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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id A812DC6FD20 for ; Sat, 25 Mar 2023 20:56:25 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230405AbjCYU4X (ORCPT ); Sat, 25 Mar 2023 16:56:23 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:36932 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229659AbjCYU4U (ORCPT ); Sat, 25 Mar 2023 16:56:20 -0400 Received: from mx01.omp.ru (mx01.omp.ru [90.154.21.10]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D1B60A5CB; Sat, 25 Mar 2023 13:56:18 -0700 (PDT) Received: from [192.168.1.103] (178.176.79.104) by msexch01.omp.ru (10.188.4.12) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA384) id 15.2.986.14; Sat, 25 Mar 2023 23:56:10 +0300 Subject: Re: [PATCH net-next] sh_eth: remove open coded netif_running() To: Geert Uytterhoeven CC: Wolfram Sang , , , Geert Uytterhoeven , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , References: <20230321065826.2044-1-wsa+renesas@sang-engineering.com> <79d945a4-e105-4bc4-3e73-64971731660e@omp.ru> From: Sergey Shtylyov Organization: Open Mobile Platform Message-ID: <346b2451-6862-011e-9842-284a43fcf337@omp.ru> Date: Sat, 25 Mar 2023 23:56:09 +0300 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.10.1 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset="utf-8" Content-Language: en-US Content-Transfer-Encoding: 7bit X-Originating-IP: [178.176.79.104] X-ClientProxiedBy: msexch01.omp.ru (10.188.4.12) To msexch01.omp.ru (10.188.4.12) X-KSE-ServerInfo: msexch01.omp.ru, 9 X-KSE-AntiSpam-Interceptor-Info: scan successful X-KSE-AntiSpam-Version: 5.9.59, Database issued on: 03/25/2023 20:40:46 X-KSE-AntiSpam-Status: KAS_STATUS_NOT_DETECTED X-KSE-AntiSpam-Method: none X-KSE-AntiSpam-Rate: 59 X-KSE-AntiSpam-Info: Lua profiles 176289 [Mar 24 2023] X-KSE-AntiSpam-Info: Version: 5.9.59.0 X-KSE-AntiSpam-Info: Envelope from: s.shtylyov@omp.ru X-KSE-AntiSpam-Info: LuaCore: 507 507 08d345461d9bcca7095738422a5279ab257bb65a X-KSE-AntiSpam-Info: {rep_avail} X-KSE-AntiSpam-Info: {Tracking_from_domain_doesnt_match_to} X-KSE-AntiSpam-Info: {relay has no DNS name} X-KSE-AntiSpam-Info: {SMTP from is not routable} X-KSE-AntiSpam-Info: {Found in DNSBL: 178.176.79.104 in (user) dbl.spamhaus.org} X-KSE-AntiSpam-Info: 127.0.0.199:7.1.2;178.176.79.104:7.4.1,7.7.3;omp.ru:7.1.1;d41d8cd98f00b204e9800998ecf8427e.com:7.1.1 X-KSE-AntiSpam-Info: {iprep_blacklist} X-KSE-AntiSpam-Info: ApMailHostAddress: 178.176.79.104 X-KSE-AntiSpam-Info: {DNS response errors} X-KSE-AntiSpam-Info: Rate: 59 X-KSE-AntiSpam-Info: Status: not_detected X-KSE-AntiSpam-Info: Method: none X-KSE-AntiSpam-Info: Auth:dmarc=temperror header.from=omp.ru;spf=temperror smtp.mailfrom=omp.ru;dkim=none X-KSE-Antiphishing-Info: Clean X-KSE-Antiphishing-ScanningType: Heuristic X-KSE-Antiphishing-Method: None X-KSE-Antiphishing-Bases: 03/25/2023 20:43:00 X-KSE-AttachmentFiltering-Interceptor-Info: protection disabled X-KSE-Antivirus-Interceptor-Info: scan successful X-KSE-Antivirus-Info: Clean, bases: 3/25/2023 6:14:00 PM X-KSE-BulkMessagesFiltering-Scan-Result: InTheLimit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hello! On 3/23/23 11:32 AM, Geert Uytterhoeven wrote: [...] >>> It had a purpose back in the days, but today we have a handy helper. >> >> Well, the is_opened flag doesn't get set/cleared at the same time as >> __LINK_STATE_START. I'm not sure they are interchangeable... >> >>> Reported-by: Geert Uytterhoeven >>> Signed-off-by: Wolfram Sang > >>> --- a/drivers/net/ethernet/renesas/sh_eth.c >>> +++ b/drivers/net/ethernet/renesas/sh_eth.c >>> @@ -2441,8 +2441,6 @@ static int sh_eth_open(struct net_device *ndev) >>> >>> netif_start_queue(ndev); >>> >>> - mdp->is_opened = 1; >>> - >> >> __LINK_STATE_START gets set before the ndo_open() method call, so >> before the RPM call that enbales the clocks... >> >>> return ret; >>> >>> out_free_irq: >>> @@ -2565,7 +2563,7 @@ static struct net_device_stats *sh_eth_get_stats(struct net_device *ndev) >>> if (mdp->cd->no_tx_cntrs) >>> return &ndev->stats; >>> >>> - if (!mdp->is_opened) >>> + if (!netif_running(ndev)) >>> return &ndev->stats; >> >> I guess mdp->is_opened is checked here to avoid reading the counter >> regs when RPM hasn't been called yet to enable the clocks... > > Exactly, cfr. commit 7fa2955ff70ce453 ("sh_eth: Fix sleeping function > called from invalid context"). Yeah, pm_runtime_get_sync() couldn't be called in this case as netstat_show() invoked read_lock() that ensued calling preempt_disable()... > So you mean sh_eth_get_stats() can now be called after setting > __LINK_STATE_START, but before RPM has enabled the clocks? Yes, probably... > Is there some protection against parallel execution of ndo_open() > and get_stats()? Haven't seen it (yet?)... > Gr{oetje,eeting}s, > > Geert MBR, Sergey