[PATCH AUTOSEL 4.9 10/13] r8169: fix NAPI handling under high load

From: Sasha Levin
Date: Tue Oct 30 2018 - 09:30:53 EST

From: Heiner Kallweit <hkallweit1@xxxxxxxxx>

[ Upstream commit 6b839b6cf9eada30b086effb51e5d6076bafc761 ]

rtl_rx() and rtl_tx() are called only if the respective bits are set
in the interrupt status register. Under high load NAPI may not be
able to process all data (work_done == budget) and it will schedule
subsequent calls to the poll callback.
rtl_ack_events() however resets the bits in the interrupt status
register, therefore subsequent calls to rtl8169_poll() won't call
rtl_rx() and rtl_tx() - chip interrupts are still disabled.

Fix this by calling rtl_rx() and rtl_tx() independent of the bits
set in the interrupt status register. Both functions will detect
if there's nothing to do for them.

Fixes: da78dbff2e05 ("r8169: remove work from irq handler.")
Signed-off-by: Heiner Kallweit <hkallweit1@xxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
drivers/net/ethernet/realtek/r8169.c | 8 +++-----
1 file changed, 3 insertions(+), 5 deletions(-)

diff --git a/drivers/net/ethernet/realtek/r8169.c b/drivers/net/ethernet/realtek/r8169.c
index 20f5c0cabc89..24754d3fb0ac 100644
--- a/drivers/net/ethernet/realtek/r8169.c
+++ b/drivers/net/ethernet/realtek/r8169.c
@@ -7559,17 +7559,15 @@ static int rtl8169_poll(struct napi_struct *napi, int budget)
struct rtl8169_private *tp = container_of(napi, struct rtl8169_private, napi);
struct net_device *dev = tp->dev;
u16 enable_mask = RTL_EVENT_NAPI | tp->event_slow;
- int work_done= 0;
+ int work_done;
u16 status;

status = rtl_get_events(tp);
rtl_ack_events(tp, status & ~tp->event_slow);

- if (status & RTL_EVENT_NAPI_RX)
- work_done = rtl_rx(dev, tp, (u32) budget);
+ work_done = rtl_rx(dev, tp, (u32) budget);

- if (status & RTL_EVENT_NAPI_TX)
- rtl_tx(dev, tp);
+ rtl_tx(dev, tp);

if (status & tp->event_slow) {
enable_mask &= ~tp->event_slow;