netdev - Re: [PATCH] skbuff: fix compilation warnings in skb

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Date:   Tue, 16 Jul 2019 17:04:19 +0200
From:   Willem de Bruijn <willemdebruijn.kernel@...il.com>
To:     Qian Cai <cai@....pw>
Cc:     David Miller <davem@...emloft.net>,
        Willem de Bruijn <willemb@...gle.com>,
        clang-built-linux@...glegroups.com,
        Network Development <netdev@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] skbuff: fix compilation warnings in skb_dump()

On Tue, Jul 16, 2019 at 4:56 PM Qian Cai <cai@....pw> wrote:
>
> The commit 6413139dfc64 ("skbuff: increase verbosity when dumping skb
> data") introduced a few compilation warnings.
>
> net/core/skbuff.c:766:32: warning: format specifies type 'unsigned
> short' but the argument has type 'unsigned int' [-Wformat]
>                        level, sk->sk_family, sk->sk_type,
> sk->sk_protocol);
>                                              ^~~~~~~~~~~
> net/core/skbuff.c:766:45: warning: format specifies type 'unsigned
> short' but the argument has type 'unsigned int' [-Wformat]
>                        level, sk->sk_family, sk->sk_type,
> sk->sk_protocol);
> ^~~~~~~~~~~~~~~

Ah, I looked at sk_family (skc_family), which is type unsigned short.

But sk_type and sk_protocol are defined as

 unsigned int            sk_padding : 1,
                                sk_kern_sock : 1,
                                sk_no_check_tx : 1,
                                sk_no_check_rx : 1,
                                sk_userlocks : 4,
                                sk_protocol  : 8,
                                sk_type      : 16;

So %u is indeed needed instead of %hu.

> Fix them by using the proper types, and also fix some checkpatch
> warnings by using pr_info().
>
> WARNING: printk() should include KERN_<LEVEL> facility level
> +               printk("%ssk family=%hu type=%u proto=%u\n",

Converting printk to pr_info lowers all levels to KERN_INFO.

skb_dump takes an explicit parameter level to be able to log at
KERN_ERR or KERN_WARNING

I would like to avoid those checkpatch warnings, but this is not the
right approach.

> Fixes: 6413139dfc64 ("skbuff: increase verbosity when dumping skb data")

Thanks. For a v2, please mark the target branch, as [PATCH net v2].