8139too: revisit napi_complete_done() usage

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.syrjala@linux.intel.com>
Tested-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/drivers/net/ethernet/realtek/8139too.c b/drivers/net/ethernet/realtek/8139too.c
index ca22f2898664617656f7fa6e4e98df1e7aa3bc26..d24b47b8e0b27e0f44243f5a1011779c0ebd09f9 100644 (file)
--- 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);