netdev - [PATCH 1/3] Partial revert "e1000e: Avoid receiver overrun interrupt bursts"

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Message-Id: <20180126091236.13044-2-bpoirier@suse.com>
Date:   Fri, 26 Jan 2018 18:12:34 +0900
From:   Benjamin Poirier <bpoirier@...e.com>
To:     Jeff Kirsher <jeffrey.t.kirsher@...el.com>
Cc:     Alexander Duyck <alexander.duyck@...il.com>,
        intel-wired-lan@...ts.osuosl.org, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH 1/3] Partial revert "e1000e: Avoid receiver overrun interrupt bursts"

This reverts commit 4aea7a5c5e940c1723add439f4088844cd26196d.

We keep the fix for the first part of the problem (1) described in the log
of that commit however we use the implementation of e1000_msix_other() from
before commit 16ecba59bc33 ("e1000e: Do not read ICR in Other interrupt").
We remove the fix for the second part of the problem (2).

Bursts of "Other" interrupts may once again occur during rxo (receive
overflow) traffic conditions. This is deemed acceptable in the interest of
reverting driver code back to its previous state. The e1000e driver should
be in "maintenance" mode and we want to avoid unforeseen fallout from
changes that are not strictly necessary.

Link: https://www.spinics.net/lists/netdev/msg480675.html
Signed-off-by: Benjamin Poirier <bpoirier@...e.com>
---
 drivers/net/ethernet/intel/e1000e/defines.h |  1 -
 drivers/net/ethernet/intel/e1000e/netdev.c  | 32 +++++++++++------------------
 2 files changed, 12 insertions(+), 21 deletions(-)

diff --git a/drivers/net/ethernet/intel/e1000e/defines.h b/drivers/net/ethernet/intel/e1000e/defines.h
index afb7ebe20b24..0641c0098738 100644
--- a/drivers/net/ethernet/intel/e1000e/defines.h
+++ b/drivers/net/ethernet/intel/e1000e/defines.h
@@ -398,7 +398,6 @@
 #define E1000_ICR_LSC           0x00000004 /* Link Status Change */
 #define E1000_ICR_RXSEQ         0x00000008 /* Rx sequence error */
 #define E1000_ICR_RXDMT0        0x00000010 /* Rx desc min. threshold (0) */
-#define E1000_ICR_RXO           0x00000040 /* Receiver Overrun */
 #define E1000_ICR_RXT0          0x00000080 /* Rx timer intr (ring 0) */
 #define E1000_ICR_ECCER         0x00400000 /* Uncorrectable ECC Error */
 /* If this bit asserted, the driver should claim the interrupt */
diff --git a/drivers/net/ethernet/intel/e1000e/netdev.c b/drivers/net/ethernet/intel/e1000e/netdev.c
index 9f18d39bdc8f..398e940436f8 100644
--- a/drivers/net/ethernet/intel/e1000e/netdev.c
+++ b/drivers/net/ethernet/intel/e1000e/netdev.c
@@ -1914,30 +1914,23 @@ static irqreturn_t e1000_msix_other(int __always_unused irq, void *data)
 	struct net_device *netdev = data;
 	struct e1000_adapter *adapter = netdev_priv(netdev);
 	struct e1000_hw *hw = &adapter->hw;
-	u32 icr;
-	bool enable = true;
-
-	icr = er32(ICR);
-	if (icr & E1000_ICR_RXO) {
-		ew32(ICR, E1000_ICR_RXO);
-		enable = false;
-		/* napi poll will re-enable Other, make sure it runs */
-		if (napi_schedule_prep(&adapter->napi)) {
-			adapter->total_rx_bytes = 0;
-			adapter->total_rx_packets = 0;
-			__napi_schedule(&adapter->napi);
-		}
-	}
-	if (icr & E1000_ICR_LSC) {
-		ew32(ICR, E1000_ICR_LSC);
+	u32 icr = er32(ICR);
+
+	if (icr & adapter->eiac_mask)
+		ew32(ICS, (icr & adapter->eiac_mask));
+
+	if (icr & E1000_ICR_OTHER) {
+		if (!(icr & E1000_ICR_LSC))
+			goto no_link_interrupt;
 		hw->mac.get_link_status = true;
 		/* guard against interrupt when we're going down */
 		if (!test_bit(__E1000_DOWN, &adapter->state))
 			mod_timer(&adapter->watchdog_timer, jiffies + 1);
 	}
 
-	if (enable && !test_bit(__E1000_DOWN, &adapter->state))
-		ew32(IMS, E1000_IMS_OTHER);
+no_link_interrupt:
+	if (!test_bit(__E1000_DOWN, &adapter->state))
+		ew32(IMS, E1000_IMS_LSC | E1000_IMS_OTHER);
 
 	return IRQ_HANDLED;
 }
@@ -2707,8 +2700,7 @@ static int e1000e_poll(struct napi_struct *napi, int weight)
 		napi_complete_done(napi, work_done);
 		if (!test_bit(__E1000_DOWN, &adapter->state)) {
 			if (adapter->msix_entries)
-				ew32(IMS, adapter->rx_ring->ims_val |
-				     E1000_IMS_OTHER);
+				ew32(IMS, adapter->rx_ring->ims_val);
 			else
 				e1000_irq_enable(adapter);
 		}
-- 
2.15.1