In commit 16ad3f4022bb ("tipc: introduce variable window congestion
control"), we enable user to set the link 'max_win' value which is used
as the upper threshold for the variable link window algorithm later.
However, since it is done by the same netlink command property
'TIPC_NLA_PROP_WIN' that was used to set the actual link window before,
it appears to be a non backward compatible issue when user tries to get
the value back but finds a different value (i.e. the variable window at
that moment).
Besides, there is another flaw with the 'max_win' where it is set to be
'TIPC_MAX_LINK_WIN' (i.e. 8191) by default that is obviously unexpected
(the variable link window will take place and go beyond that might harm
the underlying device...). The value is actually derived from the lower
bearer & media layers (i.e. 'eth' media) at the initializing time where
the default value should be 'TIPC_DEF_LINK_WIN' (i.e. 50) instead.
We fix the issue #1 by returning the 'max_win' which is exactly the one
set by user, while setting back the 'max_win' for the 'eth' media to be
the said value for the #2.
Note: the changes do not affect the variable link window mechanism, but
make the right thing i.e. it will work only when user really wants.
Fixes: 16ad3f4022bb ("tipc: introduce variable window congestion control")
Reported-by: Hoang Le <hoang.h...@dektech.com.au>
Reported-by: Thang Ngo <thang.h....@dektech.com.au>
Signed-off-by: Tuong Lien <tuong.t.l...@dektech.com.au>
---
net/tipc/eth_media.c | 2 +-
net/tipc/link.c | 2 +-
2 files changed, 2 insertions(+), 2 deletions(-)
diff --git a/net/tipc/eth_media.c b/net/tipc/eth_media.c
index 8b0bb600602d..675b947eab89 100644
--- a/net/tipc/eth_media.c
+++ b/net/tipc/eth_media.c
@@ -93,7 +93,7 @@ struct tipc_media eth_media_info = {
.priority = TIPC_DEF_LINK_PRI,
.tolerance = TIPC_DEF_LINK_TOL,
.min_win = TIPC_DEF_LINK_WIN,
- .max_win = TIPC_MAX_LINK_WIN,
+ .max_win = TIPC_DEF_LINK_WIN,
.type_id = TIPC_MEDIA_TYPE_ETH,
.hwaddr_len = ETH_ALEN,
.name = "eth"
diff --git a/net/tipc/link.c b/net/tipc/link.c
index ee3b8d0576b8..28834dafdc98 100644
--- a/net/tipc/link.c
+++ b/net/tipc/link.c
@@ -2662,7 +2662,7 @@ int __tipc_nl_add_link(struct net *net, struct
tipc_nl_msg *msg,
if (nla_put_u32(msg->skb, TIPC_NLA_PROP_TOL, link->tolerance))
goto prop_msg_full;
if (nla_put_u32(msg->skb, TIPC_NLA_PROP_WIN,
- link->window))
+ link->max_win))
goto prop_msg_full;
if (nla_put_u32(msg->skb, TIPC_NLA_PROP_PRIO, link->priority))
goto prop_msg_full;
--
2.13.7
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