Re: [PATCH 13/21] fbcon: move more common code into fb_open()

Sam Ravnborg
2022-02-05T22:51:54Z

On Mon, Jan 31, 2022 at 10:05:44PM +0100, Daniel Vetter wrote:
> No idea why con2fb_acquire_newinfo() initializes much less than
> fbcon_startup(), but so be it. From a quick look most of the
> un-initialized stuff should be fairly harmless, but who knows.
>
> Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
> Cc: Daniel Vetter <daniel@ffwll.ch>
> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
> Cc: Thomas Zimmermann <tzimmermann@suse.de>
> Cc: Claudio Suarez <cssk@net-c.es>
> Cc: Du Cheng <ducheng2@gmail.com>
> ---
> drivers/video/fbdev/core/fbcon.c | 74 +++++++++++++-------------------
> 1 file changed, 31 insertions(+), 43 deletions(-)
>
> diff --git a/drivers/video/fbdev/core/fbcon.c b/drivers/video/fbdev/core/fbcon.c
> index b83a5a77d8a8..5a3391ff038d 100644
> --- a/drivers/video/fbdev/core/fbcon.c
> +++ b/drivers/video/fbdev/core/fbcon.c
> @@ -680,8 +680,18 @@ static int fbcon_invalid_charcount(struct fb_info *info, unsigned charcount)
>
> #endif /* CONFIG_MISC_TILEBLITTING */
>
> +static void fbcon_release(struct fb_info *info)
> +{
> + if (info->fbops->fb_release)
> + info->fbops->fb_release(info, 0);
> +
> + module_put(info->fbops->owner);
> +}
> +
> static int fbcon_open(struct fb_info *info)
> {
> + struct fbcon_ops *ops;
> +
> if (!try_module_get(info->fbops->owner))
> return -ENODEV;
>
> @@ -691,19 +701,22 @@ static int fbcon_open(struct fb_info *info)
> return -ENODEV;
> }
>
> - return 0;
> -}
> + ops = kzalloc(sizeof(struct fbcon_ops), GFP_KERNEL);
> + if (!ops) {
> + fbcon_release(info);
> + return -ENOMEM;
> + }
>
> -static void fbcon_release(struct fb_info *info)
> -{
> - if (info->fbops->fb_release)
> - info->fbops->fb_release(info, 0);
> + INIT_DELAYED_WORK(&ops->cursor_work, fb_flashcursor);
> + ops->info = info;
> + info->fbcon_par = ops;
> + ops->cur_blink_jiffies = HZ / 5;
>
> - module_put(info->fbops->owner);
> + return 0;
> }
>
> static int con2fb_acquire_newinfo(struct vc_data *vc, struct fb_info *info,
> - int unit, int oldidx)
> + int unit)
> {
> struct fbcon_ops *ops = NULL;
> int err;
> @@ -712,27 +725,10 @@ static int con2fb_acquire_newinfo(struct vc_data *vc, struct fb_info *info,
> if (err)
> return err;
>
> - if (!err) {
> - ops = kzalloc(sizeof(struct fbcon_ops), GFP_KERNEL);
> - if (!ops)
> - err = -ENOMEM;
> -
> - INIT_DELAYED_WORK(&ops->cursor_work, fb_flashcursor);
> - }
> -
> - if (!err) {
> - ops->cur_blink_jiffies = HZ / 5;
> - ops->info = info;
> - info->fbcon_par = ops;
> -
> - if (vc)
> - set_blitting_type(vc, info);
> - }
> + ops = info->fbcon_par;
>
> - if (err) {
> - con2fb_map[unit] = oldidx;
> - fbcon_release(info);
> - }
> + if (vc)
> + set_blitting_type(vc, info);
>
> return err;
> }
> @@ -840,9 +836,11 @@ static int set_con2fb_map(int unit, int newidx, int user)
>
> found = search_fb_in_map(newidx);
>
> - con2fb_map[unit] = newidx;
> - if (!err && !found)
> - err = con2fb_acquire_newinfo(vc, info, unit, oldidx);
> + if (!err && !found) {
> + err = con2fb_acquire_newinfo(vc, info, unit);
> + if (!err)
> + con2fb_map[unit] = newidx;
> + }
This looks like an unintentional change of functionality as con2fb_map[unit] is
only assigned when we do a con2fb_acquire_newinfo().

Staring at the code I could not say it is wrong, but not nice to hide
the change in this patch.

Sam

>
> /*
> * If old fb is not mapped to any of the consoles,
> @@ -939,20 +937,10 @@ static const char *fbcon_startup(void)
> if (fbcon_open(info))
> return NULL;
>
> - ops = kzalloc(sizeof(struct fbcon_ops), GFP_KERNEL);
> - if (!ops) {
> - fbcon_release(info);
> - return NULL;
> - }
> -
> - INIT_DELAYED_WORK(&ops->cursor_work, fb_flashcursor);
> -
> + ops = info->fbcon_par;
> ops->currcon = -1;
> ops->graphics = 1;
> ops->cur_rotate = -1;
> - ops->cur_blink_jiffies = HZ / 5;
> - ops->info = info;
> - info->fbcon_par = ops;
>
> p->con_rotate = initial_rotation;
> if (p->con_rotate == -1)
> @@ -1022,7 +1010,7 @@ static void fbcon_init(struct vc_data *vc, int init)
> return;
>
> if (!info->fbcon_par)
> - con2fb_acquire_newinfo(vc, info, vc->vc_num, -1);
> + con2fb_acquire_newinfo(vc, info, vc->vc_num);
>
> /* If we are not the first console on this
> fb, copy the font from that console */
> --
> 2.33.0