From 50100a5e39461b2a61d6040e73c384766c29975d Mon Sep 17 00:00:00 2001 From: Jon Paul Maloy Date: Fri, 22 Aug 2014 18:09:07 -0400 Subject: tipc: use pseudo message to wake up sockets after link congestion The current link implementation keeps a linked list of blocked ports/ sockets that is populated when there is link congestion. The purpose of this is to let the link know which users to wake up when the congestion abates. This adds unnecessary complexity to the data structure and the code, since it forces us to involve the link each time we want to delete a socket. It also forces us to grab the spinlock port_lock within the scope of node_lock. We want to get rid of this direct dependence, as well as the deadlock hazard resulting from the usage of port_lock. In this commit, we instead let the link keep list of a "wakeup" pseudo messages for use in such situations. Those messages are sent to the pending sockets via the ordinary message reception path, and wake up the socket's owner when they are received. This enables us to get rid of the 'waiting_ports' linked lists in struct tipc_port that manifest this direct reference. As a consequence, we can eliminate another BH entry into the socket, and hence the need to grab port_lock. This is a further step in our effort to remove port_lock altogether. Signed-off-by: Jon Maloy Reviewed-by: Erik Hugne Reviewed-by: Ying Xue Signed-off-by: David S. Miller --- net/tipc/msg.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) (limited to 'net/tipc/msg.c') diff --git a/net/tipc/msg.c b/net/tipc/msg.c index fdb92e247050..74745a47d72a 100644 --- a/net/tipc/msg.c +++ b/net/tipc/msg.c @@ -182,7 +182,7 @@ int tipc_msg_build(struct tipc_msg *mhdr, struct iovec const *iov, struct sk_buff *buf, *prev; char *pktpos; int rc; - + uint chain_sz = 0; msg_set_size(mhdr, msz); /* No fragmentation needed? */ @@ -193,6 +193,7 @@ int tipc_msg_build(struct tipc_msg *mhdr, struct iovec const *iov, return -ENOMEM; skb_copy_to_linear_data(buf, mhdr, mhsz); pktpos = buf->data + mhsz; + TIPC_SKB_CB(buf)->chain_sz = 1; if (!dsz || !memcpy_fromiovecend(pktpos, iov, offset, dsz)) return dsz; rc = -EFAULT; @@ -209,6 +210,7 @@ int tipc_msg_build(struct tipc_msg *mhdr, struct iovec const *iov, *chain = buf = tipc_buf_acquire(pktmax); if (!buf) return -ENOMEM; + chain_sz = 1; pktpos = buf->data; skb_copy_to_linear_data(buf, &pkthdr, INT_H_SIZE); pktpos += INT_H_SIZE; @@ -242,6 +244,7 @@ int tipc_msg_build(struct tipc_msg *mhdr, struct iovec const *iov, rc = -ENOMEM; goto error; } + chain_sz++; prev->next = buf; msg_set_type(&pkthdr, FRAGMENT); msg_set_size(&pkthdr, pktsz); @@ -251,7 +254,7 @@ int tipc_msg_build(struct tipc_msg *mhdr, struct iovec const *iov, pktrem = pktsz - INT_H_SIZE; } while (1); - + TIPC_SKB_CB(*chain)->chain_sz = chain_sz; msg_set_type(buf_msg(buf), LAST_FRAGMENT); return dsz; error: -- cgit v1.2.3