From: Wengang Wang <hidden> Date: 2016-01-20 05:59:55
In a bonding setting, we determines fragment size according to MTU and
PMTU associated to the bonding master. If the slave finds the fragment
size is too big, it drops the fragment and calls ip_rt_update_pmtu(),
passing _skb_ and _pmtu_, trying to update the path MTU.
Problem is that the target device that function ip_rt_update_pmtu actually
tries to update is the slave (skb->dev), not the master. Thus since no
PMTU change happens on master, the fragment size for later packets doesn't
change so all later fragments/packets are dropped too.
The fix is letting build_skb_flow_key() take care of the transition of
device index from bonding slave to the master. That makes the master become
the target device that ip_rt_update_pmtu tries to update PMTU to.
Signed-off-by: Wengang Wang <redacted>
---
net/ipv4/route.c | 13 ++++++++++++-
1 file changed, 12 insertions(+), 1 deletion(-)
In a bonding setting, we determines fragment size according to MTU and
PMTU associated to the bonding master. If the slave finds the fragment
size is too big, it drops the fragment and calls ip_rt_update_pmtu(),
passing _skb_ and _pmtu_, trying to update the path MTU.
Problem is that the target device that function ip_rt_update_pmtu actually
tries to update is the slave (skb->dev), not the master. Thus since no
PMTU change happens on master, the fragment size for later packets doesn't
change so all later fragments/packets are dropped too.
The fix is letting build_skb_flow_key() take care of the transition of
device index from bonding slave to the master. That makes the master become
the target device that ip_rt_update_pmtu tries to update PMTU to.
Signed-off-by: Wengang Wang <redacted>
---
net/ipv4/route.c | 13 ++++++++++++-
1 file changed, 12 insertions(+), 1 deletion(-)
update_pmtu is called very frequently. Is it appropriate to use
rtnl_lock here?
That is, rtnl_lock is called frequently. Maybe other functions have
little chance to call rtnl_lock.
Best Regards!
Zhu Yanjun
In a bonding setting, we determines fragment size according to MTU and
PMTU associated to the bonding master. If the slave finds the fragment
size is too big, it drops the fragment and calls ip_rt_update_pmtu(),
passing _skb_ and _pmtu_, trying to update the path MTU.
Problem is that the target device that function ip_rt_update_pmtu
actually
tries to update is the slave (skb->dev), not the master. Thus since no
PMTU change happens on master, the fragment size for later packets
doesn't
change so all later fragments/packets are dropped too.
The fix is letting build_skb_flow_key() take care of the transition of
device index from bonding slave to the master. That makes the master
become
the target device that ip_rt_update_pmtu tries to update PMTU to.
Signed-off-by: Wengang Wang <redacted>
---
net/ipv4/route.c | 13 ++++++++++++-
1 file changed, 12 insertions(+), 1 deletion(-)
update_pmtu is called very frequently. Is it appropriate to use
rtnl_lock here?
That is, rtnl_lock is called frequently. Maybe other functions have
little chance to call rtnl_lock.
Maybe this function netdev_upper_get_next_dev_rcu is better? I am not sure.
In a bonding setting, we determines fragment size according to MTU and
PMTU associated to the bonding master. If the slave finds the fragment
size is too big, it drops the fragment and calls ip_rt_update_pmtu(),
passing _skb_ and _pmtu_, trying to update the path MTU.
Problem is that the target device that function ip_rt_update_pmtu
actually
tries to update is the slave (skb->dev), not the master. Thus since no
PMTU change happens on master, the fragment size for later packets
doesn't
change so all later fragments/packets are dropped too.
The fix is letting build_skb_flow_key() take care of the transition of
device index from bonding slave to the master. That makes the master
become
the target device that ip_rt_update_pmtu tries to update PMTU to.
Signed-off-by: Wengang Wang <redacted>
---
net/ipv4/route.c | 13 ++++++++++++-
1 file changed, 12 insertions(+), 1 deletion(-)
update_pmtu is called very frequently. Is it appropriate to use
rtnl_lock here?
That is, rtnl_lock is called frequently. Maybe other functions have
little chance to call rtnl_lock.
Maybe this function netdev_master_upper_dev_get_rcu is better? I am
not sure.
Maybe this function netdev_master_upper_dev_get_rcu is better? I am not
sure.
