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| /openbmc/linux/drivers/net/ethernet/sun/ |
| H A D | sunvnet_common.c | 8778b276 Fri Oct 28 13:26:19 CDT 2016 Aaron Young <aaron.young@oracle.com> ldmvsw: tx queue stuck in stopped state after LDC reset
The following patch fixes an issue with the ldmvsw driver where
the network connection of a guest domain becomes non-functional after
the guest domain has panic'd and rebooted.
The root cause was determined to be from the following series of
events:
1. Guest domain panics - resulting in the guest no longer processing
network packets (from ldmvsw driver)
2. The ldmvsw driver (in the control domain) eventually exerts flow
control due to no more available tx drings and stops the tx queue
for the guest domain
3. The LDC of the network connection for the guest is reset when
the guest domain reboots after the panic.
4. The LDC reset event is received by the ldmvsw driver and the ldmvsw
responds by clearing the tx queue for the guest.
5. ldmvsw waits indefinitely for a DATA ACK from the guest - which is
the normal method to re-enable the tx queue. But the ACK never comes
because the tx queue was cleared due to the LDC reset.
To fix this issue, in addition to clearing the tx queue, re-enable the
tx queue on a LDC reset. This prevents the ldmvsw from getting caught in
this deadlocked state of waiting for a DATA ACK which will never come.
Signed-off-by: Aaron Young <Aaron.Young@oracle.com>
Acked-by: Sowmini Varadhan <sowmini.varadhan@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
8778b276 Fri Oct 28 13:26:19 CDT 2016 Aaron Young <aaron.young@oracle.com> ldmvsw: tx queue stuck in stopped state after LDC reset
The following patch fixes an issue with the ldmvsw driver where
the network connection of a guest domain becomes non-functional after
the guest domain has panic'd and rebooted.
The root cause was determined to be from the following series of
events:
1. Guest domain panics - resulting in the guest no longer processing
network packets (from ldmvsw driver)
2. The ldmvsw driver (in the control domain) eventually exerts flow
control due to no more available tx drings and stops the tx queue
for the guest domain
3. The LDC of the network connection for the guest is reset when
the guest domain reboots after the panic.
4. The LDC reset event is received by the ldmvsw driver and the ldmvsw
responds by clearing the tx queue for the guest.
5. ldmvsw waits indefinitely for a DATA ACK from the guest - which is
the normal method to re-enable the tx queue. But the ACK never comes
because the tx queue was cleared due to the LDC reset.
To fix this issue, in addition to clearing the tx queue, re-enable the
tx queue on a LDC reset. This prevents the ldmvsw from getting caught in
this deadlocked state of waiting for a DATA ACK which will never come.
Signed-off-by: Aaron Young <Aaron.Young@oracle.com>
Acked-by: Sowmini Varadhan <sowmini.varadhan@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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