Index: drivers/net/ppp_generic.c
===================================================================
--- eed337ef5e9ae7d62caa84b7974a11fddc7f06e0/drivers/net/ppp_generic.c (mode:100644)
+++ 0ca69fcdeff9aa93b3b76722f97b512cbb5e403b/drivers/net/ppp_generic.c (mode:100644)
@@ -1217,36 +1217,43 @@
*/
static int ppp_mp_explode(struct ppp *ppp, struct sk_buff *skb)
{
- int nch, len, fragsize;
+ int len, fragsize;
int i, bits, hdrlen, mtu;
- int flen, fnb;
+ int flen;
+ int navail, nfree;
+ int nbigger;
unsigned char *p, *q;
struct list_head *list;
struct channel *pch;
struct sk_buff *frag;
struct ppp_channel *chan;
- nch = 0;
+ nfree = 0; /* # channels which have no packet already queued */
+ navail = 0; /* total # of usable channels (not deregistered) */
hdrlen = (ppp->flags & SC_MP_XSHORTSEQ)? MPHDRLEN_SSN: MPHDRLEN;
+ i = 0;
list = &ppp->channels;
while ((list = list->next) != &ppp->channels) {
pch = list_entry(list, struct channel, clist);
- nch += pch->avail = (skb_queue_len(&pch->file.xq) == 0);
- /*
- * If a channel hasn't had a fragment yet, it has to get
- * one before we send any fragments on later channels.
- * If it can't take a fragment now, don't give any
- * to subsequent channels.
- */
- if (!pch->had_frag && !pch->avail) {
- while ((list = list->next) != &ppp->channels) {
- pch = list_entry(list, struct channel, clist);
- pch->avail = 0;
+ navail += pch->avail = (pch->chan != NULL);
+ if (pch->avail) {
+ if (skb_queue_len(&pch->file.xq) == 0
+ || !pch->had_frag) {
+ pch->avail = 2;
+ ++nfree;
}
- break;
+ if (!pch->had_frag && i < ppp->nxchan)
+ ppp->nxchan = i;
}
+ ++i;
}
- if (nch == 0)
+
+ /*
+ * Don't start sending this packet unless at least half of
+ * the channels are free. This gives much better TCP
+ * performance if we have a lot of channels.
+ */
+ if (nfree == 0 || nfree < navail / 2)
return 0; /* can't take now, leave it in xmit_pending */
/* Do protocol field compression (XXX this should be optional) */
@@ -1257,14 +1264,19 @@
--len;
}
- /* decide on fragment size */
+ /*
+ * Decide on fragment size.
+ * We create a fragment for each free channel regardless of
+ * how small they are (i.e. even 0 length) in order to minimize
+ * the time that it will take to detect when a channel drops
+ * a fragment.
+ */
fragsize = len;
- if (nch > 1) {
- int maxch = ROUNDUP(len, MIN_FRAG_SIZE);
- if (nch > maxch)
- nch = maxch;
- fragsize = ROUNDUP(fragsize, nch);
- }
+ if (nfree > 1)
+ fragsize = ROUNDUP(fragsize, nfree);
+ /* nbigger channels get fragsize bytes, the rest get fragsize-1,
+ except if nbigger==0, then they all get fragsize. */
+ nbigger = len % nfree;
/* skip to the channel after the one we last used
and start at that one */
@@ -1278,7 +1290,7 @@
/* create a fragment for each channel */
bits = B;
- do {
+ while (nfree > 0 || len > 0) {
list = list->next;
if (list == &ppp->channels) {
i = 0;
@@ -1289,61 +1301,92 @@
if (!pch->avail)
continue;
+ /*
+ * Skip this channel if it has a fragment pending already and
+ * we haven't given a fragment to all of the free channels.
+ */
+ if (pch->avail == 1) {
+ if (nfree > 0)
+ continue;
+ } else {
+ --nfree;
+ pch->avail = 1;
+ }
+
/* check the channel's mtu and whether it is still attached. */
spin_lock_bh(&pch->downl);
- if (pch->chan == 0 || (mtu = pch->chan->mtu) < hdrlen) {
- /* can't use this channel */
+ if (pch->chan == NULL) {
+ /* can't use this channel, it's being deregistered */
spin_unlock_bh(&pch->downl);
pch->avail = 0;
- if (--nch == 0)
+ if (--navail == 0)
break;
continue;
}
/*
- * We have to create multiple fragments for this channel
- * if fragsize is greater than the channel's mtu.