From: Wengang Wang <hidden> Date: 2016-01-20 07:35:19
在 2016年01月20日 14:24, zhuyj 写道:
On 01/20/2016 01:32 PM, Wengang Wang wrote:
quoted
In a bonding setting, we determines fragment size according to MTU and
PMTU associated to the bonding master. If the slave finds the fragment
size is too big, it drops the fragment and calls ip_rt_update_pmtu(),
passing _skb_ and _pmtu_, trying to update the path MTU.
Problem is that the target device that function ip_rt_update_pmtu
actually
tries to update is the slave (skb->dev), not the master. Thus since no
PMTU change happens on master, the fragment size for later packets
doesn't
change so all later fragments/packets are dropped too.
The fix is letting build_skb_flow_key() take care of the transition of
device index from bonding slave to the master. That makes the master
become
the target device that ip_rt_update_pmtu tries to update PMTU to.
Signed-off-by: Wengang Wang <redacted>
---
net/ipv4/route.c | 13 ++++++++++++-
1 file changed, 12 insertions(+), 1 deletion(-)
update_pmtu is called very frequently. Is it appropriate to use
rtnl_lock here?
By "very frequently", how frequently it is expected? And what situation
can cause that?
For my case, the update_pmtu is called only once.
thanks,
wengang
That is, rtnl_lock is called frequently. Maybe other functions have
little chance to call rtnl_lock.
Best Regards!
Zhu Yanjun
In a bonding setting, we determines fragment size according to MTU and
PMTU associated to the bonding master. If the slave finds the fragment
size is too big, it drops the fragment and calls ip_rt_update_pmtu(),
passing _skb_ and _pmtu_, trying to update the path MTU.
Problem is that the target device that function ip_rt_update_pmtu
actually
tries to update is the slave (skb->dev), not the master. Thus since no
PMTU change happens on master, the fragment size for later packets
doesn't
change so all later fragments/packets are dropped too.
The fix is letting build_skb_flow_key() take care of the transition of
device index from bonding slave to the master. That makes the master
become
the target device that ip_rt_update_pmtu tries to update PMTU to.
Signed-off-by: Wengang Wang <redacted>
---
net/ipv4/route.c | 13 ++++++++++++-
1 file changed, 12 insertions(+), 1 deletion(-)
From: Wengang Wang <hidden> Date: 2016-01-20 09:43:53
在 2016年01月20日 15:54, zhuyj 写道:
On 01/20/2016 03:38 PM, Wengang Wang wrote:
quoted
在 2016年01月20日 14:24, zhuyj 写道:
quoted
On 01/20/2016 01:32 PM, Wengang Wang wrote:
quoted
In a bonding setting, we determines fragment size according to MTU and
PMTU associated to the bonding master. If the slave finds the fragment
size is too big, it drops the fragment and calls ip_rt_update_pmtu(),
passing _skb_ and _pmtu_, trying to update the path MTU.
Problem is that the target device that function ip_rt_update_pmtu
actually
tries to update is the slave (skb->dev), not the master. Thus since no
PMTU change happens on master, the fragment size for later packets
doesn't
change so all later fragments/packets are dropped too.
The fix is letting build_skb_flow_key() take care of the transition of
device index from bonding slave to the master. That makes the
master become
the target device that ip_rt_update_pmtu tries to update PMTU to.
Signed-off-by: Wengang Wang <redacted>
---
net/ipv4/route.c | 13 ++++++++++++-
1 file changed, 12 insertions(+), 1 deletion(-)
In a bonding setting, we determines fragment size according to MTU
and
PMTU associated to the bonding master. If the slave finds the
fragment
size is too big, it drops the fragment and calls ip_rt_update_pmtu(),
passing _skb_ and _pmtu_, trying to update the path MTU.
Problem is that the target device that function ip_rt_update_pmtu
actually
tries to update is the slave (skb->dev), not the master. Thus
since no
PMTU change happens on master, the fragment size for later packets
doesn't
change so all later fragments/packets are dropped too.
The fix is letting build_skb_flow_key() take care of the
transition of
device index from bonding slave to the master. That makes the
master become
the target device that ip_rt_update_pmtu tries to update PMTU to.
Signed-off-by: Wengang Wang <redacted>
---
net/ipv4/route.c | 13 ++++++++++++-
1 file changed, 12 insertions(+), 1 deletion(-)
In a bonding setting, we determines fragment size according to MTU and
PMTU associated to the bonding master. If the slave finds the fragment
size is too big, it drops the fragment and calls ip_rt_update_pmtu(),
passing _skb_ and _pmtu_, trying to update the path MTU.
