linux-kernel - Re: [PATCH AUTOSEL 5.16 24/30] dmaengine: shdma: Fix runtime PM imbalance on error

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Message-ID: <12bdb8e2.89509.17f2f8e0337.Coremail.lyz_cs@pku.edu.cn>
Date:   Fri, 25 Feb 2022 14:25:10 +0800 (GMT+08:00)
From:   刘永志 <lyz_cs@....edu.cn>
To:     "pavel machek" <pavel@...x.de>
Cc:     "sasha levin" <sashal@...nel.org>, linux-kernel@...r.kernel.org,
        stable@...r.kernel.org, "vinod koul" <vkoul@...nel.org>,
        christophe.jaillet@...adoo.fr, arnd@...db.de,
        laurent.pinchart@...asonboard.com, dmaengine@...r.kernel.org
Subject: Re: [PATCH AUTOSEL 5.16 24/30] dmaengine: shdma: Fix runtime PM
 imbalance on error

> -----原始邮件-----
> 发件人: "Pavel Machek" <pavel@...x.de>
> 发送时间: 2022-02-25 06:39:08 (星期五)
> 收件人: "Sasha Levin" <sashal@...nel.org>
> 抄送: linux-kernel@...r.kernel.org, stable@...r.kernel.org, "Yongzhi Liu" <lyz_cs@....edu.cn>, "Vinod Koul" <vkoul@...nel.org>, christophe.jaillet@...adoo.fr, arnd@...db.de, laurent.pinchart@...asonboard.com, dmaengine@...r.kernel.org
> 主题: Re: [PATCH AUTOSEL 5.16 24/30] dmaengine: shdma: Fix runtime PM imbalance on error
> 
> Hi!
> 
> > From: Yongzhi Liu <lyz_cs@....edu.cn>
> > 
> > [ Upstream commit 455896c53d5b803733ddd84e1bf8a430644439b6 ]
> > 
> > pm_runtime_get_() increments the runtime PM usage counter even
> > when it returns an error code, thus a matching decrement is needed on
> > the error handling path to keep the counter balanced.
> 
> I don't think that's right.
> 
> Notice that -ret is ignored (checked 4.4 and 5.10), so we don't
> actually abort/return error; we just printk. We'll do two
> pm_runtime_put's after the "fix".

Thank you very much for the correction. I am very sorry that I caused you unnecessary trouble because of my carelessness.
The pm_runtime_put is indeed called later in __ld_cleanup, so only printk is needed at -ret and the patch is not right.

> 
> Please drop from -stable.
> 
> Best regards,
> 								Pavel
> -- 
> DENX Software Engineering GmbH,      Managing Director: Wolfgang Denk
> HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany