| Message ID | 20230328120412.110114-2-xuanzhuo@linux.alibaba.com (mailing list archive) |
|---|---|
| State | Changes Requested |
| Delegated to: | Netdev Maintainers |
| Headers | show |
| Series | virtio_net: refactor xdp codes | expand |
| Context | Check | Description |
|---|---|---|
| netdev/series_format | success | Posting correctly formatted |
| netdev/tree_selection | success | Clearly marked for net-next |
| netdev/fixes_present | success | Fixes tag not required for -next series |
| netdev/header_inline | success | No static functions without inline keyword in header files |
| netdev/build_32bit | success | Errors and warnings before: 18 this patch: 18 |
| netdev/cc_maintainers | success | CCed 13 of 13 maintainers |
| netdev/build_clang | success | Errors and warnings before: 18 this patch: 18 |
| netdev/verify_signedoff | success | Signed-off-by tag matches author and committer |
| netdev/deprecated_api | success | None detected |
| netdev/check_selftest | success | No net selftest shell script |
| netdev/verify_fixes | success | No Fixes tag |
| netdev/build_allmodconfig_warn | success | Errors and warnings before: 18 this patch: 18 |
| netdev/checkpatch | success | total: 0 errors, 0 warnings, 0 checks, 51 lines checked |
| netdev/kdoc | success | Errors and warnings before: 0 this patch: 0 |
| netdev/source_inline | success | Was 0 now: 0 |
On Tue, Mar 28, 2023 at 8:04 PM Xuan Zhuo <xuanzhuo@linux.alibaba.com> wrote: > > In the xdp implementation of virtio-net mergeable, it always checks > whether two page is used and a page is selected to release. This is > complicated for the processing of action, and be careful. > > In the entire process, we have such principles: > * If xdp_page is used (PASS, TX, Redirect), then we release the old > page. > * If it is a drop case, we will release two. The old page obtained from > buf is release inside err_xdp, and xdp_page needs be relased by us. > > But in fact, when we allocate a new page, we can release the old page > immediately. Then just one is using, we just need to release the new > page for drop case. On the drop path, err_xdp will release the variable > "page", so we only need to let "page" point to the new xdp_page in > advance. > > Signed-off-by: Xuan Zhuo <xuanzhuo@linux.alibaba.com> > --- > drivers/net/virtio_net.c | 15 ++++++--------- > 1 file changed, 6 insertions(+), 9 deletions(-) > > diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c > index e2560b6f7980..4d2bf1ce0730 100644 > --- a/drivers/net/virtio_net.c > +++ b/drivers/net/virtio_net.c > @@ -1245,6 +1245,9 @@ static struct sk_buff *receive_mergeable(struct net_device *dev, > if (!xdp_page) > goto err_xdp; > offset = VIRTIO_XDP_HEADROOM; > + > + put_page(page); > + page = xdp_page; > } else if (unlikely(headroom < virtnet_get_headroom(vi))) { > xdp_room = SKB_DATA_ALIGN(VIRTIO_XDP_HEADROOM + > sizeof(struct skb_shared_info)); > @@ -1259,6 +1262,9 @@ static struct sk_buff *receive_mergeable(struct net_device *dev, > page_address(page) + offset, len); > frame_sz = PAGE_SIZE; > offset = VIRTIO_XDP_HEADROOM; > + > + put_page(page); > + page = xdp_page; > } else { > xdp_page = page; > } While at this I would go a little further, just remove the above assignment then we can use: data = page_address(page) + offset; Which seems cleaner? Thanks > @@ -1278,8 +1284,6 @@ static struct sk_buff *receive_mergeable(struct net_device *dev, > if (unlikely(!head_skb)) > goto err_xdp_frags; > > - if (unlikely(xdp_page != page)) > - put_page(page); > rcu_read_unlock(); > return head_skb; > case XDP_TX: > @@ -1297,8 +1301,6 @@ static struct sk_buff *receive_mergeable(struct net_device *dev, > goto err_xdp_frags; > } > *xdp_xmit |= VIRTIO_XDP_TX; > - if (unlikely(xdp_page != page)) > - put_page(page); > rcu_read_unlock(); > goto xdp_xmit; > case XDP_REDIRECT: > @@ -1307,8 +1309,6 @@ static struct sk_buff *receive_mergeable(struct net_device *dev, > if (err) > goto err_xdp_frags; > *xdp_xmit |= VIRTIO_XDP_REDIR; > - if (unlikely(xdp_page != page)) > - put_page(page); > rcu_read_unlock(); > goto xdp_xmit; > default: > @@ -1321,9 +1321,6 @@ static struct sk_buff *receive_mergeable(struct net_device *dev, > goto err_xdp_frags; > } > err_xdp_frags: > - if (unlikely(xdp_page != page)) > - __free_pages(xdp_page, 0); > - > if (xdp_buff_has_frags(&xdp)) { > shinfo = xdp_get_shared_info_from_buff(&xdp); > for (i = 0; i < shinfo->nr_frags; i++) { > -- > 2.32.0.3.g01195cf9f >
On Fri, 31 Mar 2023 17:01:54 +0800, Jason Wang <jasowang@redhat.com> wrote: > On Tue, Mar 28, 2023 at 8:04 PM Xuan Zhuo <xuanzhuo@linux.alibaba.com> wrote: > > > > In the xdp implementation of virtio-net mergeable, it always checks > > whether two page is used and a page is selected to release. This is > > complicated for the processing of action, and be careful. > > > > In the entire process, we have such principles: > > * If xdp_page is used (PASS, TX, Redirect), then we release the old > > page. > > * If it is a drop case, we will release two. The old page obtained from > > buf is release inside err_xdp, and xdp_page needs be relased by us. > > > > But in fact, when we allocate a new page, we can release the old page > > immediately. Then just one is using, we just need to release the new > > page for drop case. On the drop path, err_xdp will release the variable > > "page", so we only need to let "page" point to the new xdp_page in > > advance. > > > > Signed-off-by: Xuan Zhuo <xuanzhuo@linux.alibaba.com> > > --- > > drivers/net/virtio_net.c | 15 ++++++--------- > > 1 file changed, 6 insertions(+), 9 deletions(-) > > > > diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c > > index e2560b6f7980..4d2bf1ce0730 100644 > > --- a/drivers/net/virtio_net.c > > +++ b/drivers/net/virtio_net.c > > @@ -1245,6 +1245,9 @@ static struct sk_buff *receive_mergeable(struct net_device *dev, > > if (!xdp_page) > > goto err_xdp; > > offset = VIRTIO_XDP_HEADROOM; > > + > > + put_page(page); > > + page = xdp_page; > > } else if (unlikely(headroom < virtnet_get_headroom(vi))) { > > xdp_room = SKB_DATA_ALIGN(VIRTIO_XDP_HEADROOM + > > sizeof(struct skb_shared_info)); > > @@ -1259,6 +1262,9 @@ static struct sk_buff *receive_mergeable(struct net_device *dev, > > page_address(page) + offset, len); > > frame_sz = PAGE_SIZE; > > offset = VIRTIO_XDP_HEADROOM; > > + > > + put_page(page); > > + page = xdp_page; > > } else { > > xdp_page = page; > > } > > While at this I would go a little further, just remove the above > assignment then we can use: > > data = page_address(page) + offset; > > Which seems cleaner? I will try. Thanks. > > Thanks > > > @@ -1278,8 +1284,6 @@ static struct sk_buff *receive_mergeable(struct net_device *dev, > > if (unlikely(!head_skb)) > > goto err_xdp_frags; > > > > - if (unlikely(xdp_page != page)) > > - put_page(page); > > rcu_read_unlock(); > > return head_skb; > > case XDP_TX: > > @@ -1297,8 +1301,6 @@ static struct sk_buff *receive_mergeable(struct net_device *dev, > > goto