gve: Fixes for napi_poll when budget is 0

Netpoll will explicilty pass the polling call with a budget of 0 to
indicate it's clearing the Tx path only. For the gve_rx_poll and
gve_xdp_poll, they were mistakenly taking the 0 budget as the indication
to do all the work. Add check to avoid the rx path and xdp path being
called when budget is 0. And also avoid napi_complete_done being called
when budget is 0 for netpoll.

Fixes: f5cedc8 ("gve: Add transmit and receive support")
Signed-off-by: Ziwei Xiao <ziweixiao@google.com>
Link: https://lore.kernel.org/r/20231114004144.2022268-1-ziweixiao@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

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

@@ -254,10 +254,13 @@ static int gve_napi_poll(struct napi_struct *napi, int budget)
 	if (block->tx) {
 		if (block->tx->q_num < priv->tx_cfg.num_queues)
 			reschedule |= gve_tx_poll(block, budget);
-		else
+		else if (budget)
 			reschedule |= gve_xdp_poll(block, budget);
 	}
 
+	if (!budget)
+		return 0;
+
 	if (block->rx) {
 		work_done = gve_rx_poll(block, budget);
 		reschedule |= work_done == budget;
@@ -298,6 +301,9 @@ static int gve_napi_poll_dqo(struct napi_struct *napi, int budget)
 	if (block->tx)
 		reschedule |= gve_tx_poll_dqo(block, /*do_clean=*/true);
 
+	if (!budget)
+		return 0;
+
 	if (block->rx) {
 		work_done = gve_rx_poll_dqo(block, budget);
 		reschedule |= work_done == budget;

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

@@ -1007,10 +1007,6 @@ int gve_rx_poll(struct gve_notify_block *block, int budget)
 
 	feat = block->napi.dev->features;
 
-	/* If budget is 0, do all the work */
-	if (budget == 0)
-		budget = INT_MAX;
-
 	if (budget > 0)
 		work_done = gve_clean_rx_done(rx, budget, feat);
 

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

@@ -925,10 +925,6 @@ bool gve_xdp_poll(struct gve_notify_block *block, int budget)
 	bool repoll;
 	u32 to_do;
 
-	/* If budget is 0, do all the work */
-	if (budget == 0)
-		budget = INT_MAX;
-
 	/* Find out how much work there is to be done */
 	nic_done = gve_tx_load_event_counter(priv, tx);
 	to_do = min_t(u32, (nic_done - tx->done), budget);