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authorVincenzo Maffione <v.maffione@gmail.com>2017-09-16 19:00:00 +0300
committerJeff Kirsher <jeffrey.t.kirsher@intel.com>2017-10-26 17:42:57 +0300
commit44c445c3d1b4eacff23141fa7977c3b2ec3a45c9 (patch)
tree27f2d4565203b13f07fb9bd69615c179fed88008 /drivers
parent78e0ea6791d7baafb8a0ca82b1bd0c7b3453c919 (diff)
downloadlinux-44c445c3d1b4eacff23141fa7977c3b2ec3a45c9.tar.xz
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>
Diffstat (limited to 'drivers')
-rw-r--r--drivers/net/ethernet/intel/e1000/e1000_main.c11
1 files 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 98375e1e1185..1982f7917a8d 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);