[bpf-next PATCH 03/16] net: do_tcp_sendpages flag to avoid SKBTX_SHARED_FRAG
flat view
STALE3150d
SUPERSEDED
From: John Fastabend <john.fastabend@gmail.com>
Date: 2018-03-05 19:51:15
Subsystem:
networking [general], networking [sockets], networking [tcp], the rest · Maintainers:
"David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Kuniyuki Iwashima, Willem de Bruijn, Neal Cardwell, Linus Torvalds
Revision v1 of 3 in this series.
Revisions (3)
- v1 current
- v2 [diff vs current]
- v3 [diff vs current]
When calling do_tcp_sendpages() from in kernel and we know the data has no references from user side we can omit SKBTX_SHARED_FRAG flag. This patch adds an internal flag, NO_SKBTX_SHARED_FRAG that can be used to omit setting SKBTX_SHARED_FRAG. The flag is not exposed to userspace because the sendpage call from the splice logic masks out all bits except MSG_MORE. Signed-off-by: John Fastabend <john.fastabend@gmail.com> --- include/linux/socket.h | 1 + net/ipv4/tcp.c | 4 +++- 2 files changed, 4 insertions(+), 1 deletion(-)
diff --git a/include/linux/socket.h b/include/linux/socket.h
index 1ce1f76..60e0148 100644
--- a/include/linux/socket.h
+++ b/include/linux/socket.h@@ -287,6 +287,7 @@ struct ucred { #define MSG_SENDPAGE_NOTLAST 0x20000 /* sendpage() internal : not the last page */ #define MSG_BATCH 0x40000 /* sendmmsg(): more messages coming */ #define MSG_EOF MSG_FIN +#define MSG_NO_SHARED_FRAGS 0x80000 /* sendpage() internal : page frags are not shared */ #define MSG_ZEROCOPY 0x4000000 /* Use user data in kernel path */ #define MSG_FASTOPEN 0x20000000 /* Send data in TCP SYN */
diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index a335397..ff8a8d3 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c@@ -994,7 +994,9 @@ ssize_t do_tcp_sendpages(struct sock *sk, struct page *page, int offset, get_page(page); skb_fill_page_desc(skb, i, page, offset, copy); } - skb_shinfo(skb)->tx_flags |= SKBTX_SHARED_FRAG; + + if (!(flags & MSG_NO_SHARED_FRAGS)) + skb_shinfo(skb)->tx_flags |= SKBTX_SHARED_FRAG; skb->len += copy; skb->data_len += copy;