[PATCH net] 8139too: revisit napi_complete_done() usage

[Eric Dumazet]

From: Eric Dumazet <eduma...@google.com>

It seems we have to be more careful in napi_complete_done()
use. This patch is not a revert, as it seems we can
avoid bug that Ville reported by moving the napi_complete_done()
test in the spinlock section.

Many thanks to Ville for detective work and all tests.

Fixes: 617f01211baf ("8139too: use napi_complete_done()")
Reported-by: Ville Syrjälä <ville.syrj...@linux.intel.com>
Tested-by: Ville Syrjälä <ville.syrj...@linux.intel.com>
---
 drivers/net/ethernet/realtek/8139too.c |    5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/net/ethernet/realtek/8139too.c 
b/drivers/net/ethernet/realtek/8139too.c
index 
89631753e79962d91456d93b71929af768917da1..cd2dbec331dd796f5296cd378561b3443f231673
 100644
--- a/drivers/net/ethernet/realtek/8139too.c
+++ b/drivers/net/ethernet/realtek/8139too.c
@@ -2135,11 +2135,12 @@ static int rtl8139_poll(struct napi_struct *napi, int 
budget)
        if (likely(RTL_R16(IntrStatus) & RxAckBits))
                work_done += rtl8139_rx(dev, tp, budget);
 
-       if (work_done < budget && napi_complete_done(napi, work_done)) {
+       if (work_done < budget) {
                unsigned long flags;
 
                spin_lock_irqsave(&tp->lock, flags);
-               RTL_W16_F(IntrMask, rtl8139_intr_mask);
+               if (napi_complete_done(napi, work_done))
+                       RTL_W16_F(IntrMask, rtl8139_intr_mask);
                spin_unlock_irqrestore(&tp->lock, flags);
        }
        spin_unlock(&tp->rx_lock);