[PATCH net-next 3/5] net: batch zerocopy_fill_skb_from_iter accounting

Pavel Begunkov
2024-06-27T12:59:46Z

Instead of accounting every page range against the socket separately, do
it in batch based on the change in skb->truesize. It's also moved into
__zerocopy_sg_from_iter(), so that zerocopy_fill_skb_from_iter() is
simpler and responsible for setting frags but not the accounting.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
---
net/core/datagram.c | 31 ++++++++++++++++++-------------
1 file changed, 18 insertions(+), 13 deletions(-)

diff --git a/net/core/datagram.c b/net/core/datagram.c
index 7f7d5da2e406..2b24d69b1e94 100644
--- a/net/core/datagram.c
+++ b/net/core/datagram.c
@@ -610,7 +610,7 @@ int skb_copy_datagram_from_iter(struct sk_buff *skb, int offset,
}
EXPORT_SYMBOL(skb_copy_datagram_from_iter);

-static int zerocopy_fill_skb_from_iter(struct sock *sk, struct sk_buff *skb,
+static int zerocopy_fill_skb_from_iter(struct sk_buff *skb,
struct iov_iter *from, size_t length)
{
int frag = skb_shinfo(skb)->nr_frags;
@@ -621,7 +621,6 @@ static int zerocopy_fill_skb_from_iter(struct sock *sk, struct sk_buff *skb,
int refs, order, n = 0;
size_t start;
ssize_t copied;
- unsigned long truesize;

if (frag == MAX_SKB_FRAGS)
return -EMSGSIZE;
@@ -633,17 +632,9 @@ static int zerocopy_fill_skb_from_iter(struct sock *sk, struct sk_buff *skb,

length -= copied;

- truesize = PAGE_ALIGN(copied + start);
skb->data_len += copied;
skb->len += copied;
- skb->truesize += truesize;
- if (sk && sk->sk_type == SOCK_STREAM) {
- sk_wmem_queued_add(sk, truesize);
- if (!skb_zcopy_pure(skb))
- sk_mem_charge(sk, truesize);
- } else {
- refcount_add(truesize, &skb->sk->sk_wmem_alloc);
- }
+ skb->truesize += PAGE_ALIGN(copied + start);

head = compound_head(pages[n]);
order = compound_order(head);
@@ -691,10 +682,24 @@ int __zerocopy_sg_from_iter(struct msghdr *msg, struct sock *sk,
struct sk_buff *skb, struct iov_iter *from,
size_t length)
{
+ unsigned long orig_size = skb->truesize;
+ unsigned long truesize;
+ int ret;
+
if (msg && msg->msg_ubuf && msg->sg_from_iter)
return msg->sg_from_iter(sk, skb, from, length);
- else
- return zerocopy_fill_skb_from_iter(sk, skb, from, length);
+
+ ret = zerocopy_fill_skb_from_iter(skb, from, length);
+ truesize = skb->truesize - orig_size;
+
+ if (sk && sk->sk_type == SOCK_STREAM) {
+ sk_wmem_queued_add(sk, truesize);
+ if (!skb_zcopy_pure(skb))
+ sk_mem_charge(sk, truesize);
+ } else {
+ refcount_add(truesize, &skb->sk->sk_wmem_alloc);
+ }
+ return ret;
}
EXPORT_SYMBOL(__zerocopy_sg_from_iter);

--
2.44.0