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Message-ID: <0879a2ff-37df-a9ae-0ce1-2bfcb2d1b322@suse.de>
Date: Thu, 10 Feb 2022 12:46:32 +0100
From: Thomas Zimmermann <tzimmermann@...e.de>
To: Daniel Vetter <daniel.vetter@...ll.ch>,
DRI Development <dri-devel@...ts.freedesktop.org>
Cc: linux-fbdev@...r.kernel.org, Du Cheng <ducheng2@...il.com>,
Tetsuo Handa <penguin-kernel@...ove.SAKURA.ne.jp>,
Intel Graphics Development <intel-gfx@...ts.freedesktop.org>,
LKML <linux-kernel@...r.kernel.org>,
Claudio Suarez <cssk@...-c.es>,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
Daniel Vetter <daniel.vetter@...el.com>,
Sam Ravnborg <sam@...nborg.org>
Subject: Re: [PATCH v2 09/19] fbcon: Extract fbcon_open/release helpers
Hi
Am 08.02.22 um 22:08 schrieb Daniel Vetter:
> There's two minor behaviour changes in here:
> - in error paths we now consistently call fb_ops->fb_release
> - fb_release really can't fail (fbmem.c ignores it too) and there's no
> reasonable cleanup we can do anyway.
>
> Note that everything in fbcon.c is protected by the big console_lock()
> lock (especially all the global variables), so the minor changes in
> ordering of setup/cleanup do not matter.
>
> v2: Explain a bit better why this is all correct (Sam)
>
> Acked-by: Sam Ravnborg <sam@...nborg.org>
> Signed-off-by: Daniel Vetter <daniel.vetter@...el.com>
> Cc: Daniel Vetter <daniel@...ll.ch>
> Cc: Claudio Suarez <cssk@...-c.es>
> Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
> Cc: Tetsuo Handa <penguin-kernel@...ove.SAKURA.ne.jp>
> Cc: Du Cheng <ducheng2@...il.com>
> ---
> drivers/video/fbdev/core/fbcon.c | 107 +++++++++++++++----------------
> 1 file changed, 53 insertions(+), 54 deletions(-)
>
> diff --git a/drivers/video/fbdev/core/fbcon.c b/drivers/video/fbdev/core/fbcon.c
> index 058e885d24f6..3e1a3e7bf527 100644
> --- a/drivers/video/fbdev/core/fbcon.c
> +++ b/drivers/video/fbdev/core/fbcon.c
> @@ -682,19 +682,37 @@ static int fbcon_invalid_charcount(struct fb_info *info, unsigned charcount)
>
> #endif /* CONFIG_MISC_TILEBLITTING */
>
> +static int fbcon_open(struct fb_info *info)
> +{
> + if (!try_module_get(info->fbops->owner))
> + return -ENODEV;
> +
> + if (info->fbops->fb_open &&
> + info->fbops->fb_open(info, 0)) {
> + module_put(info->fbops->owner);
> + return -ENODEV;
> + }
> +
> + return 0;
> +}
> +
> +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 con2fb_acquire_newinfo(struct vc_data *vc, struct fb_info *info,
> int unit, int oldidx)
> {
> struct fbcon_ops *ops = NULL;
> - int err = 0;
> -
> - if (!try_module_get(info->fbops->owner))
> - err = -ENODEV;
> + int err;
>
> - if (!err && info->fbops->fb_open &&
> - info->fbops->fb_open(info, 0))
> - err = -ENODEV;
> + err = fbcon_open(info);
> + if (err)
> + return err;
>
> if (!err) {
> ops = kzalloc(sizeof(struct fbcon_ops), GFP_KERNEL);
> @@ -715,7 +733,7 @@ static int con2fb_acquire_newinfo(struct vc_data *vc, struct fb_info *info,
>
> if (err) {
> con2fb_map[unit] = oldidx;
> - module_put(info->fbops->owner);
> + fbcon_release(info);
> }
>
> return err;
> @@ -726,45 +744,34 @@ static int con2fb_release_oldinfo(struct vc_data *vc, struct fb_info *oldinfo,
> int oldidx, int found)
> {
> struct fbcon_ops *ops = oldinfo->fbcon_par;
> - int err = 0, ret;
> + int ret;
>
> - if (oldinfo->fbops->fb_release &&
> - oldinfo->fbops->fb_release(oldinfo, 0)) {
> - con2fb_map[unit] = oldidx;
We don't need oldidx any longer?
