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=-7.3 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=no 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 EF3F0C433C1 for ; Tue, 23 Mar 2021 09:02:14 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id AB2CD619BD for ; Tue, 23 Mar 2021 09:02:14 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229804AbhCWJBn (ORCPT ); Tue, 23 Mar 2021 05:01:43 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:34196 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229493AbhCWJBP (ORCPT ); Tue, 23 Mar 2021 05:01:15 -0400 Received: from mail-pg1-x52c.google.com (mail-pg1-x52c.google.com [IPv6:2607:f8b0:4864:20::52c]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 563BAC061574 for ; Tue, 23 Mar 2021 02:01:15 -0700 (PDT) Received: by mail-pg1-x52c.google.com with SMTP id h25so11010237pgm.3 for ; Tue, 23 Mar 2021 02:01:15 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=fyArqXnJjHDh28MyaKADOf6onNt6E9lEvyDzFgvh3mY=; b=huB/b9BShjggioTljIzh59gfKp/8aJQJxPGUojT0HTsyTXHD4/2zPb6jG2p6/XQfpQ 43R74G1FVSkxGlwyk1k//zo1aiDC85P3oFg3K/dmzef79XiRlMofXaMbvDiNNOtt+avy 2p/Oczokg/XjDUidP/Uiz473H1LfIaItA976tNqlkkvmF6R0lbMh5z7iJDoaDrL8Sm10 E9onDo2jidUJ/7fLthi7uJQHwBS22wNPSqthqENXfLJLYnlHCdiyCUMhxB3rDvX/DFyA yWaAKFjAkZS5WZA/ClDehCG8cOAy+CFc7j0Xo8Qt7IRFw9fUmz3rDDP47QEBIM101jYu 3I8A== 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=fyArqXnJjHDh28MyaKADOf6onNt6E9lEvyDzFgvh3mY=; b=Z8dIGH9vY60RrBlIQvYpoW43xCy7gQsnNbDncAwSqrqDw9SVZ0+zzdZOAOhIIaWgtX +QnNznNOwHxhd1E6HLtBnI6TfwJxT/pV7ul2PtsepiU24ZBls/O9E82NBa6nvMbtR/i7 o9DYqsMgVfV6dE1jLHHZfjp68l5Yf0UOhvYMdP7njnf4livuOzEKwWK/nyQqL/fci+hQ qIs78wbsTfbkXsMr4ISJj7nFnpiIFxUb5EseQZsfP4gutF8utkk1Wu4UzRm2bEgjo2eZ CBfej8rQFXJqPbiDbw+BqWu4bmmEhQo5VjJK+xGaCUY5/OWZhlBh3UJCr6RF9mee3Ye6 osag== X-Gm-Message-State: AOAM531GYWSpMeBBeU3em0O0o5lGFtiKSbHE+t2Wg2NsyFsH4C3yQhDt 2XW7oaUkZ+4BU6T0V5lqJQD7VQ== X-Google-Smtp-Source: ABdhPJyM+E6Cf275JkaW7D3hyXAsFBC0en8IOE/onyVB70+iS/E90QG4BL5MINbOcxlEnrYjtXSS4Q== X-Received: by 2002:a63:5807:: with SMTP id m7mr3131870pgb.73.1616490074526; Tue, 23 Mar 2021 02:01:14 -0700 (PDT) Received: from localhost ([122.172.6.13]) by smtp.gmail.com with ESMTPSA id gt22sm1966188pjb.35.2021.03.23.02.01.09 (version=TLS1_2 cipher=ECDHE-ECDSA-AES128-GCM-SHA256 bits=128/128); Tue, 23 Mar 2021 02:01:10 -0700 (PDT) Date: Tue, 23 Mar 2021 14:31:08 +0530 From: Viresh Kumar To: Jie Deng Cc: linux-i2c@vger.kernel.org, virtualization@lists.linux-foundation.org, linux-kernel@vger.kernel.org, mst@redhat.com, wsa@kernel.org, jasowang@redhat.com, wsa+renesas@sang-engineering.com, andriy.shevchenko@linux.intel.com, conghui.chen@intel.com, arnd@arndb.de, kblaiech@mellanox.com, jarkko.nikula@linux.intel.com, Sergey.Semin@baikalelectronics.ru, rppt@kernel.org, loic.poulain@linaro.org, tali.perry1@gmail.com, u.kleine-koenig@pengutronix.de, bjorn.andersson@linaro.org, yu1.wang@intel.com, shuo.a.liu@intel.com, stefanha@redhat.com, pbonzini@redhat.com Subject: Re: [PATCH v10] i2c: virtio: add a virtio i2c frontend driver Message-ID: <20210323090108.ygx76exdgzudeeqi@vireshk-i7> References: <226a8d5663b7bb6f5d06ede7701eedb18d1bafa1.1616493817.git.jie.deng@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <226a8d5663b7bb6f5d06ede7701eedb18d1bafa1.1616493817.git.jie.deng@intel.com> User-Agent: NeoMutt/20180716-391-311a52 Precedence: bulk List-ID: X-Mailing-List: linux-i2c@vger.kernel.org On 23-03-21, 22:19, Jie Deng wrote: > +static int virtio_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs, int num) > +{ > + struct virtio_i2c *vi = i2c_get_adapdata(adap); > + struct virtqueue *vq = vi->vq; > + struct virtio_i2c_req *reqs; > + unsigned long time_left; > + int ret, nr; > + > + reqs = kcalloc(num, sizeof(*reqs), GFP_KERNEL); > + if (!reqs) > + return -ENOMEM; > + > + mutex_lock(&vi->lock); > + > + ret = virtio_i2c_send_reqs(vq, reqs, msgs, num); > + if (ret == 0) > + goto err_unlock_free; > + > + nr = ret; > + reinit_completion(&vi->completion); I think I may have found a possible bug here. This reinit_completion() must happen before we call virtio_i2c_send_reqs(). It is certainly possible (surely in corner cases) that virtio_i2c_msg_done() may get called right after virtio_i2c_send_reqs() and before we were able to call reinit_completion(). And in that case we will never see the completion happen at all. > + virtqueue_kick(vq); -- viresh