[PATCH net] virtio_net: fix missing dma unmap for resize

[PATCH net] virtio_net: fix missing dma unmap for resize

[Xuan Zhuo]

For rq, we have three cases getting buffers from virtio core:

1. virtqueue_get_buf{,_ctx}
2. virtqueue_detach_unused_buf
3. callback for virtqueue_resize

But in commit 295525e29a5b("virtio_net: merge dma operations when
filling mergeable buffers"), I missed the dma unmap for the #3 case.

That will leak some memory, because I did not release the pages referred
by the unused buffers.

If we do such script, we will make the system OOM.

    while true
    do
            ethtool -G ens4 rx 128
            ethtool -G ens4 rx 256
            free -m
    done

Fixes: 295525e29a5b ("virtio_net: merge dma operations when filling mergeable buffers")
Signed-off-by: Xuan Zhuo <xuanzhuo@linux.alibaba.com>
---
 drivers/net/virtio_net.c | 43 ++++++++++++++++++++--------------------
 1 file changed, 22 insertions(+), 21 deletions(-)

diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index d16f592c2061..6423a3a007ce 100644
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -408,6 +408,17 @@ static struct page *get_a_page(struct receive_queue *rq, gfp_t gfp_mask)
 	return p;
 }
 
+static void virtnet_rq_free_buf(struct virtnet_info *vi,
+				struct receive_queue *rq, void *buf)
+{
+	if (vi->mergeable_rx_bufs)
+		put_page(virt_to_head_page(buf));
+	else if (vi->big_packets)
+		give_pages(rq, buf);
+	else
+		put_page(virt_to_head_page(buf));
+}
+
 static void enable_delayed_refill(struct virtnet_info *vi)
 {
 	spin_lock_bh(&vi->refill_lock);
@@ -634,17 +645,6 @@ static void *virtnet_rq_get_buf(struct receive_queue *rq, u32 *len, void **ctx)
 	return buf;
 }
 
-static void *virtnet_rq_detach_unused_buf(struct receive_queue *rq)
-{
-	void *buf;
-
-	buf = virtqueue_detach_unused_buf(rq->vq);
-	if (buf && rq->do_dma)
-		virtnet_rq_unmap(rq, buf, 0);
-
-	return buf;
-}
-
 static void virtnet_rq_init_one_sg(struct receive_queue *rq, void *buf, u32 len)
 {
 	struct virtnet_rq_dma *dma;
@@ -1764,7 +1764,7 @@ static void receive_buf(struct virtnet_info *vi, struct receive_queue *rq,
 	if (unlikely(len < vi->hdr_len + ETH_HLEN)) {
 		pr_debug("%s: short packet %i\n", dev->name, len);
 		DEV_STATS_INC(dev, rx_length_errors);
-		virtnet_rq_free_unused_buf(rq->vq, buf);
+		virtnet_rq_free_buf(vi, rq, buf);
 		return;
 	}
 
@@ -4034,14 +4034,15 @@ static void virtnet_sq_free_unused_buf(struct virtqueue *vq, void *buf)
 static void virtnet_rq_free_unused_buf(struct virtqueue *vq, void *buf)
 {
 	struct virtnet_info *vi = vq->vdev->priv;
+	struct receive_queue *rq;
 	int i = vq2rxq(vq);
 
-	if (vi->mergeable_rx_bufs)
-		put_page(virt_to_head_page(buf));
-	else if (vi->big_packets)
-		give_pages(&vi->rq[i], buf);
-	else
-		put_page(virt_to_head_page(buf));
+	rq = &vi->rq[i];
+
+	if (rq->do_dma)
+		virtnet_rq_unmap(rq, buf, 0);
+
+	virtnet_rq_free_buf(vi, rq, buf);
 }
 
 static void free_unused_bufs(struct virtnet_info *vi)
@@ -4057,10 +4058,10 @@ static void free_unused_bufs(struct virtnet_info *vi)
 	}
 
 	for (i = 0; i < vi->max_queue_pairs; i++) {
-		struct receive_queue *rq = &vi->rq[i];
+		struct virtqueue *vq = vi->rq[i].vq;
 