There's some logic wrt to the parameter 'found' here and in
set_con2fb_map() that appears to be relevant.
Best regards
Thomas
> - if (!found && newinfo->fbops->fb_release)
> - newinfo->fbops->fb_release(newinfo, 0);
> - if (!found)
> - module_put(newinfo->fbops->owner);
> - err = -ENODEV;
> - }
> + fbcon_release(oldinfo);
>
> - if (!err) {
> - fbcon_del_cursor_work(oldinfo);
> - kfree(ops->cursor_state.mask);
> - kfree(ops->cursor_data);
> - kfree(ops->cursor_src);
> - kfree(ops->fontbuffer);
> - kfree(oldinfo->fbcon_par);
> - oldinfo->fbcon_par = NULL;
> - module_put(oldinfo->fbops->owner);
> - /*
> - If oldinfo and newinfo are driving the same hardware,
> - the fb_release() method of oldinfo may attempt to
> - restore the hardware state. This will leave the
> - newinfo in an undefined state. Thus, a call to
> - fb_set_par() may be needed for the newinfo.
> - */
> - if (newinfo && newinfo->fbops->fb_set_par) {
> - ret = newinfo->fbops->fb_set_par(newinfo);
> + fbcon_del_cursor_work(oldinfo);
> + kfree(ops->cursor_state.mask);
> + kfree(ops->cursor_data);
> + kfree(ops->cursor_src);
> + kfree(ops->fontbuffer);
> + kfree(oldinfo->fbcon_par);
> + oldinfo->fbcon_par = NULL;
> + /*
> + If oldinfo and newinfo are driving the same hardware,
> + the fb_release() method of oldinfo may attempt to
> + restore the hardware state. This will leave the
> + newinfo in an undefined state. Thus, a call to
> + fb_set_par() may be needed for the newinfo.
> + */
> + if (newinfo && newinfo->fbops->fb_set_par) {
> + ret = newinfo->fbops->fb_set_par(newinfo);
>
> - if (ret)
> - printk(KERN_ERR "con2fb_release_oldinfo: "
> - "detected unhandled fb_set_par error, "
> - "error code %d\n", ret);
> - }
> + if (ret)
> + printk(KERN_ERR "con2fb_release_oldinfo: "
> + "detected unhandled fb_set_par error, "
> + "error code %d\n", ret);
> }
>
> - return err;
> + return 0;
> }
>
> static void con2fb_init_display(struct vc_data *vc, struct fb_info *info,
> @@ -919,7 +926,6 @@ static const char *fbcon_startup(void)
> struct fbcon_display *p = &fb_display[fg_console];
> struct vc_data *vc = vc_cons[fg_console].d;
> const struct font_desc *font = NULL;
> - struct module *owner;
> struct fb_info *info = NULL;
> struct fbcon_ops *ops;
> int rows, cols;
> @@ -938,17 +944,12 @@ static const char *fbcon_startup(void)
> if (!info)
> return NULL;
>
> - owner = info->fbops->owner;
> - if (!try_module_get(owner))
> + if (fbcon_open(info))
> return NULL;
> - if (info->fbops->fb_open && info->fbops->fb_open(info, 0)) {
> - module_put(owner);
> - return NULL;
> - }
>
> ops = kzalloc(sizeof(struct fbcon_ops), GFP_KERNEL);
> if (!ops) {
> - module_put(owner);
> + fbcon_release(info);
> return NULL;
> }
>
> @@ -3314,10 +3315,6 @@ static void fbcon_exit(void)
> }
>
> if (mapped) {
> - if (info->fbops->fb_release)
> - info->fbops->fb_release(info, 0);
> - module_put(info->fbops->owner);
> -
> if (info->fbcon_par) {
> struct fbcon_ops *ops = info->fbcon_par;
>
> @@ -3327,6 +3324,8 @@ static void fbcon_exit(void)
> kfree(info->fbcon_par);
> info->fbcon_par = NULL;
> }
> +
> + fbcon_release(info);
> }
> }
> }
--
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Maxfeldstr. 5, 90409 Nürnberg, Germany
(HRB 36809, AG Nürnberg)
Geschäftsführer: Ivo Totev
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