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=-5.0 required=3.0 tests=BAYES_00,DKIM_ADSP_CUSTOM_MED, DKIM_INVALID,DKIM_SIGNED,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED,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 88E03C2D0A8 for ; Wed, 30 Sep 2020 06:10:46 +0000 (UTC) Received: from silver.osuosl.org (smtp3.osuosl.org [140.211.166.136]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 227F520754 for ; Wed, 30 Sep 2020 06:10:45 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="srdnNQg2" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 227F520754 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=gmail.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=iommu-bounces@lists.linux-foundation.org Received: from localhost (localhost [127.0.0.1]) by silver.osuosl.org (Postfix) with ESMTP id B87B520462; Wed, 30 Sep 2020 06:10:45 +0000 (UTC) X-Virus-Scanned: amavisd-new at osuosl.org Received: from silver.osuosl.org ([127.0.0.1]) by localhost (.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id HnFYuEr3umwe; Wed, 30 Sep 2020 06:10:44 +0000 (UTC) Received: from lists.linuxfoundation.org (lf-lists.osuosl.org [140.211.9.56]) by silver.osuosl.org (Postfix) with ESMTP id B6EA42041E; Wed, 30 Sep 2020 06:10:44 +0000 (UTC) Received: from lf-lists.osuosl.org (localhost [127.0.0.1]) by lists.linuxfoundation.org (Postfix) with ESMTP id 89284C016F; Wed, 30 Sep 2020 06:10:44 +0000 (UTC) Received: from fraxinus.osuosl.org (smtp4.osuosl.org [140.211.166.137]) by lists.linuxfoundation.org (Postfix) with ESMTP id E04C6C0051 for ; Wed, 30 Sep 2020 06:10:42 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by fraxinus.osuosl.org (Postfix) with ESMTP id C6CBA85E09 for ; Wed, 30 Sep 2020 06:10:42 +0000 (UTC) X-Virus-Scanned: amavisd-new at osuosl.org Received: from fraxinus.osuosl.org ([127.0.0.1]) by localhost (.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id flWGmruBi_cQ for ; Wed, 30 Sep 2020 06:10:42 +0000 (UTC) X-Greylist: domain auto-whitelisted by SQLgrey-1.7.6 Received: from mail-lj1-f194.google.com (mail-lj1-f194.google.com [209.85.208.194]) by fraxinus.osuosl.org (Postfix) with ESMTPS id 070BC8502A for ; Wed, 30 Sep 2020 06:10:42 +0000 (UTC) Received: by mail-lj1-f194.google.com with SMTP id u4so538803ljd.10 for ; Tue, 29 Sep 2020 23:10:41 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=subject:to:cc:references:from:message-id:date:user-agent :mime-version:in-reply-to:content-language:content-transfer-encoding; bh=tF1+/MycUx+KyCDTvsvj5n8w93b7S9PxVTTODrbJLlQ=; b=srdnNQg2feKgQJzm9RAwg47hsQoXa0Hg/Q3ues2KB66TP8x8y/5A3LJCtSuayucJbD VBaWOcAD68TRSQvWDlG605UftlLRtya4qHG2obIaz64msOSgSGsbGnoKlqxgjeDctpaN G0+e+LmR1IeSvoLVsE+68lLoYFw97769Mb+ZSLkToZ6kD5FM4TRt/jpe0S5J2cLHs8P8 U7s1lXwu01mPPV7GlfREG12eBepSCdePirmn9d1LqlcJQ08CebrEpsNtM/DC/Q2oK/7R vPhUVkrrfuPYfFGKMHLZEzOre3MnxfNiiw6KXOIamClZZZz6z1DOw87Mgm8yhmlVTmpr 4UIg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:to:cc:references:from:message-id:date :user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=tF1+/MycUx+KyCDTvsvj5n8w93b7S9PxVTTODrbJLlQ=; b=JwsVCpPfplZ5Squ9d3SKeAVG8CwP2FlbdvcoTNrCR6Xtr6fADBaHpPlJaZJevKo6D4 W/NbCLI8DsfhKaB0oVFZ0gwIuUJDRa32fh0iRqGz7ysrlWl0FvPdx8EkCnrVKAsJiUgs AbHdJw+dk08EPeEZ2cbdZsHaiA8gzzxvebdqWW8mqsh2i4ts6rHwkD8HBTTpaSLCcSsm giACFT4knen88C8yWeo4zSvsO/cf5xRI73HWagjaRRF5zEQRUCCcCqQJYTD4TSA/bHOf m08hkMwNYeffoiAuLy4n8a8TQ6ZZR7Sr2Ff+Xa7EpxlBBL7JeAgfYLa49cgrSa8GhnJG