-		while ((buf = virtnet_rq_detach_unused_buf(rq)) != NULL)
-			virtnet_rq_free_unused_buf(rq->vq, buf);
+		while ((buf = virtqueue_detach_unused_buf(vq)) != NULL)
+			virtnet_rq_free_unused_buf(vq, buf);
 		cond_resched();
 	}
 }
-- 
2.32.0.3.g01195cf9f

Re: [PATCH net] virtio_net: fix missing dma unmap for resize

[Paolo Abeni]

On Mon, 2023-11-06 at 16:18 +0800, Xuan Zhuo wrote:
> For rq, we have three cases getting buffers from virtio core:
> 
> 1. virtqueue_get_buf{,_ctx}
> 2. virtqueue_detach_unused_buf
> 3. callback for virtqueue_resize
> 
> But in commit 295525e29a5b("virtio_net: merge dma operations when
> filling mergeable buffers"), I missed the dma unmap for the #3 case.
> 
> That will leak some memory, because I did not release the pages referred
> by the unused buffers.
> 
> If we do such script, we will make the system OOM.
> 
>     while true
>     do
>             ethtool -G ens4 rx 128
>             ethtool -G ens4 rx 256
>             free -m
>     done
> 
> Fixes: 295525e29a5b ("virtio_net: merge dma operations when filling mergeable buffers")
> Signed-off-by: Xuan Zhuo <xuanzhuo@linux.alibaba.com>

@Micheal, @Jason: this fix LGTM, but I guess it deserve an explicit ack
from you before merging, thanks!

Paolo

Re: [PATCH net] virtio_net: fix missing dma unmap for resize

[Michael S. Tsirkin]

On Mon, Nov 06, 2023 at 04:18:32PM +0800, Xuan Zhuo wrote:
> For rq, we have three cases getting buffers from virtio core:
> 
> 1. virtqueue_get_buf{,_ctx}
> 2. virtqueue_detach_unused_buf
> 3. callback for virtqueue_resize
> 
> But in commit 295525e29a5b("virtio_net: merge dma operations when
> filling mergeable buffers"), I missed the dma unmap for the #3 case.
> 
> That will leak some memory, because I did not release the pages referred
> by the unused buffers.
> 
> If we do such script, we will make the system OOM.
> 
>     while true
>     do
>             ethtool -G ens4 rx 128
>             ethtool -G ens4 rx 256
>             free -m
>     done
> 
> Fixes: 295525e29a5b ("virtio_net: merge dma operations when filling mergeable buffers")
> Signed-off-by: Xuan Zhuo <xuanzhuo@linux.alibaba.com>
> ---
>  drivers/net/virtio_net.c | 43 ++++++++++++++++++++--------------------
>  1 file changed, 22 insertions(+), 21 deletions(-)
> 
> diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
> index d16f592c2061..6423a3a007ce 100644
> --- a/drivers/net/virtio_net.c
> +++ b/drivers/net/virtio_net.c
> @@ -408,6 +408,17 @@ static struct page *get_a_page(struct receive_queue *rq, gfp_t gfp_mask)
>  	return p;
>  }
>  
> +static void virtnet_rq_free_buf(struct virtnet_info *vi,
> +				struct receive_queue *rq, void *buf)
> +{
> +	if (vi->mergeable_rx_bufs)
> +		put_page(virt_to_head_page(buf));
> +	else if (vi->big_packets)
> +		give_pages(rq, buf);
> +	else
> +		put_page(virt_to_head_page(buf));
> +}
> +

