* Re: [PATCH 2/3] sctp: fix association hangs due to reassembly/ordering logic
2013-02-20 15:55 ` [PATCH 2/3] sctp: fix association hangs due to reassembly/ordering logic Roberts, Lee A.
@ 2013-02-20 16:38 ` Vlad Yasevich
0 siblings, 0 replies; 2+ messages in thread
From: Vlad Yasevich @ 2013-02-20 16:38 UTC (permalink / raw)
To: Roberts, Lee A.
Cc: linux-sctp@vger.kernel.org, netdev@vger.kernel.org,
linux-kernel@vger.kernel.org
On 02/20/2013 10:55 AM, Roberts, Lee A. wrote:
> From: Lee A. Roberts <lee.roberts@hp.com>
>
> Resolve SCTP association hangs observed during SCTP stress
> testing. Observable symptoms include communications hangs
> with data being held in the association reassembly and/or lobby
> (ordering) queues. Close examination of reassembly queue shows
> missing packets.
>
> In sctp_ulpq_renege_list(), do not renege packets below the
> cumulative TSN ACK point. Events being reneged from the
> ordering queue may correspond to multiple TSNs; identify
> and renege all affected packets from the tsnmap.
>
> Patch applies to linux-3.8 kernel.
>
> Signed-off-by: Lee A. Roberts <lee.roberts@hp.com>
> ---
> net/sctp/ulpqueue.c | 30 +++++++++++++++++++++++++-----
> 1 file changed, 25 insertions(+), 5 deletions(-)
>
> diff -uprN -X linux-3.8-vanilla/Documentation/dontdiff linux-3.8-SCTP
> +1/net/sctp/ulpqueue.c linux-3.8-SCTP+2/net/sctp/ulpqueue.c
> --- linux-3.8-SCTP+1/net/sctp/ulpqueue.c 2013-02-18 16:58:34.000000000
> -0700
> +++ linux-3.8-SCTP+2/net/sctp/ulpqueue.c 2013-02-20 08:17:53.679233365
> -0700
> @@ -962,20 +962,40 @@ static __u16 sctp_ulpq_renege_list(struc
> struct sk_buff_head *list, __u16 needed)
> {
> __u16 freed = 0;
> - __u32 tsn;
> - struct sk_buff *skb;
> + __u32 tsn, last_tsn;
> + struct sk_buff *skb, *flist, *last;
> struct sctp_ulpevent *event;
> struct sctp_tsnmap *tsnmap;
>
> tsnmap = &ulpq->asoc->peer.tsn_map;
>
> - while ((skb = __skb_dequeue_tail(list)) != NULL) {
> - freed += skb_headlen(skb);
> + while ((skb = skb_peek_tail(list)) != NULL) {
> event = sctp_skb2event(skb);
> tsn = event->tsn;
>
> + /* Don't renege below the Cumulative TSN ACK Point. */
> + if (TSN_lte(tsn, sctp_tsnmap_get_ctsn(tsnmap)))
> + break;
> +
> + /* Events in ordering queue may have multiple fragments
> + * corresponding to additional TSNs. Find the last one.
> + */
> + flist = skb_shinfo(skb)->frag_list;
> + for (last = flist; flist; flist = flist->next)
> + last = flist;
> + if (last)
> + last_tsn = sctp_skb2event(last)->tsn;
> + else
> + last_tsn = tsn;
> +
> + /* Unlink the event, then renege all applicable TSNs. */
> + __skb_unlink(skb, list);
> + freed += skb_headlen(skb);
This is no longer correct. You are actually freeing more space if you
are reneging a reassembled event from the the ordered queue.
Please separate the 2 patches since they fix 2 distinct bugs.
Thanks
-vlad
> sctp_ulpevent_free(event);
> - sctp_tsnmap_renege(tsnmap, tsn);
> + while (TSN_lte(tsn, last_tsn)) {
> + sctp_tsnmap_renege(tsnmap, tsn);
> + tsn++;
> + }
> if (freed >= needed)
> return freed;
> }
>
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