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author | Willem de Bruijn <willemb@google.com> | 2017-08-03 16:29:41 -0400 |
---|---|---|
committer | David S. Miller <davem@davemloft.net> | 2017-08-03 21:37:30 -0700 |
commit | 1f8b977ab32dc5d148f103326e80d9097f1cefb5 (patch) | |
tree | 1c2c09ca72dba5bd43f8b3ead791d271f075c24b /include | |
parent | 76851d1212c11365362525e1e2c0a18c97478e6b (diff) | |
download | op-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.h | 14 |
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]; |