>  static void enable_delayed_refill(struct virtnet_info *vi)
>  {
>  	spin_lock_bh(&vi->refill_lock);
> @@ -634,17 +645,6 @@ static void *virtnet_rq_get_buf(struct receive_queue *rq, u32 *len, void **ctx)
>  	return buf;
>  }
>  
> -static void *virtnet_rq_detach_unused_buf(struct receive_queue *rq)
> -{
> -	void *buf;
> -
> -	buf = virtqueue_detach_unused_buf(rq->vq);
> -	if (buf && rq->do_dma)
> -		virtnet_rq_unmap(rq, buf, 0);
> -
> -	return buf;
> -}
> -
>  static void virtnet_rq_init_one_sg(struct receive_queue *rq, void *buf, u32 len)
>  {
>  	struct virtnet_rq_dma *dma;
> @@ -1764,7 +1764,7 @@ static void receive_buf(struct virtnet_info *vi, struct receive_queue *rq,
>  	if (unlikely(len < vi->hdr_len + ETH_HLEN)) {
>  		pr_debug("%s: short packet %i\n", dev->name, len);
>  		DEV_STATS_INC(dev, rx_length_errors);
> -		virtnet_rq_free_unused_buf(rq->vq, buf);
> +		virtnet_rq_free_buf(vi, rq, buf);
>  		return;
>  	}
>  
> @@ -4034,14 +4034,15 @@ static void virtnet_sq_free_unused_buf(struct virtqueue *vq, void *buf)
>  static void virtnet_rq_free_unused_buf(struct virtqueue *vq, void *buf)
>  {
>  	struct virtnet_info *vi = vq->vdev->priv;
> +	struct receive_queue *rq;
>  	int i = vq2rxq(vq);
>  
> -	if (vi->mergeable_rx_bufs)
> -		put_page(virt_to_head_page(buf));
> -	else if (vi->big_packets)
> -		give_pages(&vi->rq[i], buf);
> -	else
> -		put_page(virt_to_head_page(buf));
> +	rq = &vi->rq[i];
> +
> +	if (rq->do_dma)
> +		virtnet_rq_unmap(rq, buf, 0);
> +
> +	virtnet_rq_free_buf(vi, rq, buf);
>  }
>  

So we have virtnet_rq_free_buf which sounds like it should free any
buf, and we have virtnet_rq_free_unused_buf which is only for unused.
Or so it would seem from names but this is not true.
Better function names?

>  static void free_unused_bufs(struct virtnet_info *vi)
> @@ -4057,10 +4058,10 @@ static void free_unused_bufs(struct virtnet_info *vi)
>  	}
>  
>  	for (i = 0; i < vi->max_queue_pairs; i++) {
> -		struct receive_queue *rq = &vi->rq[i];
> +		struct virtqueue *vq = vi->rq[i].vq;
>  
> -		while ((buf = virtnet_rq_detach_unused_buf(rq)) != NULL)
> -			virtnet_rq_free_unused_buf(rq->vq, buf);
> +		while ((buf = virtqueue_detach_unused_buf(vq)) != NULL)
> +			virtnet_rq_free_unused_buf(vq, buf);
>  		cond_resched();
>  	}
>  }
> -- 
> 2.32.0.3.g01195cf9f

Re: [PATCH net] virtio_net: fix missing dma unmap for resize

[Xuan Zhuo]

