From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 43F5DC282C0 for ; Fri, 25 Jan 2019 15:01:05 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 14668218A2 for ; Fri, 25 Jan 2019 15:01:05 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726418AbfAYPBE (ORCPT ); Fri, 25 Jan 2019 10:01:04 -0500 Received: from mga04.intel.com ([192.55.52.120]:3208 "EHLO mga04.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726122AbfAYPBE (ORCPT ); Fri, 25 Jan 2019 10:01:04 -0500 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga006.jf.intel.com ([10.7.209.51]) by fmsmga104.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 25 Jan 2019 07:01:03 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.56,521,1539673200"; d="scan'208";a="111033092" Received: from tthayer-hp-z620.an.intel.com (HELO [10.122.105.146]) ([10.122.105.146]) by orsmga006.jf.intel.com with ESMTP; 25 Jan 2019 07:01:02 -0800 Reply-To: thor.thayer@linux.intel.com Subject: Re: [PATCH v2] net: altera_tse: fix msgdma_tx_completion on non-zero fill_level case To: Atsushi Nemoto , netdev@vger.kernel.org Cc: Dalon L Westergreen , Tomonori Sakita References: <20190125.110222.956948485194493083.atsushi.nemoto@sord.co.jp> From: Thor Thayer Message-ID: Date: Fri, 25 Jan 2019 09:03:18 -0600 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.2.1 MIME-Version: 1.0 In-Reply-To: <20190125.110222.956948485194493083.atsushi.nemoto@sord.co.jp> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On 1/24/19 8:02 PM, Atsushi Nemoto wrote: > From: Tomonori Sakita > > If fill_level was not zero and status was not BUSY, > result of "tx_prod - tx_cons - inuse" might be zero. > Subtracting 1 unconditionally results invalid negative return value > on this case. > Make sure not to return an negative value. > > Signed-off-by: Tomonori Sakita > Signed-off-by: Atsushi Nemoto > Reviewed-by: Dalon L Westergreen > --- > Changes in v2: > Use max_t instead of just removing the "- 1". > > drivers/net/ethernet/altera/altera_msgdma.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/drivers/net/ethernet/altera/altera_msgdma.c b/drivers/net/ethernet/altera/altera_msgdma.c > index 0fb986b..0ae723f 100644 > --- a/drivers/net/ethernet/altera/altera_msgdma.c > +++ b/drivers/net/ethernet/altera/altera_msgdma.c > @@ -145,7 +145,8 @@ u32 msgdma_tx_completions(struct altera_tse_private *priv) > & 0xffff; > > if (inuse) { /* Tx FIFO is not empty */ > - ready = priv->tx_prod - priv->tx_cons - inuse - 1; > + ready = max_t(int, > + priv->tx_prod - priv->tx_cons - inuse - 1, 0); > } else { > /* Check for buffered last packet */ > status = csrrd32(priv->tx_dma_csr, msgdma_csroffs(status)); > Thanks for the patch! Acked-by: Thor Thayer