From: Antoine Tenart <antoine.tenart@free-electrons.com>
Date: Mon, 23 Oct 2017 15:24:31 +0200
Subject: net: mvpp2: do not call txq_done from the Tx path when Tx irqs are
 used
Patch-mainline: v4.14-rc7
Git-commit: 082297e61480c4d72ed75b31077e74aca0e7c799
References: bsc#1098633

When Tx IRQs are used, txq_bufs_free() can be called from both the Tx
path and from NAPI poll(). This led to CPU stalls as if these two tasks
(Tx and Poll) are scheduled on two CPUs at the same time, DMA unmapping
operations are done on the same txq buffers.

This patch adds a check not to call txq_done() from the Tx path if Tx
interrupts are used as it does not make sense to do so.

Fixes: edc660fa09e2 ("net: mvpp2: replace TX coalescing interrupts with hrtimer")
Signed-off-by: Antoine Tenart <antoine.tenart@free-electrons.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Acked-by: Thomas Bogendoerfer <tbogendoerfer@suse.de>
---
 drivers/net/ethernet/marvell/mvpp2.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/net/ethernet/marvell/mvpp2.c
+++ b/drivers/net/ethernet/marvell/mvpp2.c
@@ -6499,7 +6499,7 @@ out:
 	}
 
 	/* Finalize TX processing */
-	if (txq_pcpu->count >= txq->done_pkts_coal)
+	if (!port->has_tx_irqs && txq_pcpu->count >= txq->done_pkts_coal)
 		mvpp2_txq_done(port, txq, txq_pcpu);
 
 	/* Set the timer in case not all frags were processed */