linux-kernel - [PATCH AUTOSEL 4.18 32/58] net: mvpp2: fix a txq

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Date:   Mon,  8 Oct 2018 11:24:57 -0400
From:   Sasha Levin <sashal@...nel.org>
To:     stable@...r.kernel.org, linux-kernel@...r.kernel.org
Cc:     Antoine Tenart <antoine.tenart@...tlin.com>,
        "David S . Miller" <davem@...emloft.net>,
        Sasha Levin <alexander.levin@...rosoft.com>
Subject: [PATCH AUTOSEL 4.18 32/58] net: mvpp2: fix a txq_done race condition

From: Antoine Tenart <antoine.tenart@...tlin.com>

[ Upstream commit 774268f3e51b53ed432a1ec516574fd5ba469398 ]

When no Tx IRQ is available, the txq_done() routine (called from
tx_done()) shouldn't be called from the polling function, as in such
case it is already called in the Tx path thanks to an hrtimer. This
mostly occurred when using PPv2.1, as the engine then do not have Tx
IRQs.

Fixes: edc660fa09e2 ("net: mvpp2: replace TX coalescing interrupts with hrtimer")
Reported-by: Stefan Chulski <stefanc@...vell.com>
Signed-off-by: Antoine Tenart <antoine.tenart@...tlin.com>
Signed-off-by: David S. Miller <davem@...emloft.net>
Signed-off-by: Sasha Levin <alexander.levin@...rosoft.com>
---
 drivers/net/ethernet/marvell/mvpp2/mvpp2_main.c | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/drivers/net/ethernet/marvell/mvpp2/mvpp2_main.c b/drivers/net/ethernet/marvell/mvpp2/mvpp2_main.c
index 661fa5a38df2..a1c7193cf858 100644
--- a/drivers/net/ethernet/marvell/mvpp2/mvpp2_main.c
+++ b/drivers/net/ethernet/marvell/mvpp2/mvpp2_main.c
@@ -3055,10 +3055,12 @@ static int mvpp2_poll(struct napi_struct *napi, int budget)
 				   cause_rx_tx & ~MVPP2_CAUSE_MISC_SUM_MASK);
 	}
 
-	cause_tx = cause_rx_tx & MVPP2_CAUSE_TXQ_OCCUP_DESC_ALL_MASK;
-	if (cause_tx) {
-		cause_tx >>= MVPP2_CAUSE_TXQ_OCCUP_DESC_ALL_OFFSET;
-		mvpp2_tx_done(port, cause_tx, qv->sw_thread_id);
+	if (port->has_tx_irqs) {
+		cause_tx = cause_rx_tx & MVPP2_CAUSE_TXQ_OCCUP_DESC_ALL_MASK;
+		if (cause_tx) {
+			cause_tx >>= MVPP2_CAUSE_TXQ_OCCUP_DESC_ALL_OFFSET;
+			mvpp2_tx_done(port, cause_tx, qv->sw_thread_id);
+		}
 	}
 
 	/* Process RX packets */
-- 
2.17.1