Re: [PATCH 2/8] tap: Move all-ones initialisation of mac_guest to tap_sock_init()

[David Gibson <david@gibson.dropbear.id.au>]

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On Wed, May 22, 2024 at 10:59:05PM +0200, Stefano Brivio wrote:
> It has nothing to do with tap_sock_unix_init(). It used to be there as
> that function could be called multiple times per passt instance, but
> it's not the case anymore.
> 
> This also takes care of the fact that, with --fd, we wouldn't set the
> initial MAC address, so we would need to wait for the guest to send us
> an ARP packet before we could exchange data.
> 
> Fixes: 6b4e68383c66 ("passt, tap: Add --fd option")
> Signed-off-by: Stefano Brivio <sbrivio@redhat.com>

Reviewed-by: David Gibson <david@gibson.dropbear.id.au>

> ---
>  tap.c | 12 ++++++------
>  1 file changed, 6 insertions(+), 6 deletions(-)
> 
> diff --git a/tap.c b/tap.c
> index 91fd2e2..177fe26 100644
> --- a/tap.c
> +++ b/tap.c
> @@ -1111,12 +1111,6 @@ static void tap_sock_unix_init(struct ctx *c)
>  	if (fd < 0)
>  		die("UNIX socket: %s", strerror(errno));
>  
> -	/* In passt mode, we don't know the guest's MAC until it sends
> -	 * us packets.  Use the broadcast address so our first packets
> -	 * will reach it.
> -	 */
> -	memset(&c->mac_guest, 0xff, sizeof(c->mac_guest));
> -
>  	for (i = 1; i < UNIX_SOCK_MAX; i++) {
>  		char *path = addr.sun_path;
>  		int ex, ret;
> @@ -1312,6 +1306,12 @@ void tap_sock_init(struct ctx *c)
>  	if (c->mode == MODE_PASST) {
>  		if (c->fd_tap_listen == -1)
>  			tap_sock_unix_init(c);
> +
> +		/* In passt mode, we don't know the guest's MAC address until it
> +		 * sends us packets.  Use the broadcast address so that our
> +		 * first packets will reach it.
> +		 */
> +		memset(&c->mac_guest, 0xff, sizeof(c->mac_guest));
>  	} else {
>  		tap_sock_tun_init(c);
>  	}

-- 
David Gibson			| I'll have my music baroque, and my code
david AT gibson.dropbear.id.au	| minimalist, thank you.  NOT _the_ _other_
				| _way_ _around_!
http://www.ozlabs.org/~dgibson

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