net: emac: Fix napi poll list corruption

chunkeey · davem330 · commit f55956065ec9 · 2017-09-19T16:20:25.000-07:00
This patch is pretty much a carbon copy of commit 3079c65 ("caif: Fix napi poll list corruption") with "caif" replaced by "emac". The commit d75b1ad ("net: less interrupt masking in NAPI") breaks emac. It is now required that if the entire budget is consumed when poll returns, the napi poll_list must remain empty. However, like some other drivers emac tries to do a last-ditch check and if there is more work it will call napi_reschedule and then immediately process some of this new work. Should the entire budget be consumed while processing such new work then we will violate the new caller contract. This patch fixes this by not touching any work when we reschedule in emac. Signed-off-by: Christian Lamparter <chunkeey@googlemail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/net/ethernet/ibm/emac/mal.c b/drivers/net/ethernet/ibm/emac/mal.c
@@ -402,7 +402,7 @@ static int mal_poll(struct napi_struct *napi, int budget)
 	unsigned long flags;
 
 	MAL_DBG2(mal, "poll(%d)" NL, budget);
- again:
+
 	/* Process TX skbs */
 	list_for_each(l, &mal->poll_list) {
 		struct mal_commac *mc =
@@ -451,7 +451,6 @@ static int mal_poll(struct napi_struct *napi, int budget)
 			spin_lock_irqsave(&mal->lock, flags);
 			mal_disable_eob_irq(mal);
 			spin_unlock_irqrestore(&mal->lock, flags);
-			goto again;
 		}
 		mc->ops->poll_tx(mc->dev);
 	}
