Merge branch 'generic-zcopy_-functions'

Jonathan Lemon says:

====================
Generic zcopy_* functions

This is set of cleanup patches for zerocopy which are intended
to allow a introduction of a different zerocopy implementation.

The top level API will use the skb_zcopy_*() functions, while
the current TCP specific zerocopy ends up using msg_zerocopy_*()
calls.

There should be no functional changes from these patches.
====================

Link: https://lore.kernel.org/r/20210106221841.1880536-1-jonathan.lemon@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

5 files changed, 41 insertions, 46 deletions

diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index f62cae3f75d8..7626a33cce59 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -605,13 +605,14 @@ static void skb_release_data(struct sk_buff *skb)
 			      &shinfo->dataref))
 		return;
 
+	skb_zcopy_clear(skb, true);
+
 	for (i = 0; i < shinfo->nr_frags; i++)
 		__skb_frag_unref(&shinfo->frags[i]);
 
 	if (shinfo->frag_list)
 		kfree_skb_list(shinfo->frag_list);
 
-	skb_zcopy_clear(skb, true);
 	skb_free_head(skb);
 }
 
@@ -1093,7 +1094,7 @@ void mm_unaccount_pinned_pages(struct mmpin *mmp)
 }
 EXPORT_SYMBOL_GPL(mm_unaccount_pinned_pages);
 
-struct ubuf_info *sock_zerocopy_alloc(struct sock *sk, size_t size)
+struct ubuf_info *msg_zerocopy_alloc(struct sock *sk, size_t size)
 {
 	struct ubuf_info *uarg;
 	struct sk_buff *skb;
@@ -1113,25 +1114,26 @@ struct ubuf_info *sock_zerocopy_alloc(struct sock *sk, size_t size)
 		return NULL;
 	}
 
-	uarg->callback = sock_zerocopy_callback;
+	uarg->callback = msg_zerocopy_callback;
 	uarg->id = ((u32)atomic_inc_return(&sk->sk_zckey)) - 1;
 	uarg->len = 1;
 	uarg->bytelen = size;
 	uarg->zerocopy = 1;
+	uarg->flags = SKBFL_ZEROCOPY_FRAG;
 	refcount_set(&uarg->refcnt, 1);
 	sock_hold(sk);
 
 	return uarg;
 }
-EXPORT_SYMBOL_GPL(sock_zerocopy_alloc);
+EXPORT_SYMBOL_GPL(msg_zerocopy_alloc);
 
 static inline struct sk_buff *skb_from_uarg(struct ubuf_info *uarg)
 {
 	return container_of((void *)uarg, struct sk_buff, cb);
 }
 
-struct ubuf_info *sock_zerocopy_realloc(struct sock *sk, size_t size,
-					struct ubuf_info *uarg)
+struct ubuf_info *msg_zerocopy_realloc(struct sock *sk, size_t size,
+				       struct ubuf_info *uarg)
 {
 	if (uarg) {
 		const u32 byte_limit = 1 << 19;		/* limit to a few TSO */
@@ -1163,16 +1165,16 @@ struct ubuf_info *sock_zerocopy_realloc(struct sock *sk, size_t size,
 
 			/* no extra ref when appending to datagram (MSG_MORE) */
 			if (sk->sk_type == SOCK_STREAM)
-				sock_zerocopy_get(uarg);
+				net_zcopy_get(uarg);
 
 			return uarg;
 		}
 	}
 
 new_alloc:
-	return sock_zerocopy_alloc(sk, size);
+	return msg_zerocopy_alloc(sk, size);
 }
-EXPORT_SYMBOL_GPL(sock_zerocopy_realloc);
+EXPORT_SYMBOL_GPL(msg_zerocopy_realloc);
 
 static bool skb_zerocopy_notify_extend(struct sk_buff *skb, u32 lo, u16 len)
 {
@@ -1194,7 +1196,7 @@ static bool skb_zerocopy_notify_extend(struct sk_buff *skb, u32 lo, u16 len)
 	return true;
 }
 
-void sock_zerocopy_callback(struct ubuf_info *uarg, bool success)
+static void __msg_zerocopy_callback(struct ubuf_info *uarg)
 {
 	struct sk_buff *tail, *skb = skb_from_uarg(uarg);
 	struct sock_exterr_skb *serr;
@@ -1222,7 +1224,7 @@ void sock_zerocopy_callback(struct ubuf_info *uarg, bool success)
 	serr->ee.ee_origin = SO_EE_ORIGIN_ZEROCOPY;
 	serr->ee.ee_data = hi;
 	serr->ee.ee_info = lo;
-	if (!success)
+	if (!uarg->zerocopy)
 		serr->ee.ee_code |= SO_EE_CODE_ZEROCOPY_COPIED;
 
 	q = &sk->sk_error_queue;
@@ -1241,32 +1243,28 @@ release:
 	consume_skb(skb);
 	sock_put(sk);
 }
-EXPORT_SYMBOL_GPL(sock_zerocopy_callback);
 
