netdev - Re: [PATCH net-next 07/12] sctp: implement ulpevent_data for sctp_stream

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Date:   Tue, 5 Dec 2017 13:28:55 -0500
From:   Neil Horman <nhorman@...driver.com>
To:     Xin Long <lucien.xin@...il.com>
Cc:     network dev <netdev@...r.kernel.org>, linux-sctp@...r.kernel.org,
        Marcelo Ricardo Leitner <marcelo.leitner@...il.com>,
        davem@...emloft.net
Subject: Re: [PATCH net-next 07/12] sctp: implement ulpevent_data for
 sctp_stream_interleave

On Tue, Dec 05, 2017 at 11:16:04PM +0800, Xin Long wrote:
> ulpevent_data is added as a member of sctp_stream_interleave, used to
> do the most process in ulpq, including to convert data or idata chunk
> to event, reasm them in reasm queue and put them in lobby queue in
> right order, and deliver them up to user sk rx queue.
> 
> This procedure is described in section 2.2.3 of RFC8260.
> 
> It adds most functions for idata here to do the similar process as
> the old functions for data. But since the details are very different
> between them, the old functions can not be reused for idata.
> 
> event->ssn and event->ppid settings are moved to ulpevent_data from
> sctp_ulpevent_make_rcvmsg, so that sctp_ulpevent_make_rcvmsg could
> work for both data and idata.
> 
> Note that mid is added in sctp_ulpevent for idata, __packed has to
> be used for defining sctp_ulpevent, or it would exceeds the skb cb
> that saves a sctp_ulpevent variable for ulp layer process.
> 
> Signed-off-by: Xin Long <lucien.xin@...il.com>
> ---
>  include/net/sctp/stream_interleave.h |   2 +
>  include/net/sctp/structs.h           |   3 +
>  include/net/sctp/ulpevent.h          |  20 +-
>  net/sctp/sm_sideeffect.c             |   5 +-
>  net/sctp/stream_interleave.c         | 418 +++++++++++++++++++++++++++++++++++
>  net/sctp/ulpevent.c                  |   2 -
>  net/sctp/ulpqueue.c                  |  12 +-
>  7 files changed, 451 insertions(+), 11 deletions(-)
> 
> diff --git a/include/net/sctp/stream_interleave.h b/include/net/sctp/stream_interleave.h
> index d8d1b51..02f60f5 100644
> --- a/include/net/sctp/stream_interleave.h
> +++ b/include/net/sctp/stream_interleave.h
> @@ -39,6 +39,8 @@ struct sctp_stream_interleave {
>  					    int len, __u8 flags, gfp_t gfp);
>  	void	(*assign_number)(struct sctp_chunk *chunk);
>  	bool	(*validate_data)(struct sctp_chunk *chunk);
> +	int	(*ulpevent_data)(struct sctp_ulpq *ulpq,
> +				 struct sctp_chunk *chunk, gfp_t gfp);
>  };
>  
>  void sctp_stream_interleave_init(struct sctp_stream *stream);
> diff --git a/include/net/sctp/structs.h b/include/net/sctp/structs.h
> index 348b25e..d7da719 100644
> --- a/include/net/sctp/structs.h
> +++ b/include/net/sctp/structs.h
> @@ -411,6 +411,8 @@ void sctp_stream_update(struct sctp_stream *stream, struct sctp_stream *new);
>  #define sctp_mid_skip(stream, type, sid, mid) \
>  	((stream)->type[sid].mid = mid + 1)
>  
> +#define sctp_stream_in(asoc, sid) (&(asoc)->stream.in[sid])
> +
>  /*
>   * Pointers to address related SCTP functions.
>   * (i.e. things that depend on the address family.)
> @@ -1386,6 +1388,7 @@ struct sctp_stream_in {
>  		__u16 ssn;
>  	};
>  	__u32 fsn;
> +	char pd_mode;
>  };
>  
>  struct sctp_stream {
> diff --git a/include/net/sctp/ulpevent.h b/include/net/sctp/ulpevent.h
> index 231dc42..ce4f2aa 100644
> --- a/include/net/sctp/ulpevent.h
> +++ b/include/net/sctp/ulpevent.h
> @@ -45,19 +45,29 @@
>  /* A structure to carry information to the ULP (e.g. Sockets API) */
>  /* Warning: This sits inside an skb.cb[] area.  Be very careful of
>   * growing this structure as it is at the maximum limit now.
> + *
> + * sctp_ulpevent is saved in sk->cb(48 bytes), whose last 4 bytes
> + * have been taken by sock_skb_cb, So here it has to use 'packed'
> + * to make sctp_ulpevent fit into the rest 44 bytes.
>   */
>  struct sctp_ulpevent {
>  	struct sctp_association *asoc;
>  	struct sctp_chunk *chunk;
>  	unsigned int rmem_len;
> -	__u32 ppid;
> +	union {
> +		__u32 mid;
> +		__u16 ssn;
> +	};
> +	union {
> +		__u32 ppid;
> +		__u32 fsn;
> +	};
>  	__u32 tsn;
>  	__u32 cumtsn;
>  	__u16 stream;
> -	__u16 ssn;
>  	__u16 flags;
>  	__u16 msg_flags;
> -};
> +} __packed;
>  
What kind  of performance do you see before and after this patch?  I ask because
it seems like the members between ppid through stream are going to be misaligned
(not on a 4 byte boundary), now that you've made this structure packed.


Neil