netdev - [PATCH v2 net] ionic: minimal work with 0 budget

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Date: Fri, 9 Feb 2024 16:13:07 -0800
From: Shannon Nelson <shannon.nelson@....com>
To: <netdev@...r.kernel.org>, <davem@...emloft.net>, <kuba@...nel.org>,
	<edumazet@...gle.com>, <pabeni@...hat.com>
CC: <brett.creeley@....com>, <drivers@...sando.io>, Shannon Nelson
	<shannon.nelson@....com>
Subject: [PATCH v2 net] ionic: minimal work with 0 budget

We should be doing as little as possible besides freeing Tx
space when our napi routines are called with budget of 0, so
jump out before doing anything besides Tx cleaning.

See commit afbed3f74830 ("net/mlx5e: do as little as possible in napi poll when budget is 0")
for more info.

Fixes: fe8c30b50835 ("ionic: separate interrupt for Tx and Rx")
Reviewed-by: Brett Creeley <brett.creeley@....com>
Signed-off-by: Shannon Nelson <shannon.nelson@....com>
---

v2: separated this out from a net-next patchset
    https://lore.kernel.org/netdev/20240208005725.65134-1-shannon.nelson@amd.com/

 drivers/net/ethernet/pensando/ionic/ionic_txrx.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/drivers/net/ethernet/pensando/ionic/ionic_txrx.c b/drivers/net/ethernet/pensando/ionic/ionic_txrx.c
index 54cd96b035d6..6f4776759863 100644
--- a/drivers/net/ethernet/pensando/ionic/ionic_txrx.c
+++ b/drivers/net/ethernet/pensando/ionic/ionic_txrx.c
@@ -579,6 +579,9 @@ int ionic_tx_napi(struct napi_struct *napi, int budget)
 	work_done = ionic_cq_service(cq, budget,
 				     ionic_tx_service, NULL, NULL);
 
+	if (unlikely(!budget))
+		return budget;
+
 	if (work_done < budget && napi_complete_done(napi, work_done)) {
 		ionic_dim_update(qcq, IONIC_LIF_F_TX_DIM_INTR);
 		flags |= IONIC_INTR_CRED_UNMASK;
@@ -607,6 +610,9 @@ int ionic_rx_napi(struct napi_struct *napi, int budget)
 	u32 work_done = 0;
 	u32 flags = 0;
 
+	if (unlikely(!budget))
+		return budget;
+
 	lif = cq->bound_q->lif;
 	idev = &lif->ionic->idev;
 
@@ -656,6 +662,9 @@ int ionic_txrx_napi(struct napi_struct *napi, int budget)
 	tx_work_done = ionic_cq_service(txcq, IONIC_TX_BUDGET_DEFAULT,
 					ionic_tx_service, NULL, NULL);
 
+	if (unlikely(!budget))
+		return budget;
+
 	rx_work_done = ionic_cq_service(rxcq, budget,
 					ionic_rx_service, NULL, NULL);
 
-- 
2.17.1