Re: [PATCH 1/7] tap: Move the tap_hdr file to a separate file

[Laurent Vivier <lvivier@redhat.com>]

Subject: s/tap_hdr file/tap_hdr structure/


On 9/4/26 23:28, aerosouund wrote:
> From: Ammar Yasser <aerosound161@gmail.com>
> 
> It was defined in tap.h, put it on its own so that future callers won't
> need to depend on all definitions in tap.h.
> Also turn it into a union of a vnet_len and virtio_net_mrg_rxbuf
> because for vhost acceleration the frames will have this virtio net
> header prepended to them.
> 
> Signed-off-by: Eugenio Pérez <eperezma@redhat.com>

If Eugenio is the author, you should set it as the author, otherwise you should remove his 
Signed-off-by

> Signed-off-by: Ammar Yasser <aerosound161@gmail.com>
> ---
>   tap.h     |  9 +--------
>   tap_hdr.h | 23 +++++++++++++++++++++++
>   2 files changed, 24 insertions(+), 8 deletions(-)
>   create mode 100644 tap_hdr.h
> 
> diff --git a/tap.h b/tap.h
> index b335933..1625975 100644
> --- a/tap.h
> +++ b/tap.h
> @@ -10,6 +10,7 @@
>   #include <stdint.h>
>   
>   #include "passt.h"
> +#include "tap_hdr.h"
>   
>   /** L2_MAX_LEN_PASTA - Maximum frame length for pasta mode (with L2 header)
>    *
> @@ -38,14 +39,6 @@
>   
>   struct udphdr;
>   
> -/**
> - * struct tap_hdr - tap backend specific headers
> - * @vnet_len:	Frame length (for qemu socket transport)
> - */
> -struct tap_hdr {
> -	uint32_t vnet_len;
> -} __attribute__((packed));
> -
>   /**
>    * tap_hdr_iov() - struct iovec for a tap header
>    * @c:		Execution context
> diff --git a/tap_hdr.h b/tap_hdr.h
> new file mode 100644
> index 0000000..aa270b7
> --- /dev/null
> +++ b/tap_hdr.h
> @@ -0,0 +1,23 @@
> +/* SPDX-License-Identifier: GPL-2.0-or-later
> + * Copyright (c) 2021 Red Hat GmbH
> + * Author: Stefano Brivio <sbrivio@redhat.com>
> + */
> +
> +#ifndef TAP_HDR_H
> +#define TAP_HDR_H
> +
> +#include <stdint.h>
> +#include <linux/virtio_net.h>
> +
> +/**
> + * struct tap_hdr - tap backend specific headers
> + * @vnet_len:	Frame length (for qemu socket transport)

missing @hdr description

> + */
> +struct tap_hdr {
> +	union {
> +		uint32_t vnet_len;
> +		struct virtio_net_hdr_mrg_rxbuf hdr;
> +	};
> +};

This will break passt.

In tap.h, we have:
static inline struct iovec tap_hdr_iov(const struct ctx *c,
                                        struct tap_hdr *thdr)
{
         return (struct iovec){
                 .iov_base = thdr,
                 .iov_len = c->mode == MODE_PASST ? sizeof(*thdr) : 0,
         };
}

before this patch sizeof(*thdr) is 4, now it's 12.

> +
> +#endif /* TAP_HDR_H */