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=-11.0 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 C09DEC2D0A8 for ; Wed, 23 Sep 2020 10:30:05 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 769ED2388A for ; Wed, 23 Sep 2020 10:30:05 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1600857005; bh=kDV7h/VYPS+RMSk792Z6m+XVk+KE1QdwhgIYZ5PeZRs=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=xWzd880Exypnu7v5iWyHjhCL+FVWxvZEsnfa+hIpu6PDIs7OzTi2dHmIbWjmf/3fG LGE3YTHAswwNYvPfrubsKdSTbl32X6Qdxk7ngJCbFv3xkpIXm8g1Kftg78cAJoPKNp RT4tCP7wQW5ZO/4zAVRQZNFhhNd47UezP2bqZMqs= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726620AbgIWKaD (ORCPT ); Wed, 23 Sep 2020 06:30:03 -0400 Received: from mail.kernel.org ([198.145.29.99]:52640 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726420AbgIWKaC (ORCPT ); Wed, 23 Sep 2020 06:30:02 -0400 Received: from localhost (83-86-74-64.cable.dynamic.v4.ziggo.nl [83.86.74.64]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 926FD23119; Wed, 23 Sep 2020 10:30:01 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1600857002; bh=kDV7h/VYPS+RMSk792Z6m+XVk+KE1QdwhgIYZ5PeZRs=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=haLpkgm/LlmPgpPpcdrFa2++gBaAEkKrCoB3T0EfP28jHRD6SJkgpCMptKsiYv4MB X2FY9p7SdpV4dMLTTDgg4BOvA5vqABTVH4I5e553tPaavF89TKm8F7ykmNvYHOsLc+ myxl05rS2gUzdRy/nHOP1kKHhoDTqcKNjKvTwnaU= Date: Wed, 23 Sep 2020 12:30:21 +0200 From: Greg KH To: Shuah Khan Cc: rafael@kernel.org, keescook@chromium.org, linux-kernel@vger.kernel.org Subject: Re: [RFC PATCH 03/11] drivers/base: convert deferred_trigger_count and probe_count to counter_atomic Message-ID: <20200923103021.GG3154647@kroah.com> References: <576d5405373295b147a876006df6842f31d64b8a.1600816121.git.skhan@linuxfoundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <576d5405373295b147a876006df6842f31d64b8a.1600816121.git.skhan@linuxfoundation.org> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Sep 22, 2020 at 07:43:32PM -0600, Shuah Khan wrote: > counter_atomic is introduced to be used when a variable is used as > a simple counter and doesn't guard object lifetimes. This clearly > differentiates atomic_t usages that guard object lifetimes. > > counter_atomic variables will wrap around to 0 when it overflows and > should not be used to guard resource lifetimes, device usage and > open counts that control state changes, and pm states. > > deferred_trigger_count gets incremented and read. It doesn't guard > object lifetimes, device usage counts, device open counts, and pm > states. There is very little chance of this counter overflowing. > Convert it to use counter_atomic. > > This conversion doesn't change the oveflow wrap around behavior. > > probe_count gets incremented, decremented, read. It doesn't guard > object lifetimes, device usage counts, device open counts, and pm > states. There is very little chance of this counter overflowing. > This counter controls the wait for known devices to complete their > probing, and probe_count == 0 ends the wait. Other than that it > meets the other criteria to be converted. Convert it to use > counter_atomic. > > Signed-off-by: Shuah Khan > --- > drivers/base/dd.c | 19 ++++++++++--------- > 1 file changed, 10 insertions(+), 9 deletions(-) > > diff --git a/drivers/base/dd.c b/drivers/base/dd.c > index 857b0a928e8d..f49fe45960ac 100644 > --- a/drivers/base/dd.c > +++ b/drivers/base/dd.c > @@ -28,6 +28,7 @@ > #include > #include > #include > +#include > > #include "base.h" > #include "power/power.h" > @@ -54,7 +55,7 @@ > static DEFINE_MUTEX(deferred_probe_mutex); > static LIST_HEAD(deferred_probe_pending_list); > static LIST_HEAD(deferred_probe_active_list); > -static atomic_t deferred_trigger_count = ATOMIC_INIT(0); > +static struct counter_atomic deferred_trigger_count = COUNTER_ATOMIC_INIT(0); > static struct dentry *deferred_devices; > static bool initcalls_done; > > @@ -173,7 +174,7 @@ static void driver_deferred_probe_trigger(void) > * into the active list so they can be retried by the workqueue > */ > mutex_lock(&deferred_probe_mutex); > - atomic_inc(&deferred_trigger_count); > + counter_atomic_inc(&deferred_trigger_count); > list_splice_tail_init(&deferred_probe_pending_list, > &deferred_probe_active_list); > mutex_unlock(&deferred_probe_mutex); > @@ -466,7 +467,7 @@ int device_bind_driver(struct device *dev) > } > EXPORT_SYMBOL_GPL(device_bind_driver); > > -static atomic_t probe_count = ATOMIC_INIT(0); > +static struct counter_atomic probe_count = COUNTER_ATOMIC_INIT(0); > static DECLARE_WAIT_QUEUE_HEAD(probe_waitqueue); > > static void driver_deferred_probe_add_trigger(struct device *dev, > @@ -474,7 +475,7 @@ static void driver_deferred_probe_add_trigger(struct device *dev, > { > driver_deferred_probe_add(dev); > /* Did a trigger occur while probing? Need to re-trigger if yes */ > - if (local_trigger_count != atomic_read(&deferred_trigger_count)) > + if (local_trigger_count != counter_atomic_read(&deferred_trigger_count)) > driver_deferred_probe_trigger(); > } > > @@ -493,7 +494,7 @@ static DEVICE_ATTR_RO(state_synced); > static int really_probe(struct device *dev, struct device_driver *drv) > { > int ret = -EPROBE_DEFER; > - int local_trigger_count = atomic_read(&deferred_trigger_count); > + int local_trigger_count = counter_atomic_read(&deferred_trigger_count); > bool test_remove = IS_ENABLED(CONFIG_DEBUG_TEST_DRIVER_REMOVE) && > !drv->suppress_bind_attrs; > > @@ -514,7 +515,7 @@ static int really_probe(struct device *dev, struct device_driver *drv) > if (ret) > return ret; > > - atomic_inc(&probe_count); > + counter_atomic_inc(&probe_count); > pr_debug("bus: '%s': %s: probing driver %s with device %s\n", > drv->bus->name, __func__, drv->name, dev_name(dev)); > if (!list_empty(&dev->devres_head)) { > @@ -648,7 +649,7 @@ static int really_probe(struct device *dev, struct device_driver *drv) > */ > ret = 0; > done: > - atomic_dec(&probe_count); > + counter_atomic_dec(&probe_count); > wake_up_all(&probe_waitqueue); > return ret; > } > @@ -678,7 +679,7 @@ static int really_probe_debug(struct device *dev, struct device_driver *drv) > */ > int driver_probe_done(void) > { > - int local_probe_count = atomic_read(&probe_count); > + int local_probe_count = counter_atomic_read(&probe_count); > > pr_debug("%s: probe_count = %d\n", __func__, local_probe_count); > if (local_probe_count) > @@ -699,7 +700,7 @@ void wait_for_device_probe(void) > flush_work(&deferred_probe_work); > > /* wait for the known devices to complete their probing */ > - wait_event(probe_waitqueue, atomic_read(&probe_count) == 0); > + wait_event(probe_waitqueue, counter_atomic_read(&probe_count) == 0); > async_synchronize_full(); > } > EXPORT_SYMBOL_GPL(wait_for_device_probe); > -- > 2.25.1 > Reviewed-by: Greg Kroah-Hartman