From 067608e9d019d6477fd45dd948e81af0e5bf599f Mon Sep 17 00:00:00 2001 From: Jon Paul Maloy Date: Wed, 25 Jun 2014 20:41:34 -0500 Subject: [PATCH] tipc: introduce direct iovec to buffer chain fragmentation function Fragmentation at message sending is currently performed in two places in link.c, depending on whether data to be transmitted is delivered in the form of an iovec or as a big sk_buff. Those functions are also tightly entangled with the send functions that are using them. We now introduce a re-entrant, standalone function, tipc_msg_build2(), that builds a packet chain directly from an iovec. Each fragment is sized according to the MTU value given by the caller, and is prepended with a correctly built fragment header, when needed. The function is independent from who is calling and where the chain will be delivered, as long as the caller is able to indicate a correct MTU. The function is tested, but not called by anybody yet. Since it is incompatible with the existing tipc_msg_build(), and we cannot yet remove that function, we have given it a temporary name. Signed-off-by: Jon Maloy Reviewed-by: Erik Hugne Reviewed-by: Ying Xue Signed-off-by: David S. Miller --- net/tipc/msg.c | 102 +++++++++++++++++++++++++++++++++++++++++++++++++ net/tipc/msg.h | 3 ++ 2 files changed, 105 insertions(+) diff --git a/net/tipc/msg.c b/net/tipc/msg.c index e02afc96edd7..4093b4c94d26 100644 --- a/net/tipc/msg.c +++ b/net/tipc/msg.c @@ -144,6 +144,108 @@ int tipc_buf_append(struct sk_buff **headbuf, struct sk_buff **buf) return 0; } + +/** + * tipc_msg_build2 - create buffer chain containing specified header and data + * @mhdr: Message header, to be prepended to data + * @iov: User data + * @offset: Posision in iov to start copying from + * @dsz: Total length of user data + * @pktmax: Max packet size that can be used + * @chain: Buffer or chain of buffers to be returned to caller + * Returns message data size or errno: -ENOMEM, -EFAULT + */ +int tipc_msg_build2(struct tipc_msg *mhdr, struct iovec const *iov, + int offset, int dsz, int pktmax , struct sk_buff **chain) +{ + int mhsz = msg_hdr_sz(mhdr); + int msz = mhsz + dsz; + int pktno = 1; + int pktsz; + int pktrem = pktmax; + int drem = dsz; + struct tipc_msg pkthdr; + struct sk_buff *buf, *prev; + char *pktpos; + int rc; + + msg_set_size(mhdr, msz); + + /* No fragmentation needed? */ + if (likely(msz <= pktmax)) { + buf = tipc_buf_acquire(msz); + *chain = buf; + if (unlikely(!buf)) + return -ENOMEM; + skb_copy_to_linear_data(buf, mhdr, mhsz); + pktpos = buf->data + mhsz; + if (!dsz || !memcpy_fromiovecend(pktpos, iov, offset, dsz)) + return dsz; + rc = -EFAULT; + goto error; + } + + /* Prepare reusable fragment header */ + tipc_msg_init(&pkthdr, MSG_FRAGMENTER, FIRST_FRAGMENT, + INT_H_SIZE, msg_destnode(mhdr)); + msg_set_size(&pkthdr, pktmax); + msg_set_fragm_no(&pkthdr, pktno); + + /* Prepare first fragment */ + *chain = buf = tipc_buf_acquire(pktmax); + if (!buf) + return -ENOMEM; + pktpos = buf->data; + skb_copy_to_linear_data(buf, &pkthdr, INT_H_SIZE); + pktpos += INT_H_SIZE; + pktrem -= INT_H_SIZE; + skb_copy_to_linear_data_offset(buf, INT_H_SIZE, mhdr, mhsz); + pktpos += mhsz; + pktrem -= mhsz; + + do { + if (drem < pktrem) + pktrem = drem; + + if (memcpy_fromiovecend(pktpos, iov, offset, pktrem)) { + rc = -EFAULT; + goto error; + } + drem -= pktrem; + offset += pktrem; + + if (!drem) + break; + + /* Prepare new fragment: */ + if (drem < (pktmax - INT_H_SIZE)) + pktsz = drem + INT_H_SIZE; + else + pktsz = pktmax; + prev = buf; + buf = tipc_buf_acquire(pktsz); + if (!buf) { + rc = -ENOMEM; + goto error; + } + prev->next = buf; + msg_set_type(&pkthdr, FRAGMENT); + msg_set_size(&pkthdr, pktsz); + msg_set_fragm_no(&pkthdr, ++pktno); + skb_copy_to_linear_data(buf, &pkthdr, INT_H_SIZE); + pktpos = buf->data + INT_H_SIZE; + pktrem = pktsz - INT_H_SIZE; + + } while (1); + + msg_set_type(buf_msg(buf), LAST_FRAGMENT); + return dsz; +error: + kfree_skb_list(*chain); + *chain = NULL; + return rc; +} + /** * tipc_msg_bundle(): Append contents of a buffer to tail of an existing one * @bbuf: the existing buffer ("bundle") diff --git a/net/tipc/msg.h b/net/tipc/msg.h index 41a05fa8d608..5e1339d60c69 100644 --- a/net/tipc/msg.h +++ b/net/tipc/msg.h @@ -737,4 +737,7 @@ bool tipc_msg_bundle(struct sk_buff *bbuf, struct sk_buff *buf, u32 mtu); bool tipc_msg_make_bundle(struct sk_buff **buf, u32 mtu, u32 dnode); +int tipc_msg_build2(struct tipc_msg *mhdr, struct iovec const *iov, + int offset, int dsz, int mtu , struct sk_buff **chain); + #endif -- GitLab