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

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

[Sasha Levin]

From: Yongzhi Liu <lyz_cs@pku.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.

Signed-off-by: Yongzhi Liu <lyz_cs@pku.edu.cn>
Link: https://lore.kernel.org/r/1642311296-87020-1-git-send-email-lyz_cs@pku.edu.cn
Signed-off-by: Vinod Koul <vkoul@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/dma/sh/shdma-base.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/dma/sh/shdma-base.c b/drivers/dma/sh/shdma-base.c
index 7f72b3f4cd1ae..19ac95c0098f0 100644
--- a/drivers/dma/sh/shdma-base.c
+++ b/drivers/dma/sh/shdma-base.c
@@ -115,8 +115,10 @@ static dma_cookie_t shdma_tx_submit(struct dma_async_tx_descriptor *tx)
 		ret = pm_runtime_get(schan->dev);
 
 		spin_unlock_irq(&schan->chan_lock);
-		if (ret < 0)
+		if (ret < 0) {
 			dev_err(schan->dev, "%s(): GET = %d\n", __func__, ret);
+			pm_runtime_put(schan->dev);
+		}
 
 		pm_runtime_barrier(schan->dev);
 
-- 
2.34.1

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

[Pavel Machek]

[-- Attachment #1: Type: text/plain, Size: 716 bytes --]

Hi!

> From: Yongzhi Liu <lyz_cs@pku.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".

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

[-- Attachment #2: signature.asc --]
[-- Type: application/pgp-signature, Size: 195 bytes --]

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

[刘永志]

> -----原始邮件-----
> 发件人: "Pavel Machek" <pavel@denx.de>
> 发送时间: 2022-02-25 06:39:08 (星期五)
> 收件人: "Sasha Levin" <sashal@kernel.org>
> 抄送: linux-kernel@vger.kernel.org, stable@vger.kernel.org, "Yongzhi Liu" <lyz_cs@pku.edu.cn>, "Vinod Koul" <vkoul@kernel.org>, christophe.jaillet@wanadoo.fr, arnd@arndb.de, laurent.pinchart@ideasonboard.com, dmaengine@vger.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@pku.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