Dbhw== X-Gm-Message-State: AOAM531ib+HD1OKkJRxC0Yz0b4QG5Iiam3PhJxz68k99IWqHQqHvO1lN PouMc8drfPZyaw8SukbemYg= X-Google-Smtp-Source: ABdhPJwQtAdUuITXXpykkxgwWFhu2CUYJjNGKst4ciCzx9dSlJJoZPdAALZZNafTQuN9U8PB3hKmcA== X-Received: by 2002:a05:651c:227:: with SMTP id z7mr352115ljn.99.1601446239924; Tue, 29 Sep 2020 23:10:39 -0700 (PDT) Received: from [192.168.2.145] (109-252-170-211.dynamic.spd-mgts.ru. [109.252.170.211]) by smtp.googlemail.com with ESMTPSA id t13sm61057ljc.70.2020.09.29.23.10.38 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 29 Sep 2020 23:10:39 -0700 (PDT) Subject: Re: [PATCH v2 2/3] iommu/tegra-smmu: Rework .probe_device and .attach_dev To: Nicolin Chen References: <20200930003013.31289-1-nicoleotsuka@gmail.com> <20200930003013.31289-3-nicoleotsuka@gmail.com> <75514da5-e63a-9e51-8376-abbd12c324d1@gmail.com> <20200930054900.GG31821@Asurada-Nvidia> From: Dmitry Osipenko Message-ID: Date: Wed, 30 Sep 2020 09:10:38 +0300 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 MIME-Version: 1.0 In-Reply-To: <20200930054900.GG31821@Asurada-Nvidia> Content-Language: en-US Cc: linux-kernel@vger.kernel.org, iommu@lists.linux-foundation.org, krzk@kernel.org, jonathanh@nvidia.com, thierry.reding@gmail.com, linux-tegra@vger.kernel.org X-BeenThere: iommu@lists.linux-foundation.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: Development issues for Linux IOMMU support List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: base64 Errors-To: iommu-bounces@lists.linux-foundation.org Sender: "iommu" MzAuMDkuMjAyMCAwODo0OSwgTmljb2xpbiBDaGVuINC/0LjRiNC10YI6Cj4gT24gV2VkLCBTZXAg MzAsIDIwMjAgYXQgMDg6MTE6NTJBTSArMDMwMCwgRG1pdHJ5IE9zaXBlbmtvIHdyb3RlOgo+PiAz MC4wOS4yMDIwIDAzOjMwLCBOaWNvbGluIENoZW4g0L/QuNGI0LXRgjoKPj4+ICsJLyogQW4gaW52 YWxpZCBtYyBwb2ludGVyIG1lYW5zIG1jIGFuZCBzbW11IGRyaXZlcnMgYXJlIG5vdCByZWFkeSAq Lwo+Pj4gKwlpZiAoSVNfRVJSX09SX05VTEwobWMpKQo+Pgo+PiB0ZWdyYV9nZXRfbWVtb3J5X2Nv bnRyb2xsZXIoKSBkb2Vzbid0IHJldHVybiBOVUxMLgo+IAo+IFdlbGwsIEkgZG9uJ3Qgd2FudCB0 byBhc3N1bWUgdGhhdCBpdCdkIGRvIHRoYXQgZm9yZXZlciwgYW5kIHRoZQo+IE5VTEwgY2hlY2sg b2YgSVNfRVJSX09SX05VTEwgaXMgbWFya2VkICJ1bmxpa2VseSIgc28gaXQgZG9lc24ndAo+IGh1 cnQgdG8gaGF2ZS4KPiAKCkkgZG9uJ3Qgc2VlIGFueSByZWFzb25zIHdoeSBpdCB3b24ndCBkbyB0 aGF0IGZvcmV2ZXIuCgpTZWNvbmRseSwgcHVibGljIGZ1bmN0aW9uIGNhbid0IGJlIGNoYW5nZWQg cmFuZG9tbHkgd2l0aG91dCB1cGRhdGluZyBhbGwKdGhlIGNhbGxlcnMuCgpIZW5jZSB0aGVyZSBp cyBubyBuZWVkIHRvIGhhbmRsZSBjYXNlcyB0aGF0IGNhbid0IGV2ZXIgaGFwcGVuIGFuZCBpdApo dXJ0cyByZWFkYWJpbGl0eSBvZiB0aGUgY29kZSArIG9yaWdpbmFsIGVycm9yIGNvZGUgaXMgbWlz c2VkLgpfX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fXwppb21t dSBtYWlsaW5nIGxpc3QKaW9tbXVAbGlzdHMubGludXgtZm91bmRhdGlvbi5vcmcKaHR0cHM6Ly9s aXN0cy5saW51eGZvdW5kYXRpb24ub3JnL21haWxtYW4vbGlzdGluZm8vaW9tbXU= 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=-5.3 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 11D1FC2D0A8 for ; Wed, 30 Sep 2020 06:10:43 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id AFB0C20759 for ; Wed, 30 Sep 2020 06:10:42 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="srdnNQg2" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1725777AbgI3GKm (ORCPT ); Wed, 30 Sep 2020 02:10:42 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:40840 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725320AbgI3GKm (ORCPT ); Wed, 30 Sep 2020 02:10:42 -0400 Received: from mail-lj1-x241.google.com (mail-lj1-x241.google.com [IPv6:2a00:1450:4864:20::241]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D2687C061755; Tue, 29 Sep 2020 23:10:41 -0700 (PDT) Received: by mail-lj1-x241.google.com with SMTP id s205so546187lja.7; Tue, 29 Sep 2020 23:10:41 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=subject:to:cc:references:from:message-id:date:user-agent :mime-version:in-reply-to:content-language:content-transfer-encoding; bh=tF1+/MycUx+KyCDTvsvj5n8w93b7S9PxVTTODrbJLlQ=; b=srdnNQg2feKgQJzm9RAwg47hsQoXa0Hg/Q3ues2KB66TP8x8y/5A3LJCtSuayucJbD VBaWOcAD68TRSQvWDlG605UftlLRtya4qHG2obIaz64msOSgSGsbGnoKlqxgjeDctpaN G0+e+LmR1IeSvoLVsE+68lLoYFw97769Mb+ZSLkToZ6kD5FM4TRt/jpe0S5J2cLHs8P8 U7s1lXwu01mPPV7GlfREG12eBepSCdePirmn9d1LqlcJQ08CebrEpsNtM/DC/Q2oK/7R vPhUVkrrfuPYfFGKMHLZEzOre3MnxfNiiw6KXOIamClZZZz6z1DOw87Mgm8yhmlVTmpr 4UIg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:to:cc:references:from:message-id:date :user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=tF1+/MycUx+KyCDTvsvj5n8w93b7S9PxVTTODrbJLlQ=; b=HAjHy8Nm48zBdGtTJahMlDeSi5lfI+O64LafJA5B8ggHd69q0F+OSKRmi0Aadsgfls qBJYR1M83UXwLKl0XgC8Lx1NGQdpJ2Fc7e1GbZ4wpeOy6uAcPvSQOTLoftVXihqS7GVL hDcbO9Gcwmz9WiZ3Ydi7jDMJNix45kKQt0J6/4jqAtEehugwUbWy3y3tZaOzeBgcT3Ld 8xUn/UQeJ/wSlBNzWdbUb0H2hiQiJs1uxyVBqahqu/ckQ0UtizVZ4DZ7Uhd+JNZrQKMC ix5tb8W+2JDg9CXJa2YP3LPu8QkOYsLik8w2XombpsKj4+QiHtkJ2TW183wtF5cevBOj qbdA== X-Gm-Message-State: AOAM533c3Jj/pcXlvhwKENoiWk5myaDA2I8UfpSeWsd8CeGlHPoueQmP SuAJlg5WKQa3Bzj+PvlYC0H2MjPMGfk= X-Google-Smtp-Source: ABdhPJwQtAdUuITXXpykkxgwWFhu2CUYJjNGKst4ciCzx9dSlJJoZPdAALZZNafTQuN9U8PB3hKmcA== X-Received: by 2002:a05:651c:227:: with SMTP id z7mr352115ljn.99.1601446239924; Tue, 29 Sep 2020 23:10:39 -0700 (PDT) Received: from [192.168.2.145] (109-252-170-211.dynamic.spd-mgts.ru. [109.252.170.211]) by smtp.googlemail.com with ESMTPSA id t13sm61057ljc.70.2020.09.29.23.10.38 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 29 Sep 2020 23:10:39 -0700 (PDT) Subject: Re: [PATCH v2 2/3] iommu/tegra-smmu: Rework .probe_device and .attach_dev To: Nicolin Chen Cc: thierry.reding@gmail.com, joro@8bytes.org, krzk@kernel.org, vdumpa@nvidia.com, jonathanh@nvidia.com, linux-tegra@vger.kernel.org, iommu@lists.linux-foundation.org, linux-kernel@vger.kernel.org References: <20200930003013.31289-1-nicoleotsuka@gmail.com> <20200930003013.31289-3-nicoleotsuka@gmail.com> <75514da5-e63a-9e51-8376-abbd12c324d1@gmail.com> <20200930054900.GG31821@Asurada-Nvidia> From: Dmitry Osipenko Message-ID: Date: Wed, 30 Sep 2020 09:10:38 +0300 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 MIME-Version: 1.0 In-Reply-To: <20200930054900.GG31821@Asurada-Nvidia> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-tegra@vger.kernel.org 30.09.2020 08:49, Nicolin Chen пишет: > On Wed, Sep 30, 2020 at 08:11:52AM +0300, Dmitry Osipenko wrote: >> 30.09.2020 03:30, Nicolin Chen пишет: >>> + /* An invalid mc pointer means mc and smmu drivers are not ready */ >>> + if (IS_ERR_OR_NULL(mc)) >> >> tegra_get_memory_controller() doesn't return NULL. > > Well, I don't want to assume that it'd do that forever, and the > NULL check of IS_ERR_OR_NULL is marked "unlikely" so it doesn't > hurt to have. > I don't see any reasons why it won't do that forever. Secondly, public function can't be changed randomly without updating all the callers. Hence there is no need to handle cases that can't ever happen and it hurts readability of the code + original error code is missed.