netdev - [PATCH net 06/11] qlcnic: remove ndo_poll

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Date:   Thu, 27 Sep 2018 09:31:56 -0700
From:   Eric Dumazet <edumazet@...gle.com>
To:     "David S . Miller" <davem@...emloft.net>
Cc:     netdev <netdev@...r.kernel.org>,
        Eric Dumazet <edumazet@...gle.com>,
        Michael Chan <michael.chan@...adcom.com>,
        Aviad Krawczyk <aviad.krawczyk@...wei.com>,
        Song Liu <songliubraving@...com>,
        Douglas Miller <dougmill@...ux.vnet.ibm.com>,
        Yisen Zhuang <yisen.zhuang@...wei.com>,
        "Michael S . Tsirkin" <mst@...hat.com>,
        Jason Wang <jasowang@...hat.com>,
        Harish Patil <harish.patil@...ium.com>,
        Manish Chopra <manish.chopra@...ium.com>,
        Netanel Belgazal <netanel@...zon.com>,
        Solarflare linux maintainers <linux-net-drivers@...arflare.com>,
        Thomas Falcon <tlfalcon@...ux.vnet.ibm.com>
Subject: [PATCH net 06/11] qlcnic: remove ndo_poll_controller

As diagnosed by Song Liu, ndo_poll_controller() can
be very dangerous on loaded hosts, since the cpu
calling ndo_poll_controller() might steal all NAPI
contexts (for all RX/TX queues of the NIC). This capture
can last for unlimited amount of time, since one
cpu is generally not able to drain all the queues under load.

qlcnic uses NAPI for TX completions, so we better let core
networking stack call the napi->poll() to avoid the capture.

Signed-off-by: Eric Dumazet <edumazet@...gle.com>
Cc: Harish Patil <harish.patil@...ium.com>
Cc: Manish Chopra <manish.chopra@...ium.com>
---
 .../net/ethernet/qlogic/qlcnic/qlcnic_main.c  | 45 -------------------
 1 file changed, 45 deletions(-)

diff --git a/drivers/net/ethernet/qlogic/qlcnic/qlcnic_main.c b/drivers/net/ethernet/qlogic/qlcnic/qlcnic_main.c
index 2d38d1ac2aae58fd210030c7b143011f76b921cc..dbd48012224f2467d27134eedc692a68b92b1a04 100644
--- a/drivers/net/ethernet/qlogic/qlcnic/qlcnic_main.c
+++ b/drivers/net/ethernet/qlogic/qlcnic/qlcnic_main.c
@@ -59,9 +59,6 @@ static int qlcnic_close(struct net_device *netdev);
 static void qlcnic_tx_timeout(struct net_device *netdev);
 static void qlcnic_attach_work(struct work_struct *work);
 static void qlcnic_fwinit_work(struct work_struct *work);
-#ifdef CONFIG_NET_POLL_CONTROLLER
-static void qlcnic_poll_controller(struct net_device *netdev);
-#endif
 
 static void qlcnic_idc_debug_info(struct qlcnic_adapter *adapter, u8 encoding);
 static int qlcnic_can_start_firmware(struct qlcnic_adapter *adapter);
@@ -545,9 +542,6 @@ static const struct net_device_ops qlcnic_netdev_ops = {
 	.ndo_udp_tunnel_add	= qlcnic_add_vxlan_port,
 	.ndo_udp_tunnel_del	= qlcnic_del_vxlan_port,
 	.ndo_features_check	= qlcnic_features_check,
-#ifdef CONFIG_NET_POLL_CONTROLLER
-	.ndo_poll_controller = qlcnic_poll_controller,
-#endif
 #ifdef CONFIG_QLCNIC_SRIOV
 	.ndo_set_vf_mac		= qlcnic_sriov_set_vf_mac,
 	.ndo_set_vf_rate	= qlcnic_sriov_set_vf_tx_rate,
@@ -3200,45 +3194,6 @@ static irqreturn_t qlcnic_msix_tx_intr(int irq, void *data)
 	return IRQ_HANDLED;
 }
 
-#ifdef CONFIG_NET_POLL_CONTROLLER
-static void qlcnic_poll_controller(struct net_device *netdev)
-{
-	struct qlcnic_adapter *adapter = netdev_priv(netdev);
-	struct qlcnic_host_sds_ring *sds_ring;
-	struct qlcnic_recv_context *recv_ctx;
-	struct qlcnic_host_tx_ring *tx_ring;
-	int ring;
-
-	if (!test_bit(__QLCNIC_DEV_UP, &adapter->state))
-		return;
-
-	recv_ctx = adapter->recv_ctx;
-
-	for (ring = 0; ring < adapter->drv_sds_rings; ring++) {
-		sds_ring = &recv_ctx->sds_rings[ring];
-		qlcnic_disable_sds_intr(adapter, sds_ring);
-		napi_schedule(&sds_ring->napi);
-	}
-
-	if (adapter->flags & QLCNIC_MSIX_ENABLED) {
-		/* Only Multi-Tx queue capable devices need to
-		 * schedule NAPI for TX rings
-		 */
-		if ((qlcnic_83xx_check(adapter) &&
-		     (adapter->flags & QLCNIC_TX_INTR_SHARED)) ||
-		    (qlcnic_82xx_check(adapter) &&
-		     !qlcnic_check_multi_tx(adapter)))
-			return;
-
-		for (ring = 0; ring < adapter->drv_tx_rings; ring++) {
-			tx_ring = &adapter->tx_ring[ring];
-			qlcnic_disable_tx_intr(adapter, tx_ring);
-			napi_schedule(&tx_ring->napi);
-		}
-	}
-}
-#endif
-
 static void
 qlcnic_idc_debug_info(struct qlcnic_adapter *adapter, u8 encoding)
 {
-- 
2.19.0.605.g01d371f741-goog