Problem is that the target device that function ip_rt_update_pmtu actually
tries to update is the slave (skb->dev), not the master. Thus since no
PMTU change happens on master, the fragment size for later packets doesn't
change so all later fragments/packets are dropped too.
The fix is letting build_skb_flow_key() take care of the transition of
device index from bonding slave to the master. That makes the master become
the target device that ip_rt_update_pmtu tries to update PMTU to.
Signed-off-by: Wengang Wang <redacted>
---
net/ipv4/route.c | 13 ++++++++++++-
1 file changed, 12 insertions(+), 1 deletion(-)
As zhuyj said, this is called from dev_queue_xmit, so you cannot take
rtnl_lock here.
+ if (master)
+ oif = master->ifindex;
You cannot dereference master after you release the rtnl lock.
So it would probably be best to use netdev_master_upper_dev_get_rcu,
as zhuyj suggested earlier, and make sure that you only use the result
between rcu_read_lock()/rcu_read_unlock():
rcu_read_lock();
master = netdev_master_upper_dev_get_rcu(skb->dev);
if (master)
oif = master->ifindex;
rcu_read_unlock();
Thanks,
--
Sabrina
From: Wengang Wang <hidden> Date: 2016-01-21 02:37:16
在 2016年01月20日 17:56, zhuyj 写道:
On 01/20/2016 05:47 PM, Wengang Wang wrote:
quoted
在 2016年01月20日 15:54, zhuyj 写道:
quoted
On 01/20/2016 03:38 PM, Wengang Wang wrote:
quoted
在 2016年01月20日 14:24, zhuyj 写道:
quoted
On 01/20/2016 01:32 PM, Wengang Wang wrote:
quoted
In a bonding setting, we determines fragment size according to
MTU and
PMTU associated to the bonding master. If the slave finds the
fragment
size is too big, it drops the fragment and calls
ip_rt_update_pmtu(),
passing _skb_ and _pmtu_, trying to update the path MTU.
Problem is that the target device that function ip_rt_update_pmtu
actually
tries to update is the slave (skb->dev), not the master. Thus
since no
PMTU change happens on master, the fragment size for later
packets doesn't
change so all later fragments/packets are dropped too.
The fix is letting build_skb_flow_key() take care of the
transition of
device index from bonding slave to the master. That makes the
master become
the target device that ip_rt_update_pmtu tries to update PMTU to.
Signed-off-by: Wengang Wang <redacted>
---
net/ipv4/route.c | 13 ++++++++++++-
1 file changed, 12 insertions(+), 1 deletion(-)
For ipip, yes seems update_pmtu is called in line for each call of
queue_xmit. Do you know if it's a good configuration for ipip + bonding?
Other's comment and suggestion?
thanks,
wengang
From: Wengang Wang <hidden> Date: 2016-01-21 05:12:27
在 2016年01月20日 23:18, Sabrina Dubroca 写道:
2016-01-20, 13:32:13 +0800, Wengang Wang wrote:
quoted
In a bonding setting, we determines fragment size according to MTU and
PMTU associated to the bonding master. If the slave finds the fragment
size is too big, it drops the fragment and calls ip_rt_update_pmtu(),
passing _skb_ and _pmtu_, trying to update the path MTU.
Problem is that the target device that function ip_rt_update_pmtu actually
tries to update is the slave (skb->dev), not the master. Thus since no
PMTU change happens on master, the fragment size for later packets doesn't
change so all later fragments/packets are dropped too.
The fix is letting build_skb_flow_key() take care of the transition of
device index from bonding slave to the master. That makes the master become
the target device that ip_rt_update_pmtu tries to update PMTU to.
Signed-off-by: Wengang Wang <redacted>
---
net/ipv4/route.c | 13 ++++++++++++-
1 file changed, 12 insertions(+), 1 deletion(-)
As zhuyj said, this is called from dev_queue_xmit, so you cannot take
rtnl_lock here.
quoted
+ if (master)
+ oif = master->ifindex;
You cannot dereference master after you release the rtnl lock.
So it would probably be best to use netdev_master_upper_dev_get_rcu,
as zhuyj suggested earlier, and make sure that you only use the result
between rcu_read_lock()/rcu_read_unlock():
rcu_read_lock();
master = netdev_master_upper_dev_get_rcu(skb->dev);
if (master)
oif = master->ifindex;
rcu_read_unlock();