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authorWillem de Bruijn <willemb@google.com>2017-08-03 16:29:41 -0400
committerDavid S. Miller <davem@davemloft.net>2017-08-03 21:37:30 -0700
commit1f8b977ab32dc5d148f103326e80d9097f1cefb5 (patch)
tree1c2c09ca72dba5bd43f8b3ead791d271f075c24b /include
parent76851d1212c11365362525e1e2c0a18c97478e6b (diff)
downloadop-kernel-dev-1f8b977ab32dc5d148f103326e80d9097f1cefb5.zip
op-kernel-dev-1f8b977ab32dc5d148f103326e80d9097f1cefb5.tar.gz
sock: enable MSG_ZEROCOPY
Prepare the datapath for refcounted ubuf_info. Clone ubuf_info with skb_zerocopy_clone() wherever needed due to skb split, merge, resize or clone. Split skb_orphan_frags into two variants. The split, merge, .. paths support reference counted zerocopy buffers, so do not do a deep copy. Add skb_orphan_frags_rx for paths that may loop packets to receive sockets. That is not allowed, as it may cause unbounded latency. Deep copy all zerocopy copy buffers, ref-counted or not, in this path. The exact locations to modify were chosen by exhaustively searching through all code that might modify skb_frag references and/or the the SKBTX_DEV_ZEROCOPY tx_flags bit. The changes err on the safe side, in two ways. (1) legacy ubuf_info paths virtio and tap are not modified. They keep a 1:1 ubuf_info to sk_buff relationship. Calls to skb_orphan_frags still call skb_copy_ubufs and thus copy frags in this case. (2) not all copies deep in the stack are addressed yet. skb_shift, skb_split and skb_try_coalesce can be refined to avoid copying. These are not in the hot path and this patch is hairy enough as is, so that is left for future refinement. Signed-off-by: Willem de Bruijn <willemb@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'include')
-rw-r--r--include/linux/skbuff.h14
1 files changed, 13 insertions, 1 deletions
diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index 59cff7a..e538793 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -2512,7 +2512,17 @@ static inline void skb_orphan(struct sk_buff *skb)
*/
static inline int skb_orphan_frags(struct sk_buff *skb, gfp_t gfp_mask)
{
- if (likely(!(skb_shinfo(skb)->tx_flags & SKBTX_DEV_ZEROCOPY)))
+ if (likely(!skb_zcopy(skb)))
+ return 0;
+ if (skb_uarg(skb)->callback == sock_zerocopy_callback)
+ return 0;
+ return skb_copy_ubufs(skb, gfp_mask);
+}
+
+/* Frags must be orphaned, even if refcounted, if skb might loop to rx path */
+static inline int skb_orphan_frags_rx(struct sk_buff *skb, gfp_t gfp_mask)
+{
+ if (likely(!skb_zcopy(skb)))
return 0;
return skb_copy_ubufs(skb, gfp_mask);
}
@@ -2944,6 +2954,8 @@ static inline int skb_add_data(struct sk_buff *skb,
static inline bool skb_can_coalesce(struct sk_buff *skb, int i,
const struct page *page, int off)
{
+ if (skb_zcopy(skb))
+ return false;
if (i) {
const struct skb_frag_struct *frag = &skb_shinfo(skb)->frags[i - 1];
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