Merge branch 'tipc_fragmentation'

Erik Hugne says:

====================
tipc: message reassembly using fragment chain

We introduce a new reassembly algorithm that improves performance
and eliminates the risk of causing out-of-memory situations.

v3: -Use skb_try_coalesce, and revert to fraglist if this does not succeed.
    -Make sure reassembly list head is uncloned.

v2: -Rebased on Ying's indentation fix.
    -Node unlock call in msg_fragmenter case moved from patch #2 to #1.
     ('continue' with this lock held would cause spinlock recursion if only
      patch #1 is used)
====================
Signed-off-by: David S. Miller <davem@davemloft.net>

net/tipc/bcast.c

@@ -480,18 +480,24 @@ void tipc_bclink_recv_pkt(struct sk_buff *buf)
 			tipc_node_unlock(node);
 			tipc_link_recv_bundle(buf);
 		} else if (msg_user(msg) == MSG_FRAGMENTER) {
-			int ret = tipc_link_recv_fragment(&node->bclink.defragm,
-						      &buf, &msg);
-			if (ret < 0)
+			int ret;
+			ret = tipc_link_recv_fragment(&node->bclink.reasm_head,
+						      &node->bclink.reasm_tail,
+						      &buf);
+			if (ret == LINK_REASM_ERROR)
 				goto unlock;
 			spin_lock_bh(&bc_lock);
 			bclink_accept_pkt(node, seqno);
 			bcl->stats.recv_fragments++;
-			if (ret > 0)
+			if (ret == LINK_REASM_COMPLETE) {
 				bcl->stats.recv_fragmented++;
+				/* Point msg to inner header */
+				msg = buf_msg(buf);
+				spin_unlock_bh(&bc_lock);
+				goto receive;
+			}
 			spin_unlock_bh(&bc_lock);
 			tipc_node_unlock(node);
-			tipc_net_route_msg(buf);
 		} else if (msg_user(msg) == NAME_DISTRIBUTOR) {
 			spin_lock_bh(&bc_lock);
 			bclink_accept_pkt(node, seqno);

net/tipc/link.c

@@ -404,15 +404,9 @@ static void link_release_outqueue(struct tipc_link *l_ptr)
  */
 void tipc_link_reset_fragments(struct tipc_link *l_ptr)
 {
-	struct sk_buff *buf = l_ptr->defragm_buf;
-	struct sk_buff *next;
-
-	while (buf) {
-		next = buf->next;
-		kfree_skb(buf);
-		buf = next;
-	}
-	l_ptr->defragm_buf = NULL;
+	kfree_skb(l_ptr->reasm_head);
+	l_ptr->reasm_head = NULL;
+	l_ptr->reasm_tail = NULL;
 }
 
 /**
@@ -1649,15 +1643,18 @@ void tipc_recv_msg(struct sk_buff *head, struct tipc_bearer *b_ptr)
 			continue;
 		case MSG_FRAGMENTER:
 			l_ptr->stats.recv_fragments++;
-			ret = tipc_link_recv_fragment(&l_ptr->defragm_buf,
-						      &buf, &msg);
-			if (ret == 1) {
+			ret = tipc_link_recv_fragment(&l_ptr->reasm_head,
+						      &l_ptr->reasm_tail,
+						      &buf);
+			if (ret == LINK_REASM_COMPLETE) {
 				l_ptr->stats.recv_fragmented++;
+				msg = buf_msg(buf);
 				goto deliver;
 			}
-			if (ret == -1)
-				l_ptr->next_in_no--;
-			break;
+			if (ret == LINK_REASM_ERROR)
+				tipc_link_reset(l_ptr);
+			tipc_node_unlock(n_ptr);
+			continue;
 		case CHANGEOVER_PROTOCOL:
 			type = msg_type(msg);
 			if (link_recv_changeover_msg(&l_ptr, &buf)) {
@@ -2341,115 +2338,48 @@ static int link_send_long_buf(struct tipc_link *l_ptr, struct sk_buff *buf)
 	return dsz;
 }
 
