[RFC,net-next,01/12] vhost_net: introduce helper to initialize tx iov iter
diff mbox

Message ID 1526893473-20128-2-git-send-email-jasowang@redhat.com
State New
Headers show

Commit Message

Jason Wang May 21, 2018, 9:04 a.m. UTC
Signed-off-by: Jason Wang <jasowang@redhat.com>
---
 drivers/vhost/net.c | 34 +++++++++++++++++++++++-----------
 1 file changed, 23 insertions(+), 11 deletions(-)

Comments

Jesse Brandeburg May 21, 2018, 4:24 p.m. UTC | #1
Hi Jason, a few nits. 

On Mon, 21 May 2018 17:04:22 +0800 Jason wrote:
> Signed-off-by: Jason Wang <jasowang@redhat.com>
> ---
>  drivers/vhost/net.c | 34 +++++++++++++++++++++++-----------
>  1 file changed, 23 insertions(+), 11 deletions(-)
> 
> diff --git a/drivers/vhost/net.c b/drivers/vhost/net.c
> index c4b49fc..15d191a 100644
> --- a/drivers/vhost/net.c
> +++ b/drivers/vhost/net.c
> @@ -459,6 +459,26 @@ static bool vhost_exceeds_maxpend(struct vhost_net *net)
>  	       min_t(unsigned int, VHOST_MAX_PEND, vq->num >> 2);
>  }
>  
> +static size_t init_iov_iter(struct vhost_virtqueue *vq, struct iov_iter *iter,
> +			    size_t hdr_size, int out)
> +{
> +	/* Skip header. TODO: support TSO. */
> +	size_t len = iov_length(vq->iov, out);
> +
> +	iov_iter_init(iter, WRITE, vq->iov, out, len);
> +	iov_iter_advance(iter, hdr_size);
> +	/* Sanity check */
> +	if (!iov_iter_count(iter)) {
> +		vq_err(vq, "Unexpected header len for TX: "
> +			"%zd expected %zd\n",
> +			len, hdr_size);

ok, it was like this before, but please unwrap the string in " ", there
should be no line breaks in string declarations and they are allowed to
go over 80 characters.

> +		return -EFAULT;
> +	}
> +	len = iov_iter_count(iter);
> +
> +	return len;
> +}
> +
>  /* Expects to be always run from workqueue - which acts as
>   * read-size critical section for our kind of RCU. */
>  static void handle_tx(struct vhost_net *net)
> @@ -521,18 +541,10 @@ static void handle_tx(struct vhost_net *net)
>  			       "out %d, int %d\n", out, in);
>  			break;
>  		}
> -		/* Skip header. TODO: support TSO. */
> -		len = iov_length(vq->iov, out);
> -		iov_iter_init(&msg.msg_iter, WRITE, vq->iov, out, len);
> -		iov_iter_advance(&msg.msg_iter, hdr_size);
> -		/* Sanity check */
> -		if (!msg_data_left(&msg)) {
> -			vq_err(vq, "Unexpected header len for TX: "
> -			       "%zd expected %zd\n",
> -			       len, hdr_size);
> +
> +		len = init_iov_iter(vq, &msg.msg_iter, hdr_size, out);
> +		if (len < 0)

len is declared as size_t, which is unsigned, and can never be
negative.  I'm pretty sure this is a bug.


>  			break;
> -		}
> -		len = msg_data_left(&msg);
>  
>  		zcopy_used = zcopy && len >= VHOST_GOODCOPY_LEN
>  				   && !vhost_exceeds_maxpend(net)
Jason Wang May 22, 2018, 12:26 p.m. UTC | #2
On 2018年05月22日 00:24, Jesse Brandeburg wrote:
> Hi Jason, a few nits.
>
> On Mon, 21 May 2018 17:04:22 +0800 Jason wrote:
>> Signed-off-by: Jason Wang <jasowang@redhat.com>
>> ---
>>   drivers/vhost/net.c | 34 +++++++++++++++++++++++-----------
>>   1 file changed, 23 insertions(+), 11 deletions(-)
>>
>> diff --git a/drivers/vhost/net.c b/drivers/vhost/net.c
>> index c4b49fc..15d191a 100644
>> --- a/drivers/vhost/net.c
>> +++ b/drivers/vhost/net.c
>> @@ -459,6 +459,26 @@ static bool vhost_exceeds_maxpend(struct vhost_net *net)
>>   	       min_t(unsigned int, VHOST_MAX_PEND, vq->num >> 2);
>>   }
>>   
>> +static size_t init_iov_iter(struct vhost_virtqueue *vq, struct iov_iter *iter,
>> +			    size_t hdr_size, int out)
>> +{
>> +	/* Skip header. TODO: support TSO. */
>> +	size_t len = iov_length(vq->iov, out);
>> +
>> +	iov_iter_init(iter, WRITE, vq->iov, out, len);
>> +	iov_iter_advance(iter, hdr_size);
>> +	/* Sanity check */
>> +	if (!iov_iter_count(iter)) {
>> +		vq_err(vq, "Unexpected header len for TX: "
>> +			"%zd expected %zd\n",
>> +			len, hdr_size);
> ok, it was like this before, but please unwrap the string in " ", there
> should be no line breaks in string declarations and they are allowed to
> go over 80 characters.

