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authorMarcelo Ricardo Leitner <marcelo.leitner@gmail.com>2016-12-23 14:29:02 -0200
committerDavid S. Miller <davem@davemloft.net>2016-12-23 14:01:35 -0500
commit58b94d88deb9ac913740e7778f2005f3ce6d0443 (patch)
tree83ff0487747e1c8b7bebb11596fe8eb528acdacb
parente57cbe48a6b7a9a05a058aee5336d25407ad1c2c (diff)
downloadlinux-stericsson-58b94d88deb9ac913740e7778f2005f3ce6d0443.tar.gz
sctp: do not loose window information if in rwnd_over
It's possible that we receive a packet that is larger than current window. If it's the first packet in this way, it will cause it to increase rwnd_over. Then, if we receive another data chunk (specially as SCTP allows you to have one data chunk in flight even during 0 window), rwnd_over will be overwritten instead of added to. In the long run, this could cause the window to grow bigger than its initial size, as rwnd_over would be charged only for the last received data chunk while the code will try open the window for all packets that were received and had its value in rwnd_over overwritten. This, then, can lead to the worsening of payload/buffer ratio and cause rwnd_press to kick in more often. The fix is to sum it too, same as is done for rwnd_press, so that if we receive 3 chunks after closing the window, we still have to release that same amount before re-opening it. Log snippet from sctp_test exhibiting the issue: [ 146.209232] sctp: sctp_assoc_rwnd_decrease: asoc:ffff88013928e000 rwnd decreased by 1 to (0, 1, 114221) [ 146.209232] sctp: sctp_assoc_rwnd_decrease: association:ffff88013928e000 has asoc->rwnd:0, asoc->rwnd_over:1! [ 146.209232] sctp: sctp_assoc_rwnd_decrease: asoc:ffff88013928e000 rwnd decreased by 1 to (0, 1, 114221) [ 146.209232] sctp: sctp_assoc_rwnd_decrease: association:ffff88013928e000 has asoc->rwnd:0, asoc->rwnd_over:1! [ 146.209232] sctp: sctp_assoc_rwnd_decrease: asoc:ffff88013928e000 rwnd decreased by 1 to (0, 1, 114221) [ 146.209232] sctp: sctp_assoc_rwnd_decrease: association:ffff88013928e000 has asoc->rwnd:0, asoc->rwnd_over:1! [ 146.209232] sctp: sctp_assoc_rwnd_decrease: asoc:ffff88013928e000 rwnd decreased by 1 to (0, 1, 114221) Signed-off-by: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
-rw-r--r--net/sctp/associola.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/net/sctp/associola.c b/net/sctp/associola.c
index 68428e1f7181..56ddcfaeb4f6 100644
--- a/net/sctp/associola.c
+++ b/net/sctp/associola.c
@@ -1539,7 +1539,7 @@ void sctp_assoc_rwnd_decrease(struct sctp_association *asoc, unsigned int len)
asoc->rwnd = 0;
}
} else {
- asoc->rwnd_over = len - asoc->rwnd;
+ asoc->rwnd_over += len - asoc->rwnd;
asoc->rwnd = 0;
}