers/video/fbdev/core/bitblit.c
> +++ b/drivers/video/fbdev/core/bitblit.c
> @@ -384,15 +384,18 @@ static int bit_update_start(struct fb_info *info)
> return err;
> }
>
> +static const struct fbcon_bitops bit_fbcon_bitops = {
> + .bmove = bit_bmove,
> + .clear = bit_clear,
> + .putcs = bit_putcs,
> + .clear_margins = bit_clear_margins,
> + .cursor = bit_cursor,
> + .update_start = bit_update_start,
> +};
> +
> void fbcon_set_bitops(struct fbcon *confb)
> {
> - confb->bmove = bit_bmove;
> - confb->clear = bit_clear;
> - confb->putcs = bit_putcs;
> - confb->clear_margins = bit_clear_margins;
> - confb->cursor = bit_cursor;
> - confb->update_start = bit_update_start;
> - confb->rotate_font = NULL;
> + confb->bitops = &bit_fbcon_bitops;
>
> if (confb->rotate)
> fbcon_set_rotate(confb);
fbcon_set_rotate() is only used to set the correct bitops.
It would be simpler to just do
if (confb->rotate)
confb->bitops = fbcon_rotate_get_ops();
And rename fbcon_set_rotate() to fbcon_rotate_get_ops() and return the
pointer to the struct.
The no need to pass the struct, and it is obvious that the bitops are
overwritten.
Sam
