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Groups > linux.kernel > #1612652 > unrolled thread

[PATCH V2 net-next 5/7] tun: support receiving skb through msg_control

Started byJason Wang <jasowang@redhat.com>
First post2017-03-30 09:30 +0200
Last post2017-03-31 06:20 +0200
Articles 3 — 2 participants

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  [PATCH V2 net-next 5/7] tun: support receiving skb through msg_control Jason Wang <jasowang@redhat.com> - 2017-03-30 09:30 +0200
    Re: [PATCH V2 net-next 5/7] tun: support receiving skb through  msg_control "Michael S. Tsirkin" <mst@redhat.com> - 2017-03-30 17:10 +0200
      Re: [PATCH V2 net-next 5/7] tun: support receiving skb through  msg_control Jason Wang <jasowang@redhat.com> - 2017-03-31 06:20 +0200

#1612652 — [PATCH V2 net-next 5/7] tun: support receiving skb through msg_control

FromJason Wang <jasowang@redhat.com>
Date2017-03-30 09:30 +0200
Subject[PATCH V2 net-next 5/7] tun: support receiving skb through msg_control
Message-ID<tqCGR-2MS-5@gated-at.bofh.it>
This patch makes tun_recvmsg() can receive from skb from its caller
through msg_control. Vhost_net will be the first user.

Signed-off-by: Jason Wang <jasowang@redhat.com>
---
 drivers/net/tun.c | 18 ++++++++++--------
 1 file changed, 10 insertions(+), 8 deletions(-)

diff --git a/drivers/net/tun.c b/drivers/net/tun.c
index 70dd9ec..a82bced 100644
--- a/drivers/net/tun.c
+++ b/drivers/net/tun.c
@@ -1498,9 +1498,8 @@ static struct sk_buff *tun_ring_recv(struct tun_file *tfile, int noblock,
 
 static ssize_t tun_do_read(struct tun_struct *tun, struct tun_file *tfile,
 			   struct iov_iter *to,
-			   int noblock)
+			   int noblock, struct sk_buff *skb)
 {
-	struct sk_buff *skb;
 	ssize_t ret;
 	int err;
 
@@ -1509,10 +1508,12 @@ static ssize_t tun_do_read(struct tun_struct *tun, struct tun_file *tfile,
 	if (!iov_iter_count(to))
 		return 0;
 
-	/* Read frames from ring */
-	skb = tun_ring_recv(tfile, noblock, &err);
-	if (!skb)
-		return err;
+	if (!skb) {
+		/* Read frames from ring */
+		skb = tun_ring_recv(tfile, noblock, &err);
+		if (!skb)
+			return err;
+	}
 
 	ret = tun_put_user(tun, tfile, skb, to);
 	if (unlikely(ret < 0))
@@ -1532,7 +1533,7 @@ static ssize_t tun_chr_read_iter(struct kiocb *iocb, struct iov_iter *to)
 
 	if (!tun)
 		return -EBADFD;
-	ret = tun_do_read(tun, tfile, to, file->f_flags & O_NONBLOCK);
+	ret = tun_do_read(tun, tfile, to, file->f_flags & O_NONBLOCK, NULL);
 	ret = min_t(ssize_t, ret, len);
 	if (ret > 0)
 		iocb->ki_pos = ret;
@@ -1634,7 +1635,8 @@ static int tun_recvmsg(struct socket *sock, struct msghdr *m, size_t total_len,
 					 SOL_PACKET, TUN_TX_TIMESTAMP);
 		goto out;
 	}
-	ret = tun_do_read(tun, tfile, &m->msg_iter, flags & MSG_DONTWAIT);
+	ret = tun_do_read(tun, tfile, &m->msg_iter, flags & MSG_DONTWAIT,
+			  m->msg_control);
 	if (ret > (ssize_t)total_len) {
 		m->msg_flags |= MSG_TRUNC;
 		ret = flags & MSG_TRUNC ? ret : total_len;
-- 
2.7.4

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#1613145 — Re: [PATCH V2 net-next 5/7] tun: support receiving skb through msg_control

From"Michael S. Tsirkin" <mst@redhat.com>
Date2017-03-30 17:10 +0200
SubjectRe: [PATCH V2 net-next 5/7] tun: support receiving skb through msg_control
Message-ID<tqJS1-8b4-3@gated-at.bofh.it>
In reply to#1612652
On Thu, Mar 30, 2017 at 03:22:28PM +0800, Jason Wang wrote:
> This patch makes tun_recvmsg() can receive from skb from its caller
> through msg_control. Vhost_net will be the first user.
> 
> Signed-off-by: Jason Wang <jasowang@redhat.com>

Do we need to bother with tun? I didn't realize one
can even use that with vhost. What would be the point of
all the virtio header stuff dealing with checksums etc?

