linux-kernel - [PATCH] dmaengine: fix balance of privatecnt inc/dec operations

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Date:	Fri, 07 Aug 2015 12:26:47 +0200
From:	Robert Baldyga <r.baldyga@...sung.com>
To:	vinod.koul@...el.com
Cc:	dan.j.williams@...el.com, dmaengine@...r.kernel.org,
	linux-kernel@...r.kernel.org, m.szyprowski@...sung.com,
	k.kozlowski@...sung.com, Robert Baldyga <r.baldyga@...sung.com>
Subject: [PATCH] dmaengine: fix balance of privatecnt inc/dec operations

This patch increments privatecnt value and set DMA_PRIVATE in device
caps in dma_request_slave_channel() function. This is needed to keep
privatecnt increment/decrement balance.

As function dma_release_channel() decrements privatecnt counter, we need
to increment it when channel is requested. Otherwise privatecnt drops
into negatives after few dma_release_channel() calls.

Reported-by: Krzysztof Kozlowski <k.kozlowski@...sung.com>
Signed-off-by: Robert Baldyga <r.baldyga@...sung.com>
---
 drivers/dma/dmaengine.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/dma/dmaengine.c b/drivers/dma/dmaengine.c
index 4a4cce1..3ff284c 100644
--- a/drivers/dma/dmaengine.c
+++ b/drivers/dma/dmaengine.c
@@ -689,6 +689,10 @@ struct dma_chan *dma_request_slave_channel(struct device *dev,
 	struct dma_chan *ch = dma_request_slave_channel_reason(dev, name);
 	if (IS_ERR(ch))
 		return NULL;
+
+	dma_cap_set(DMA_PRIVATE, ch->device->cap_mask);
+	ch->device->privatecnt++;
+
 	return ch;
 }
 EXPORT_SYMBOL_GPL(dma_request_slave_channel);
-- 
1.9.1

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