-void sock_zerocopy_put(struct ubuf_info *uarg)
+void msg_zerocopy_callback(struct sk_buff *skb, struct ubuf_info *uarg,
+			   bool success)
 {
-	if (uarg && refcount_dec_and_test(&uarg->refcnt)) {
-		if (uarg->callback)
-			uarg->callback(uarg, uarg->zerocopy);
-		else
-			consume_skb(skb_from_uarg(uarg));
-	}
+	uarg->zerocopy = uarg->zerocopy & success;
+
+	if (refcount_dec_and_test(&uarg->refcnt))
+		__msg_zerocopy_callback(uarg);
 }
-EXPORT_SYMBOL_GPL(sock_zerocopy_put);
+EXPORT_SYMBOL_GPL(msg_zerocopy_callback);
 
-void sock_zerocopy_put_abort(struct ubuf_info *uarg, bool have_uref)
+void msg_zerocopy_put_abort(struct ubuf_info *uarg, bool have_uref)
 {
-	if (uarg) {
-		struct sock *sk = skb_from_uarg(uarg)->sk;
+	struct sock *sk = skb_from_uarg(uarg)->sk;
 
-		atomic_dec(&sk->sk_zckey);
-		uarg->len--;
+	atomic_dec(&sk->sk_zckey);
+	uarg->len--;
 
-		if (have_uref)
-			sock_zerocopy_put(uarg);
-	}
+	if (have_uref)
+		msg_zerocopy_callback(NULL, uarg, true);
 }
-EXPORT_SYMBOL_GPL(sock_zerocopy_put_abort);
+EXPORT_SYMBOL_GPL(msg_zerocopy_put_abort);
 
 int skb_zerocopy_iter_dgram(struct sk_buff *skb, struct msghdr *msg, int len)
 {
@@ -1330,7 +1328,7 @@ static int skb_zerocopy_clone(struct sk_buff *nskb, struct sk_buff *orig,
  *	@skb: the skb to modify
  *	@gfp_mask: allocation priority
  *
- *	This must be called on SKBTX_DEV_ZEROCOPY skb.
+ *	This must be called on skb with SKBFL_ZEROCOPY_ENABLE.
  *	It will copy all frags into kernel and drop the reference
  *	to userspace pages.
  *
@@ -3267,8 +3265,7 @@ void skb_split(struct sk_buff *skb, struct sk_buff *skb1, const u32 len)
 {
 	int pos = skb_headlen(skb);
 
-	skb_shinfo(skb1)->tx_flags |= skb_shinfo(skb)->tx_flags &
-				      SKBTX_SHARED_FRAG;
+	skb_shinfo(skb1)->flags |= skb_shinfo(skb)->flags & SKBFL_SHARED_FRAG;
 	skb_zerocopy_clone(skb1, skb, 0);
 	if (len < pos)	/* Split line is inside header. */
 		skb_split_inside_header(skb, skb1, len, pos);
@@ -3957,8 +3954,8 @@ normal:
 		skb_copy_from_linear_data_offset(head_skb, offset,
 						 skb_put(nskb, hsize), hsize);
 
-		skb_shinfo(nskb)->tx_flags |= skb_shinfo(head_skb)->tx_flags &
-					      SKBTX_SHARED_FRAG;
+		skb_shinfo(nskb)->flags |= skb_shinfo(head_skb)->flags &
+					   SKBFL_SHARED_FRAG;
 
 		if (skb_orphan_frags(frag_skb, GFP_ATOMIC) ||
 		    skb_zerocopy_clone(nskb, frag_skb, GFP_ATOMIC))
diff --git a/net/ipv4/ip_output.c b/net/ipv4/ip_output.c
index 89fff5f59eea..102b1998ba3c 100644
--- a/net/ipv4/ip_output.c
+++ b/net/ipv4/ip_output.c
@@ -1018,7 +1018,7 @@ static int __ip_append_data(struct sock *sk,
 		csummode = CHECKSUM_PARTIAL;
 
