netdev - [PATCH net 07/11] qlogic: netxen: remove ndo_poll

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Message-Id: <20180927163201.56609-8-edumazet@google.com>
Date:   Thu, 27 Sep 2018 09:31:57 -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>,
        Rahul Verma <rahul.verma@...ium.com>
Subject: [PATCH net 07/11] qlogic: netxen: 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.

netxen 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: Manish Chopra <manish.chopra@...ium.com>
Cc: Rahul Verma <rahul.verma@...ium.com>
---
 .../ethernet/qlogic/netxen/netxen_nic_main.c  | 23 -------------------
 1 file changed, 23 deletions(-)

diff --git a/drivers/net/ethernet/qlogic/netxen/netxen_nic_main.c b/drivers/net/ethernet/qlogic/netxen/netxen_nic_main.c
index 69aa7fc392c5e4ad1cbcd9025f56bffdf3aa92c7..59c70be22a84c11262388529cf0ddf09887cea96 100644
--- a/drivers/net/ethernet/qlogic/netxen/netxen_nic_main.c
+++ b/drivers/net/ethernet/qlogic/netxen/netxen_nic_main.c
@@ -72,9 +72,6 @@ static void netxen_schedule_work(struct netxen_adapter *adapter,
 		work_func_t func, int delay);
 static void netxen_cancel_fw_work(struct netxen_adapter *adapter);
 static int netxen_nic_poll(struct napi_struct *napi, int budget);
-#ifdef CONFIG_NET_POLL_CONTROLLER
-static void netxen_nic_poll_controller(struct net_device *netdev);
-#endif
 
 static void netxen_create_sysfs_entries(struct netxen_adapter *adapter);
 static void netxen_remove_sysfs_entries(struct netxen_adapter *adapter);
@@ -581,9 +578,6 @@ static const struct net_device_ops netxen_netdev_ops = {
 	.ndo_tx_timeout	   = netxen_tx_timeout,
 	.ndo_fix_features = netxen_fix_features,
 	.ndo_set_features = netxen_set_features,
-#ifdef CONFIG_NET_POLL_CONTROLLER
-	.ndo_poll_controller = netxen_nic_poll_controller,
-#endif
 };
 
 static inline bool netxen_function_zero(struct pci_dev *pdev)
@@ -2402,23 +2396,6 @@ static int netxen_nic_poll(struct napi_struct *napi, int budget)
 	return work_done;
 }
 
-#ifdef CONFIG_NET_POLL_CONTROLLER
-static void netxen_nic_poll_controller(struct net_device *netdev)
-{
-	int ring;
-	struct nx_host_sds_ring *sds_ring;
-	struct netxen_adapter *adapter = netdev_priv(netdev);
-	struct netxen_recv_context *recv_ctx = &adapter->recv_ctx;
-
-	disable_irq(adapter->irq);
-	for (ring = 0; ring < adapter->max_sds_rings; ring++) {
-		sds_ring = &recv_ctx->sds_rings[ring];
-		netxen_intr(adapter->irq, sds_ring);
-	}
-	enable_irq(adapter->irq);
-}
-#endif
-
 static int
 nx_incr_dev_ref_cnt(struct netxen_adapter *adapter)
 {
-- 
2.19.0.605.g01d371f741-goog