From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932752AbdK1KoG (ORCPT ); Tue, 28 Nov 2017 05:44:06 -0500 Received: from mail.linuxfoundation.org ([140.211.169.12]:60804 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754946AbdK1Kn4 (ORCPT ); Tue, 28 Nov 2017 05:43:56 -0500 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Simon Guinot , "David S. Miller" Subject: [PATCH 4.14 026/193] net: mvneta: fix handling of the Tx descriptor counter Date: Tue, 28 Nov 2017 11:24:33 +0100 Message-Id: <20171128100614.744512381@linuxfoundation.org> X-Mailer: git-send-email 2.15.0 In-Reply-To: <20171128100613.638270407@linuxfoundation.org> References: <20171128100613.638270407@linuxfoundation.org> User-Agent: quilt/0.65 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 4.14-stable review patch. If anyone has any objections, please let me know. ------------------ From: Simon Guinot commit 0d63785c6b94b5d2f095f90755825f90eea791f5 upstream. 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") Signed-off-by: Simon Guinot Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman --- drivers/net/ethernet/marvell/mvneta.c | 13 ++++++++----- 1 file changed, 8 insertions(+), 5 deletions(-) --- 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(str { 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 */ + do { + val = min(pend_desc, 255); + mvreg_write(pp, MVNETA_TXQ_UPDATE_REG(txq->id), val); + pend_desc -= val; + } while (pend_desc > 0); txq->pending = 0; }