Hello,

Please picked up this patch for linux 4.4 and 4.9. Compiled/tested without problem.

Thank.

[ Upstream commit 44c445c3d1b4eacff23141fa7977c3b2ec3a45c9 ]

From: Vincenzo Maffione v.maffione@gmail.com Date: Sat, 16 Sep 2017 18:00:00 +0200 Subject: [PATCH] e1000: fix race condition between e1000_down() and e1000_watchdog

This patch fixes a race condition that can result into the interface being up and carrier on, but with transmits disabled in the hardware. The bug may show up by repeatedly IFF_DOWN+IFF_UP the interface, which allows e1000_watchdog() interleave with e1000_down().

CPU x CPU y -------------------------------------------------------------------- e1000_down(): netif_carrier_off() e1000_watchdog(): if (carrier == off) { netif_carrier_on(); enable_hw_transmit(); } disable_hw_transmit(); e1000_watchdog(): /* carrier on, do nothing */

Signed-off-by: Vincenzo Maffione v.maffione@gmail.com Tested-by: Aaron Brown aaron.f.brown@intel.com Signed-off-by: Jeff Kirsher jeffrey.t.kirsher@intel.com --- drivers/net/ethernet/intel/e1000/e1000_main.c | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/drivers/net/ethernet/intel/e1000/e1000_main.c b/drivers/net/ethernet/intel/e1000/e1000_main.c index 98375e1e1185e..1982f7917a8d5 100644 --- a/drivers/net/ethernet/intel/e1000/e1000_main.c +++ b/drivers/net/ethernet/intel/e1000/e1000_main.c @@ -520,8 +520,6 @@ void e1000_down(struct e1000_adapter *adapter) struct net_device *netdev = adapter->netdev; u32 rctl, tctl;

- netif_carrier_off(netdev); - /* disable receives in the hardware */ rctl = er32(RCTL); ew32(RCTL, rctl & ~E1000_RCTL_EN); @@ -537,6 +535,15 @@ void e1000_down(struct e1000_adapter *adapter) E1000_WRITE_FLUSH(); msleep(10);

+ /* Set the carrier off after transmits have been disabled in the + * hardware, to avoid race conditions with e1000_watchdog() (which + * may be running concurrently to us, checking for the carrier + * bit to decide whether it should enable transmits again). Such + * a race condition would result into transmission being disabled + * in the hardware until the next IFF_DOWN+IFF_UP cycle. + */ + netif_carrier_off(netdev); + napi_disable(&adapter->napi);

e1000_irq_disable(adapter);