Re: [PATCH net v3 4/9] tun: Decouple vnet from tun_struct

[Willem de Bruijn <willemdebruijn.kernel@gmail.com>]

Akihiko Odaki wrote:
> Decouple vnet-related functions from tun_struct so that we can reuse
> them for tap in the future.
> 
> Signed-off-by: Akihiko Odaki <akihiko.odaki@daynix.com>
> ---
>  drivers/net/tun.c | 53 +++++++++++++++++++++++++++--------------------------
>  1 file changed, 27 insertions(+), 26 deletions(-)
> 
> diff --git a/drivers/net/tun.c b/drivers/net/tun.c
> index ec56ac865848..add09dfdada5 100644
> --- a/drivers/net/tun.c
> +++ b/drivers/net/tun.c
> @@ -298,16 +298,16 @@ static bool tun_napi_frags_enabled(const struct tun_file *tfile)
>  	return tfile->napi_frags_enabled;
>  }
>  
> -static inline bool tun_legacy_is_little_endian(struct tun_struct *tun)
> +static inline bool tun_legacy_is_little_endian(unsigned int flags)
>  {
>  	return !(IS_ENABLED(CONFIG_TUN_VNET_CROSS_LE) &&
> -		 (tun->flags & TUN_VNET_BE)) &&
> +		 (flags & TUN_VNET_BE)) &&
>  		virtio_legacy_is_little_endian();
>  }
>  
> -static long tun_get_vnet_be(struct tun_struct *tun, int __user *argp)
> +static long tun_get_vnet_be(unsigned int flags, int __user *argp)
>  {
> -	int be = !!(tun->flags & TUN_VNET_BE);
> +	int be = !!(flags & TUN_VNET_BE);
>  
>  	if (!IS_ENABLED(CONFIG_TUN_VNET_CROSS_LE))
>  		return -EINVAL;
> @@ -318,7 +318,7 @@ static long tun_get_vnet_be(struct tun_struct *tun, int __user *argp)
>  	return 0;
>  }
>  
> -static long tun_set_vnet_be(struct tun_struct *tun, int __user *argp)
> +static long tun_set_vnet_be(unsigned int *flags, int __user *argp)
>  {
>  	int be;
>  
> @@ -329,27 +329,26 @@ static long tun_set_vnet_be(struct tun_struct *tun, int __user *argp)
>  		return -EFAULT;
>  
>  	if (be)
> -		tun->flags |= TUN_VNET_BE;
> +		*flags |= TUN_VNET_BE;
>  	else
> -		tun->flags &= ~TUN_VNET_BE;
> +		*flags &= ~TUN_VNET_BE;
>  
>  	return 0;
>  }
>  
> -static inline bool tun_is_little_endian(struct tun_struct *tun)
> +static inline bool tun_is_little_endian(unsigned int flags)
>  {
> -	return tun->flags & TUN_VNET_LE ||
> -		tun_legacy_is_little_endian(tun);
> +	return flags & TUN_VNET_LE || tun_legacy_is_little_endian(flags);
>  }
>  
> -static inline u16 tun16_to_cpu(struct tun_struct *tun, __virtio16 val)
> +static inline u16 tun16_to_cpu(unsigned int flags, __virtio16 val)
>  {
> -	return __virtio16_to_cpu(tun_is_little_endian(tun), val);
> +	return __virtio16_to_cpu(tun_is_little_endian(flags), val);
>  }
>  
> -static inline __virtio16 cpu_to_tun16(struct tun_struct *tun, u16 val)
> +static inline __virtio16 cpu_to_tun16(unsigned int flags, u16 val)
>  {
> -	return __cpu_to_virtio16(tun_is_little_endian(tun), val);
> +	return __cpu_to_virtio16(tun_is_little_endian(flags), val);
>  }
>  
>  static inline u32 tun_hashfn(u32 rxhash)
> @@ -1764,6 +1763,7 @@ static ssize_t tun_get_user(struct tun_struct *tun, struct tun_file *tfile,
>  
>  	if (tun->flags & IFF_VNET_HDR) {
>  		int vnet_hdr_sz = READ_ONCE(tun->vnet_hdr_sz);
> +		int flags = tun->flags;