On Thu, 9 Nov 2023 07:06:16 -0500, "Michael S. Tsirkin" <mst@redhat.com> wrote:
> On Mon, Nov 06, 2023 at 04:18:32PM +0800, Xuan Zhuo wrote:
> > For rq, we have three cases getting buffers from virtio core:
> >
> > 1. virtqueue_get_buf{,_ctx}
> > 2. virtqueue_detach_unused_buf
> > 3. callback for virtqueue_resize
> >
> > But in commit 295525e29a5b("virtio_net: merge dma operations when
> > filling mergeable buffers"), I missed the dma unmap for the #3 case.
> >
> > That will leak some memory, because I did not release the pages referred
> > by the unused buffers.
> >
> > If we do such script, we will make the system OOM.
> >
> >     while true
> >     do
> >             ethtool -G ens4 rx 128
> >             ethtool -G ens4 rx 256
> >             free -m
> >     done
> >
> > Fixes: 295525e29a5b ("virtio_net: merge dma operations when filling mergeable buffers")
> > Signed-off-by: Xuan Zhuo <xuanzhuo@linux.alibaba.com>
> > ---
> >  drivers/net/virtio_net.c | 43 ++++++++++++++++++++--------------------
> >  1 file changed, 22 insertions(+), 21 deletions(-)
> >
> > diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
> > index d16f592c2061..6423a3a007ce 100644
> > --- a/drivers/net/virtio_net.c
> > +++ b/drivers/net/virtio_net.c
> > @@ -408,6 +408,17 @@ static struct page *get_a_page(struct receive_queue *rq, gfp_t gfp_mask)
> >  	return p;
> >  }
> >
> > +static void virtnet_rq_free_buf(struct virtnet_info *vi,
> > +				struct receive_queue *rq, void *buf)
> > +{
> > +	if (vi->mergeable_rx_bufs)
> > +		put_page(virt_to_head_page(buf));
> > +	else if (vi->big_packets)
> > +		give_pages(rq, buf);
> > +	else
> > +		put_page(virt_to_head_page(buf));
> > +}
> > +
>
> >  static void enable_delayed_refill(struct virtnet_info *vi)
> >  {
> >  	spin_lock_bh(&vi->refill_lock);
> > @@ -634,17 +645,6 @@ static void *virtnet_rq_get_buf(struct receive_queue *rq, u32 *len, void **ctx)
> >  	return buf;
> >  }
> >
> > -static void *virtnet_rq_detach_unused_buf(struct receive_queue *rq)
> > -{
> > -	void *buf;
> > -
> > -	buf = virtqueue_detach_unused_buf(rq->vq);
> > -	if (buf && rq->do_dma)
> > -		virtnet_rq_unmap(rq, buf, 0);
> > -
> > -	return buf;
> > -}
> > -
> >  static void virtnet_rq_init_one_sg(struct receive_queue *rq, void *buf, u32 len)
> >  {
> >  	struct virtnet_rq_dma *dma;
> > @@ -1764,7 +1764,7 @@ static void receive_buf(struct virtnet_info *vi, struct receive_queue *rq,
> >  	if (unlikely(len < vi->hdr_len + ETH_HLEN)) {
> >  		pr_debug("%s: short packet %i\n", dev->name, len);
> >  		DEV_STATS_INC(dev, rx_length_errors);
> > -		virtnet_rq_free_unused_buf(rq->vq, buf);
> > +		virtnet_rq_free_buf(vi, rq, buf);
> >  		return;
> >  	}
> >
> > @@ -4034,14 +4034,15 @@ static void virtnet_sq_free_unused_buf(struct virtqueue *vq, void *buf)
> >  static void virtnet_rq_free_unused_buf(struct virtqueue *vq, void *buf)
> >  {
> >  	struct virtnet_info *vi = vq->vdev->priv;
> > +	struct receive_queue *rq;
> >  	int i = vq2rxq(vq);
> >
> > -	if (vi->mergeable_rx_bufs)
> > -		put_page(virt_to_head_page(buf));
> > -	else if (vi->big_packets)
> > -		give_pages(&vi->rq[i], buf);
> > -	else
> > -		put_page(virt_to_head_page(buf));
> > +	rq = &vi->rq[i];
> > +
> > +	if (rq->do_dma)
> > +		virtnet_rq_unmap(rq, buf, 0);
> > +
> > +	virtnet_rq_free_buf(vi, rq, buf);
> >  }
> >
>
> So we have virtnet_rq_free_buf which sounds like it should free any
> buf, and we have virtnet_rq_free_unused_buf which is only for unused.
> Or so it would seem from names but this is not true.
> Better function names?

