ibm emac: Don't call napi_complete if napi_reschedule failed

This patch fixes a bug which would trigger the BUG_ON() at
net/core/dev.c:4156. It was found that this was due to continuing
processing in the current poll call even when the call to
napi_reschedule failed, indicating the device was already on the
polling list. This resulted in an extra call to napi_complete which
triggered the BUG_ON().

This patch ensures that we only contine processing rotting packets in
the current mal_poll call if we are not already on the polling list.

Signed-off-by: Alistair Popple <alistair@popple.id.au>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 4 insertions, 8 deletions

diff --git a/drivers/net/ethernet/ibm/emac/mal.c b/drivers/net/ethernet/ibm/emac/mal.c
index dac564c25440..909f9b6698b5 100644
--- a/drivers/net/ethernet/ibm/emac/mal.c
+++ b/drivers/net/ethernet/ibm/emac/mal.c
@@ -442,15 +442,11 @@ static int mal_poll(struct napi_struct *napi, int budget)
                 if (unlikely(mc->ops->peek_rx(mc->dev) ||
                              test_bit(MAL_COMMAC_RX_STOPPED, &mc->flags))) {
                         MAL_DBG2(mal, "rotting packet" NL);
-                        if (napi_reschedule(napi))
-                                mal_disable_eob_irq(mal);
-                        else
-                                MAL_DBG2(mal, "already in poll list" NL);
-
-                        if (budget > 0)
-                                goto again;
-                        else
+                        if (!napi_reschedule(napi))
                                 goto more_work;
+
+                        mal_disable_eob_irq(mal);
+                        goto again;
                 }
                 mc->ops->poll_tx(mc->dev);
         }