Here and elsewhere: instead of passing around and repeatedly parsing
flags, have a variable is_little_endian (or is_le)?
>  
>  		if (iov_iter_count(from) < vnet_hdr_sz)
>  			return -EINVAL;
> @@ -1772,12 +1772,12 @@ static ssize_t tun_get_user(struct tun_struct *tun, struct tun_file *tfile,
>  			return -EFAULT;
>  
>  		if ((gso.flags & VIRTIO_NET_HDR_F_NEEDS_CSUM) &&
> -		    tun16_to_cpu(tun, gso.csum_start) + tun16_to_cpu(tun, gso.csum_offset) + 2 > tun16_to_cpu(tun, gso.hdr_len))
> -			gso.hdr_len = cpu_to_tun16(tun, tun16_to_cpu(tun, gso.csum_start) + tun16_to_cpu(tun, gso.csum_offset) + 2);
> +		    tun16_to_cpu(flags, gso.csum_start) + tun16_to_cpu(flags, gso.csum_offset) + 2 > tun16_to_cpu(flags, gso.hdr_len))
> +			gso.hdr_len = cpu_to_tun16(flags, tun16_to_cpu(flags, gso.csum_start) + tun16_to_cpu(flags, gso.csum_offset) + 2);
>  
> -		if (tun16_to_cpu(tun, gso.hdr_len) > iov_iter_count(from))
> +		if (tun16_to_cpu(flags, gso.hdr_len) > iov_iter_count(from))
>  			return -EINVAL;
> -		hdr_len = tun16_to_cpu(tun, gso.hdr_len);
> +		hdr_len = tun16_to_cpu(flags, gso.hdr_len);
>  		iov_iter_advance(from, vnet_hdr_sz - sizeof(gso));
>  	}
>  
> @@ -1854,7 +1854,7 @@ static ssize_t tun_get_user(struct tun_struct *tun, struct tun_file *tfile,
>  		}
>  	}
>  
> -	if (virtio_net_hdr_to_skb(skb, &gso, tun_is_little_endian(tun))) {
> +	if (virtio_net_hdr_to_skb(skb, &gso, tun_is_little_endian(tun->flags))) {
>  		atomic_long_inc(&tun->rx_frame_errors);
>  		err = -EINVAL;
>  		goto free_skb;
> @@ -2108,23 +2108,24 @@ static ssize_t tun_put_user(struct tun_struct *tun,
>  
>  	if (vnet_hdr_sz) {
>  		struct virtio_net_hdr gso;
> +		int flags = tun->flags;
>  
>  		if (iov_iter_count(iter) < vnet_hdr_sz)
>  			return -EINVAL;
>  
>  		if (virtio_net_hdr_from_skb(skb, &gso,
> -					    tun_is_little_endian(tun), true,
> +					    tun_is_little_endian(flags), true,
>  					    vlan_hlen)) {
>  			struct skb_shared_info *sinfo = skb_shinfo(skb);
>  
>  			if (net_ratelimit()) {
>  				netdev_err(tun->dev, "unexpected GSO type: 0x%x, gso_size %d, hdr_len %d\n",
> -					   sinfo->gso_type, tun16_to_cpu(tun, gso.gso_size),
> -					   tun16_to_cpu(tun, gso.hdr_len));
> +					   sinfo->gso_type, tun16_to_cpu(flags, gso.gso_size),
> +					   tun16_to_cpu(flags, gso.hdr_len));
>  				print_hex_dump(KERN_ERR, "tun: ",
>  					       DUMP_PREFIX_NONE,
>  					       16, 1, skb->head,
> -					       min((int)tun16_to_cpu(tun, gso.hdr_len), 64), true);
> +					       min((int)tun16_to_cpu(flags, gso.hdr_len), 64), true);
>  			}
>  			WARN_ON_ONCE(1);
>  			return -EINVAL;
> @@ -2493,7 +2494,7 @@ static int tun_xdp_one(struct tun_struct *tun,
>  	skb_reserve(skb, xdp->data - xdp->data_hard_start);
>  	skb_put(skb, xdp->data_end - xdp->data);
>  
> -	if (virtio_net_hdr_to_skb(skb, gso, tun_is_little_endian(tun))) {
> +	if (virtio_net_hdr_to_skb(skb, gso, tun_is_little_endian(tun->flags))) {
>  		atomic_long_inc(&tun->rx_frame_errors);
>  		kfree_skb(skb);
>  		ret = -EINVAL;
> @@ -3322,11 +3323,11 @@ static long __tun_chr_ioctl(struct file *file, unsigned int cmd,
>  		break;
>  
>  	case TUNGETVNETBE:
> -		ret = tun_get_vnet_be(tun, argp);
> +		ret = tun_get_vnet_be(tun->flags, argp);
>  		break;
>  
>  	case TUNSETVNETBE:
> -		ret = tun_set_vnet_be(tun, argp);
> +		ret = tun_set_vnet_be(&tun->flags, argp);
>  		break;
>  
>  	case TUNATTACHFILTER:
> 
> -- 
> 2.47.1
>