[PATCH RFC 1/6] skbuff: support per-page destructors in copy_ubufs
From: "Michael S. Tsirkin" <mst@redhat.com>
Date: 2012-05-07 13:54:28
Subsystem:
networking [general], the rest · Maintainers:
"David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Linus Torvalds
sunrpc wants to use zero copy with tcp which means some fragments are zero copy while others are not. This in turn means there's no per skb destructor_arg, instead some fragments have destructors. Teach skb_copy_ubufs and skb_release_data to handle such skbs. Signed-off-by: Michael S. Tsirkin <mst@redhat.com> --- net/core/skbuff.c | 18 ++++++++++++++---- 1 files changed, 14 insertions(+), 4 deletions(-)
diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index c81240c..bd28e80 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c@@ -423,7 +423,7 @@ static void skb_release_data(struct sk_buff *skb) struct ubuf_info *uarg; uarg = skb_shinfo(skb)->destructor_arg; - if (uarg->callback) + if (uarg && uarg->callback) uarg->callback(uarg); }
@@ -721,6 +721,8 @@ int skb_copy_ubufs(struct sk_buff *skb, gfp_t gfp_mask) for (i = 0; i < num_frags; i++) { u8 *vaddr; skb_frag_t *f = &skb_shinfo(skb)->frags[i]; + if (unlikely((!uarg && !f->page.destructor))) + continue; page = alloc_page(GFP_ATOMIC); if (!page) {
@@ -740,13 +742,21 @@ int skb_copy_ubufs(struct sk_buff *skb, gfp_t gfp_mask) } /* skb frags release userspace buffers */ - for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) - skb_frag_unref(skb, i); + for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) { + skb_frag_t *f = &skb_shinfo(skb)->frags[i]; + if (unlikely((!uarg && !f->page.destructor))) + continue; + __skb_frag_unref(f); + } - uarg->callback(uarg); + if (uarg) + uarg->callback(uarg); /* skb frags point to kernel buffers */ for (i = skb_shinfo(skb)->nr_frags; i > 0; i--) { + skb_frag_t *f = &skb_shinfo(skb)->frags[i]; + if (unlikely((!uarg && !f->page.destructor))) + continue; __skb_fill_page_desc(skb, i-1, head, 0, skb_shinfo(skb)->frags[i - 1].size); head = (struct page *)head->private;
--
MST