netdev - [PATCH v2 2/2] ibmvnic: fix race with multiple open/close

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Date:   Tue,  2 Feb 2021 21:06:50 -0800
From:   Sukadev Bhattiprolu <sukadev@...ux.ibm.com>
To:     netdev@...r.kernel.org
Cc:     Dany Madden <drt@...ux.ibm.com>, Lijun Pan <ljp@...ux.ibm.com>,
        Rick Lindsley <ricklind@...ux.ibm.com>, abdhalee@...ibm.com,
        sukadev@...ux.ibm.com
Subject: [PATCH v2 2/2] ibmvnic: fix race with multiple open/close

If two or more instances of 'ip link set' commands race and first one
already brings the interface up (or down), the subsequent instances
can simply return without redoing the up/down operation.

Fixes: ed651a10875f ("ibmvnic: Updated reset handling")
Reported-by: Abdul Haleem <abdhalee@...ibm.com>
Tested-by: Abdul Haleem <abdhalee@...ibm.com>
Signed-off-by: Sukadev Bhattiprolu <sukadev@...ux.ibm.com>

---
Changelog[v2] For consistency with ibmvnic_open() use "goto out" and return
	      from end of function.
---
 drivers/net/ethernet/ibm/ibmvnic.c | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/drivers/net/ethernet/ibm/ibmvnic.c b/drivers/net/ethernet/ibm/ibmvnic.c
index 78d244aeee69..df1b4884b4e8 100644
--- a/drivers/net/ethernet/ibm/ibmvnic.c
+++ b/drivers/net/ethernet/ibm/ibmvnic.c
@@ -1219,6 +1219,14 @@ static int ibmvnic_open(struct net_device *netdev)
 		goto out;
 	}
 
+	/* If adapter is already open, we don't have to do anything. */
+	if (adapter->state == VNIC_OPEN) {
+		netdev_dbg(netdev, "[S:%d] adapter already open\n",
+			   adapter->state);
+		rc = 0;
+		goto out;
+	}
+
 	if (adapter->state != VNIC_CLOSED) {
 		rc = ibmvnic_login(netdev);
 		if (rc)
@@ -1392,6 +1400,12 @@ static int ibmvnic_close(struct net_device *netdev)
 		return 0;
 	}
 
+	/* If adapter is already closed, we don't have to do anything. */
+	if (adapter->state == VNIC_CLOSED) {
+		netdev_dbg(netdev, "[S:%d] adapter already closed\n",
+			   adapter->state);
+		return 0;
+	}
 	rc = __ibmvnic_close(netdev);
 	ibmvnic_cleanup(netdev);
 
-- 
2.26.2