Re: [PATCH] udp: Rename udp_buf_sock_to_tap() and udp_vu_sock_to_tap()

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

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On Thu, Dec 11, 2025 at 03:16:26PM +0100, Laurent Vivier wrote:
> The function udp_vu_sock_to_tap() sends data to the vhost-user interface,
> not the tap interface. Rename it to udp_sock_to_vu() to accurately reflect
> its destination.
> 
> The function udp_buf_sock_to_tap() includes a "buf_" prefix that is now
> redundant. Since the functions can be distinguished by their destination
> (to_tap vs. to_vu), drop the prefix and rename it to udp_sock_to_tap().
> 
> No functional change.
> 
> Signed-off-by: Laurent Vivier <lvivier@redhat.com>

Eh, I mean using "tap" to mean the guest side interface, even if it's
not based on /dev/net/tap is pretty well established at this point.

I do think udp_sock_to_vu() is a better name regardless.  I'm a bit
less convinced on renaming udp_buf_sock_to_tap().  If we're trying to
abandon the "tap means any guest interface" convention, then
udp_sock_to_tap() is still inaccurate, since it can also send to a
qemu socket.  If we're not trying to abandon that convention then it
suggests that the function does any forwarding to the guest, not just
the non-vu case.

> ---
>  udp.c    | 15 +++++++--------
>  udp_vu.c |  4 ++--
>  udp_vu.h |  2 +-
>  3 files changed, 10 insertions(+), 11 deletions(-)
> 
> diff --git a/udp.c b/udp.c
> index 08bec50a27af..10704681973b 100644
> --- a/udp.c
> +++ b/udp.c
> @@ -824,14 +824,14 @@ static void udp_sock_to_sock(const struct ctx *c, int from_s, int n,
>  }
>  
>  /**
> - * udp_buf_sock_to_tap() - Forward datagrams from socket to tap
> + * udp_sock_to_tap() - Forward datagrams from socket to tap
>   * @c:		Execution context
>   * @s:		Socket to read data from
>   * @n:		Maximum number of datagrams to forward
>   * @tosidx:	Flow & side to forward data from @s to
>   */
> -static void udp_buf_sock_to_tap(const struct ctx *c, int s, int n,
> -				flow_sidx_t tosidx)
> +static void udp_sock_to_tap(const struct ctx *c, int s, int n,
> +			    flow_sidx_t tosidx)
>  {
>  	const struct flowside *toside = flowside_at_sidx(tosidx);
>  	struct udp_flow *uflow = udp_at_sidx(tosidx);
> @@ -892,9 +892,9 @@ void udp_sock_fwd(const struct ctx *c, int s, uint8_t frompif,
>  			udp_sock_to_sock(c, s, 1, tosidx);
>  		} else if (topif == PIF_TAP) {
>  			if (c->mode == MODE_VU)
> -				udp_vu_sock_to_tap(c, s, 1, tosidx);
> +				udp_sock_to_vu(c, s, 1, tosidx);
>  			else
> -				udp_buf_sock_to_tap(c, s, 1, tosidx);
> +				udp_sock_to_tap(c, s, 1, tosidx);
>  		} else if (flow_sidx_valid(tosidx)) {
>  			struct udp_flow *uflow = udp_at_sidx(tosidx);
>  
> @@ -972,10 +972,9 @@ void udp_sock_handler(const struct ctx *c, union epoll_ref ref,
>  			udp_sock_to_sock(c, ref.fd, n, tosidx);
>  		} else if (topif == PIF_TAP) {
>  			if (c->mode == MODE_VU) {
> -				udp_vu_sock_to_tap(c, s, UDP_MAX_FRAMES,
> -						   tosidx);
> +				udp_sock_to_vu(c, s, UDP_MAX_FRAMES, tosidx);
>  			} else {
> -				udp_buf_sock_to_tap(c, s, n, tosidx);
> +				udp_sock_to_tap(c, s, n, tosidx);
>  			}
>  		} else {
>  			flow_err(uflow,
> diff --git a/udp_vu.c b/udp_vu.c
> index c30dcf97698f..f7ed6bc6a67c 100644
> --- a/udp_vu.c
> +++ b/udp_vu.c
> @@ -197,13 +197,13 @@ static void udp_vu_csum(const struct flowside *toside, int iov_used)
>  }
>  
>  /**
> - * udp_vu_sock_to_tap() - Forward datagrams from socket to tap
> + * udp_sock_to_vu() - Forward datagrams from socket to vhost-user
>   * @c:		Execution context
>   * @s:		Socket to read data from
>   * @n:		Maximum number of datagrams to forward
>   * @tosidx:	Flow & side to forward data from @s to
>   */
> -void udp_vu_sock_to_tap(const struct ctx *c, int s, int n, flow_sidx_t tosidx)
> +void udp_sock_to_vu(const struct ctx *c, int s, int n, flow_sidx_t tosidx)
>  {
>  	const struct flowside *toside = flowside_at_sidx(tosidx);
>  	bool v6 = !(inany_v4(&toside->eaddr) && inany_v4(&toside->oaddr));
> diff --git a/udp_vu.h b/udp_vu.h
> index 576b0e716f3d..669bde1c10dc 100644
> --- a/udp_vu.h
> +++ b/udp_vu.h
> @@ -8,6 +8,6 @@
>  
>  void udp_vu_listen_sock_data(const struct ctx *c, union epoll_ref ref,
>  			     const struct timespec *now);
> -void udp_vu_sock_to_tap(const struct ctx *c, int s, int n, flow_sidx_t tosidx);
> +void udp_sock_to_vu(const struct ctx *c, int s, int n, flow_sidx_t tosidx);
>  
>  #endif /* UDP_VU_H */
> -- 
> 2.51.1
> 

-- 
David Gibson (he or they)	| 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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