netdev - [PATCH net-next 2/2] r8169: remove member irq_enabled from struct rtl8169

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Date:   Wed, 19 Aug 2020 13:03:13 +0200
From:   Heiner Kallweit <hkallweit1@...il.com>
To:     Jakub Kicinski <kuba@...nel.org>,
        Realtek linux nic maintainers <nic_swsd@...ltek.com>,
        David Miller <davem@...emloft.net>
Cc:     "netdev@...r.kernel.org" <netdev@...r.kernel.org>
Subject: [PATCH net-next 2/2] r8169: remove member irq_enabled from struct
 rtl8169_private

After making use of the gro_flush_timeout attribute I once got a
tx timeout due to an interrupt that wasn't handled. Seems using
irq_enabled can be racy, and it's not needed any longer anyway,
so remove it. I've never seen a report about such a race before,
therefore treat the change as an improvement.

There's just one small drawback: If a legacy PCI interrupt is used,
and if this interrupt is shared with a device with high interrupt
rate, then we may handle interrupts even if NAPI disabled them,
and we may see a certain performance decrease under high network load.

Signed-off-by: Heiner Kallweit <hkallweit1@...il.com>
---
 drivers/net/ethernet/realtek/r8169_main.c | 6 +-----
 1 file changed, 1 insertion(+), 5 deletions(-)

diff --git a/drivers/net/ethernet/realtek/r8169_main.c b/drivers/net/ethernet/realtek/r8169_main.c
index dbc324c53..c427865d5 100644
--- a/drivers/net/ethernet/realtek/r8169_main.c
+++ b/drivers/net/ethernet/realtek/r8169_main.c
@@ -617,7 +617,6 @@ struct rtl8169_private {
 		struct work_struct work;
 	} wk;
 
-	unsigned irq_enabled:1;
 	unsigned supports_gmii:1;
 	unsigned aspm_manageable:1;
 	dma_addr_t counters_phys_addr;
@@ -1280,12 +1279,10 @@ static void rtl_irq_disable(struct rtl8169_private *tp)
 		RTL_W32(tp, IntrMask_8125, 0);
 	else
 		RTL_W16(tp, IntrMask, 0);
-	tp->irq_enabled = 0;
 }
 
 static void rtl_irq_enable(struct rtl8169_private *tp)
 {
-	tp->irq_enabled = 1;
 	if (rtl_is_8125(tp))
 		RTL_W32(tp, IntrMask_8125, tp->irq_mask);
 	else
@@ -4541,8 +4538,7 @@ static irqreturn_t rtl8169_interrupt(int irq, void *dev_instance)
 	struct rtl8169_private *tp = dev_instance;
 	u32 status = rtl_get_events(tp);
 
-	if (!tp->irq_enabled || (status & 0xffff) == 0xffff ||
-	    !(status & tp->irq_mask))
+	if ((status & 0xffff) == 0xffff || !(status & tp->irq_mask))
 		return IRQ_NONE;
 
 	if (unlikely(status & SYSErr)) {
-- 
2.28.0