linux-kernel - [PATCH v4 04/58] dmaengine: Rework dma_chan

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Date:	Tue, 28 Oct 2014 22:25:19 +0100
From:	Maxime Ripard <maxime.ripard@...e-electrons.com>
To:	Vinod Koul <vinod.koul@...el.com>, dmaengine@...r.kernel.org
Cc:	linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
	Laurent Pinchart <laurent.pinchart@...asonboard.com>,
	Antoine Ténart <antoine@...e-electrons.com>,
	Russell King <linux@....linux.org.uk>, lars@...afoo.de,
	Maxime Ripard <maxime.ripard@...e-electrons.com>
Subject: [PATCH v4 04/58] dmaengine: Rework dma_chan_get

dma_chan_get uses a rather interesting error handling and code path.

Change it to something more usual in the kernel.

Signed-off-by: Maxime Ripard <maxime.ripard@...e-electrons.com>
Acked-by: Laurent Pinchart <laurent.pinchart@...asonboard.com>
---
 drivers/dma/dmaengine.c | 36 +++++++++++++++++++-----------------
 1 file changed, 19 insertions(+), 17 deletions(-)

diff --git a/drivers/dma/dmaengine.c b/drivers/dma/dmaengine.c
index 24bfaf0b92ba..72f10e2f5c32 100644
--- a/drivers/dma/dmaengine.c
+++ b/drivers/dma/dmaengine.c
@@ -222,31 +222,33 @@ static void balance_ref_count(struct dma_chan *chan)
  */
 static int dma_chan_get(struct dma_chan *chan)
 {
-	int err = -ENODEV;
 	struct module *owner = dma_chan_to_owner(chan);
+	int ret;
 
+	/* The channel is already in use, update client count */
 	if (chan->client_count) {
 		__module_get(owner);
-		err = 0;
-	} else if (try_module_get(owner))
-		err = 0;
+		goto out;
+	}
 
-	if (err == 0)
-		chan->client_count++;
+	if (!try_module_get(owner))
+		return -ENODEV;
 
 	/* allocate upon first client reference */
-	if (chan->client_count == 1 && err == 0) {
-		int desc_cnt = chan->device->device_alloc_chan_resources(chan);
-
-		if (desc_cnt < 0) {
-			err = desc_cnt;
-			chan->client_count = 0;
-			module_put(owner);
-		} else if (!dma_has_cap(DMA_PRIVATE, chan->device->cap_mask))
-			balance_ref_count(chan);
-	}
+	ret = chan->device->device_alloc_chan_resources(chan);
+	if (ret < 0)
+		goto err_out;
 
-	return err;
+	if (!dma_has_cap(DMA_PRIVATE, chan->device->cap_mask))
+		balance_ref_count(chan);
+
+out:
+	chan->client_count++;
+	return 0;
+
+err_out:
+	module_put(owner);
+	return ret;
 }
 
 /**
-- 
2.1.1

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