Commit 52267790 authored by Willem de Bruijn's avatar Willem de Bruijn Committed by David S. Miller

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: default avatarWillem de Bruijn <willemb@google.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 3ece7826
......@@ -429,6 +429,7 @@ enum {
SKBTX_SCHED_TSTAMP = 1 << 6,
};
#define SKBTX_ZEROCOPY_FRAG (SKBTX_DEV_ZEROCOPY | SKBTX_SHARED_FRAG)
#define SKBTX_ANY_SW_TSTAMP (SKBTX_SW_TSTAMP | \
SKBTX_SCHED_TSTAMP)
#define SKBTX_ANY_TSTAMP (SKBTX_HW_TSTAMP | SKBTX_ANY_SW_TSTAMP)
......@@ -445,8 +446,28 @@ struct ubuf_info {
void (*callback)(struct ubuf_info *, bool zerocopy_success);
void *ctx;
unsigned long desc;
u16 zerocopy:1;
atomic_t refcnt;
};
#define skb_uarg(SKB) ((struct ubuf_info *)(skb_shinfo(SKB)->destructor_arg))
struct ubuf_info *sock_zerocopy_alloc(struct sock *sk, size_t size);
static inline void sock_zerocopy_get(struct ubuf_info *uarg)
{
atomic_inc(&uarg->refcnt);
}
void sock_zerocopy_put(struct ubuf_info *uarg);
void sock_zerocopy_put_abort(struct ubuf_info *uarg);
void sock_zerocopy_callback(struct ubuf_info *uarg, bool success);
int skb_zerocopy_iter_stream(struct sock *sk, struct sk_buff *skb,
struct msghdr *msg, int len,
struct ubuf_info *uarg);
/* This data is invariant across clones and lives at
* the end of the header data, ie. at skb->end.
*/
......@@ -1214,6 +1235,45 @@ static inline struct skb_shared_hwtstamps *skb_hwtstamps(struct sk_buff *skb)
return &skb_shinfo(skb)->hwtstamps;
}
static inline struct ubuf_info *skb_zcopy(struct sk_buff *skb)
{
bool is_zcopy = skb && skb_shinfo(skb)->tx_flags & SKBTX_DEV_ZEROCOPY;
return is_zcopy ? skb_uarg(skb) : NULL;
}
static inline void skb_zcopy_set(struct sk_buff *skb, struct ubuf_info *uarg)
{
if (skb && uarg && !skb_zcopy(skb)) {
sock_zerocopy_get(uarg);
skb_shinfo(skb)->destructor_arg = uarg;
skb_shinfo(skb)->tx_flags |= SKBTX_ZEROCOPY_FRAG;
}
}
/* Release a reference on a zerocopy structure */
static inline void skb_zcopy_clear(struct sk_buff *skb, bool zerocopy)
{
struct ubuf_info *uarg = skb_zcopy(skb);
if (uarg) {
uarg->zerocopy = uarg->zerocopy && zerocopy;
sock_zerocopy_put(uarg);
skb_shinfo(skb)->tx_flags &= ~SKBTX_ZEROCOPY_FRAG;
}
}
/* Abort a zerocopy operation and revert zckey on error in send syscall */
static inline void skb_zcopy_abort(struct sk_buff *skb)
{
struct ubuf_info *uarg = skb_zcopy(skb);
if (uarg) {
sock_zerocopy_put_abort(uarg);
skb_shinfo(skb)->tx_flags &= ~SKBTX_ZEROCOPY_FRAG;
}
}
/**
* skb_queue_empty - check if a queue is empty
* @list: queue head
......
......@@ -287,6 +287,7 @@ struct ucred {
#define MSG_BATCH 0x40000 /* sendmmsg(): more messages coming */
#define MSG_EOF MSG_FIN
#define MSG_ZEROCOPY 0x4000000 /* Use user data in kernel path */
#define MSG_FASTOPEN 0x20000000 /* Send data in TCP SYN */
#define MSG_CMSG_CLOEXEC 0x40000000 /* Set close_on_exec for file
descriptor received through
......
......@@ -294,6 +294,7 @@ struct sock_common {
* @sk_stamp: time stamp of last packet received
* @sk_tsflags: SO_TIMESTAMPING socket options
* @sk_tskey: counter to disambiguate concurrent tstamp requests
* @sk_zckey: counter to order MSG_ZEROCOPY notifications
* @sk_socket: Identd and reporting IO signals
* @sk_user_data: RPC layer private data
* @sk_frag: cached page frag
......@@ -462,6 +463,7 @@ struct sock {
u16 sk_tsflags;
u8 sk_shutdown;
u32 sk_tskey;
atomic_t sk_zckey;
struct socket *sk_socket;
void *sk_user_data;
#ifdef CONFIG_SECURITY
......
