From mboxrd@z Thu Jan 1 00:00:00 1970 From: Simon Guinot Subject: [PATCH] net: mvneta: fix handling of the Tx descriptor counter Date: Wed, 8 Nov 2017 17:58:35 +0100 Message-ID: <20171108165835.13453-1-simon.guinot@sequanux.org> References: Cc: netdev@vger.kernel.org, =?UTF-8?q?Sven=20M=C3=BCller?= , Andreas Tobler , =?UTF-8?q?Gr=C3=A9gory=20Clement?= , =?UTF-8?q?Antoine=20T=C3=A9nart?= , Marcin Wojtas , Simon Guinot , stable@vger.kernel.org To: Thomas Petazzoni Return-path: Received: from vm1.sequanux.org ([188.165.36.56]:33806 "EHLO vm1.sequanux.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752364AbdKHQ6j (ORCPT ); Wed, 8 Nov 2017 11:58:39 -0500 In-Reply-To: Sender: netdev-owner@vger.kernel.org List-ID: The mvneta controller provides a 8-bit register to update the pending Tx descriptor counter. Then, a maximum of 255 Tx descriptors can be added at once. In the current code the mvneta_txq_pend_desc_add function assumes the caller takes care of this limit. But it is not the case. In some situations (xmit_more flag), more than 255 descriptors are added. When this happens, the Tx descriptor counter register is updated with a wrong value, which breaks the whole Tx queue management. This patch fixes the issue by allowing the mvneta_txq_pend_desc_add function to process more than 255 Tx descriptors. Fixes: 2a90f7e1d5d0 ("net: mvneta: add xmit_more support") Cc: stable@vger.kernel.org # 4.11+ Signed-off-by: Simon Guinot --- drivers/net/ethernet/marvell/mvneta.c | 16 +++++++++------- 1 file changed, 9 insertions(+), 7 deletions(-) diff --git a/drivers/net/ethernet/marvell/mvneta.c b/drivers/net/ethernet/marvell/mvneta.c index 64a04975bcf8..027c08ce4e5d 100644 --- a/drivers/net/ethernet/marvell/mvneta.c +++ b/drivers/net/ethernet/marvell/mvneta.c @@ -816,11 +816,14 @@ static void mvneta_txq_pend_desc_add(struct mvneta_port *pp, { u32 val; - /* Only 255 descriptors can be added at once ; Assume caller - * process TX desriptors in quanta less than 256 - */ - val = pend_desc + txq->pending; - mvreg_write(pp, MVNETA_TXQ_UPDATE_REG(txq->id), val); + pend_desc += txq->pending; + + /* Only 255 Tx descriptors can be added at once */ + while (pend_desc > 0) { + val = min(pend_desc, 255); + mvreg_write(pp, MVNETA_TXQ_UPDATE_REG(txq->id), val); + pend_desc -= val; + } txq->pending = 0; } @@ -2413,8 +2416,7 @@ static int mvneta_tx(struct sk_buff *skb, struct net_device *dev) if (txq->count >= txq->tx_stop_threshold) netif_tx_stop_queue(nq); - if (!skb->xmit_more || netif_xmit_stopped(nq) || - txq->pending + frags > MVNETA_TXQ_DEC_SENT_MASK) + if (!skb->xmit_more || netif_xmit_stopped(nq)) mvneta_txq_pend_desc_add(pp, txq, frags); else txq->pending += frags; -- 2.9.3