openwrt/target/linux/ipq806x/patches-3.18/150-dmaengine-Rework-dma_chan_get.patch

From d2f4f99db3e9ec8b063cf2e45704e2bb95428317 Mon Sep 17 00:00:00 2001
From: Maxime Ripard <maxime.ripard@free-electrons.com>
Date: Mon, 17 Nov 2014 14:41:58 +0100
Subject: [PATCH] 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@free-electrons.com>
Acked-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>
---
 drivers/dma/dmaengine.c | 36 +++++++++++++++++++-----------------
 1 file changed, 19 insertions(+), 17 deletions(-)

--- a/drivers/dma/dmaengine.c
+++ b/drivers/dma/dmaengine.c
@@ -222,31 +222,33 @@ static void balance_ref_count(struct dma
  */
 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);
-	}
-
-	return err;
+	ret = chan->device->device_alloc_chan_resources(chan);
+	if (ret < 0)
+		goto err_out;
+
+	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;
 }
 
 /**