......@@ -18,10 +18,13 @@ struct sock_extended_err {
#define SO_EE_ORIGIN_ICMP 2
#define SO_EE_ORIGIN_ICMP6 3
#define SO_EE_ORIGIN_TXSTATUS 4
#define SO_EE_ORIGIN_ZEROCOPY 5
#define SO_EE_ORIGIN_TIMESTAMPING SO_EE_ORIGIN_TXSTATUS
#define SO_EE_OFFENDER(ee) ((struct sockaddr*)((ee)+1))
#define SO_EE_CODE_ZEROCOPY_COPIED 1
/**
* struct scm_timestamping - timestamps exposed through cmsg
*
......
......@@ -573,27 +573,12 @@ int skb_copy_datagram_from_iter(struct sk_buff *skb, int offset,
}
EXPORT_SYMBOL(skb_copy_datagram_from_iter);
/**
* zerocopy_sg_from_iter - Build a zerocopy datagram from an iov_iter
* @skb: buffer to copy
* @from: the source to copy from
*
* The function will first copy up to headlen, and then pin the userspace
* pages and build frags through them.
*
* Returns 0, -EFAULT or -EMSGSIZE.
*/
int zerocopy_sg_from_iter(struct sk_buff *skb, struct iov_iter *from)
int __zerocopy_sg_from_iter(struct sock *sk, struct sk_buff *skb,
struct iov_iter *from, size_t length)
{
int len = iov_iter_count(from);
int copy = min_t(int, skb_headlen(skb), len);
int frag = 0;
int frag = skb_shinfo(skb)->nr_frags;
/* copy up to skb headlen */
if (skb_copy_datagram_from_iter(skb, 0, from, copy))
return -EFAULT;
while (iov_iter_count(from)) {
while (length && iov_iter_count(from)) {
struct page *pages[MAX_SKB_FRAGS];
size_t start;
ssize_t copied;
......@@ -603,18 +588,24 @@ int zerocopy_sg_from_iter(struct sk_buff *skb, struct iov_iter *from)
if (frag == MAX_SKB_FRAGS)
return -EMSGSIZE;
copied = iov_iter_get_pages(from, pages, ~0U,
copied = iov_iter_get_pages(from, pages, length,
MAX_SKB_FRAGS - frag, &start);
if (copied < 0)
return -EFAULT;
iov_iter_advance(from, copied);
length -= copied;
truesize = PAGE_ALIGN(copied + start);
skb->data_len += copied;
skb->len += copied;
skb->truesize += truesize;
refcount_add(truesize, &skb->sk->sk_wmem_alloc);
if (sk && sk->sk_type == SOCK_STREAM) {
sk->sk_wmem_queued += truesize;
sk_mem_charge(sk, truesize);
} else {
refcount_add(truesize, &skb->sk->sk_wmem_alloc);
}
while (copied) {
int size = min_t(int, copied, PAGE_SIZE - start);
skb_fill_page_desc(skb, frag++, pages[n], start, size);
......@@ -625,6 +616,28 @@ int zerocopy_sg_from_iter(struct sk_buff *skb, struct iov_iter *from)
}
return 0;
}
EXPORT_SYMBOL(__zerocopy_sg_from_iter);
/**
* zerocopy_sg_from_iter - Build a zerocopy datagram from an iov_iter
* @skb: buffer to copy
* @from: the source to copy from
*
* The function will first copy up to headlen, and then pin the userspace
* pages and build frags through them.
*
* Returns 0, -EFAULT or -EMSGSIZE.
*/
int zerocopy_sg_from_iter(struct sk_buff *skb, struct iov_iter *from)
{
int copy = min_t(int, skb_headlen(skb), iov_iter_count(from));
/* copy up to skb headlen */
if (skb_copy_datagram_from_iter(skb, 0, from, copy))
return -EFAULT;
return __zerocopy_sg_from_iter(NULL, skb, from, ~0U);
}
EXPORT_SYMBOL(zerocopy_sg_from_iter);
static int skb_copy_and_csum_datagram(const struct sk_buff *skb, int offset,
......
......@@ -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
......
......@@ -1670,6 +1670,7 @@ struct sock *sk_clone_lock(const struct sock *sk, const gfp_t priority)
atomic_set(&newsk->sk_drops, 0);
newsk->sk_send_head = NULL;
newsk->sk_userlocks = sk->sk_userlocks & ~SOCK_BINDPORT_LOCK;
atomic_set(&newsk->sk_zckey, 0);
sock_reset_flag(newsk, SOCK_DONE);
......@@ -2722,6 +2723,7 @@ void sock_init_data(struct socket *sock, struct sock *sk)
sk->sk_sndtimeo = MAX_SCHEDULE_TIMEOUT;
sk->sk_stamp = SK_DEFAULT_STAMP;
atomic_set(&sk->sk_zckey, 0);
#ifdef CONFIG_NET_RX_BUSY_POLL
sk->sk_napi_id = 0;
......
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