Even if you see a use-case is it worth optimizing?


> ---
>  drivers/net/tun.c | 18 ++++++++++--------
>  1 file changed, 10 insertions(+), 8 deletions(-)
> 
> diff --git a/drivers/net/tun.c b/drivers/net/tun.c
> index 70dd9ec..a82bced 100644
> --- a/drivers/net/tun.c
> +++ b/drivers/net/tun.c
> @@ -1498,9 +1498,8 @@ static struct sk_buff *tun_ring_recv(struct tun_file *tfile, int noblock,
>  
>  static ssize_t tun_do_read(struct tun_struct *tun, struct tun_file *tfile,
>  			   struct iov_iter *to,
> -			   int noblock)
> +			   int noblock, struct sk_buff *skb)
>  {
> -	struct sk_buff *skb;
>  	ssize_t ret;
>  	int err;
>  
> @@ -1509,10 +1508,12 @@ static ssize_t tun_do_read(struct tun_struct *tun, struct tun_file *tfile,
>  	if (!iov_iter_count(to))
>  		return 0;
>  
> -	/* Read frames from ring */
> -	skb = tun_ring_recv(tfile, noblock, &err);
> -	if (!skb)
> -		return err;
> +	if (!skb) {
> +		/* Read frames from ring */
> +		skb = tun_ring_recv(tfile, noblock, &err);
> +		if (!skb)
> +			return err;
> +	}
>  
>  	ret = tun_put_user(tun, tfile, skb, to);
>  	if (unlikely(ret < 0))
> @@ -1532,7 +1533,7 @@ static ssize_t tun_chr_read_iter(struct kiocb *iocb, struct iov_iter *to)
>  
>  	if (!tun)
>  		return -EBADFD;
> -	ret = tun_do_read(tun, tfile, to, file->f_flags & O_NONBLOCK);
> +	ret = tun_do_read(tun, tfile, to, file->f_flags & O_NONBLOCK, NULL);
>  	ret = min_t(ssize_t, ret, len);
>  	if (ret > 0)
>  		iocb->ki_pos = ret;
> @@ -1634,7 +1635,8 @@ static int tun_recvmsg(struct socket *sock, struct msghdr *m, size_t total_len,
>  					 SOL_PACKET, TUN_TX_TIMESTAMP);
>  		goto out;
>  	}
> -	ret = tun_do_read(tun, tfile, &m->msg_iter, flags & MSG_DONTWAIT);
> +	ret = tun_do_read(tun, tfile, &m->msg_iter, flags & MSG_DONTWAIT,
> +			  m->msg_control);
>  	if (ret > (ssize_t)total_len) {
>  		m->msg_flags |= MSG_TRUNC;
>  		ret = flags & MSG_TRUNC ? ret : total_len;
> -- 
> 2.7.4

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#1613626 — Re: [PATCH V2 net-next 5/7] tun: support receiving skb through msg_control

FromJason Wang <jasowang@redhat.com>
Date2017-03-31 06:20 +0200
SubjectRe: [PATCH V2 net-next 5/7] tun: support receiving skb through msg_control
Message-ID<tqWcy-7Zp-3@gated-at.bofh.it>
In reply to#1613145

On 2017年03月30日 23:06, Michael S. Tsirkin wrote:
> On Thu, Mar 30, 2017 at 03:22:28PM +0800, Jason Wang wrote:
>> This patch makes tun_recvmsg() can receive from skb from its caller
>> through msg_control. Vhost_net will be the first user.
>>
>> Signed-off-by: Jason Wang<jasowang@redhat.com>
> Do we need to bother with tun? I didn't realize one
> can even use that with vhost. What would be the point of
> all the virtio header stuff dealing with checksums etc?
>
> Even if you see a use-case is it worth optimizing?
>
>

It's for tap in fact. I use "tun" just because we have already had a 
tap.c which is used by macvtap.

Thanks

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