Subject: Re: [PATCH RFC v2 1/2] can: fix multiple delivery of a single CAN frame for overlapping CAN filters

From: Marc Kleine-Budde <[email-masked]>
Date: Mon, 30 Mar 2015 11:50:15 +0200

On 03/29/2015 08:09 PM, Oliver Hartkopp wrote:
> The CAN_RAW socket can set multiple CAN identifier specific filters that lead
> to multiple filters in the af_can.c filter processing. These filters are
> indenpendent from each other which leads to logical OR'ed filters when applied.
> 
> This patch makes sure that every CAN frame which is filtered for a specific
> socket is only delivered once to the user space. This is independent from the
> number of matching CAN filters of this socket.
> 
> As the can_raw() function is executed from NET_RX softirq the introduced
> variables are implemented as per-CPU variables to avoid extensive locking at
> CAN frame reception time.
> 
> Signed-off-by: Oliver Hartkopp <[email-masked]>
> ---
>  net/can/raw.c | 28 ++++++++++++++++++++++++++++
>  1 file changed, 28 insertions(+)
> 
> diff --git a/net/can/raw.c b/net/can/raw.c
> index 00c13ef..866a9b3 100644
> --- a/net/can/raw.c
> +++ b/net/can/raw.c
> @@ -86,6 +86,8 @@ struct raw_sock {
>  	struct can_filter dfilter; /* default/single filter */
>  	struct can_filter *filter; /* pointer to filter(s) */
>  	can_err_mask_t err_mask;
> +	struct sk_buff __percpu **uniq_skb;
> +	ktime_t __percpu *uniq_tstamp;

What about creating a struct to hold the ktime_t and the skb? BTW: the
pointer to the skb can be marked as const.

Marc
-- 
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