Sorry. not get it.

virtnet_rq_free_buf() that free the buf passed in. That is called by
virtnet_rq_free_unused_buf or receive_buf to free the buffer. I think
the name is right.

virtnet_rq_free_unused_buf is called by free_unused_bufs() and the
virtqueue_resize() to free the unused bufs. I think this name is right also.

So I do not get your mean.
Are there any details I've overlooked?

Thanks.

>
> >  static void free_unused_bufs(struct virtnet_info *vi)
> > @@ -4057,10 +4058,10 @@ static void free_unused_bufs(struct virtnet_info *vi)
> >  	}
> >
> >  	for (i = 0; i < vi->max_queue_pairs; i++) {
> > -		struct receive_queue *rq = &vi->rq[i];
> > +		struct virtqueue *vq = vi->rq[i].vq;
> >
> > -		while ((buf = virtnet_rq_detach_unused_buf(rq)) != NULL)
> > -			virtnet_rq_free_unused_buf(rq->vq, buf);
> > +		while ((buf = virtqueue_detach_unused_buf(vq)) != NULL)
> > +			virtnet_rq_free_unused_buf(vq, buf);
> >  		cond_resched();
> >  	}
> >  }
> > --
> > 2.32.0.3.g01195cf9f
>

Re: [PATCH net] virtio_net: fix missing dma unmap for resize

[Michael S. Tsirkin]

