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authorBen McKeegan <ben@netservers.co.uk>2009-07-28 03:43:57 -0400
committerDavid S. Miller <davem@davemloft.net>2009-08-02 15:20:31 -0400
commita53a8b56827cc429c6d9f861ad558beeb5f6103f (patch)
treea7af8f3197dd2361d27adfd74781bb7922931791 /drivers
parent0a924578bc4a2823a95c151f56975c71f5c156bb (diff)
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 <ben@netservers.co.uk> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'drivers')
-rw-r--r--drivers/net/ppp_generic.c34
1 files changed, 18 insertions, 16 deletions
diff --git a/drivers/net/ppp_generic.c b/drivers/net/ppp_generic.c
index 639d11bc444e..cd37d739ac74 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)
1384 1384
1385 /* create a fragment for each channel */ 1385 /* create a fragment for each channel */
1386 bits = B; 1386 bits = B;
1387 while (nfree > 0 && len > 0) { 1387 while (len > 0) {
1388 list = list->next; 1388 list = list->next;
1389 if (list == &ppp->channels) { 1389 if (list == &ppp->channels) {
1390 i = 0; 1390 i = 0;
@@ -1431,29 +1431,31 @@ static int ppp_mp_explode(struct ppp *ppp, struct sk_buff *skb)
1431 *otherwise divide it according to the speed 1431 *otherwise divide it according to the speed
1432 *of the channel we are going to transmit on 1432 *of the channel we are going to transmit on
1433 */ 1433 */
1434 if (pch->speed == 0) { 1434 if (nfree > 0) {
1435 flen = totlen/nfree ; 1435 if (pch->speed == 0) {
1436 if (nbigger > 0) { 1436 flen = totlen/nfree ;
1437 flen++; 1437 if (nbigger > 0) {
1438 nbigger--; 1438 flen++;
1439 } 1439 nbigger--;
1440 } else { 1440 }
1441 flen = (((totfree - nzero)*(totlen + hdrlen*totfree)) / 1441 } else {
1442 ((totspeed*totfree)/pch->speed)) - hdrlen; 1442 flen = (((totfree - nzero)*(totlen + hdrlen*totfree)) /
1443 if (nbigger > 0) { 1443 ((totspeed*totfree)/pch->speed)) - hdrlen;
1444 flen += ((totfree - nzero)*pch->speed)/totspeed; 1444 if (nbigger > 0) {
1445 nbigger -= ((totfree - nzero)*pch->speed)/ 1445 flen += ((totfree - nzero)*pch->speed)/totspeed;
1446 nbigger -= ((totfree - nzero)*pch->speed)/
1446 totspeed; 1447 totspeed;
1448 }
1447 } 1449 }
1450 nfree--;
1448 } 1451 }
1449 nfree--;
1450 1452
1451 /* 1453 /*
1452 *check if we are on the last channel or 1454 *check if we are on the last channel or
1453 *we exceded the lenght of the data to 1455 *we exceded the lenght of the data to
1454 *fragment 1456 *fragment
1455 */ 1457 */
1456 if ((nfree == 0) || (flen > len)) 1458 if ((nfree <= 0) || (flen > len))
1457 flen = len; 1459 flen = len;
1458 /* 1460 /*
1459 *it is not worth to tx on slow channels: 1461 *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)
1467 continue; 1469 continue;
1468 } 1470 }
1469 1471
1470 mtu = pch->chan->mtu + 2 - hdrlen; 1472 mtu = pch->chan->mtu - hdrlen;
1471 if (mtu < 4) 1473 if (mtu < 4)
1472 mtu = 4; 1474 mtu = 4;
1473 if (flen > mtu) 1475 if (flen > mtu)