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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 49CFAC433F5 for ; Fri, 20 May 2022 16:19:50 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1347554AbiETQTt (ORCPT ); Fri, 20 May 2022 12:19:49 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57318 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231239AbiETQTs (ORCPT ); Fri, 20 May 2022 12:19:48 -0400 Received: from relay11.mail.gandi.net (relay11.mail.gandi.net [217.70.178.231]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 61AF384A05 for ; Fri, 20 May 2022 09:19:47 -0700 (PDT) Received: (Authenticated sender: alexandre.belloni@bootlin.com) by mail.gandi.net (Postfix) with ESMTPSA id 984E8100007; Fri, 20 May 2022 16:19:44 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bootlin.com; s=gm1; t=1653063586; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=twx5Nb38K4nE0qC7jQM3s5f/W4tlMVf9Nz1Y2ag8Kto=; b=isvkgAh5OhsVS0sJhO70VCoKvfzkvhx8WuAWDUAGCcQG5LLkHLZttFCG2pccv/s++2nuOK Mzqwpy35LJcc5n2Yjivv64C8/E1gmYgowdv15Ds5Z3meUYvH21eQpg/qMLdOLncvBUsBVz KTvBL8ZDq1BpBRzbkXV8UkL23dGZzyOFocrLO9Fn9QndV0eLW+V0ZU9yWYRmDIr3T6kQ19 a9O48gYBA4hjsQgZyNueqAzAyKwogE1YuzU3Irt7J9XmF4NM4Wglzp+pQiNpFVmP6etbSc zYoRRR9pMs8eq7H/9CVh0fOfF1MQJw4TknbImwWZJZ3eGrwkSkJ2UIJhVDOcgQ== Date: Fri, 20 May 2022 18:19:44 +0200 From: Alexandre Belloni To: Tetsuo Handa Cc: Alessandro Zummo , linux-rtc@vger.kernel.org Subject: Re: [PATCH v3] rtc: Avoid flush_scheduled_work() usage Message-ID: References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-rtc@vger.kernel.org Hello, On 20/05/2022 23:33:47+0900, Tetsuo Handa wrote: > Flushing system-wide workqueues is dangerous and will be forbidden. > Replace system_wq with local rtc_wq. > > While we are at it, remove unused rtc_dev_exit(). > > Link: https://lkml.kernel.org/r/49925af7-78a8-a3dd-bce6-cfc02e1a9236@I-love.SAKURA.ne.jp > Signed-off-by: Tetsuo Handa > --- > Changes in v3: > Fix build error. > Forgot to replace flush_scheduled_work(). > > Changes in v2: > Remove unused rtc_dev_exit(). > > Since rtc_dev_init() is built into vmlinux, there is no point with > recovery. > > This patch blindly converts schedule_work() into queue_work() within > drivers/rtc/dev.c, based on an assumption that none of work items > outside of drivers/rtc/dev.c needs to be handled by rtc_wq. > Did I convert correctly? > Yes and no, this could be a bit more clever and create the workqueue only for the devices that actually need it. I worked on something after seeing your first email a while ago but I needed more time to test it. > drivers/rtc/dev.c | 18 ++++++++---------- > drivers/rtc/rtc-core.h | 5 ----- > 2 files changed, 8 insertions(+), 15 deletions(-) > > diff --git a/drivers/rtc/dev.c b/drivers/rtc/dev.c > index 69325aeede1a..a7346f03a5b2 100644 > --- a/drivers/rtc/dev.c > +++ b/drivers/rtc/dev.c > @@ -17,6 +17,7 @@ > #include "rtc-core.h" > > static dev_t rtc_devt; > +static struct workqueue_struct *rtc_wq; > > #define RTC_DEV_MAX 16 /* 16 RTCs should be enough for everyone... */ > > @@ -62,7 +63,7 @@ static void rtc_uie_task(struct work_struct *work) > rtc->uie_timer_active = 1; > rtc->uie_task_active = 0; > add_timer(&rtc->uie_timer); > - } else if (schedule_work(&rtc->uie_task) == 0) { > + } else if (queue_work(rtc_wq, &rtc->uie_task) == 0) { > rtc->uie_task_active = 0; > } > spin_unlock_irq(&rtc->irq_lock); > @@ -78,7 +79,7 @@ static void rtc_uie_timer(struct timer_list *t) > spin_lock_irqsave(&rtc->irq_lock, flags); > rtc->uie_timer_active = 0; > rtc->uie_task_active = 1; > - if ((schedule_work(&rtc->uie_task) == 0)) > + if (queue_work(rtc_wq, &rtc->uie_task) == 0) > rtc->uie_task_active = 0; > spin_unlock_irqrestore(&rtc->irq_lock, flags); > } > @@ -96,7 +97,7 @@ static int clear_uie(struct rtc_device *rtc) > } > if (rtc->uie_task_active) { > spin_unlock_irq(&rtc->irq_lock); > - flush_scheduled_work(); > + flush_workqueue(rtc_wq); > spin_lock_irq(&rtc->irq_lock); > } > rtc->uie_irq_active = 0; > @@ -119,7 +120,7 @@ static int set_uie(struct rtc_device *rtc) > rtc->stop_uie_polling = 0; > rtc->oldsecs = tm.tm_sec; > rtc->uie_task_active = 1; > - if (schedule_work(&rtc->uie_task) == 0) > + if (queue_work(rtc_wq, &rtc->uie_task) == 0) > rtc->uie_task_active = 0; > } > rtc->irq_data = 0; > @@ -562,13 +563,10 @@ void __init rtc_dev_init(void) > { > int err; > > + rtc_wq = alloc_workqueue("rtc_wq", 0, 0); > + BUG_ON(!rtc_wq); > + > err = alloc_chrdev_region(&rtc_devt, 0, RTC_DEV_MAX, "rtc"); > if (err < 0) > pr_err("failed to allocate char dev region\n"); > } > - > -void __exit rtc_dev_exit(void) > -{ > - if (rtc_devt) > - unregister_chrdev_region(rtc_devt, RTC_DEV_MAX); This is very unrelated and should be in a different patch. > -} > diff --git a/drivers/rtc/rtc-core.h b/drivers/rtc/rtc-core.h > index 0abf98983e13..4b10a1b8f370 100644 > --- a/drivers/rtc/rtc-core.h > +++ b/drivers/rtc/rtc-core.h > @@ -2,7 +2,6 @@ > #ifdef CONFIG_RTC_INTF_DEV > > extern void __init rtc_dev_init(void); > -extern void __exit rtc_dev_exit(void); > extern void rtc_dev_prepare(struct rtc_device *rtc); > > #else > @@ -11,10 +10,6 @@ static inline void rtc_dev_init(void) > { > } > > -static inline void rtc_dev_exit(void) > -{ > -} > - > static inline void rtc_dev_prepare(struct rtc_device *rtc) > { > } > -- > 2.34.1 > > -- Alexandre Belloni, co-owner and COO, Bootlin Embedded Linux and Kernel engineering https://bootlin.com