On Fri, May 14, 2021 at 1:32 PM Linus Torvalds
<torvalds@xxxxxxxxxxxxxxxxxxxx> wrote:
>
> Another alternative would be to just delay the resize to when vcmode
> is put back to text mode again. That sounds somewhat reasonable to me,
> but it's a pretty big thing.
Actually thinking more about that option, it sounds horrible. It would
mean that we'd continue to use the old geometry for the actual VC
buffers for a random time, and then change it to the new geometry at
some arbitrary point.
So I think the only reasonable approach (apart from just my "don't do
that then") might be to just always call ->con_resize().
There are only actually three cases of "->con_resize()", so it might
not be too bad.
Looking at it, both sisusbcon_resize() and vgacon_resize() seem to be
trivially fine in KD_GRAPHICS mode.
vgacon already seems to have that "!vga_is_gfx" test, and does
vgacon_doresize() at vgacon_switch(). It might need to add a
vgacon_doresize() to the vgacon_blank() case 0 code so that it
actually does the right thing when going back to KD_TEXT mode.
And fbcon_resize() looks like it might be mostly ok with it too.
Again, there is a con_is_visible() test, and I suspect that might need
to be changed to
if (con_is_visible(vc) && vc->vc_mode == KD_TEXT)
instead, but it doesn't look _too_ bad.
So I think just removing the "vc->vc_mode != KD_GRAPHICS" test from
resize_screen() might be the way to go. That way, the low-level data
structures actually are in sync with the resize, and the "out of
bounds" bug should never happen.
Would you mind testing that?
Linus
