netdev - [PATCH net 3/3] ibmvnic: delay complete()

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Date:   Fri, 29 Oct 2021 15:03:16 -0700
From:   Sukadev Bhattiprolu <sukadev@...ux.ibm.com>
To:     netdev@...r.kernel.org
Cc:     Brian King <brking@...ux.ibm.com>, Dany Madden <drt@...ux.ibm.com>,
        abdhalee@...ibm.com, vaish123@...ibm.com
Subject: [PATCH net 3/3] ibmvnic: delay complete()

If we get CRQ_INIT, we set errno to -EIO and first call complete() to
notify the waiter. Then we try to schedule a FAILOVER reset. If this
occurs while adapter is in PROBING state, ibmvnic_reset() changes the
error code to EAGAIN and returns without scheduling the FAILOVER. The
purpose of setting error code to EAGAIN is to ask the waiter to retry.

But due to the earlier complete() call, the waiter may already have seen
the -EIO response and decided not to retry. This can cause intermittent
failures when bringing up ibmvnic adapters during boot, specially in
in kexec/kdump kernels.

Defer the complete() call until after scheduling the reset.

Also streamline the error code to EAGAIN. Don't see why we need EIO
sometimes. All 3 callers of ibmvnic_reset_init() can handle EAGAIN.

Fixes: 17c8705838a5 ("ibmvnic: Return error code if init interrupted by transport event")
Reported-by: Vaishnavi Bhat <vaish123@...ibm.com>
Signed-off-by: Sukadev Bhattiprolu <sukadev@...ux.ibm.com>
---
 drivers/net/ethernet/ibm/ibmvnic.c | 16 +++++++++-------
 1 file changed, 9 insertions(+), 7 deletions(-)

diff --git a/drivers/net/ethernet/ibm/ibmvnic.c b/drivers/net/ethernet/ibm/ibmvnic.c
index 50956f622b11..29cbf60dfd79 100644
--- a/drivers/net/ethernet/ibm/ibmvnic.c
+++ b/drivers/net/ethernet/ibm/ibmvnic.c
@@ -2755,7 +2755,7 @@ static int ibmvnic_reset(struct ibmvnic_adapter *adapter,
 
 	if (adapter->state == VNIC_PROBING) {
 		netdev_warn(netdev, "Adapter reset during probe\n");
-		adapter->init_done_rc = EAGAIN;
+		adapter->init_done_rc = -EAGAIN;
 		ret = EAGAIN;
 		goto err;
 	}
@@ -5266,11 +5266,6 @@ static void ibmvnic_handle_crq(union ibmvnic_crq *crq,
 			 */
 			adapter->login_pending = false;
 
-			if (!completion_done(&adapter->init_done)) {
-				complete(&adapter->init_done);
-				adapter->init_done_rc = -EIO;
-			}
-
 			if (adapter->state == VNIC_DOWN)
 				rc = ibmvnic_reset(adapter, VNIC_RESET_PASSIVE_INIT);
 			else
@@ -5291,6 +5286,13 @@ static void ibmvnic_handle_crq(union ibmvnic_crq *crq,
 					   rc);
 				adapter->failover_pending = false;
 			}
+
+			if (!completion_done(&adapter->init_done)) {
+				complete(&adapter->init_done);
+				if (!adapter->init_done_rc)
+					adapter->init_done_rc = -EAGAIN;
+			}
+
 			break;
 		case IBMVNIC_CRQ_INIT_COMPLETE:
 			dev_info(dev, "Partner initialization complete\n");
@@ -5763,7 +5765,7 @@ static int ibmvnic_probe(struct vio_dev *dev, const struct vio_device_id *id)
 		}
 
 		rc = ibmvnic_reset_init(adapter, false);
-	} while (rc == EAGAIN);
+	} while (rc == -EAGAIN);
 
 	/* We are ignoring the error from ibmvnic_reset_init() assuming that the
 	 * partner is not ready. CRQ is not active. When the partner becomes
-- 
2.26.2