Re: [PATCH] firmware: sysfb: Fix reference count of sysfb parent device

[Thomas Zimmermann <tzimmermann@suse.de>]

Hi

Am 28.06.24 um 20:54 schrieb Marek Olšák:
> Hi Thomas,
>
> FYI, this doesn't fix the issue of lightdm not being able to start for me.

Of course, that's expected. It's a different bug.

Best regards
Thomas

>
> Marek
>
>
> Marek
>
> On Tue, Jun 25, 2024 at 4:18 AM Thomas Zimmermann <tzimmermann@suse.de> wrote:
>> Retrieving the system framebuffer's parent device in sysfb_init()
>> increments the parent device's reference count. Hence release the
>> reference before leaving the init function.
>>
>> Adding the sysfb platform device acquires and additional reference
>> for the parent. This keeps the parent device around while the system
>> framebuffer is in use.
>>
>> Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
>> Fixes: 9eac534db001 ("firmware/sysfb: Set firmware-framebuffer parent device")
>> Cc: Thomas Zimmermann <tzimmermann@suse.de>
>> Cc: Javier Martinez Canillas <javierm@redhat.com>
>> Cc: Helge Deller <deller@gmx.de>
>> Cc: Jani Nikula <jani.nikula@intel.com>
>> Cc: Dan Carpenter <dan.carpenter@linaro.org>
>> Cc: Arnd Bergmann <arnd@arndb.de>
>> Cc: Sui Jingfeng <suijingfeng@loongson.cn>
>> Cc: <stable@vger.kernel.org> # v6.9+
>> ---
>>   drivers/firmware/sysfb.c | 13 +++++++++----
>>   1 file changed, 9 insertions(+), 4 deletions(-)
>>
>> diff --git a/drivers/firmware/sysfb.c b/drivers/firmware/sysfb.c
>> index 880ffcb50088..dd274563deeb 100644
>> --- a/drivers/firmware/sysfb.c
>> +++ b/drivers/firmware/sysfb.c
>> @@ -101,8 +101,10 @@ static __init struct device *sysfb_parent_dev(const struct screen_info *si)
>>          if (IS_ERR(pdev)) {
>>                  return ERR_CAST(pdev);
>>          } else if (pdev) {
>> -               if (!sysfb_pci_dev_is_enabled(pdev))
>> +               if (!sysfb_pci_dev_is_enabled(pdev)) {
>> +                       pci_dev_put(pdev);
>>                          return ERR_PTR(-ENODEV);
>> +               }
>>                  return &pdev->dev;
>>          }
>>
>> @@ -137,7 +139,7 @@ static __init int sysfb_init(void)
>>          if (compatible) {
>>                  pd = sysfb_create_simplefb(si, &mode, parent);
>>                  if (!IS_ERR(pd))
>> -                       goto unlock_mutex;
>> +                       goto put_device;
>>          }
>>
>>          /* if the FB is incompatible, create a legacy framebuffer device */
>> @@ -155,7 +157,7 @@ static __init int sysfb_init(void)
>>          pd = platform_device_alloc(name, 0);
>>          if (!pd) {
>>                  ret = -ENOMEM;
>> -               goto unlock_mutex;
>> +               goto put_device;
>>          }
>>
>>          pd->dev.parent = parent;
>> @@ -170,9 +172,12 @@ static __init int sysfb_init(void)
>>          if (ret)
>>                  goto err;
>>
>> -       goto unlock_mutex;
>> +
>> +       goto put_device;
>>   err:
>>          platform_device_put(pd);
>> +put_device:
>> +       put_device(parent);
>>   unlock_mutex:
>>          mutex_unlock(&disable_lock);
>>          return ret;
>> --
>> 2.45.2
>>

-- 
--
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Frankenstrasse 146, 90461 Nuernberg, Germany
GF: Ivo Totev, Andrew Myers, Andrew McDonald, Boudien Moerman
HRB 36809 (AG Nuernberg)