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=-6.8 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS autolearn=unavailable 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 A8E33C2BD09 for ; Wed, 4 Dec 2019 12:45:20 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 6CB3D20833 for ; Wed, 4 Dec 2019 12:45:20 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=verdurent-com.20150623.gappssmtp.com header.i=@verdurent-com.20150623.gappssmtp.com header.b="D1ekevAW" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727855AbfLDMpT (ORCPT ); Wed, 4 Dec 2019 07:45:19 -0500 Received: from mail-ua1-f66.google.com ([209.85.222.66]:45811 "EHLO mail-ua1-f66.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726832AbfLDMpT (ORCPT ); Wed, 4 Dec 2019 07:45:19 -0500 Received: by mail-ua1-f66.google.com with SMTP id w10so2683584uar.12 for ; Wed, 04 Dec 2019 04:45:18 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=verdurent-com.20150623.gappssmtp.com; s=20150623; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=I9943LC2W7GsN2VUvqciqhs/8irYc/Qkc8ElGhd6zWY=; b=D1ekevAWvG+e76RI65wfYbzcBE//kYMXdoapAplUlqEKsH4lspdwwbuzCIsIT2rtnh teHLwE8FcjmIdJ49WoIO3Bf/vg4AcQL7Yv79j4W0JTj/5Rx7UxGyWPInSerl/AM+bSvW orZxCtyqnmw2Qq/FMPznXPj0oUldse3cTNv7YVtcHf5lhwwN/LN57yq1yI8lYTuEngev VkDvmAwvtRUgHtsdWqsAYP27U9sCFGQVBeHYsA2CwWd92QIjCLCq7Mm1k9EIlW1+xtDs qpsKc57ER7izsMdTaHgEOanMx2naxLKsqvXDiCbBFL3YS7pS4HlBCNYocQ/XzbAvnz83 ykGA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=I9943LC2W7GsN2VUvqciqhs/8irYc/Qkc8ElGhd6zWY=; b=HWaBppUJBosDSaFvKm2eblhUpOejvKm+mvsROYmOlzZeUQQ3NE2gFpdQQtbXTKL2Ee DtP8Q/L4tcUkj41x60xI0dHkUVGOZFmq/PzQzwjo9urvINDInqj/0QEPVgOccrl70n9L 7EzRcihTDxEs51fkCBaaKPMon5Xb3XndHUD0Gz3Vm8a4fyH0IJ3RVsmr9gmNE6MQimkg 7g04umULLy/eTJB/v2nU1tdJNMDYDeUSYCzxnxMGYaDLjz18exqucY+a+PYT6/olJ+Tu EWLZxpnot3+tO8lppVSTrw+U+M/uh9fQLRli9vh04xzzpwJKipsyJX8uke+wdbxDuTeW 5wqg== X-Gm-Message-State: APjAAAXKtwJcEpMzvyZBVtRZ9y93Odtk3XkRDqa/bT/c0NePX1Ouyy0H GBNWcz2M8YXDoKukS0rx1GOA/CCJm3X5uCboJE5YS45kmF0qJQ== X-Google-Smtp-Source: APXvYqzuDbb/FE6aisnhUS4N4Cr5qvRQgmOLAGnNdex1jh+7Kfj7K66vq/MMKaXX5/JENpgqwfDSOBiCzC2R8WXXQus= X-Received: by 2002:ab0:7027:: with SMTP id u7mr2326314ual.94.1575463517590; Wed, 04 Dec 2019 04:45:17 -0800 (PST) MIME-Version: 1.0 References: <20191015061349.141448-1-wvw@google.com> In-Reply-To: From: Amit Kucheria Date: Wed, 4 Dec 2019 18:15:06 +0530 Message-ID: Subject: Re: [PATCH] thermal: create softlink by name for thermal_zone and cooling_device To: Wei Wang Cc: Wei Wang , Zhang Rui , Eduardo Valentin , Daniel Lezcano , Linux PM list , LKML Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Nov 11, 2019 at 11:22 PM Wei Wang wrote: > > On Sun, Nov 10, 2019 at 9:26 PM Amit Kucheria > wrote: > > > > On Thu, Oct 17, 2019 at 3:04 AM Wei Wang wrote: > > > > > > On Wed, Oct 16, 2019 at 10:16 AM Amit Kucheria > > > wrote: > > > > > > > > On Wed, Oct 16, 2019 at 10:20 PM Amit Kucheria > > > > wrote: > > > > > > > > > > On Tue, Oct 15, 2019 at 11:43 AM Wei Wang wrote: > > > > > > > > > > > > The paths thermal_zone%d and cooling_device%d are not intuitive and the > > > > > > numbers are subject to change due to device tree change. This usually > > > > > > leads to tree traversal in userspace code. > > > > > > The patch creates `tz-by-name' and `cdev-by-name' for thermal zone and > > > > > > cooling_device respectively. > > > > > > > > > > I like this. > > > > > > > > > > > Signed-off-by: Wei Wang > > > > > > --- > > > > > > drivers/thermal/thermal_core.c | 23 +++++++++++++++++++++-- > > > > > > 1 file changed, 21 insertions(+), 2 deletions(-) > > > > > > > > > > > > diff --git a/drivers/thermal/thermal_core.c b/drivers/thermal/thermal_core.c > > > > > > index d4481cc8958f..0ff8fb1d7b0a 100644 > > > > > > --- a/drivers/thermal/thermal_core.c > > > > > > +++ b/drivers/thermal/thermal_core.c > > > > > > @@ -22,6 +22,7 @@ > > > > > > #include > > > > > > #include > > > > > > #include > > > > > > +#include > > > > > > > > > > > > #define CREATE_TRACE_POINTS > > > > > > #include > > > > > > @@ -46,6 +47,8 @@ static DEFINE_MUTEX(poweroff_lock); > > > > > > > > > > > > static atomic_t in_suspend; > > > > > > static bool power_off_triggered; > > > > > > +static struct kobject *cdev_link_kobj; > > > > > > +static struct kobject *tz_link_kobj; > > > > > > > > > > > > static struct thermal_governor *def_governor; > > > > > > > > > > > > @@ -954,7 +957,7 @@ __thermal_cooling_device_register(struct device_node *np, > > > > > > struct thermal_zone_device *pos = NULL; > > > > > > int result; > > > > > > > > > > > > - if (type && strlen(type) >= THERMAL_NAME_LENGTH) > > > > > > + if (!type || !type[0] || strlen(type) >= THERMAL_NAME_LENGTH) > > > > > > return ERR_PTR(-EINVAL); > > > > > > > > > > This should be a separate fix, if needed. > > > Agree, but the link now requires that "" as invalid _type_. > > > > I'm not sure I understand. What does this change have to do with > > adding symlinks below? > > > > cdev->type will be used later in sysfs_create_link and adding "" as > symlink is kind of bad practise AIUI. > Perhaps I'm being dense here, in which case my apologies. But what stops us from splitting the patch into two? 1. Make type == "" as invalid by using your change above and fixing up the strlcpy(cdev->type....) further down. 2. Create the actual symlinks in a separate patch. Regards, Amit > > > > > > > > > > > if (!ops || !ops->get_max_state || !ops->get_cur_state || > > > > > > @@ -989,9 +992,15 @@ __thermal_cooling_device_register(struct device_node *np, > > > > > > return ERR_PTR(result); > > > > > > } > > > > > > > > > > > > - /* Add 'this' new cdev to the global cdev list */ > > > > > > + /* Add 'this' new cdev to the global cdev list and create link*/ > > > > > > mutex_lock(&thermal_list_lock); > > > > > > list_add(&cdev->node, &thermal_cdev_list); > > > > > > + if (!cdev_link_kobj) > > > > > > + cdev_link_kobj = kobject_create_and_add("cdev-by-name", > > > > > > + cdev->device.kobj.parent); > > > > > > + if (!cdev_link_kobj || sysfs_create_link(cdev_link_kobj, > > > > > > + &cdev->device.kobj, cdev->type)) > > > > > > + dev_err(&cdev->device, "Failed to create cdev-by-name link\n"); > > > > > > > > > > Any reason not to use the following form instead? It seems easier to read. > > > > > > > > > > if (!cdev_link_kobj) { > > > > > cdev_link_kobj = kobject_create_and_add("cdev-by-name", > > > > > cdev->device.kobj.parent); > > > > > ret = sysfs_create_link(cdev_link_kobj, > > > > > &cdev->device.kobj, cdev->type)) > > > > > if (ret) > > > > > dev_err(&cdev->device, "Failed to create > > > > > cdev-by-name link\n"); > > > > > } > > > > > > > > I can now see why you had to do that - none of the other links would > > > > get created after the first one. > > > > > > > > Perhaps create the directories in the __init functions and only create > > > > the links here? > > > > > > > AFAICT, this is no such API except the private get_device_parent() > > > under driver/base/. Also the lazy initialization makes sense in such > > > case when there is no thermal device attached. Looks like the class > > > dir is also lazy-initialized when first device registered > > > https://elixir.bootlin.com/linux/v5.3.5/source/drivers/base/core.c#L1790. > > > > OK. > > > > > > > > > > > > mutex_unlock(&thermal_list_lock); > > > > > > > > > > > > /* Update binding information for 'this' new cdev */ > > > > > > @@ -1157,6 +1166,8 @@ void thermal_cooling_device_unregister(struct thermal_cooling_device *cdev) > > > > > > } > > > > > > } > > > > > > } > > > > > > + if (cdev_link_kobj) > > > > > > + sysfs_remove_link(cdev_link_kobj, cdev->type); > > > > > > > > > > > > mutex_unlock(&thermal_list_lock); > > > > > > > > > > > > @@ -1340,6 +1351,12 @@ thermal_zone_device_register(const char *type, int trips, int mask, > > > > > > > > > > > > mutex_lock(&thermal_list_lock); > > > > > > list_add_tail(&tz->node, &thermal_tz_list); > > > > > > + if (!tz_link_kobj) > > > > > > + tz_link_kobj = kobject_create_and_add("tz-by-name", > > > > > > + tz->device.kobj.parent); > > > > > > + if (!tz_link_kobj || sysfs_create_link(tz_link_kobj, > > > > > > + &tz->device.kobj, tz->type)) > > > > > > + dev_err(&tz->device, "Failed to create tz-by-name link\n"); > > > > > > > > > > Same as above. > > > > > > > > > > > mutex_unlock(&thermal_list_lock); > > > > > > > > > > > > /* Bind cooling devices for this zone */ > > > > > > @@ -1411,6 +1428,8 @@ void thermal_zone_device_unregister(struct thermal_zone_device *tz) > > > > > > } > > > > > > } > > > > > > } > > > > > > + if (tz_link_kobj) > > > > > > + sysfs_remove_link(tz_link_kobj, tz->type); > > > > > > > > > > > > mutex_unlock(&thermal_list_lock); > > > > > > > > > > > > -- > > > > > > 2.23.0.700.g56cf767bdb-goog > > > > > >