+ * Create a fragment for this channel of
+ * min(max(mtu+2-hdrlen, 4), fragsize, len) bytes.
+ * If mtu+2-hdrlen < 4, that is a ridiculously small
+ * MTU, so we use mtu = 2 + hdrlen.
*/
if (fragsize > len)
fragsize = len;
- for (flen = fragsize; flen > 0; flen -= fnb) {
- fnb = flen;
- if (fnb > mtu + 2 - hdrlen)
- fnb = mtu + 2 - hdrlen;
- if (fnb >= len)
- bits |= E;
- frag = alloc_skb(fnb + hdrlen, GFP_ATOMIC);
- if (frag == 0)
- goto noskb;
- q = skb_put(frag, fnb + hdrlen);
- /* make the MP header */
- q[0] = PPP_MP >> 8;
- q[1] = PPP_MP;
- if (ppp->flags & SC_MP_XSHORTSEQ) {
- q[2] = bits + ((ppp->nxseq >> 8) & 0xf);
- q[3] = ppp->nxseq;
- } else {
- q[2] = bits;
- q[3] = ppp->nxseq >> 16;
- q[4] = ppp->nxseq >> 8;
- q[5] = ppp->nxseq;
- }
+ flen = fragsize;
+ mtu = pch->chan->mtu + 2 - hdrlen;
+ if (mtu < 4)
+ mtu = 4;
+ if (flen > mtu)
+ flen = mtu;
+ if (flen == len && nfree == 0)
+ bits |= E;
+ frag = alloc_skb(flen + hdrlen + (flen == 0), GFP_ATOMIC);
+ if (frag == 0)
+ goto noskb;
+ q = skb_put(frag, flen + hdrlen);
+
+ /* make the MP header */
+ q[0] = PPP_MP >> 8;
+ q[1] = PPP_MP;
+ if (ppp->flags & SC_MP_XSHORTSEQ) {
+ q[2] = bits + ((ppp->nxseq >> 8) & 0xf);
+ q[3] = ppp->nxseq;
+ } else {
+ q[2] = bits;
+ q[3] = ppp->nxseq >> 16;
+ q[4] = ppp->nxseq >> 8;
+ q[5] = ppp->nxseq;
+ }
- /* copy the data in */
- memcpy(q + hdrlen, p, fnb);
+ /*
+ * Copy the data in.
+ * Unfortunately there is a bug in older versions of
+ * the Linux PPP multilink reconstruction code where it
+ * drops 0-length fragments. Therefore we make sure the
+ * fragment has at least one byte of data. Any bytes
+ * we add in this situation will end up as padding on the
+ * end of the reconstructed packet.
+ */
+ if (flen == 0)
+ *skb_put(frag, 1) = 0;
+ else
+ memcpy(q + hdrlen, p, flen);
- /* try to send it down the channel */
- chan = pch->chan;
- if (!chan->ops->start_xmit(chan, frag))
- skb_queue_tail(&pch->file.xq, frag);
- pch->had_frag = 1;
- p += fnb;
- len -= fnb;
- ++ppp->nxseq;
- bits = 0;
- }
+ /* try to send it down the channel */
+ chan = pch->chan;
+ if (skb_queue_len(&pch->file.xq)
+ || !chan->ops->start_xmit(chan, frag))
+ skb_queue_tail(&pch->file.xq, frag);
+ pch->had_frag = 1;
+ p += flen;
+ len -= flen;
+ ++ppp->nxseq;
+ bits = 0;
spin_unlock_bh(&pch->downl);
- } while (len > 0);
+
+ if (--nbigger == 0 && fragsize > 0)
+ --fragsize;
+ }
ppp->nxchan = i;
return 1;
@@ -1422,7 +1465,7 @@
kfree_skb(skb);
return;
}
-
+
proto = PPP_PROTO(skb);
read_lock_bh(&pch->upl);
if (pch->ppp == 0 || proto >= 0xc000 || proto == PPP_CCPFRAG) {
@@ -1691,7 +1734,7 @@
struct list_head *l;
int mphdrlen = (ppp->flags & SC_MP_SHORTSEQ)? MPHDRLEN_SSN: MPHDRLEN;
- if (!pskb_may_pull(skb, mphdrlen + 1) || ppp->mrru == 0)
+ if (!pskb_may_pull(skb, mphdrlen) || ppp->mrru == 0)
goto err; /* no good, throw it away */
/* Decode sequence number and begin/end bits */