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From: Ruoyu Wang <ruoyuw560@gmail.com>
To: dmaengine@vger.kernel.org
Cc: vkoul@kernel.org, Frank.Li@kernel.org, ed.blake@sondrel.com,
	linux-kernel@vger.kernel.org, Ruoyu Wang <ruoyuw560@gmail.com>
Subject: [PATCH] dmaengine: img-mdc: Fix runtime PM usage counter leak
Date: Thu, 13 Aug 2026 23:31:43 +0800	[thread overview]
Message-ID: <20260813153143.3953303-1-ruoyuw560@gmail.com> (raw)

pm_runtime_get_sync() leaves the IMG MDC device's usage counter
incremented when runtime resume fails. mdc_alloc_chan_resources() returns
that error to the DMA core, so the channel's client count is not
incremented and mdc_free_chan_resources() is not called to drop the
reference. Repeated allocation attempts can therefore accumulate usage
references and prevent runtime suspend.

Use pm_runtime_resume_and_get() so a failed resume does not retain a
usage reference while successful allocations remain paired with
mdc_free_chan_resources(). DMA core only treats negative return values as
allocation failures, so the helper's zero success return preserves
behavior.

This issue was found by a static analysis checker and confirmed by manual
source review.

Fixes: 56d355e6f586 ("dmaengine: img-mdc: Add runtime PM")
Signed-off-by: Ruoyu Wang <ruoyuw560@gmail.com>
---
 drivers/dma/img-mdc-dma.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/dma/img-mdc-dma.c b/drivers/dma/img-mdc-dma.c
index b3765ba1580308..a3192d49b6c860 100644
--- a/drivers/dma/img-mdc-dma.c
+++ b/drivers/dma/img-mdc-dma.c
@@ -738,7 +738,7 @@ static int mdc_alloc_chan_resources(struct dma_chan *chan)
 	struct mdc_chan *mchan = to_mdc_chan(chan);
 	struct device *dev = mdma2dev(mchan->mdma);
 
-	return pm_runtime_get_sync(dev);
+	return pm_runtime_resume_and_get(dev);
 }
 
 static void mdc_free_chan_resources(struct dma_chan *chan)
-- 
2.51.0


             reply	other threads:[~2026-08-13 15:31 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-08-13 15:31 Ruoyu Wang [this message]
2026-08-13 15:45 ` [PATCH] dmaengine: img-mdc: Fix runtime PM usage counter leak sashiko-bot
2026-08-13 16:16 ` Frank Li

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