[PATCH 5.12 484/700] ibmvnic: account for bufs already saved in indir_buf

[Greg Kroah-Hartman]

From: Sukadev Bhattiprolu <sukadev@xxxxxxxxxxxxx>

[ Upstream commit 72368f8b2b9e4106072a2728bed3367d54641c22 ]

This fixes a crash in replenish_rx_pool() when called from ibmvnic_poll()
after a previous call to replenish_rx_pool() encountered an error when
allocating a socket buffer.

Thanks to Rick Lindsley and Dany Madden for helping debug the crash.

Fixes: 4f0b6812e9b9 ("ibmvnic: Introduce batched RX buffer descriptor transmission")
Signed-off-by: Sukadev Bhattiprolu <sukadev@xxxxxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 drivers/net/ethernet/ibm/ibmvnic.c | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/ibm/ibmvnic.c b/drivers/net/ethernet/ibm/ibmvnic.c
index e8f4bdb1079c..f1a6f454fe97 100644
--- a/drivers/net/ethernet/ibm/ibmvnic.c
+++ b/drivers/net/ethernet/ibm/ibmvnic.c
@@ -328,7 +328,14 @@ static void replenish_rx_pool(struct ibmvnic_adapter *adapter,
 
 	rx_scrq = adapter->rx_scrq[pool->index];
 	ind_bufp = &rx_scrq->ind_buf;
-	for (i = 0; i < count; ++i) {
+
+	/* netdev_skb_alloc() could have failed after we saved a few skbs
+	 * in the indir_buf and we would not have sent them to VIOS yet.
+	 * To account for them, start the loop at ind_bufp->index rather
+	 * than 0. If we pushed all the skbs to VIOS, ind_bufp->index will
+	 * be 0.
+	 */
+	for (i = ind_bufp->index; i < count; ++i) {
 		skb = netdev_alloc_skb(adapter->netdev, pool->buff_size);
 		if (!skb) {
 			dev_err(dev, "Couldn't replenish rx buff\n");
-- 
2.30.2