netdev - Re: [PATCH net-next] netdevsim: correctly check return value of debugfs_create

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Date:   Thu, 7 Dec 2017 17:12:06 -0800
From:   Jakub Kicinski <jakub.kicinski@...ronome.com>
To:     Prashant Bhole <bhole_prashant_q7@....ntt.co.jp>
Cc:     "David S . Miller" <davem@...emloft.net>, netdev@...r.kernel.org
Subject: Re: [PATCH net-next] netdevsim: correctly check return value of
 debugfs_create_dir

On Fri,  8 Dec 2017 09:52:50 +0900, Prashant Bhole wrote:
> Return value is now checked with IS_ERROR_OR_NULL because
> debugfs_create_dir doesn't return error value. It either returns
> NULL or a valid pointer.
> 
> Signed-off-by: Prashant Bhole <bhole_prashant_q7@....ntt.co.jp>
> ---
>  drivers/net/netdevsim/netdev.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/net/netdevsim/netdev.c b/drivers/net/netdevsim/netdev.c
> index eb8c679fca9f..88d8ee2c89da 100644
> --- a/drivers/net/netdevsim/netdev.c
> +++ b/drivers/net/netdevsim/netdev.c
> @@ -469,7 +469,7 @@ static int __init nsim_module_init(void)
>  	int err;
>  
>  	nsim_ddir = debugfs_create_dir(DRV_NAME, NULL);
> -	if (IS_ERR(nsim_ddir))
> +	if (IS_ERR_OR_NULL(nsim_ddir))
>  		return PTR_ERR(nsim_ddir);

PTR_ERR() will not be good in case of NULL, no?  But it's anyone's guess
what the correct error code would then be... the EEXIST from
start_creating() I was after is dropped in debugfs_create_dir(), as you
previously pointed out.

Maybe just drop this error handling here and in nsim_bpf_create_prog().
Let's consistently ignore all DebugFS errors.  Sorry about going back
and forth on this a little bit.

>  	err = bus_register(&nsim_bus);