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=-7.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS 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 7DA1EC433DF for ; Tue, 7 Jul 2020 15:59:22 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 5B2D820674 for ; Tue, 7 Jul 2020 15:59:22 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1594137562; bh=pHABt1xkSO30pAE6pokYsrVBJow+rhBN54eHVjPGB24=; h=References:In-Reply-To:From:Date:Subject:To:Cc:List-ID:From; b=FkRR7wOT54t3LZckOvAnwwcESXO6pKUkXWwSyBNN+l2oJcGSwQ4Tx2PAZ8t544GEJ btRWFU8ZgHHMg2Re/nfhOEm9r2c2nFZGPYfQ64qVsI9qiTHb+TIBnGrxjJw4hMSmQG oLNB38b9a5fGlEHZgLjCKmop4RyQfCfwozIDdbHQ= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728528AbgGGP7V (ORCPT ); Tue, 7 Jul 2020 11:59:21 -0400 Received: from mail-oo1-f66.google.com ([209.85.161.66]:35238 "EHLO mail-oo1-f66.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727079AbgGGP7U (ORCPT ); Tue, 7 Jul 2020 11:59:20 -0400 Received: by mail-oo1-f66.google.com with SMTP id k47so4707041ool.2 for ; Tue, 07 Jul 2020 08:59:20 -0700 (PDT) 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=ybKYjyxhBNv1kTn9dag4mFuNouSoGCR2/Y20joSpfWA=; b=aOin9jLMmI+aTwtKSECSRBbu9zlMTTARa11CekVdx4rOqDkF8y8MTDlgt/prS8gEsC ZzGhFYcmJLnKY5y4qXGcc6iobndOJnhq8Kz91mFOR5MDdSEowBDISgf8gVyobhWcq12e JXrxyfdQHCJDGaxCj7pcRz3BUvTAAGyR5yM9fejeAImONzLbSr3XgGesPSWW5hifBJd5 eCDMObkFA/REhQYopCu/c9t8dkiaLwgLdmnvhezHzzJZopz8Ea6f1uH+zDmk83McKpDZ BGs2hflYC4UdK+MxJtVgGN75R32ymx2N/sb2imIP4VO6kRV6mEGLC4oxBJS9Z/afiW3F X6eA== X-Gm-Message-State: AOAM5314unHPBfnTtgt0mwT8crLwYEN/6sMzBcZ+uyHalBgoY7zAHdu2 OaPrkZXEMj19w98Ftyi9ucDY52t0dZ5TNDLOub8= X-Google-Smtp-Source: ABdhPJxgIcG1DZyavED8sdSqF07AzJotJeUnC8/Ncw9mnaxVZb6e+P2ytm8y9iWc+fyHIcwiLTvMhXzxRPXtsphT+HE= X-Received: by 2002:a4a:2459:: with SMTP id v25mr47061329oov.75.1594137559641; Tue, 07 Jul 2020 08:59:19 -0700 (PDT) MIME-Version: 1.0 References: <20200701194259.3337652-1-saravanak@google.com> <20200701194259.3337652-2-saravanak@google.com> In-Reply-To: <20200701194259.3337652-2-saravanak@google.com> From: "Rafael J. Wysocki" Date: Tue, 7 Jul 2020 17:59:08 +0200 Message-ID: Subject: Re: [PATCH v1 1/3] driver core: Don't do deferred probe in parallel with kernel_init thread To: Saravana Kannan Cc: Greg Kroah-Hartman , "Rafael J. Wysocki" , Linux Kernel Mailing List , Geert Uytterhoeven , "Cc: Android Kernel" 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 Wed, Jul 1, 2020 at 9:43 PM Saravana Kannan wrote: > > The current deferred probe implementation can mess up suspend/resume > ordering if deferred probe thread is kicked off in parallel with the > main initcall thread (kernel_init thread) [1]. > > For example: > > Say device-B is a consumer of device-A. > > Initcall thread Deferred probe thread > =============== ===================== > 1. device-A is added. > 2. device-B is added. > 3. dpm_list is now [device-A, device-B]. > 4. driver-A defers probe of device-A. > 5. device-A is moved to > end of dpm_list > 6. dpm_list is now > [device-B, device-A] > 7. driver-B is registereed and probes device-B. > 8. dpm_list stays as [device-B, device-A]. > > The reverse order of dpm_list is used for suspend. So in this case > device-A would incorrectly get suspended before device-B. > > Commit 716a7a259690 ("driver core: fw_devlink: Add support for batching > fwnode parsing") kicked off the deferred probe thread early during boot > to run in parallel with the initcall thread and caused suspend/resume > regressions. This patch removes the parallel run of the deferred probe > thread to avoid the suspend/resume regressions. > > [1] - https://lore.kernel.org/lkml/CAGETcx8W96KAw-d_siTX4qHB_-7ddk0miYRDQeHE6E0_8qx-6Q@mail.gmail.com/ > > Fixes: 716a7a259690 ("driver core: fw_devlink: Add support for batching fwnode parsing") > Signed-off-by: Saravana Kannan > --- > drivers/base/base.h | 1 - > drivers/base/core.c | 1 - > drivers/base/dd.c | 5 ----- > 3 files changed, 7 deletions(-) > > diff --git a/drivers/base/base.h b/drivers/base/base.h > index 95c22c0f9036..40fb069a8a7e 100644 > --- a/drivers/base/base.h > +++ b/drivers/base/base.h > @@ -153,7 +153,6 @@ extern char *make_class_name(const char *name, struct kobject *kobj); > extern int devres_release_all(struct device *dev); > extern void device_block_probing(void); > extern void device_unblock_probing(void); > -extern void driver_deferred_probe_force_trigger(void); > > /* /sys/devices directory */ > extern struct kset *devices_kset; > diff --git a/drivers/base/core.c b/drivers/base/core.c > index 67d39a90b45c..35cc9896eb9e 100644 > --- a/drivers/base/core.c > +++ b/drivers/base/core.c > @@ -1323,7 +1323,6 @@ void fw_devlink_resume(void) > goto out; > > device_link_add_missing_supplier_links(); > - driver_deferred_probe_force_trigger(); So it looks like this was not needed after all. What was the role of it then? > out: > mutex_unlock(&defer_fw_devlink_lock); > } > diff --git a/drivers/base/dd.c b/drivers/base/dd.c > index 9a1d940342ac..48ca81cb8ebc 100644 > --- a/drivers/base/dd.c > +++ b/drivers/base/dd.c > @@ -164,11 +164,6 @@ static void driver_deferred_probe_trigger(void) > if (!driver_deferred_probe_enable) > return; > > - driver_deferred_probe_force_trigger(); > -} > - > -void driver_deferred_probe_force_trigger(void) > -{ > /* > * A successful probe means that all the devices in the pending list > * should be triggered to be reprobed. Move all the deferred devices > -- > 2.27.0.212.ge8ba1cc988-goog >