err_xdp_frags; > > } > > *xdp_xmit |= VIRTIO_XDP_TX; > > - if (unlikely(xdp_page != page)) > > - put_page(page); > > rcu_read_unlock(); > > goto xdp_xmit; > > case XDP_REDIRECT: > > @@ -1307,8 +1309,6 @@ static struct sk_buff *receive_mergeable(struct net_device *dev, > > if (err) > > goto err_xdp_frags; > > *xdp_xmit |= VIRTIO_XDP_REDIR; > > - if (unlikely(xdp_page != page)) > > - put_page(page); > > rcu_read_unlock(); > > goto xdp_xmit; > > default: > > @@ -1321,9 +1321,6 @@ static struct sk_buff *receive_mergeable(struct net_device *dev, > > goto err_xdp_frags; > > } > > err_xdp_frags: > > - if (unlikely(xdp_page != page)) > > - __free_pages(xdp_page, 0); > > - > > if (xdp_buff_has_frags(&xdp)) { > > shinfo = xdp_get_shared_info_from_buff(&xdp); > > for (i = 0; i < shinfo->nr_frags; i++) { > > -- > > 2.32.0.3.g01195cf9f > > >
diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c index e2560b6f7980..4d2bf1ce0730 100644 --- a/drivers/net/virtio_net.c +++ b/drivers/net/virtio_net.c @@ -1245,6 +1245,9 @@ static struct sk_buff *receive_mergeable(struct net_device *dev, if (!xdp_page) goto err_xdp; offset = VIRTIO_XDP_HEADROOM; + + put_page(page); + page = xdp_page; } else if (unlikely(headroom < virtnet_get_headroom(vi))) { xdp_room = SKB_DATA_ALIGN(VIRTIO_XDP_HEADROOM + sizeof(struct skb_shared_info)); @@ -1259,6 +1262,9 @@ static struct sk_buff *receive_mergeable(struct net_device *dev, page_address(page) + offset, len); frame_sz = PAGE_SIZE; offset = VIRTIO_XDP_HEADROOM; + + put_page(page); + page = xdp_page; } else { xdp_page = page; } @@ -1278,8 +1284,6 @@ static struct sk_buff *receive_mergeable(struct net_device *dev, if (unlikely(!head_skb)) goto err_xdp_frags; - if (unlikely(xdp_page != page)) - put_page(page); rcu_read_unlock(); return head_skb; case XDP_TX: @@ -1297,8 +1301,6 @@ static struct sk_buff *receive_mergeable(struct net_device *dev, goto err_xdp_frags; } *xdp_xmit |= VIRTIO_XDP_TX; - if (unlikely(xdp_page != page)) - put_page(page); rcu_read_unlock(); goto xdp_xmit; case XDP_REDIRECT: @@ -1307,8 +1309,6 @@ static struct sk_buff *receive_mergeable(struct net_device *dev, if (err) goto err_xdp_frags; *xdp_xmit |= VIRTIO_XDP_REDIR; - if (unlikely(xdp_page != page)) - put_page(page); rcu_read_unlock(); goto xdp_xmit; default: @@ -1321,9 +1321,6 @@ static struct sk_buff *receive_mergeable(struct net_device *dev, goto err_xdp_frags; } err_xdp_frags: - if (unlikely(xdp_page != page)) - __free_pages(xdp_page, 0); - if (xdp_buff_has_frags(&xdp)) { shinfo = xdp_get_shared_info_from_buff(&xdp); for (i = 0; i < shinfo->nr_frags; i++) {
In the xdp implementation of virtio-net mergeable, it always checks whether two page is used and a page is selected to release. This is complicated for the processing of action, and be careful. In the entire process, we have such principles: * If xdp_page is used (PASS, TX, Redirect), then we release the old page. * If it is a drop case, we will release two. The old page obtained from buf is release inside err_xdp, and xdp_page needs be relased by us. But in fact, when we allocate a new page, we can release the old page immediately. Then just one is using, we just need to release the new page for drop case. On the drop path, err_xdp will release the variable "page", so we only need to let "page" point to the new xdp_page in advance. Signed-off-by: Xuan Zhuo <xuanzhuo@linux.alibaba.com> --- drivers/net/virtio_net.c | 15 ++++++--------- 1 file changed, 6 insertions(+), 9 deletions(-)