On Fri, Nov 10, 2023 at 09:58:45AM +0800, Xuan Zhuo wrote:
> On Thu, 9 Nov 2023 07:06:16 -0500, "Michael S. Tsirkin" <mst@redhat.com> wrote:
> > On Mon, Nov 06, 2023 at 04:18:32PM +0800, Xuan Zhuo wrote:
> > > For rq, we have three cases getting buffers from virtio core:
> > >
> > > 1. virtqueue_get_buf{,_ctx}
> > > 2. virtqueue_detach_unused_buf
> > > 3. callback for virtqueue_resize
> > >
> > > But in commit 295525e29a5b("virtio_net: merge dma operations when
> > > filling mergeable buffers"), I missed the dma unmap for the #3 case.
> > >
> > > That will leak some memory, because I did not release the pages referred
> > > by the unused buffers.
> > >
> > > If we do such script, we will make the system OOM.
> > >
> > >     while true
> > >     do
> > >             ethtool -G ens4 rx 128
> > >             ethtool -G ens4 rx 256
> > >             free -m
> > >     done
> > >
> > > Fixes: 295525e29a5b ("virtio_net: merge dma operations when filling mergeable buffers")
> > > Signed-off-by: Xuan Zhuo <xuanzhuo@linux.alibaba.com>
> > > ---
> > >  drivers/net/virtio_net.c | 43 ++++++++++++++++++++--------------------
> > >  1 file changed, 22 insertions(+), 21 deletions(-)
> > >
> > > diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
> > > index d16f592c2061..6423a3a007ce 100644
> > > --- a/drivers/net/virtio_net.c
> > > +++ b/drivers/net/virtio_net.c
> > > @@ -408,6 +408,17 @@ static struct page *get_a_page(struct receive_queue *rq, gfp_t gfp_mask)
> > >  	return p;
> > >  }
> > >
> > > +static void virtnet_rq_free_buf(struct virtnet_info *vi,
> > > +				struct receive_queue *rq, void *buf)
> > > +{
> > > +	if (vi->mergeable_rx_bufs)
> > > +		put_page(virt_to_head_page(buf));
> > > +	else if (vi->big_packets)
> > > +		give_pages(rq, buf);
> > > +	else
> > > +		put_page(virt_to_head_page(buf));
> > > +}
> > > +
> >
> > >  static void enable_delayed_refill(struct virtnet_info *vi)
> > >  {
> > >  	spin_lock_bh(&vi->refill_lock);
> > > @@ -634,17 +645,6 @@ static void *virtnet_rq_get_buf(struct receive_queue *rq, u32 *len, void **ctx)
> > >  	return buf;
> > >  }
> > >
> > > -static void *virtnet_rq_detach_unused_buf(struct receive_queue *rq)
> > > -{
> > > -	void *buf;
> > > -
> > > -	buf = virtqueue_detach_unused_buf(rq->vq);
> > > -	if (buf && rq->do_dma)
> > > -		virtnet_rq_unmap(rq, buf, 0);
> > > -
> > > -	return buf;
> > > -}
> > > -
> > >  static void virtnet_rq_init_one_sg(struct receive_queue *rq, void *buf, u32 len)
> > >  {
> > >  	struct virtnet_rq_dma *dma;
> > > @@ -1764,7 +1764,7 @@ static void receive_buf(struct virtnet_info *vi, struct receive_queue *rq,
> > >  	if (unlikely(len < vi->hdr_len + ETH_HLEN)) {
> > >  		pr_debug("%s: short packet %i\n", dev->name, len);
> > >  		DEV_STATS_INC(dev, rx_length_errors);
> > > -		virtnet_rq_free_unused_buf(rq->vq, buf);
> > > +		virtnet_rq_free_buf(vi, rq, buf);
> > >  		return;
> > >  	}
> > >
> > > @@ -4034,14 +4034,15 @@ static void virtnet_sq_free_unused_buf(struct virtqueue *vq, void *buf)
> > >  static void virtnet_rq_free_unused_buf(struct virtqueue *vq, void *buf)
> > >  {
> > >  	struct virtnet_info *vi = vq->vdev->priv;
> > > +	struct receive_queue *rq;
> > >  	int i = vq2rxq(vq);
> > >
> > > -	if (vi->mergeable_rx_bufs)
> > > -		put_page(virt_to_head_page(buf));
> > > -	else if (vi->big_packets)
> > > -		give_pages(&vi->rq[i], buf);
> > > -	else
> > > -		put_page(virt_to_head_page(buf));
> > > +	rq = &vi->rq[i];
> > > +
> > > +	if (rq->do_dma)
> > > +		virtnet_rq_unmap(rq, buf, 0);
> > > +
> > > +	virtnet_rq_free_buf(vi, rq, buf);
> > >  }
> > >
> >
> > So we have virtnet_rq_free_buf which sounds like it should free any
> > buf, and we have virtnet_rq_free_unused_buf which is only for unused.
> > Or so it would seem from names but this is not true.
> > Better function names?
> 
> Sorry. not get it.
> 
> virtnet_rq_free_buf() that free the buf passed in. That is called by
> virtnet_rq_free_unused_buf or receive_buf to free the buffer. I think
> the name is right.
> 
> virtnet_rq_free_unused_buf is called by free_unused_bufs() and the
> virtqueue_resize() to free the unused bufs. I think this name is right also.
> 
> So I do not get your mean.
> Are there any details I've overlooked?
> 
> Thanks.

Bad function names - they are too similar. Function name should
say what it does not where it's called from.
What is the difference? That virtnet_rq_free_unused_buf unmaps
and frees and virtnet_rq_free_buf just frees memory?


> >
> > >  static void free_unused_bufs(struct virtnet_info *vi)
> > > @@ -4057,10 +4058,10 @@ static void free_unused_bufs(struct virtnet_info *vi)
> > >  	}
> > >
> > >  	for (i = 0; i < vi->max_queue_pairs; i++) {
> > > -		struct receive_queue *rq = &vi->rq[i];
> > > +		struct virtqueue *vq = vi->rq[i].vq;
> > >
> > > -		while ((buf = virtnet_rq_detach_unused_buf(rq)) != NULL)
> > > -			virtnet_rq_free_unused_buf(rq->vq, buf);
> > > +		while ((buf = virtqueue_detach_unused_buf(vq)) != NULL)
> > > +			virtnet_rq_free_unused_buf(vq, buf);
> > >  		cond_resched();
> > >  	}
> > >  }
> > > --
> > > 2.32.0.3.g01195cf9f
> >