Ok.

>
>> +		return -EFAULT;
>> +	}
>> +	len = iov_iter_count(iter);
>> +
>> +	return len;
>> +}
>> +
>>   /* Expects to be always run from workqueue - which acts as
>>    * read-size critical section for our kind of RCU. */
>>   static void handle_tx(struct vhost_net *net)
>> @@ -521,18 +541,10 @@ static void handle_tx(struct vhost_net *net)
>>   			       "out %d, int %d\n", out, in);
>>   			break;
>>   		}
>> -		/* Skip header. TODO: support TSO. */
>> -		len = iov_length(vq->iov, out);
>> -		iov_iter_init(&msg.msg_iter, WRITE, vq->iov, out, len);
>> -		iov_iter_advance(&msg.msg_iter, hdr_size);
>> -		/* Sanity check */
>> -		if (!msg_data_left(&msg)) {
>> -			vq_err(vq, "Unexpected header len for TX: "
>> -			       "%zd expected %zd\n",
>> -			       len, hdr_size);
>> +
>> +		len = init_iov_iter(vq, &msg.msg_iter, hdr_size, out);
>> +		if (len < 0)
> len is declared as size_t, which is unsigned, and can never be
> negative.  I'm pretty sure this is a bug.

Yes, let me fix it in next version.

Thanks

>
>
>>   			break;
>> -		}
>> -		len = msg_data_left(&msg);
>>   
>>   		zcopy_used = zcopy && len >= VHOST_GOODCOPY_LEN
>>   				   && !vhost_exceeds_maxpend(net)

Patch
diff mbox

diff --git a/drivers/vhost/net.c b/drivers/vhost/net.c
index c4b49fc..15d191a 100644
--- a/drivers/vhost/net.c
+++ b/drivers/vhost/net.c
@@ -459,6 +459,26 @@  static bool vhost_exceeds_maxpend(struct vhost_net *net)
 	       min_t(unsigned int, VHOST_MAX_PEND, vq->num >> 2);
 }
 
+static size_t init_iov_iter(struct vhost_virtqueue *vq, struct iov_iter *iter,
+			    size_t hdr_size, int out)
+{
+	/* Skip header. TODO: support TSO. */
+	size_t len = iov_length(vq->iov, out);
+
+	iov_iter_init(iter, WRITE, vq->iov, out, len);
+	iov_iter_advance(iter, hdr_size);
+	/* Sanity check */
+	if (!iov_iter_count(iter)) {
+		vq_err(vq, "Unexpected header len for TX: "
+			"%zd expected %zd\n",
+			len, hdr_size);
+		return -EFAULT;
+	}
+	len = iov_iter_count(iter);
+
+	return len;
+}
+
 /* Expects to be always run from workqueue - which acts as
  * read-size critical section for our kind of RCU. */
 static void handle_tx(struct vhost_net *net)
@@ -521,18 +541,10 @@  static void handle_tx(struct vhost_net *net)
 			       "out %d, int %d\n", out, in);
 			break;
 		}
-		/* Skip header. TODO: support TSO. */
-		len = iov_length(vq->iov, out);
-		iov_iter_init(&msg.msg_iter, WRITE, vq->iov, out, len);
-		iov_iter_advance(&msg.msg_iter, hdr_size);
-		/* Sanity check */
-		if (!msg_data_left(&msg)) {
-			vq_err(vq, "Unexpected header len for TX: "
-			       "%zd expected %zd\n",
-			       len, hdr_size);
+
+		len = init_iov_iter(vq, &msg.msg_iter, hdr_size, out);
+		if (len < 0)
 			break;
-		}
-		len = msg_data_left(&msg);
 
 		zcopy_used = zcopy && len >= VHOST_GOODCOPY_LEN
 				   && !vhost_exceeds_maxpend(net)