sock: add MSG_ZEROCOPY
The kernel supports zerocopy sendmsg in virtio and tap. Expand the infrastructure to support other socket types. Introduce a completion notification channel over the socket error queue. Notifications are returned with ee_origin SO_EE_ORIGIN_ZEROCOPY. ee_errno is 0 to avoid blocking the send/recv path on receiving notifications. Add reference counting, to support the skb split, merge, resize and clone operations possible with SOCK_STREAM and other socket types. The patch does not yet modify any datapaths. Signed-off-by: Willem de Bruijn <willemb@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Willem de Bruijn
committed by
David S. Miller
David S. Miller
parent
3ece782693
commit
52267790ef
@@ -915,6 +915,139 @@ struct sk_buff *skb_morph(struct sk_buff *dst, struct sk_buff *src)
|
||||
}
|
||||
EXPORT_SYMBOL_GPL(skb_morph);
|
||||
|
||||
struct ubuf_info *sock_zerocopy_alloc(struct sock *sk, size_t size)
|
||||
{
|
||||
struct ubuf_info *uarg;
|
||||
struct sk_buff *skb;
|
||||
|
||||
WARN_ON_ONCE(!in_task());
|
||||
|
||||
skb = sock_omalloc(sk, 0, GFP_KERNEL);
|
||||
if (!skb)
|
||||
return NULL;
|
||||
|
||||
BUILD_BUG_ON(sizeof(*uarg) > sizeof(skb->cb));
|
||||
uarg = (void *)skb->cb;
|
||||
|
||||
uarg->callback = sock_zerocopy_callback;
|
||||
uarg->desc = atomic_inc_return(&sk->sk_zckey) - 1;
|
||||
uarg->zerocopy = 1;
|
||||
atomic_set(&uarg->refcnt, 0);
|
||||
sock_hold(sk);
|
||||
|
||||
return uarg;
|
||||
}
|
||||
EXPORT_SYMBOL_GPL(sock_zerocopy_alloc);
|
||||
|
||||
static inline struct sk_buff *skb_from_uarg(struct ubuf_info *uarg)
|
||||
{
|
||||
return container_of((void *)uarg, struct sk_buff, cb);
|
||||
}
|
||||
|
||||
void sock_zerocopy_callback(struct ubuf_info *uarg, bool success)
|
||||
{
|
||||
struct sk_buff *skb = skb_from_uarg(uarg);
|
||||
struct sock_exterr_skb *serr;
|
||||
struct sock *sk = skb->sk;
|
||||
u16 id = uarg->desc;
|
||||
|
||||
if (sock_flag(sk, SOCK_DEAD))
|
||||
goto release;
|
||||
|
||||
serr = SKB_EXT_ERR(skb);
|
||||
memset(serr, 0, sizeof(*serr));
|
||||
serr->ee.ee_errno = 0;
|
||||
serr->ee.ee_origin = SO_EE_ORIGIN_ZEROCOPY;
|
||||
serr->ee.ee_data = id;
|
||||
if (!success)
|
||||
serr->ee.ee_code |= SO_EE_CODE_ZEROCOPY_COPIED;
|
||||
|
||||
skb_queue_tail(&sk->sk_error_queue, skb);
|
||||
skb = NULL;
|
||||
|
||||
sk->sk_error_report(sk);
|
||||
|
||||
release:
|
||||
consume_skb(skb);
|
||||
sock_put(sk);
|
||||
}
|
||||
EXPORT_SYMBOL_GPL(sock_zerocopy_callback);
|
||||
|
||||
void sock_zerocopy_put(struct ubuf_info *uarg)
|
||||
{
|
||||
if (uarg && atomic_dec_and_test(&uarg->refcnt)) {
|
||||
if (uarg->callback)
|
||||
uarg->callback(uarg, uarg->zerocopy);
|
||||
else
|
||||
consume_skb(skb_from_uarg(uarg));
|
||||
}
|
||||
}
|
||||
EXPORT_SYMBOL_GPL(sock_zerocopy_put);
|
||||
|
||||
void sock_zerocopy_put_abort(struct ubuf_info *uarg)
|
||||
{
|
||||
if (uarg) {
|
||||
struct sock *sk = skb_from_uarg(uarg)->sk;
|
||||
|
||||
atomic_dec(&sk->sk_zckey);
|
||||
|
||||
/* sock_zerocopy_put expects a ref. Most sockets take one per
|
||||
* skb, which is zero on abort. tcp_sendmsg holds one extra, to
|
||||
* avoid an skb send inside the main loop triggering uarg free.
|
||||
*/
|
||||
if (sk->sk_type != SOCK_STREAM)
|
||||
atomic_inc(&uarg->refcnt);
|
||||
|
||||
sock_zerocopy_put(uarg);
|
||||
}
|
||||
}
|
||||
EXPORT_SYMBOL_GPL(sock_zerocopy_put_abort);
|
||||
|
||||
extern int __zerocopy_sg_from_iter(struct sock *sk, struct sk_buff *skb,
|
||||
struct iov_iter *from, size_t length);
|
||||
|
||||
int skb_zerocopy_iter_stream(struct sock *sk, struct sk_buff *skb,
|
||||
struct msghdr *msg, int len,
|
||||
struct ubuf_info *uarg)
|
||||
{
|
||||
struct iov_iter orig_iter = msg->msg_iter;
|
||||
int err, orig_len = skb->len;
|
||||
|
||||
err = __zerocopy_sg_from_iter(sk, skb, &msg->msg_iter, len);
|
||||
if (err == -EFAULT || (err == -EMSGSIZE && skb->len == orig_len)) {
|
||||
/* Streams do not free skb on error. Reset to prev state. */
|
||||
msg->msg_iter = orig_iter;
|
||||
___pskb_trim(skb, orig_len);
|
||||
return err;
|
||||
}
|
||||
|
||||
skb_zcopy_set(skb, uarg);
|
||||
return skb->len - orig_len;
|
||||
}
|
||||
EXPORT_SYMBOL_GPL(skb_zerocopy_iter_stream);
|
||||
|
||||
/* unused only until next patch in the series; will remove attribute */
|
||||
static int __attribute__((unused))
|
||||
skb_zerocopy_clone(struct sk_buff *nskb, struct sk_buff *orig,
|
||||
gfp_t gfp_mask)
|
||||
{
|
||||
if (skb_zcopy(orig)) {
|
||||
if (skb_zcopy(nskb)) {
|
||||
/* !gfp_mask callers are verified to !skb_zcopy(nskb) */
|
||||
if (!gfp_mask) {
|
||||
WARN_ON_ONCE(1);
|
||||
return -ENOMEM;
|
||||
}
|
||||
if (skb_uarg(nskb) == skb_uarg(orig))
|
||||
return 0;
|
||||
if (skb_copy_ubufs(nskb, GFP_ATOMIC))
|
||||
return -EIO;
|
||||
}
|
||||
skb_zcopy_set(nskb, skb_uarg(orig));
|
||||
}
|
||||
return 0;
|
||||
}
|
||||
|
||||
/**
|
||||
* skb_copy_ubufs - copy userspace skb frags buffers to kernel
|
||||
* @skb: the skb to modify
|
||||
|
||||
Reference in New Issue
Block a user