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Message-ID: <20220427203248.GA2175@duo.ucw.cz>
Date: Wed, 27 Apr 2022 22:32:48 +0200
From: Pavel Machek <pavel@...x.de>
To: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc: linux-kernel@...r.kernel.org, stable@...r.kernel.org,
Zhang Qilong <zhangqilong3@...wei.com>,
Vinod Koul <vkoul@...nel.org>, Sasha Levin <sashal@...nel.org>
Subject: Re: [PATCH 5.10 14/86] dmaengine: mediatek:Fix PM usage reference
leak of mtk_uart_apdma_alloc_chan_resources
Hi!
> > pm_runtime_get_sync will increment pm usage counter even it failed.
> > Forgetting to putting operation will result in reference leak here.
> > We fix it:
> > 1) Replacing it with pm_runtime_resume_and_get to keep usage counter
> > balanced.
>
> Suspect.
>
> > 2) Add putting operation before returning error.
>
> Yes but you also put in success case, which is likely
> wrong. mtk_uart_apdma_free_chan_resources() does second put.
This is possible fix for the second problem:
Signed-off-by: Pavel Machek <pavel@...x.de>
diff --git a/drivers/dma/mediatek/mtk-uart-apdma.c b/drivers/dma/mediatek/mtk-uart-apdma.c
index a1517ef1f4a0..8ec046a7e714 100644
--- a/drivers/dma/mediatek/mtk-uart-apdma.c
+++ b/drivers/dma/mediatek/mtk-uart-apdma.c
@@ -300,7 +300,8 @@ static int mtk_uart_apdma_alloc_chan_resources(struct dma_chan *chan)
if (mtkd->support_33bits)
mtk_uart_apdma_write(c, VFF_4G_SUPPORT, VFF_4G_SUPPORT_CLR_B);
-
+ return 0;
+
err_pm:
pm_runtime_put_noidle(mtkd->ddev.dev);
return ret;
Best regards,
Pavel
--
DENX Software Engineering GmbH, Managing Director: Wolfgang Denk
HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany
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