Re: [PATCH] tty: nozomi: Return an error when failing to create the sysfs

[Greg KH <gregkh@linuxfoundation.org>]

On Thu, Jun 09, 2022 at 04:31:33PM +0800, Zheyu Ma wrote:
> The driver does not handle the error of the creation of sysfs, resulting
> in duplicate file names being created.
> 
> The following log can reveal it:
> 
> [   52.907211] sysfs: cannot create duplicate filename '/devices/pci0000:00/0000:00:05.0/card_type'

How is the same file being created in a normal codepath?

Is the same device being registered twice somehow?

> [   52.907224] Call Trace:
> [   52.907269]  sysfs_add_file_mode_ns+0x23f/0x2b0
> [   52.907281]  sysfs_create_file_ns+0xe9/0x170
> [   52.907321]  nozomi_card_init+0x97f/0x12c0 [nozomi]
> 
> Fix this bug by returning an error when failing to create the sysfs.
> 
> Fixes: 20fd1e3bea55 ("nozomi driver")
> Signed-off-by: Zheyu Ma <zheyuma97@gmail.com>
> ---
>  drivers/tty/nozomi.c | 24 ++++++++++++++++++++----
>  1 file changed, 20 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/tty/nozomi.c b/drivers/tty/nozomi.c
> index 0454c78deee6..d0ad1b9898f5 100644
> --- a/drivers/tty/nozomi.c
> +++ b/drivers/tty/nozomi.c
> @@ -1282,14 +1282,26 @@ static ssize_t open_ttys_show(struct device *dev, struct device_attribute *attr,
>  }
>  static DEVICE_ATTR_RO(open_ttys);
>  
> -static void make_sysfs_files(struct nozomi *dc)
> +static int make_sysfs_files(struct nozomi *dc)
>  {
> -	if (device_create_file(&dc->pdev->dev, &dev_attr_card_type))
> +	int err;
> +
> +	err = device_create_file(&dc->pdev->dev, &dev_attr_card_type);

Drivers shouldn't be calling this function anyway, it's a race
condition.  How about switching this to use the proper device groups
functionality instead which moves all of the handling of the sysfs files
to the driver core so that the driver can not get it wrong?

That should solve the error handling case.  The fact that this is trying
to be created twice is a symptom of a worse problem here.  How are you
duplicating this?

thanks,

greg k-h