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[libteam]: Fix libteam race condition when interface is created and e…
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…nslaved (#2449)

The race condition could happen like this:
When an interface is enslaved into the port channel immediately after
it is created, the order of creating the ifinfo and linking the ifinfo to
the port is not guaranteed.

Please check the patch commit message to get full details.

Signed-off-by: Shu0T1an ChenG <shuche@microsoft.com>
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Shuotian Cheng authored and lguohan committed Jan 16, 2019
1 parent 0256af3 commit 09b9db0
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@@ -0,0 +1,45 @@
From 9a27e9b85afbbf6235e61c2426481e49a2139219 Mon Sep 17 00:00:00 2001
From: Shu0T1an ChenG <shuche@microsoft.com>
Date: Tue, 15 Jan 2019 12:23:02 -0800
Subject: [PATCH] Fix ifinfo_link_with_port race condition with newlink

The race condition could happen like this:
When an interface is enslaved into the port channel immediately after
it is created, the order of creating the ifinfo and linking the ifinfo to
the port is not guaranteed.

The team handler will listen to both netlink message to track new links
get created to allocate the ifinfo and add the ifinfo into its linked list,
and the team port change message to link the new port with ifinfo found
in its linkedin list. However, when the ifinfo is not yet created, the error
message "Failed to link port with ifinfo" is thrown with member port failed
to be added into the team handler's port list.

This fix adds a condition to check if ifinfo_link_with_port is linking ifinfo
to a port or to the team interface itself. If it is a port, ifinfo_find_create
function is used to fix the race condition.

Signed-off-by: Shu0T1an ChenG <shuche@microsoft.com>
---
libteam/ifinfo.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/libteam/ifinfo.c b/libteam/ifinfo.c
index 44de4ca..444e0cd 100644
--- a/libteam/ifinfo.c
+++ b/libteam/ifinfo.c
@@ -429,7 +429,10 @@ int ifinfo_link_with_port(struct team_handle *th, uint32_t ifindex,
{
struct team_ifinfo *ifinfo;

- ifinfo = ifinfo_find(th, ifindex);
+ if (port)
+ ifinfo = ifinfo_find_create(th, ifindex);
+ else
+ ifinfo = ifinfo_find(th, ifindex);
if (!ifinfo)
return -ENOENT;
if (ifinfo->linked)
--
2.1.4

1 change: 1 addition & 0 deletions src/libteam/Makefile
Original file line number Diff line number Diff line change
Expand Up @@ -20,6 +20,7 @@ $(addprefix $(DEST)/, $(MAIN_TARGET)): $(DEST)/% :
git apply ../0003-teamd-lacp-runner-will-send-lacp-update-right-after-.patch
git apply ../0004-libteam-Add-lacp-fallback-support-for-single-member-.patch
git apply ../0005-libteam-Add-warm_reboot-mode.patch
git apply ../0006-Fix-ifinfo_link_with_port-race-condition-with-newlink.patch
popd

# Obtain debian packaging
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