[PATCH net-next v1 04/14] amd-xgbe: Add a check for an skb in the timestamp path

[Tom Lendacky]

Spurious Tx timestamp interrupts can cause an oops in the Tx timestamp
processing function if a Tx timestamp skb is NULL. Add a check to insure
a Tx timestamp skb is present before attempting to use it.

Signed-off-by: Tom Lendacky <thomas.lenda...@amd.com>
---
 drivers/net/ethernet/amd/xgbe/xgbe-drv.c |    7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/amd/xgbe/xgbe-drv.c 
b/drivers/net/ethernet/amd/xgbe/xgbe-drv.c
index a934bd5..2068510 100644
--- a/drivers/net/ethernet/amd/xgbe/xgbe-drv.c
+++ b/drivers/net/ethernet/amd/xgbe/xgbe-drv.c
@@ -1212,6 +1212,10 @@ static void xgbe_tx_tstamp(struct work_struct *work)
        u64 nsec;
        unsigned long flags;
 
+       spin_lock_irqsave(&pdata->tstamp_lock, flags);
+       if (!pdata->tx_tstamp_skb)
+               goto unlock;
+
        if (pdata->tx_tstamp) {
                nsec = timecounter_cyc2time(&pdata->tstamp_tc,
                                            pdata->tx_tstamp);
@@ -1223,8 +1227,9 @@ static void xgbe_tx_tstamp(struct work_struct *work)
 
        dev_kfree_skb_any(pdata->tx_tstamp_skb);
 
-       spin_lock_irqsave(&pdata->tstamp_lock, flags);
        pdata->tx_tstamp_skb = NULL;
+
+unlock:
        spin_unlock_irqrestore(&pdata->tstamp_lock, flags);
 }