-/*
- * A pending message being re-assembled must store certain values
- * to handle subsequent fragments correctly. The following functions
- * help storing these values in unused, available fields in the
- * pending message. This makes dynamic memory allocation unnecessary.
- */
-static void set_long_msg_seqno(struct sk_buff *buf, u32 seqno)
-{
-	msg_set_seqno(buf_msg(buf), seqno);
-}
-
-static u32 get_fragm_size(struct sk_buff *buf)
-{
-	return msg_ack(buf_msg(buf));
-}
-
-static void set_fragm_size(struct sk_buff *buf, u32 sz)
-{
-	msg_set_ack(buf_msg(buf), sz);
-}
-
-static u32 get_expected_frags(struct sk_buff *buf)
-{
-	return msg_bcast_ack(buf_msg(buf));
-}
-
-static void set_expected_frags(struct sk_buff *buf, u32 exp)
-{
-	msg_set_bcast_ack(buf_msg(buf), exp);
-}
-
 /*
  * tipc_link_recv_fragment(): Called with node lock on. Returns
  * the reassembled buffer if message is complete.
  */
-int tipc_link_recv_fragment(struct sk_buff **pending, struct sk_buff **fb,
-			    struct tipc_msg **m)
-{
-	struct sk_buff *prev = NULL;
-	struct sk_buff *fbuf = *fb;
-	struct tipc_msg *fragm = buf_msg(fbuf);
-	struct sk_buff *pbuf = *pending;
-	u32 long_msg_seq_no = msg_long_msgno(fragm);
-
-	*fb = NULL;
-
-	/* Is there an incomplete message waiting for this fragment? */
-	while (pbuf && ((buf_seqno(pbuf) != long_msg_seq_no) ||
-			(msg_orignode(fragm) != msg_orignode(buf_msg(pbuf))))) {
-		prev = pbuf;
-		pbuf = pbuf->next;
-	}
-
-	if (!pbuf && (msg_type(fragm) == FIRST_FRAGMENT)) {
-		struct tipc_msg *imsg = (struct tipc_msg *)msg_data(fragm);
-		u32 msg_sz = msg_size(imsg);
-		u32 fragm_sz = msg_data_sz(fragm);
-		u32 exp_fragm_cnt;
-		u32 max =  TIPC_MAX_USER_MSG_SIZE + NAMED_H_SIZE;
-
-		if (msg_type(imsg) == TIPC_MCAST_MSG)
-			max = TIPC_MAX_USER_MSG_SIZE + MCAST_H_SIZE;
-		if (fragm_sz == 0 || msg_size(imsg) > max) {
-			kfree_skb(fbuf);
+int tipc_link_recv_fragment(struct sk_buff **head, struct sk_buff **tail,
+			    struct sk_buff **fbuf)
+{
+	struct sk_buff *frag = *fbuf;
+	struct tipc_msg *msg = buf_msg(frag);
+	u32 fragid = msg_type(msg);
+	bool headstolen;
+	int delta;
+
+	skb_pull(frag, msg_hdr_sz(msg));
+	if (fragid == FIRST_FRAGMENT) {
+		if (*head || skb_unclone(frag, GFP_ATOMIC))
+			goto out_free;
+		*head = frag;
+		skb_frag_list_init(*head);
 		return 0;
-		}
-		exp_fragm_cnt = msg_sz / fragm_sz + !!(msg_sz % fragm_sz);
-		pbuf = tipc_buf_acquire(msg_size(imsg));
-		if (pbuf != NULL) {
-			pbuf->next = *pending;
-			*pending = pbuf;
-			skb_copy_to_linear_data(pbuf, imsg,
-						msg_data_sz(fragm));
-			/*  Prepare buffer for subsequent fragments. */
-			set_long_msg_seqno(pbuf, long_msg_seq_no);
-			set_fragm_size(pbuf, fragm_sz);
-			set_expected_frags(pbuf, exp_fragm_cnt - 1);
+	} else if (skb_try_coalesce(*head, frag, &headstolen, &delta)) {
+		kfree_skb_partial(frag, headstolen);
 	} else {
-			pr_debug("Link unable to reassemble fragmented message\n");
-			kfree_skb(fbuf);
-			return -1;
-		}
-		kfree_skb(fbuf);
-		return 0;
-	} else if (pbuf && (msg_type(fragm) != FIRST_FRAGMENT)) {
-		u32 dsz = msg_data_sz(fragm);
-		u32 fsz = get_fragm_size(pbuf);
-		u32 crs = ((msg_fragm_no(fragm) - 1) * fsz);
-		u32 exp_frags = get_expected_frags(pbuf) - 1;
-		skb_copy_to_linear_data_offset(pbuf, crs,
-					       msg_data(fragm), dsz);
-		kfree_skb(fbuf);
-
-		/* Is message complete? */
-		if (exp_frags == 0) {
-			if (prev)
-				prev->next = pbuf->next;
+		if (!*head)
+			goto out_free;
+		if (!skb_has_frag_list(*head))
+			skb_shinfo(*head)->frag_list = frag;
 		else
-				*pending = pbuf->next;
-			msg_reset_reroute_cnt(buf_msg(pbuf));
-			*fb = pbuf;
-			*m = buf_msg(pbuf);
-			return 1;
+			(*tail)->next = frag;
+		*tail = frag;
+		(*head)->truesize += frag->truesize;
 	}
-		set_expected_frags(pbuf, exp_frags);
-		return 0;
+	if (fragid == LAST_FRAGMENT) {
+		*fbuf = *head;
+		*tail = *head = NULL;
+		return LINK_REASM_COMPLETE;
 	}
-	kfree_skb(fbuf);
 	return 0;
+out_free:
+	pr_warn_ratelimited("Link unable to reassemble fragmented message\n");
+	kfree_skb(*fbuf);
+	return LINK_REASM_ERROR;
 }
 
 static void link_set_supervision_props(struct tipc_link *l_ptr, u32 tolerance)

net/tipc/link.h

@@ -40,6 +40,12 @@
 #include "msg.h"
 #include "node.h"
 
