netdev - [RFC PATCH 1/3] chelsio: cxgb: Remove ndo_poll

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Date:   Thu, 24 Dec 2020 14:11:46 +0100
From:   "Ahmed S. Darwish" <a.darwish@...utronix.de>
To:     Rahul Lakkireddy <rahul.lakkireddy@...lsio.com>,
        Rohit Maheshwari <rohitm@...lsio.com>,
        Vinay Kumar Yadav <vinay.yadav@...lsio.com>,
        Vishal Kulkarni <vishal@...lsio.com>, netdev@...r.kernel.org
Cc:     "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        "Sebastian A. Siewior" <bigeasy@...utronix.de>,
        "Ahmed S. Darwish" <a.darwish@...utronix.de>
Subject: [RFC PATCH 1/3] chelsio: cxgb: Remove ndo_poll_controller()

Since commit ac3d9dd034e5 ("netpoll: make ndo_poll_controller()
optional"), networking drivers which use NAPI for clearing their TX
completions should not provide an ndo_poll_controller(). Netpoll simply
triggers the necessary TX queues cleanup by synchronously calling the
driver's NAPI poll handler -- with irqs off and a zero budget.

Modify the cxgb's poll method to clear the TX queues upon zero budget.
Per API requirements, make sure to never consume any RX packet in that
case (budget=0), and thus also not to increment the budget upon return.

Afterwards, remove ndo_poll_controller().

Link: https://lkml.kernel.org/r/20180921222752.101307-1-edumazet@google.com
Link: https://lkml.kernel.org/r/A782704A-DF97-4E85-B10A-D2268A67DFD7@fb.com
References: 822d54b9c2c1 ("netpoll: Drop budget parameter from NAPI polling call hierarchy")
Signed-off-by: Ahmed S. Darwish <a.darwish@...utronix.de>
Cc: Eric Dumazet <edumazet@...gle.com>
---
 drivers/net/ethernet/chelsio/cxgb/cxgb2.c | 14 --------------
 drivers/net/ethernet/chelsio/cxgb/sge.c   |  9 ++++++++-
 2 files changed, 8 insertions(+), 15 deletions(-)

diff --git a/drivers/net/ethernet/chelsio/cxgb/cxgb2.c b/drivers/net/ethernet/chelsio/cxgb/cxgb2.c
index 0e4a0f413960..7b5a98330ef7 100644
--- a/drivers/net/ethernet/chelsio/cxgb/cxgb2.c
+++ b/drivers/net/ethernet/chelsio/cxgb/cxgb2.c
@@ -878,17 +878,6 @@ static int t1_set_features(struct net_device *dev, netdev_features_t features)
 
 	return 0;
 }
-#ifdef CONFIG_NET_POLL_CONTROLLER
-static void t1_netpoll(struct net_device *dev)
-{
-	unsigned long flags;
-	struct adapter *adapter = dev->ml_priv;
-
-	local_irq_save(flags);
-	t1_interrupt(adapter->pdev->irq, adapter);
-	local_irq_restore(flags);
-}
-#endif
 
 /*
  * Periodic accumulation of MAC statistics.  This is used only if the MAC
@@ -973,9 +962,6 @@ static const struct net_device_ops cxgb_netdev_ops = {
 	.ndo_set_mac_address	= t1_set_mac_addr,
 	.ndo_fix_features	= t1_fix_features,
 	.ndo_set_features	= t1_set_features,
-#ifdef CONFIG_NET_POLL_CONTROLLER
-	.ndo_poll_controller	= t1_netpoll,
-#endif
 };
 
 static int init_one(struct pci_dev *pdev, const struct pci_device_id *ent)
diff --git a/drivers/net/ethernet/chelsio/cxgb/sge.c b/drivers/net/ethernet/chelsio/cxgb/sge.c
index 2d9c2b5a690a..d6df1a87db0b 100644
--- a/drivers/net/ethernet/chelsio/cxgb/sge.c
+++ b/drivers/net/ethernet/chelsio/cxgb/sge.c
@@ -1609,7 +1609,14 @@ static int process_pure_responses(struct adapter *adapter)
 int t1_poll(struct napi_struct *napi, int budget)
 {
 	struct adapter *adapter = container_of(napi, struct adapter, napi);
-	int work_done = process_responses(adapter, budget);
+	int work_done = 0;
+
+	if (budget)
+		work_done = process_responses(adapter, budget);
+	else {
+		/* budget=0 means: don't poll rx data */
+		process_pure_responses(adapter);
+	}
 
 	if (likely(work_done < budget)) {
 		napi_complete_done(napi, work_done);
-- 
2.29.2