Patch "net: emac: Fix napi poll list corruption" has been added to the 4.13-stable tree

This is a note to let you know that I've just added the patch titled

net: emac: Fix napi poll list corruption

to the 4.13-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
net-emac-fix-napi-poll-list-corruption.patch
and it can be found in the queue-4.13 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Christian Lamparter <[email protected]>
Date: Tue, 19 Sep 2017 19:35:18 +0200
Subject: net: emac: Fix napi poll list corruption

From: Christian Lamparter <[email protected]>

[ Upstream commit f55956065ec94e3e9371463d693a1029c4cc3007 ]

This patch is pretty much a carbon copy of
commit 3079c652141f ("caif: Fix napi poll list corruption") with "caif" replaced by "emac".

The commit d75b1ade567f ("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.

---
 drivers/net/ethernet/ibm/emac/mal.c |    3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

@@ -402,7 +402,7 @@ static int mal_poll(struct napi_struct *
 	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 *
 			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);
 	}

Patches currently in stable-queue which might be from [email protected] are

queue-4.13/net-emac-fix-napi-poll-list-corruption.patch