Re: [PATCH net v3] ibmvnic: Continue with reset if set link down failed

On 2021-05-04 12:31, Lijun Pan wrote:

On Tue, May 4, 2021 at 2:27 PM Lijun Pan [off-list ref] wrote:

quoted

On Tue, May 4, 2021 at 2:14 PM Dany Madden [off-list ref] wrote:

quoted

When ibmvnic gets a FATAL error message from the vnicserver, it marks
the Command Respond Queue (CRQ) inactive and resets the adapter. If this
FATAL reset fails and a transmission timeout reset follows, the CRQ is
still inactive, ibmvnic's attempt to set link down will also fail. If
ibmvnic abandons the reset because of this failed set link down and this
is the last reset in the workqueue, then this adapter will be left in an
inoperable state.

Instead, make the driver ignore this link down failure and continue to
free and re-register CRQ so that the adapter has an opportunity to
recover.

Fixes: ed651a10875f ("ibmvnic: Updated reset handling")
Signed-off-by: Dany Madden <redacted>
Reviewed-by: Rick Lindsley <ricklind@linux.ibm.com>
Reviewed-by: Sukadev Bhattiprolu <redacted>
---
Changes in V2:
- Update description to clarify background for the patch
- Include Reviewed-by tags
Changes in V3:
- Add comment above the code change
---
 drivers/net/ethernet/ibm/ibmvnic.c | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/drivers/net/ethernet/ibm/ibmvnic.c b/drivers/net/ethernet/ibm/ibmvnic.c
index 5788bb956d73..9e005a08d43b 100644
--- a/drivers/net/ethernet/ibm/ibmvnic.c
+++ b/drivers/net/ethernet/ibm/ibmvnic.c

@@ -2017,8 +2017,15 @@ static int do_reset(struct ibmvnic_adapter *adapter,
                        rtnl_unlock();
                        rc = set_link_state(adapter, IBMVNIC_LOGICAL_LNK_DN);
                        rtnl_lock();
-                       if (rc)
-                               goto out;
+
+                       /* Attempted to set the link down. It could fail if the
+                        * vnicserver has already torn down the CRQ. We will
+                        * note it and continue with reset to reinit the CRQ.
+                        */
+                       if (rc) {
+                               netdev_dbg(netdev,
+                                          "Setting link down failed rc=%d. Continue anyway\n", rc);
+                       }

There are other places which check and rely on the return value of
this function. Your change makes that inconsistent. Can you stop

To be more specific, __ibmvnic_close, __ibmvnic_open both call this
set_link_state.

Inconsistent would have been not checking for the rc at all. Here we 
checked and noted it that there are times that it's ok to continue.

quoted

posting new versions and soliciting the maintainer to accept it before
there is material change? There are many ways to make reset
successful. I think this is the worst approach of all.

Can you show me a patch that is better than this one, that has gone thru 
a 30+ hours of testing?

quoted

quoted

                        if (adapter->state == VNIC_OPEN) {
                                /* When we dropped rtnl, ibmvnic_open() got
--
2.18.2