[PATCH 3.16 318/328] r8169: fix NAPI handling under high load

From: Ben Hutchings
Date: Sun Dec 09 2018 - 17:03:26 EST

3.16.62-rc1 review patch. If anyone has any objections, please let me know.


From: Heiner Kallweit <hkallweit1@xxxxxxxxx>

commit 6b839b6cf9eada30b086effb51e5d6076bafc761 upstream.

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: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
drivers/net/ethernet/realtek/r8169.c | 8 +++-----
1 file changed, 3 insertions(+), 5 deletions(-)

--- a/drivers/net/ethernet/realtek/r8169.c
+++ b/drivers/net/ethernet/realtek/r8169.c
@@ -6417,17 +6417,15 @@ static int rtl8169_poll(struct napi_stru
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;