From a53a8b56827cc429c6d9f861ad558beeb5f6103f Mon Sep 17 00:00:00 2001 From: Ben McKeegan Date: Tue, 28 Jul 2009 07:43:57 +0000 Subject: [PATCH] ppp: fix lost fragments in ppp_mp_explode() (resubmit) This patch fixes the corner cases where the sum of MTU of the free channels (adjusted for fragmentation overheads) is less than the MTU of PPP link. There are at least 3 situations where this case might arise: - some of the channels are busy - the multilink session is running in a degraded state (i.e. with less than its full complement of active channels) - by design, where multilink protocol is being used to artificially increase the effective link MTU of a single link. Without this patch, at most 1 fragment is ever sent per free channel for a given PPP frame and any remaining part of the PPP frame that does not fit into those fragments is silently discarded. This patch restores the original behaviour which was broken by commit 9c705260feea6ae329bc6b6d5f6d2ef0227eda0a 'ppp:ppp_mp_explode() redesign'. Once all 'free' channels have been given a fragment, an additional fragment is queued to each available channel in turn, as many times as necessary, until the entire PPP frame has been consumed. Signed-off-by: Ben McKeegan Signed-off-by: David S. Miller --- drivers/net/ppp_generic.c | 34 ++++++++++++++++++---------------- 1 file changed, 18 insertions(+), 16 deletions(-) diff --git a/drivers/net/ppp_generic.c b/drivers/net/ppp_generic.c index 639d11bc444..cd37d739ac7 100644 --- a/drivers/net/ppp_generic.c +++ b/drivers/net/ppp_generic.c @@ -1384,7 +1384,7 @@ static int ppp_mp_explode(struct ppp *ppp, struct sk_buff *skb) /* create a fragment for each channel */ bits = B; - while (nfree > 0 && len > 0) { + while (len > 0) { list = list->next; if (list == &ppp->channels) { i = 0; @@ -1431,29 +1431,31 @@ static int ppp_mp_explode(struct ppp *ppp, struct sk_buff *skb) *otherwise divide it according to the speed *of the channel we are going to transmit on */ - if (pch->speed == 0) { - flen = totlen/nfree ; - if (nbigger > 0) { - flen++; - nbigger--; - } - } else { - flen = (((totfree - nzero)*(totlen + hdrlen*totfree)) / - ((totspeed*totfree)/pch->speed)) - hdrlen; - if (nbigger > 0) { - flen += ((totfree - nzero)*pch->speed)/totspeed; - nbigger -= ((totfree - nzero)*pch->speed)/ + if (nfree > 0) { + if (pch->speed == 0) { + flen = totlen/nfree ; + if (nbigger > 0) { + flen++; + nbigger--; + } + } else { + flen = (((totfree - nzero)*(totlen + hdrlen*totfree)) / + ((totspeed*totfree)/pch->speed)) - hdrlen; + if (nbigger > 0) { + flen += ((totfree - nzero)*pch->speed)/totspeed; + nbigger -= ((totfree - nzero)*pch->speed)/ totspeed; + } } + nfree--; } - nfree--; /* *check if we are on the last channel or *we exceded the lenght of the data to *fragment */ - if ((nfree == 0) || (flen > len)) + if ((nfree <= 0) || (flen > len)) flen = len; /* *it is not worth to tx on slow channels: @@ -1467,7 +1469,7 @@ static int ppp_mp_explode(struct ppp *ppp, struct sk_buff *skb) continue; } - mtu = pch->chan->mtu + 2 - hdrlen; + mtu = pch->chan->mtu - hdrlen; if (mtu < 4) mtu = 4; if (flen > mtu) -- 2.39.5