 	if (flags & MSG_ZEROCOPY && length && sock_flag(sk, SOCK_ZEROCOPY)) {
-		uarg = sock_zerocopy_realloc(sk, length, skb_zcopy(skb));
+		uarg = msg_zerocopy_realloc(sk, length, skb_zcopy(skb));
 		if (!uarg)
 			return -ENOBUFS;
 		extra_uref = !skb_zcopy(skb);	/* only ref on new uarg */
@@ -1230,8 +1230,7 @@ alloc_new_skb:
 error_efault:
 	err = -EFAULT;
 error:
-	if (uarg)
-		sock_zerocopy_put_abort(uarg, extra_uref);
+	net_zcopy_put_abort(uarg, extra_uref);
 	cork->length -= length;
 	IP_INC_STATS(sock_net(sk), IPSTATS_MIB_OUTDISCARDS);
 	refcount_add(wmem_alloc_delta, &sk->sk_wmem_alloc);
diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index ed42d2193c5c..2267d21c73a6 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -1010,7 +1010,7 @@ new_segment:
 	}
 
 	if (!(flags & MSG_NO_SHARED_FRAGS))
-		skb_shinfo(skb)->tx_flags |= SKBTX_SHARED_FRAG;
+		skb_shinfo(skb)->flags |= SKBFL_SHARED_FRAG;
 
 	skb->len += copy;
 	skb->data_len += copy;
@@ -1217,7 +1217,7 @@ int tcp_sendmsg_locked(struct sock *sk, struct msghdr *msg, size_t size)
 
 	if (flags & MSG_ZEROCOPY && size && sock_flag(sk, SOCK_ZEROCOPY)) {
 		skb = tcp_write_queue_tail(sk);
-		uarg = sock_zerocopy_realloc(sk, size, skb_zcopy(skb));
+		uarg = msg_zerocopy_realloc(sk, size, skb_zcopy(skb));
 		if (!uarg) {
 			err = -ENOBUFS;
 			goto out_err;
@@ -1429,7 +1429,7 @@ out:
 		tcp_push(sk, flags, mss_now, tp->nonagle, size_goal);
 	}
 out_nopush:
-	sock_zerocopy_put(uarg);
+	net_zcopy_put(uarg);
 	return copied + copied_syn;
 
 do_error:
@@ -1440,7 +1440,7 @@ do_fault:
 	if (copied + copied_syn)
 		goto out;
 out_err:
-	sock_zerocopy_put_abort(uarg, true);
+	net_zcopy_put_abort(uarg, true);
 	err = sk_stream_error(sk, flags, err);
 	/* make sure we wake any epoll edge trigger waiter */
 	if (unlikely(tcp_rtx_and_write_queues_empty(sk) && err == -EAGAIN)) {
diff --git a/net/ipv6/ip6_output.c b/net/ipv6/ip6_output.c
index 749ad72386b2..072ce9678616 100644
--- a/net/ipv6/ip6_output.c
+++ b/net/ipv6/ip6_output.c
@@ -1471,7 +1471,7 @@ emsgsize:
 		csummode = CHECKSUM_PARTIAL;
 
 	if (flags & MSG_ZEROCOPY && length && sock_flag(sk, SOCK_ZEROCOPY)) {
-		uarg = sock_zerocopy_realloc(sk, length, skb_zcopy(skb));
+		uarg = msg_zerocopy_realloc(sk, length, skb_zcopy(skb));
 		if (!uarg)
 			return -ENOBUFS;
 		extra_uref = !skb_zcopy(skb);	/* only ref on new uarg */
@@ -1715,8 +1715,7 @@ alloc_new_skb:
 error_efault:
 	err = -EFAULT;
 error:
-	if (uarg)
-		sock_zerocopy_put_abort(uarg, extra_uref);
+	net_zcopy_put_abort(uarg, extra_uref);
 	cork->length -= length;
 	IP6_INC_STATS(sock_net(sk), rt->rt6i_idev, IPSTATS_MIB_OUTDISCARDS);
 	refcount_add(wmem_alloc_delta, &sk->sk_wmem_alloc);
diff --git a/net/kcm/kcmsock.c b/net/kcm/kcmsock.c
index a9eb616f5521..d0b56ffbb057 100644
--- a/net/kcm/kcmsock.c
+++ b/net/kcm/kcmsock.c
@@ -786,7 +786,7 @@ static ssize_t kcm_sendpage(struct socket *sock, struct page *page,
 
 		if (skb_can_coalesce(skb, i, page, offset)) {
 			skb_frag_size_add(&skb_shinfo(skb)->frags[i - 1], size);
-			skb_shinfo(skb)->tx_flags |= SKBTX_SHARED_FRAG;
+			skb_shinfo(skb)->flags |= SKBFL_SHARED_FRAG;
 			goto coalesced;
 		}
 
@@ -834,7 +834,7 @@ static ssize_t kcm_sendpage(struct socket *sock, struct page *page,
 
 	get_page(page);
 	skb_fill_page_desc(skb, i, page, offset, size);
-	skb_shinfo(skb)->tx_flags |= SKBTX_SHARED_FRAG;
+	skb_shinfo(skb)->flags |= SKBFL_SHARED_FRAG;
 
 coalesced:
 	skb->len += size;