Re: [PATCH net] virtio_net: fix missing dma unmap for resize

[Xuan Zhuo]

On Fri, 10 Nov 2023 00:37:32 -0500, "Michael S. Tsirkin" <mst@redhat.com> wrote:
> On Fri, Nov 10, 2023 at 09:58:45AM +0800, Xuan Zhuo wrote:
> > On Thu, 9 Nov 2023 07:06:16 -0500, "Michael S. Tsirkin" <mst@redhat.com> wrote:
> > > On Mon, Nov 06, 2023 at 04:18:32PM +0800, Xuan Zhuo wrote:
> > > > For rq, we have three cases getting buffers from virtio core:
> > > >
> > > > 1. virtqueue_get_buf{,_ctx}
> > > > 2. virtqueue_detach_unused_buf
> > > > 3. callback for virtqueue_resize
> > > >
> > > > But in commit 295525e29a5b("virtio_net: merge dma operations when
> > > > filling mergeable buffers"), I missed the dma unmap for the #3 case.
> > > >
> > > > That will leak some memory, because I did not release the pages referred
> > > > by the unused buffers.
> > > >
> > > > If we do such script, we will make the system OOM.
> > > >
> > > >     while true
> > > >     do
> > > >             ethtool -G ens4 rx 128
> > > >             ethtool -G ens4 rx 256
> > > >             free -m
> > > >     done
> > > >
> > > > Fixes: 295525e29a5b ("virtio_net: merge dma operations when filling mergeable buffers")
> > > > Signed-off-by: Xuan Zhuo <xuanzhuo@linux.alibaba.com>
> > > > ---
> > > >  drivers/net/virtio_net.c | 43 ++++++++++++++++++++--------------------
> > > >  1 file changed, 22 insertions(+), 21 deletions(-)
> > > >
> > > > diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
> > > > index d16f592c2061..6423a3a007ce 100644
> > > > --- a/drivers/net/virtio_net.c
> > > > +++ b/drivers/net/virtio_net.c
> > > > @@ -408,6 +408,17 @@ static struct page *get_a_page(struct receive_queue *rq, gfp_t gfp_mask)
> > > >  	return p;
> > > >  }
> > > >
> > > > +static void virtnet_rq_free_buf(struct virtnet_info *vi,
> > > > +				struct receive_queue *rq, void *buf)
> > > > +{
> > > > +	if (vi->mergeable_rx_bufs)
> > > > +		put_page(virt_to_head_page(buf));
> > > > +	else if (vi->big_packets)
> > > > +		give_pages(rq, buf);
> > > > +	else
> > > > +		put_page(virt_to_head_page(buf));
> > > > +}
> > > > +
> > >
> > > >  static void enable_delayed_refill(struct virtnet_info *vi)
> > > >  {
> > > >  	spin_lock_bh(&vi->refill_lock);
> > > > @@ -634,17 +645,6 @@ static void *virtnet_rq_get_buf(struct receive_queue *rq, u32 *len, void **ctx)
> > > >  	return buf;
> > > >  }
> > > >
> > > > -static void *virtnet_rq_detach_unused_buf(struct receive_queue *rq)
> > > > -{
> > > > -	void *buf;
> > > > -
> > > > -	buf = virtqueue_detach_unused_buf(rq->vq);
> > > > -	if (buf && rq->do_dma)
> > > > -		virtnet_rq_unmap(rq, buf, 0);
> > > > -
> > > > -	return buf;
> > > > -}
> > > > -
> > > >  static void virtnet_rq_init_one_sg(struct receive_queue *rq, void *buf, u32 len)
> > > >  {
> > > >  	struct virtnet_rq_dma *dma;
> > > > @@ -1764,7 +1764,7 @@ static void receive_buf(struct virtnet_info *vi, struct receive_queue *rq,
