From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Google-Smtp-Source: AH8x2243NymiAH+LRNL0gbaj+cSxB5TjPXj/sMIXaQUHI/veaxe/tP+C8DuNg9K17nqrmvEcU7AD ARC-Seal: i=1; a=rsa-sha256; t=1518431904; cv=none; d=google.com; s=arc-20160816; b=HKOATw5/rA14uG3blez+d6C8IkcO7mBOKYEt+5XES2IwMUlPLG26RQ0Xlro9b7CUUZ IKAOqaqm/Nj11+AGcWIJ/pPgi2u4M/Lx1OjZrExfPfipQ720/RcMIaw0qF1On953ntXl 1YgsSkF4AvyD4h2eNG4KQiHTPnLbw4e+27qQPxHB1mT9Fwol9mRJtEMZotzPpCYia6nR tJSwgk2tO0QWc65thEvElpgYcYtIqbdB3uaTv/oZ4sleQa8AXdHG+TwOXGBcIjgPCNm7 esxA4H32fxZ5BVZ0R29JHiIcf2LAlYm9c4tbhtQLSaH0Fh8cH9w/3Pj1Y9tKJesOmRus MaVg== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=content-transfer-encoding:mime-version:references:in-reply-to:date :cc:to:from:subject:message-id:arc-authentication-results; bh=90JOzHh9LTnC2Zov/ZadPtGXAS2HAoNaX3wMq3ISpLk=; b=lWzj/jSkZz9b3B/LH0NOzDKtUZ+z/Yo73Pf3U2PnqqlkPkWzYL+Q2VDwMGkZr6B6z3 vscFgtdGIIJk5E0dYMSMWj2ZbiwX5a+fG3CtkjgbdOgbjDN6a3MdHhd5zGen7lQ45iCw LbUPvJ/IAoZOXBq3+QFu8+y/Q1x7TGqvaf5PeP4Lstcz82NwJ/WNtwqPOHpG5R1H2mhK AJfmECIZ/Or5ww815dO0tuSI+KF7mJdOgEBcgusIebmu+hGfhA1AGH+FDfis0MxWf/Vn Mbob3PC6yryqJuwJ+kjTRyrDpuLqp4YPphvUtBmyCMYVIcT+Uc/QmAVsr63Cj/YHEjy1 TGWA== ARC-Authentication-Results: i=1; mx.google.com; spf=pass (google.com: best guess record for domain of l.stach@pengutronix.de designates 2001:67c:670:201:290:27ff:fe1d:cc33 as permitted sender) smtp.mailfrom=l.stach@pengutronix.de Authentication-Results: mx.google.com; spf=pass (google.com: best guess record for domain of l.stach@pengutronix.de designates 2001:67c:670:201:290:27ff:fe1d:cc33 as permitted sender) smtp.mailfrom=l.stach@pengutronix.de Message-ID: <1518431893.2744.1.camel@pengutronix.de> Subject: Re: [PATCH] base: power: domain: Replace mdelay with msleep From: Lucas Stach To: Ulf Hansson , Jia-Ju Bai Cc: "Rafael J. Wysocki" , Kevin Hilman , Len Brown , Pavel Machek , Greg Kroah-Hartman , Linux PM , Linux Kernel Mailing List Date: Mon, 12 Feb 2018 11:38:13 +0100 In-Reply-To: References: <1516955899-31810-1-git-send-email-baijiaju1990@gmail.com> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.22.6-1+deb9u1 Mime-Version: 1.0 Content-Transfer-Encoding: 8bit X-SA-Exim-Connect-IP: 2001:67c:670:100:fa0f:41ff:fe58:4010 X-SA-Exim-Mail-From: l.stach@pengutronix.de X-SA-Exim-Scanned: No (on metis.ext.pengutronix.de); SAEximRunCond expanded to false X-PTX-Original-Recipient: gregkh@linuxfoundation.org X-getmail-retrieved-from-mailbox: INBOX X-GMAIL-THRID: =?utf-8?q?1590643262439305991?= X-GMAIL-MSGID: =?utf-8?q?1592191252904483155?= X-Mailing-List: linux-kernel@vger.kernel.org List-ID: Am Freitag, den 09.02.2018, 14:58 +0100 schrieb Ulf Hansson: > On 26 January 2018 at 09:38, Jia-Ju Bai > wrote: > > After checking all possible call chains to genpd_dev_pm_detach() > > and > > genpd_dev_pm_attach() here, > > my tool finds that these functions are never called in atomic > > context, > > namely never in an interrupt handler or holding a spinlock. > > Thus mdelay can be replaced with msleep to avoid busy wait. > > > > This is found by a static analysis tool named DCNS written by > > myself. > > > > Signed-off-by: Jia-Ju Bai > > --- > >  drivers/base/power/domain.c |    4 ++-- > >  1 file changed, 2 insertions(+), 2 deletions(-) > > > > diff --git a/drivers/base/power/domain.c > > b/drivers/base/power/domain.c > > index 0c80bea..f84ac72 100644 > > --- a/drivers/base/power/domain.c > > +++ b/drivers/base/power/domain.c > > @@ -2144,7 +2144,7 @@ static void genpd_dev_pm_detach(struct device > > *dev, bool power_off) > >                 if (ret != -EAGAIN) > >                         break; > > > > -               mdelay(i); > > +               msleep(i); > > This looks like a nice improvement, however moving to msleep() makes > the call to cond_resched() below a bit superfluous. Perhaps remove > that as well. At least for small values of i, msleep also has a high chance to overshoot the desired sleep by a lot. It would be better to convert them to usleep_range with an acceptable slack. Regards, Lucas > >                 cond_resched(); > >         } > > > > @@ -2231,7 +2231,7 @@ int genpd_dev_pm_attach(struct device *dev) > >                 if (ret != -EAGAIN) > >                         break; > > > > -               mdelay(i); > > +               msleep(i); > > Ditto. > > >                 cond_resched(); > >         } > >         mutex_unlock(&gpd_list_lock); > > -- > > 1.7.9.5 > > > > Kind regards > Uffe