Re: [PATCH 26/30] fbdev/core: Add fb_device_{create,destroy}()

Sam Ravnborg
2023-06-07T19:46:59Z

Hi Thomas,

On Mon, Jun 05, 2023 at 04:48:08PM +0200, Thomas Zimmermann wrote:
> Move the logic to create and destroy fbdev devices into the new
> helpers fb_device_create() and fb_device_destroy().
>
> There was a call to fb_cleanup_device() in do_unregister_framebuffer()
> that was too late. The device had already been removed at this point.
> Move the call into fb_device_destroy().
>
> Declare the helpers in the new internal header file fb_internal.h, as
s/ / /
> they are only used within the fbdev core module.
>
> Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
> ---
> drivers/video/fbdev/core/fb_internal.h | 12 ++++++++
> drivers/video/fbdev/core/fbmem.c | 21 +++-----------
> drivers/video/fbdev/core/fbsysfs.c | 38 ++++++++++++++++++++++++--
> include/linux/fb.h | 3 --
> 4 files changed, 52 insertions(+), 22 deletions(-)
> create mode 100644 drivers/video/fbdev/core/fb_internal.h
>
> diff --git a/drivers/video/fbdev/core/fb_internal.h b/drivers/video/fbdev/core/fb_internal.h
> new file mode 100644
> index 000000000000..0b9640ae7a3d
> --- /dev/null
> +++ b/drivers/video/fbdev/core/fb_internal.h
> @@ -0,0 +1,12 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +
> +#ifndef _FB_INTERNAL_H
> +#define _FB_INTERNAL_H
> +
> +struct fb_info;
> +
> +/* fbsysfs.c */
> +int fb_device_create(struct fb_info *fb_info);
> +void fb_device_destroy(struct fb_info *fb_info);
> +
> +#endif
> diff --git a/drivers/video/fbdev/core/fbmem.c b/drivers/video/fbdev/core/fbmem.c
> index f91ae7d4c94d..66532774d351 100644
> --- a/drivers/video/fbdev/core/fbmem.c
> +++ b/drivers/video/fbdev/core/fbmem.c
> @@ -40,6 +40,8 @@
> #include <video/nomodeset.h>
> #include <video/vga.h>
>
> +#include "fb_internal.h"
> +
> /*
> * Frame buffer device initialization and setup routines
> */
> @@ -1447,14 +1449,7 @@ static int do_register_framebuffer(struct fb_info *fb_info)
> mutex_init(&fb_info->lock);
> mutex_init(&fb_info->mm_lock);
>
> - fb_info->dev = device_create(fb_class, fb_info->device,
> - MKDEV(FB_MAJOR, i), NULL, "fb%d", i);
> - if (IS_ERR(fb_info->dev)) {
> - /* Not fatal */
> - printk(KERN_WARNING "Unable to create device for framebuffer %d; errno = %ld\n", i, PTR_ERR(fb_info->dev));
> - fb_info->dev = NULL;
> - } else
> - fb_init_device(fb_info);
> + fb_device_create(fb_info);
The return result is ignored here.
If we do not need it in later patches then drop the return result.

>
> if (fb_info->pixmap.addr == NULL) {
> fb_info->pixmap.addr = kmalloc(FBPIXMAPSIZE, GFP_KERNEL);
> @@ -1515,16 +1510,9 @@ static void unlink_framebuffer(struct fb_info *fb_info)
> if (WARN_ON(i < 0 || i >= FB_MAX || registered_fb[i] != fb_info))
> return;
>
> - if (!fb_info->dev)
> - return;
> -
> - device_destroy(fb_class, MKDEV(FB_MAJOR, i));
> -
> + fb_device_destroy(fb_info);
> pm_vt_switch_unregister(fb_info->device);
> -
> unbind_console(fb_info);
> -
> - fb_info->dev = NULL;
> }
>
> static void do_unregister_framebuffer(struct fb_info *fb_info)
> @@ -1539,7 +1527,6 @@ static void do_unregister_framebuffer(struct fb_info *fb_info)
> fb_destroy_modelist(&fb_info->modelist);
> registered_fb[fb_info->node] = NULL;
> num_registered_fb--;
> - fb_cleanup_device(fb_info);
> #ifdef CONFIG_GUMSTIX_AM200EPD
> {
> struct fb_event event;
> diff --git a/drivers/video/fbdev/core/fbsysfs.c b/drivers/video/fbdev/core/fbsysfs.c
> index 849073f1ca06..fafe574398b0 100644
> --- a/drivers/video/fbdev/core/fbsysfs.c
> +++ b/drivers/video/fbdev/core/fbsysfs.c
> @@ -8,6 +8,9 @@
> #include <linux/console.h>
> #include <linux/fb.h>
> #include <linux/fbcon.h>
> +#include <linux/major.h>
> +
> +#include "fb_internal.h"
>
> #define FB_SYSFS_FLAG_ATTR 1
>
> @@ -435,7 +438,7 @@ static struct device_attribute device_attrs[] = {
> #endif
> };
>
> -int fb_init_device(struct fb_info *fb_info)
> +static int fb_init_device(struct fb_info *fb_info)
> {
> int i, error = 0;
>
> @@ -459,7 +462,7 @@ int fb_init_device(struct fb_info *fb_info)
> return 0;
> }
>
> -void fb_cleanup_device(struct fb_info *fb_info)
> +static void fb_cleanup_device(struct fb_info *fb_info)
> {
> unsigned int i;
>
> @@ -470,3 +473,34 @@ void fb_cleanup_device(struct fb_info *fb_info)
> fb_info->class_flag &= ~FB_SYSFS_FLAG_ATTR;
> }
> }
> +
> +int fb_device_create(struct fb_info *fb_info)
> +{
> + int node = fb_info->node;
> + dev_t devt = MKDEV(FB_MAJOR, node);
> + int ret;
> +
> + fb_info->dev = device_create(fb_class, fb_info->device, devt, NULL, "fb%d", node);
> + if (IS_ERR(fb_info->dev)) {
> + /* Not fatal */
> + ret = PTR_ERR(fb_info->dev);
This error code is lost as we always return 0.
> + pr_warn("Unable to create device for framebuffer %d; error %d\n", node, ret);
> + fb_info->dev = NULL;
> + } else {
> + fb_init_device(fb_info);
> + }
> +
> + return 0;
> +}
> +
> +void fb_device_destroy(struct fb_info *fb_info)
> +{
> + dev_t devt = MKDEV(FB_MAJOR, fb_info->node);
> +
> + if (!fb_info->dev)
> + return;
> +
> + fb_cleanup_device(fb_info);
> + device_destroy(fb_class, devt);
> + fb_info->dev = NULL;
> +}
> diff --git a/include/linux/fb.h b/include/linux/fb.h
> index ce6823e157e6..1988d11f78bc 100644
> --- a/include/linux/fb.h
> +++ b/include/linux/fb.h
> @@ -735,11 +735,8 @@ static inline bool fb_be_math(struct fb_info *info)
> #endif /* CONFIG_FB_FOREIGN_ENDIAN */
> }
>
> -/* drivers/video/fbsysfs.c */
> extern struct fb_info *framebuffer_alloc(size_t size, struct device *dev);
> extern void framebuffer_release(struct fb_info *info);
> -extern int fb_init_device(struct fb_info *fb_info);
> -extern void fb_cleanup_device(struct fb_info *head);
> extern void fb_bl_default_curve(struct fb_info *fb_info, u8 off, u8 min, u8 max);
>
> /* drivers/video/fbmon.c */
> --
> 2.40.1