2018-09-18 14:59:51

by Antoine Tenart

Subject: [PATCH net] net: mvpp2: fix a txq_done race condition

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 <[email protected]>
Signed-off-by: Antoine Tenart <[email protected]>
---
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 702fec82d806..38cc01beea79 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

2018-09-19 03:14:47

by David Miller

Subject: Re: [PATCH net] net: mvpp2: fix a txq_done race condition

From: Antoine Tenart <[email protected]>
Date: Tue, 18 Sep 2018 16:58:47 +0200

> 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 <[email protected]>
> Signed-off-by: Antoine Tenart <[email protected]>

Applied and queued up for -stable.