[PATCH 3/7] net: micro-optimize skb_datagram_iter

Hannes Reinecke
2024-06-26T12:14:08Z

From: Sagi Grimberg <sagi@grimberg.me>

We only use the mapping in a single context in a short and contained scope,
so kmap_local_page is sufficient and cheaper. This will also allow
skb_datagram_iter to be called from softirq context.

Signed-off-by: Sagi Grimberg <sagi@grimberg.me>
Signed-off-by: Hannes Reinecke <hare@kernel.org>
---
net/core/datagram.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/net/core/datagram.c b/net/core/datagram.c
index e614cfd8e14a..95f242591fd2 100644
--- a/net/core/datagram.c
+++ b/net/core/datagram.c
@@ -417,14 +417,14 @@ static int __skb_datagram_iter(const struct sk_buff *skb, int offset,
end = start + skb_frag_size(frag);
if ((copy = end - offset) > 0) {
struct page *page = skb_frag_page(frag);
- u8 *vaddr = kmap(page);
+ u8 *vaddr = kmap_local_page(page);

if (copy > len)
copy = len;
n = INDIRECT_CALL_1(cb, simple_copy_to_iter,
vaddr + skb_frag_off(frag) + offset - start,
copy, data, to);
- kunmap(page);
+ kunmap_local(vaddr);
offset += n;
if (n != copy)
goto short_copy;
--
2.35.3