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8139too: revisit napi_complete_done() usage
authorEric Dumazet <edumazet@google.com>
Mon, 18 Sep 2017 20:03:43 +0000 (13:03 -0700)
committerDavid S. Miller <davem@davemloft.net>
Tue, 19 Sep 2017 03:57:00 +0000 (20:57 -0700)
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>
drivers/net/ethernet/realtek/8139too.c

index ca22f28..d24b47b 100644 (file)
@@ -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);