+/*
+ * Link reassembly status codes
+ */
+#define LINK_REASM_ERROR	-1
+#define LINK_REASM_COMPLETE	1
+
 /*
  * Out-of-range value for link sequence numbers
  */
@@ -134,7 +140,8 @@ struct tipc_stats {
  * @next_out: ptr to first unsent outbound message in queue
  * @waiting_ports: linked list of ports waiting for link congestion to abate
  * @long_msg_seq_no: next identifier to use for outbound fragmented messages
- * @defragm_buf: list of partially reassembled inbound message fragments
+ * @reasm_head: list head of partially reassembled inbound message fragments
+ * @reasm_tail: last fragment received
  * @stats: collects statistics regarding link activity
  */
 struct tipc_link {
@@ -196,9 +203,10 @@ struct tipc_link {
 	struct sk_buff *next_out;
 	struct list_head waiting_ports;
 
-	/* Fragmentation/defragmentation */
+	/* Fragmentation/reassembly */
 	u32 long_msg_seq_no;
-	struct sk_buff *defragm_buf;
+	struct sk_buff *reasm_head;
+	struct sk_buff *reasm_tail;
 
 	/* Statistics */
 	struct tipc_stats stats;
@@ -229,9 +237,9 @@ int tipc_link_send_sections_fast(struct tipc_port *sender,
 				 struct iovec const *msg_sect,
 				 unsigned int len, u32 destnode);
 void tipc_link_recv_bundle(struct sk_buff *buf);
-int  tipc_link_recv_fragment(struct sk_buff **pending,
-			     struct sk_buff **fb,
-			     struct tipc_msg **msg);
+int  tipc_link_recv_fragment(struct sk_buff **reasm_head,
+			     struct sk_buff **reasm_tail,
+			     struct sk_buff **fbuf);
 void tipc_link_send_proto_msg(struct tipc_link *l_ptr, u32 msg_typ, int prob,
 			      u32 gap, u32 tolerance, u32 priority,
 			      u32 acked_mtu);

net/tipc/msg.h

@@ -554,12 +554,6 @@ static inline void msg_set_last_bcast(struct tipc_msg *m, u32 n)
 	msg_set_bits(m, 4, 16, 0xffff, n);
 }
 
-
-static inline u32 msg_fragm_no(struct tipc_msg *m)
-{
-	return msg_bits(m, 4, 16, 0xffff);
-}
-
 static inline void msg_set_fragm_no(struct tipc_msg *m, u32 n)
 {
 	msg_set_bits(m, 4, 16, 0xffff, n);
@@ -576,12 +570,6 @@ static inline void msg_set_next_sent(struct tipc_msg *m, u32 n)
 	msg_set_bits(m, 4, 0, 0xffff, n);
 }
 
-
-static inline u32 msg_long_msgno(struct tipc_msg *m)
-{
-	return msg_bits(m, 4, 0, 0xffff);
-}
-
 static inline void msg_set_long_msgno(struct tipc_msg *m, u32 n)
 {
 	msg_set_bits(m, 4, 0, 0xffff, n);

net/tipc/node.c

@@ -298,9 +298,10 @@ static void node_lost_contact(struct tipc_node *n_ptr)
 		}
 		n_ptr->bclink.deferred_size = 0;
 
-		if (n_ptr->bclink.defragm) {
-			kfree_skb(n_ptr->bclink.defragm);
-			n_ptr->bclink.defragm = NULL;
+		if (n_ptr->bclink.reasm_head) {
+			kfree_skb(n_ptr->bclink.reasm_head);
+			n_ptr->bclink.reasm_head = NULL;
+			n_ptr->bclink.reasm_tail = NULL;
 		}
 
 		tipc_bclink_remove_node(n_ptr->addr);

net/tipc/node.h

@@ -74,7 +74,8 @@
  *    @deferred_size: number of OOS b'cast messages in deferred queue
  *    @deferred_head: oldest OOS b'cast message received from node
  *    @deferred_tail: newest OOS b'cast message received from node
- *    @defragm: list of partially reassembled b'cast message fragments from node
+ *    @reasm_head: broadcast reassembly queue head from node
+ *    @reasm_tail: last broadcast fragment received from node
  *    @recv_permitted: true if node is allowed to receive b'cast messages
  */
 struct tipc_node {
@@ -98,7 +99,8 @@ struct tipc_node {
 		u32 deferred_size;
 		struct sk_buff *deferred_head;
 		struct sk_buff *deferred_tail;
-		struct sk_buff *defragm;
+		struct sk_buff *reasm_head;
+		struct sk_buff *reasm_tail;
 		bool recv_permitted;
 	} bclink;
 };