> > > >  	if (unlikely(len < vi->hdr_len + ETH_HLEN)) {
> > > >  		pr_debug("%s: short packet %i\n", dev->name, len);
> > > >  		DEV_STATS_INC(dev, rx_length_errors);
> > > > -		virtnet_rq_free_unused_buf(rq->vq, buf);
> > > > +		virtnet_rq_free_buf(vi, rq, buf);
> > > >  		return;
> > > >  	}
> > > >
> > > > @@ -4034,14 +4034,15 @@ static void virtnet_sq_free_unused_buf(struct virtqueue *vq, void *buf)
> > > >  static void virtnet_rq_free_unused_buf(struct virtqueue *vq, void *buf)
> > > >  {
> > > >  	struct virtnet_info *vi = vq->vdev->priv;
> > > > +	struct receive_queue *rq;
> > > >  	int i = vq2rxq(vq);
> > > >
> > > > -	if (vi->mergeable_rx_bufs)
> > > > -		put_page(virt_to_head_page(buf));
> > > > -	else if (vi->big_packets)
> > > > -		give_pages(&vi->rq[i], buf);
> > > > -	else
> > > > -		put_page(virt_to_head_page(buf));
> > > > +	rq = &vi->rq[i];
> > > > +
> > > > +	if (rq->do_dma)
> > > > +		virtnet_rq_unmap(rq, buf, 0);
> > > > +
> > > > +	virtnet_rq_free_buf(vi, rq, buf);
> > > >  }
> > > >
> > >
> > > So we have virtnet_rq_free_buf which sounds like it should free any
> > > buf, and we have virtnet_rq_free_unused_buf which is only for unused.
> > > Or so it would seem from names but this is not true.
> > > Better function names?
> >
> > Sorry. not get it.
> >
> > virtnet_rq_free_buf() that free the buf passed in. That is called by
> > virtnet_rq_free_unused_buf or receive_buf to free the buffer. I think
> > the name is right.
> >
> > virtnet_rq_free_unused_buf is called by free_unused_bufs() and the
> > virtqueue_resize() to free the unused bufs. I think this name is right also.
> >
> > So I do not get your mean.
> > Are there any details I've overlooked?
> >
> > Thanks.
>
> Bad function names - they are too similar. Function name should
> say what it does not where it's called from.
> What is the difference? That virtnet_rq_free_unused_buf unmaps
> and frees and virtnet_rq_free_buf just frees memory?

Yes. virtnet_rq_free_buf frees memory.

For this patch, I think virtnet_rq_free_buf is ok.
virtnet_rq_free_buf is as your request.
virtnet_rq_free_unused_buf is named as it want to do. Or as you said.
Indeed these are similar.

Could you give some advices?

Thanks.



>
>
> > >
> > > >  static void free_unused_bufs(struct virtnet_info *vi)
> > > > @@ -4057,10 +4058,10 @@ static void free_unused_bufs(struct virtnet_info *vi)
> > > >  	}
> > > >
> > > >  	for (i = 0; i < vi->max_queue_pairs; i++) {
> > > > -		struct receive_queue *rq = &vi->rq[i];
> > > > +		struct virtqueue *vq = vi->rq[i].vq;
> > > >
> > > > -		while ((buf = virtnet_rq_detach_unused_buf(rq)) != NULL)
> > > > -			virtnet_rq_free_unused_buf(rq->vq, buf);
> > > > +		while ((buf = virtqueue_detach_unused_buf(vq)) != NULL)
> > > > +			virtnet_rq_free_unused_buf(vq, buf);
> > > >  		cond_resched();
> > > >  	}
> > > >  }
> > > > --
> > > > 2.32.0.3.g01195cf9f
> > >
>