[Somehow, my TB hates your mails - it just presents empty bodies to me
when I hit reply. Strange.]

Wolfgang Grandegger wrote:
> This patch enables ARP support for the RT-Proxy Linux device.
> Incoming ARP replys are delivered to both, the RTnet and the
> Linux network stack. The RT-Proxy then gets attached to the
> corresponding RTnet device, rteth0 by default. You can enable
> this feature with the configure option "--enable-proxy-arp".

Maybe the same question here: Do we need an extra knob for this, or are
all proxy scenarios fine this enabled?

> 
> Note: this patch requires running "scripts/autogen.sh"
> 
> Signed-off-by: Wolfang Grandegger <[EMAIL PROTECTED]>
> Index: rtnet/stack/ipv4/arp.c
> ===================================================================
> --- rtnet.orig/stack/ipv4/arp.c
> +++ rtnet/stack/ipv4/arp.c
> @@ -25,6 +25,9 @@
>  #include <stack_mgr.h>
>  #include <ipv4/arp.h>
>  
> +#ifdef CONFIG_RTNET_ADDON_PROXY_ARP
> +#include <ipv4/ip_input.h>
> +#endif /* CONFIG_RTNET_ADDON_PROXY_ARP */
>  
>  /***
>   *  arp_send:   Create and send an arp packet. If (dest_hw == NULL),
> @@ -174,6 +177,12 @@ int rt_arp_rcv(struct rtskb *skb, struct
>      }
>  
>  out:
> +#ifdef CONFIG_RTNET_ADDON_PROXY_ARP
> +    if (rt_ip_fallback_handler) {
> +         rt_ip_fallback_handler(skb);
> +         return 0;
> +    }
> +#endif

Hmm, I wonder what prevents ARP requests being answered twice: first by
RTnet (a few lines above this hunk), and then potentially also by Linux.


>      kfree_rtskb(skb);
>      return 0;
>  }
> Index: rtnet/addons/rtnetproxy.c
> ===================================================================
> --- rtnet.orig/addons/rtnetproxy.c
> +++ rtnet/addons/rtnetproxy.c
> @@ -105,6 +105,14 @@ static rtdm_task_t rtnetproxy_thread;
>  
>  static rtdm_sem_t rtnetproxy_sem;
>  
> +#ifdef CONFIG_RTNET_ADDON_PROXY_ARP
> +static char* rtdev_attach = "rteth0";
> +module_param(rtdev_attach, charp, 0444);
> +MODULE_PARM_DESC(rtdev_attach, "Attach to the specified RTnet device");
> +
> +struct rtnet_device *rtnetproxy_rtdev;
> +#endif
> +
>  /* ***********************************************************************
>   * Returns the next pointer from the ringbuffer or zero if nothing is
>   * available
> @@ -181,7 +189,10 @@ static inline void send_data_out(struct 
>  {
>  
>      struct rtskb        *rtskb;
> +#ifndef CONFIG_RTNET_ADDON_PROXY_ARP
>      struct dest_route   rt;
> +    int rc;
> +#endif
>  
>      struct skb_data_format
>      {
> @@ -194,7 +205,6 @@ static inline void send_data_out(struct 
>                                    * thus no spaces are allowed! */
>  
>      struct skb_data_format *pData;
> -    int rc;
>  
>      /* Copy the data from the standard sk_buff to the realtime sk_buff:
>       * Both have the same length. */
> @@ -208,6 +218,18 @@ static inline void send_data_out(struct 
>  
>      pData = (struct skb_data_format*) rtskb->data;
>  
> +#ifdef CONFIG_RTNET_ADDON_PROXY_ARP
> +     rtskb->rtdev = rtnetproxy_rtdev;
> +
> +        /* Call the actual transmit function */
> +        rtdev_xmit_proxy(rtskb);
> +
> +        /* The rtskb is freed somewhere deep in the driver...
> +         * No need to do it here. */
> +
> +        rtdev_dereference(rtskb->rtdev);

I know this pattern is not new, but looking at it I wonder if this isn't
generation a potential use-after-release (if xmitting causes an
immediate rtskb release)...

Jan

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