Subject: Re: [PATCH] IPV4: add raw drops counter

From: Eric Dumazet <[email-masked]>
Date: Tue, 13 Nov 2007 12:11:17 +0100

Wang Chen a écrit :
> Add raw drops counter for IPv4 in /proc/net/raw .
>
> Signed-off-by: Wang Chen <[email-masked]>
> ---
>  include/net/sock.h |    2 ++
>  net/core/sock.c    |    1 +
>  net/ipv4/raw.c     |   16 +++++++++-------
>  3 files changed, 12 insertions(+), 7 deletions(-)
>
> diff -Nurp linux-2.6.24-rc2.org/include/net/sock.h linux-2.6.24-rc2/include/net/sock.h
> --- linux-2.6.24-rc2.org/include/net/sock.h	2007-11-09 16:37:08.000000000 +0800
> +++ linux-2.6.24-rc2/include/net/sock.h	2007-11-13 15:19:20.000000000 +0800
> @@ -156,6 +156,7 @@ struct sock_common {
>    *	@sk_prot_creator: sk_prot of original sock creator (see ipv6_setsockopt, IPV6_ADDRFORM for instance)
>    *	@sk_err: last error
>    *	@sk_err_soft: errors that don't cause failure but are the cause of a persistent failure not just 'timed out'
> +  *	@sk_drops: raw drops counter
>    *	@sk_ack_backlog: current listen backlog
>    *	@sk_max_ack_backlog: listen backlog set in listen()
>    *	@sk_priority: %SO_PRIORITY setting
> @@ -239,6 +240,7 @@ struct sock {
>  	rwlock_t		sk_callback_lock;
>  	int			sk_err,
>  				sk_err_soft;
> +	atomic_t		sk_drops;
>   
This doesnt need an atomic_t , just an 'unsigned int' is OK, since 
sock_queue_rcv_skb() is called on a locked socket.

Also, I suggest doing the sk_drops increment in sock_queue_rcv_skb() so 
that it can be used for other sockets as well ?

I like having this counter per socket, but only if an application can 
retrieve its value with a getsockopt() call, dont you think ?

getsockopt(sock, SOL_SOCKET, SO_DROPSCNT, &val, &vallen);