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authorJon Maloy <jon.maloy@ericsson.com>2018-01-08 21:03:24 +0100
committerDavid S. Miller <davem@davemloft.net>2018-01-09 12:35:57 -0500
commit4ea5dab541717fc55cad609360b100857af770b0 (patch)
tree57ab48f7b7bb99a56a81f4a4644659a0da2a94c8
parent8d5dee21f6f01f4632c10b750709a1383eefc7aa (diff)
downloadlinux-4ea5dab541717fc55cad609360b100857af770b0.tar.bz2
tipc: let group member stay in JOINED mode if unable to reclaim
We handle a corner case in the function tipc_group_update_rcv_win(). During extreme pessure it might happen that a message receiver has all its active senders in RECLAIMING or REMITTED mode, meaning that there is nobody to reclaim advertisements from if an additional sender tries to go active. Currently we just set the new sender to ACTIVE anyway, hence at least theoretically opening up for a receiver queue overflow by exceeding the MAX_ACTIVE limit. The correct solution to this is to instead add the member to the pending queue, while letting the oldest member in that queue revert to JOINED state. In this commit we refactor the code for handling message arrival from a JOINED member, both to make it more comprehensible and to cover the case described above. Acked-by: Ying Xue <ying.xue@windriver.com> Signed-off-by: Jon Maloy <jon.maloy@ericsson.com> Signed-off-by: David S. Miller <davem@davemloft.net>
-rw-r--r--net/tipc/group.c34
1 files changed, 22 insertions, 12 deletions
diff --git a/net/tipc/group.c b/net/tipc/group.c
index e5daeb093879..652fa66a87f6 100644
--- a/net/tipc/group.c
+++ b/net/tipc/group.c
@@ -569,24 +569,34 @@ void tipc_group_update_rcv_win(struct tipc_group *grp, int blks, u32 node,
switch (m->state) {
case MBR_JOINED:
- /* Reclaim advertised space from least active member */
- if (!list_empty(active) && active_cnt >= reclaim_limit) {
+ /* First, decide if member can go active */
+ if (active_cnt <= max_active) {
+ m->state = MBR_ACTIVE;
+ list_add_tail(&m->list, active);
+ grp->active_cnt++;
+ tipc_group_proto_xmit(grp, m, GRP_ADV_MSG, xmitq);
+ } else {
+ m->state = MBR_PENDING;
+ list_add_tail(&m->list, &grp->pending);
+ }
+
+ if (active_cnt < reclaim_limit)
+ break;
+
+ /* Reclaim from oldest active member, if possible */
+ if (!list_empty(active)) {
rm = list_first_entry(active, struct tipc_member, list);
rm->state = MBR_RECLAIMING;
list_del_init(&rm->list);
tipc_group_proto_xmit(grp, rm, GRP_RECLAIM_MSG, xmitq);
- }
- /* If max active, become pending and wait for reclaimed space */
- if (active_cnt >= max_active) {
- m->state = MBR_PENDING;
- list_add_tail(&m->list, &grp->pending);
break;
}
- /* Otherwise become active */
- m->state = MBR_ACTIVE;
- list_add_tail(&m->list, &grp->active);
- grp->active_cnt++;
- /* Fall through */
+ /* Nobody to reclaim from; - revert oldest pending to JOINED */
+ pm = list_first_entry(&grp->pending, struct tipc_member, list);
+ list_del_init(&pm->list);
+ pm->state = MBR_JOINED;
+ tipc_group_proto_xmit(grp, pm, GRP_ADV_MSG, xmitq);
+ break;
case MBR_ACTIVE:
if (!list_is_last(&m->list, &grp->active))
list_move_tail(&m->list, &grp->active);