[NET]: Fix drivers to handle napi_disable() disabling interrupts.

When we add the generic napi_disable_pending() breakout
logic to net_rx_action() it means that napi_disable()
can cause NAPI poll interrupt events to be disabled.

And this is exactly what we want.  If a napi_disable()
is pending, and we are looping in the ->poll(), we want
->poll() event interrupts to stay disabled and we want
to complete the NAPI poll ASAP.

When ->poll() break out during device down was being handled on a
per-driver basis, often these drivers would turn interrupts back on
when '!netif_running()' was detected.

And this would just cause a reschedule of the NAPI ->poll() in the
interrupt handler before the napi_disable() could get in there and
grab the NAPI_STATE_SCHED bit.

The vast majority of drivers don't care if napi_disable() might have
the side effect of disabling NAPI ->poll() event interrupts.  In all
such cases, when a napi_disable() is performed, the driver just
disabled interrupts or is about to.

However there were three exceptions to this in PCNET32, R8169, and
SKY2.  To fix those cases, at the subsequent napi_enable() points, I
added code to ensure that the ->poll() interrupt events are enabled in
the hardware.

Signed-off-by: David S. Miller <davem@davemloft.net>
Acked-by:  Don Fry <pcnet32@verizon.net>

1 files changed, 3 insertions, 0 deletions

diff --git a/drivers/net/sky2.c b/drivers/net/sky2.c
index a74fc11a6482..52ec89b82f64 100644
--- a/drivers/net/sky2.c
+++ b/drivers/net/sky2.c
@@ -1168,6 +1168,7 @@ static void sky2_vlan_rx_register(struct net_device *dev, struct vlan_group *grp
                              TX_VLAN_TAG_OFF);
         }
 
+        sky2_read32(hw, B0_Y2_SP_LISR);
         napi_enable(&hw->napi);
         netif_tx_unlock_bh(dev);
 }
@@ -2043,6 +2044,7 @@ static int sky2_change_mtu(struct net_device *dev, int new_mtu)
         err = sky2_rx_start(sky2);
         sky2_write32(hw, B0_IMSK, imask);
 
+        sky2_read32(hw, B0_Y2_SP_LISR);
         napi_enable(&hw->napi);
 
         if (err)
@@ -3861,6 +3863,7 @@ static int sky2_debug_show(struct seq_file *seq, void *v)
                    last = sky2_read16(hw, Y2_QADDR(rxqaddr[port], PREF_UNIT_PUT_IDX)),
                    sky2_read16(hw, Y2_QADDR(rxqaddr[port], PREF_UNIT_LAST_IDX)));
 
+        sky2_read32(hw, B0_Y2_SP_LISR);
         napi_enable(&hw->napi);
         return 0;
 }