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=-8.3 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 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 1A2CDC3F2D1 for ; Mon, 2 Mar 2020 09:23:07 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id E39A624695 for ; Mon, 2 Mar 2020 09:23:06 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="aYnyAQOr" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727406AbgCBJXF (ORCPT ); Mon, 2 Mar 2020 04:23:05 -0500 Received: from mail-pj1-f66.google.com ([209.85.216.66]:40327 "EHLO mail-pj1-f66.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726654AbgCBJXF (ORCPT ); Mon, 2 Mar 2020 04:23:05 -0500 Received: by mail-pj1-f66.google.com with SMTP id 12so4178685pjb.5 for ; Mon, 02 Mar 2020 01:23:04 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=X50f3KltXHYHA3hHiuSfi+hu3pg0WDIwQipk7QuSG+4=; b=aYnyAQOr9VuGffJkqNSsTkS7Qnfhqmk/Qy4UVEYJIwqHwVBpNQYLwR/5BrQVsvWZ45 4HivLJnIcEKz/4ok5iRRuRf/P25hVn+iLj7EEZR036jusbBNXOPuPoSxaPnt+cp74ukS tR8P2q9Ea48odYx0/axNp+nAOk0wPQUtrL3WCvtW2HlUYW7hN8Ujd8LG6eTSPEbnGq1D OgWwUiXn/cojeQyODLM1AM9cvEe+ZE4c84OEYCsvvg7HeUyBsM6ZdDtZcHr6/Wcq8xI9 D83fhow5waF3bE/RjePjD5GDrvagf/4nXJOsT/GIjhC/+I5b5LGsiwupvJdoI1AFPPcH oVeA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to:user-agent; bh=X50f3KltXHYHA3hHiuSfi+hu3pg0WDIwQipk7QuSG+4=; b=SplvaTnXME6TLNPI59PX1NtjA7a6v4/mVX3v71JBDg5m5pva/RpJqHTE3syNzcGjOc pkHJ4LRpcXoWV4DiQP97JY9xoeQWab2Kt/iObpyW05Y0ha0BmsEWwOlK8cwLM9cQeIDI 0f+Y7N0Ue2DDaFu1AznWenwPGBJvOCPf+mdZy+0fvZoJAcQAqAOvScK6IFGeWwSXjZdn loqgOLxluiEGRCB65OSjljVE7rvaLseqQ1Asm0pyWYzGxCI0dUlpTp7h9UODTZTzJx0C FwwEP2Q4mwsFWcXpS2vTX1T+zI8yUvLr3Ufy9DOZhJxLI1qDPbudA7o82nK8KmhPEg0o mQBA== X-Gm-Message-State: ANhLgQ1WY22Moyh7PmoZchLFATwMtdbcG/btsToYfLh5APXlUUPav58Q 9dfYiMpH367Qaj9K1MV/30g= X-Google-Smtp-Source: ADFU+vvW98z93Yp+1Dy8C/iQY3xi+XM1cHEXPmj/VK4MkhXgtgex+cQP4PWoRYXQausGSGTCX5UPrA== X-Received: by 2002:a17:902:467:: with SMTP id 94mr5771812ple.302.1583140984048; Mon, 02 Mar 2020 01:23:04 -0800 (PST) Received: from localhost ([43.224.245.180]) by smtp.gmail.com with ESMTPSA id a36sm19887909pga.32.2020.03.02.01.23.02 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 02 Mar 2020 01:23:03 -0800 (PST) Date: Mon, 2 Mar 2020 17:23:01 +0800 From: sunjunyong To: Luis Chamberlain Cc: gregkh@linuxfoundation.org, rafael@kernel.org, sunjunyong@xiaomi.com, linux-kernel@vger.kernel.org Subject: Re: [PATCH] firmware: fix a double abort case with fw_load_sysfs_fallback Message-ID: <20200302092301.GA25139@mi-OptiPlex-7050> References: <1582876593-27926-1-git-send-email-sunjunyong@xiaomi.com> <20200228130735.GA11244@42.do-not-panic.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200228130735.GA11244@42.do-not-panic.com> User-Agent: Mutt/1.5.24 (2015-08-30) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Luis: This issue is caused by concurrent situation like below: when thread 1# wait firmware loading, thread 2# may write -1 to abort loading and wakeup thread 1# before it timeout. so wait_for_completion_killable_timeout of thread 1# would return remaining time which is != 0 with fw_st->status FW_STATUS_ABORTED. And the results would be converted into err -ENOENT in __fw_state_wait_common and transfered to fw_load_sysfs_fallback in thread 1#. The -ENOENT means firmware status is already at ABORTED, so fw_load_sysfs_fallback no need to get mutex to abort again. BTW,the double abort issue would not cause kernel panic but slow down it sometimes. ----------------------------- thread 1#,wait for loading fw_load_sysfs_fallback ->fw_sysfs_wait_timeout ->__fw_state_wait_common ->wait_for_completion_killable_timeout in __fw_state_wait_common, ... 93 ret = wait_for_completion_killable_timeout(&fw_st->completion, timeout); 94 if (ret != 0 && fw_st->status == FW_STATUS_ABORTED) 95 return -ENOENT; 96 if (!ret) 97 return -ETIMEDOUT; 98 99 return ret < 0 ? ret : 0; ----------------------------- thread 2#, write -1 to abort loading firmware_loading_store ->fw_load_abort ->__fw_load_abort ->fw_state_aborted ->__fw_state_set ->complete_all in __fw_state_set, ... 111 if (status == FW_STATUS_DONE || status == FW_STATUS_ABORTED) 112 complete_all(&fw_st->completion); ... ----------------------------- On Fri, Feb 28, 2020 at 01:07:35PM +0000, Luis Chamberlain wrote: > On Fri, Feb 28, 2020 at 03:56:33PM +0800, Junyong Sun wrote: > > fw_sysfs_wait_timeout may return err with -ENOENT > > at fw_load_sysfs_fallback and firmware is already > > in abort status, no need to abort again, so skip it. > > What exactly is caused by this issue though? Are you seeing > a kernel panic, some extra messages in the kernel log? This > informationw ould be useful for the kernel commit log. > > > Signed-off-by: Junyong Sun > > --- > > drivers/base/firmware_loader/fallback.c | 2 +- > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > diff --git a/drivers/base/firmware_loader/fallback.c b/drivers/base/firmware_loader/fallback.c > > index 8704e1b..1e9c96e 100644 > > --- a/drivers/base/firmware_loader/fallback.c > > +++ b/drivers/base/firmware_loader/fallback.c > > @@ -525,7 +525,7 @@ static int fw_load_sysfs_fallback(struct fw_sysfs *fw_sysfs, > > } > > > > retval = fw_sysfs_wait_timeout(fw_priv, timeout); > > - if (retval < 0) { > > + if (retval < 0 && retval != -ENOENT) { > > mutex_lock(&fw_lock); > > fw_load_abort(fw_sysfs); > > mutex_unlock(&fw_lock); > > -- > > 2.7.4 > >