gve: Fix XDP TX completion handling when counters overflow

[ Upstream commit 03b54ba ]

In gve_clean_xdp_done, the driver processes the TX completions based on
a 32-bit NIC counter and a 32-bit completion counter stored in the tx
queue.

Fix the for loop so that the counter wraparound is handled correctly.

Fixes: 75eaae1 ("gve: Add XDP DROP and TX support for GQI-QPL format")
Signed-off-by: Joshua Washington <[email protected]>
Signed-off-by: Praveen Kaligineedi <[email protected]>
Reviewed-by: Simon Horman <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Jakub Kicinski <[email protected]>
Signed-off-by: Sasha Levin <[email protected]>

drivers/net/ethernet/google/gve/gve_tx.c

@@ -158,15 +158,16 @@ static int gve_clean_xdp_done(struct gve_priv *priv, struct gve_tx_ring *tx,
 			      u32 to_do)
 {
 	struct gve_tx_buffer_state *info;
-	u32 clean_end = tx->done + to_do;
 	u64 pkts = 0, bytes = 0;
 	size_t space_freed = 0;
 	u32 xsk_complete = 0;
 	u32 idx;
+	int i;
 
-	for (; tx->done < clean_end; tx->done++) {
+	for (i = 0; i < to_do; i++) {
 		idx = tx->done & tx->mask;
 		info = &tx->info[idx];
+		tx->done++;
 
 		if (unlikely(!info->xdp.size))
 			continue;