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=-5.7 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,NICE_REPLY_A,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 D2E16C433F5 for ; Fri, 17 Sep 2021 15:07:03 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B0E16611C4 for ; Fri, 17 Sep 2021 15:07:03 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S244871AbhIQPIY (ORCPT ); Fri, 17 Sep 2021 11:08:24 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45214 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1343682AbhIQPIR (ORCPT ); Fri, 17 Sep 2021 11:08:17 -0400 Received: from mail-lf1-x133.google.com (mail-lf1-x133.google.com [IPv6:2a00:1450:4864:20::133]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 42F68C0617B0 for ; Fri, 17 Sep 2021 08:06:28 -0700 (PDT) Received: by mail-lf1-x133.google.com with SMTP id bq5so34317391lfb.9 for ; Fri, 17 Sep 2021 08:06:28 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=message-id:date:mime-version:user-agent:subject:content-language :from:to:cc:references:in-reply-to:content-transfer-encoding; bh=69GiEXKdxt+heGKGrbL9Gx4hEjgC+QbxrWSsOk2igRI=; b=NQYj7NnZDoDKkzXPvTD+hAVBr9Dkyab+NW985IjEd6ASiEXrJCd3ZHOVOGeO1tMg7i Ac/gNUpxC9X3+nTaa+FIY3AYYL6kvIF3y2YtdQOMO4haPe9jd5U6pG/LWhuNuiVf2ZKd PQhktx8xNYT+19D4vSVO8w/OFDUb3ki5CXa7cZKvXF0EvU8HjwGu/fEMKRGUD0EbQqqd 002PnxwosU4JZYsTgaL+xtVIgpZGYB4C353WdU73LPD0Bh1Xj2QSNm0EImELfqs/c2cu fnj0VMX30d3M9Y3doLAUdLHdKcgoL0Sm4KntKdGn8nmPgSU2Ch527yrXEhrB9vhqzOpe fABQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:message-id:date:mime-version:user-agent:subject :content-language:from:to:cc:references:in-reply-to :content-transfer-encoding; bh=69GiEXKdxt+heGKGrbL9Gx4hEjgC+QbxrWSsOk2igRI=; b=g9gP5uxvY6czpN03UQd+PrK1MuxhZhEQSrMIFdiLhJsM0LkCNm6enOflytFd0k2S+Y /tF5iHkCPoBXykjAEpaN43nQnssea7Wj8dwazDcluVtk5v/FDFizweF9h6Tl2YD8hOeM Ev8B4JNdFxHTGx1IKNOoIMfOo2XwIpUcM+1q9R1nDEL4VAqzwgdAH4uLz2my/zO5JozG gK7e2O2/CXfZiRaDlEzWPwjOP/wKrh6NSPSxYIoGjEUDBsqcjsfUnMboJL/Dx6njyejV zCOml9GB9ptGpKsX6/ZEF49QZg7KnL5qYta7+JBHVOAbeepqdOyYzSGvNImXn+D6qRfL 75NA== X-Gm-Message-State: AOAM533EH9E9d772pC1M2nwpyfeJKtwmXxjsLENrdGjCMKDsCyIJJB9v IR+Z4ppaGAFlMdwCKdFW540= X-Google-Smtp-Source: ABdhPJz/TwYXrI1XJ2iaymgE0fildrBim7Lw6rJyEaWfVPSUeZ0fZO5TuStQyGxVQZG24EfK5iepmw== X-Received: by 2002:a05:6512:10c8:: with SMTP id k8mr8591405lfg.326.1631891168976; Fri, 17 Sep 2021 08:06:08 -0700 (PDT) Received: from [192.168.1.11] ([46.235.67.49]) by smtp.gmail.com with ESMTPSA id e24sm548860lfs.212.2021.09.17.08.06.08 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 17 Sep 2021 08:06:08 -0700 (PDT) Message-ID: Date: Fri, 17 Sep 2021 18:06:06 +0300 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.0.3 Subject: Re: [PATCH v7 19/19] staging: r8188eu: remove shared buffer for usb requests Content-Language: en-US From: Pavel Skripkin To: Greg Kroah-Hartman , Larry Finger , Phillip Potter Cc: linux-staging@lists.linux.dev, linux-kernel@vger.kernel.org, David Laight , Dan Carpenter , "Fabio M. De Francesco" References: <20210917071837.10926-1-fmdefrancesco@gmail.com> <20210917071837.10926-20-fmdefrancesco@gmail.com> In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 9/17/21 18:03, Pavel Skripkin wrote: > On 9/17/21 17:55, Greg Kroah-Hartman wrote: >> On Fri, Sep 17, 2021 at 09:18:37AM +0200, Fabio M. De Francesco wrote: >>> From: Pavel Skripkin >>> >>> This driver used shared buffer for usb requests. It led to using >>> mutexes, i.e no usb requests can be done in parallel. >>> >>> USB requests can be fired in parallel since USB Core allows it. In >>> order to allow them, remove usb_vendor_req_buf from dvobj_priv (since >>> USB I/O is the only user of it) and remove also usb_vendor_req_mutex >>> (since there is nothing to protect). >> >> Ah, you are removing this buffer, nice! >> >> But, just because the USB core allows multiple messages to be sent to a >> device at the same time, does NOT mean that the device itself can handle >> that sort of a thing. >> >> Keeping that lock might be a good idea, until you can prove otherwise. >> You never know, maybe there's never any contention at all for it because >> these accesses are all done in a serial fashion and the lock >> grab/release is instant. But if that is not the case, you might really >> get a device confused here by throwing multiple control messages at it >> in ways that it is not set up to handle at all. >> >> So please do not drop the lock. >> >> More comments below. >> > > We have tested this change. I've tested it in qemu with TP-Link > TL-WN722N v2 / v3 [Realtek RTL8188EUS], and Fabio has tested it on his > host for like a whole evening. > > I agree, that our testing does not cover all possible cases and I can't > say it was "good stress testing", so, I think, we need some comments > from maintainers. > > @Larry, @Phillip, does this change looks reasonable for this chip? > ^^^^^^^^^^^ I mean mutex removal, sorry for confusion :) With regards, Pavel Skripkin