This is a note to let you know that I've just added the patch titled
net: use indirect call wrappers for skb_copy_datagram_iter()
to the 5.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
net-use-indirect-call-wrappers-for-skb_copy_datagram.patch
and it can be found in the queue-5.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 507ac3e03289889dc9fd44bc0550c20b317056f0
Author: Eric Dumazet <edumazet@xxxxxxxxxx>
Date: Tue Mar 24 19:23:21 2020 -0700
net: use indirect call wrappers for skb_copy_datagram_iter()
commit 29f3490ba9d2399d3d1b20c4aa74592d92bd4e11 upstream.
TCP recvmsg() calls skb_copy_datagram_iter(), which
calls an indirect function (cb pointing to simple_copy_to_iter())
for every MSS (fragment) present in the skb.
CONFIG_RETPOLINE=y forces a very expensive operation
that we can avoid thanks to indirect call wrappers.
This patch gives a 13% increase of performance on
a single flow, if the bottleneck is the thread reading
the TCP socket.
Fixes: 950fcaecd5cc ("datagram: consolidate datagram copy to iter helpers")
Signed-off-by: Eric Dumazet <edumazet@xxxxxxxxxx>
Acked-by: Paolo Abeni <pabeni@xxxxxxxxxx>
Acked-by: Willem de Bruijn <willemb@xxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
diff --git a/net/core/datagram.c b/net/core/datagram.c
index da3c24ed129cd..189ad4c73a3fe 100644
--- a/net/core/datagram.c
+++ b/net/core/datagram.c
@@ -51,6 +51,7 @@
#include <linux/slab.h>
#include <linux/pagemap.h>
#include <linux/uio.h>
+#include <linux/indirect_call_wrapper.h>
#include <net/protocol.h>
#include <linux/skbuff.h>
@@ -407,6 +408,11 @@ int skb_kill_datagram(struct sock *sk, struct sk_buff *skb, unsigned int flags)
}
EXPORT_SYMBOL(skb_kill_datagram);
+INDIRECT_CALLABLE_DECLARE(static size_t simple_copy_to_iter(const void *addr,
+ size_t bytes,
+ void *data __always_unused,
+ struct iov_iter *i));
+
static int __skb_datagram_iter(const struct sk_buff *skb, int offset,
struct iov_iter *to, int len, bool fault_short,
size_t (*cb)(const void *, size_t, void *,
@@ -420,7 +426,8 @@ static int __skb_datagram_iter(const struct sk_buff *skb, int offset,
if (copy > 0) {
if (copy > len)
copy = len;
- n = cb(skb->data + offset, copy, data, to);
+ n = INDIRECT_CALL_1(cb, simple_copy_to_iter,
+ skb->data + offset, copy, data, to);
offset += n;
if (n != copy)
goto short_copy;
@@ -442,8 +449,9 @@ static int __skb_datagram_iter(const struct sk_buff *skb, int offset,
if (copy > len)
copy = len;
- n = cb(vaddr + skb_frag_off(frag) + offset - start,
- copy, data, to);
+ n = INDIRECT_CALL_1(cb, simple_copy_to_iter,
+ vaddr + skb_frag_off(frag) + offset - start,
+ copy, data, to);
kunmap(page);
offset += n;
if (n != copy)
