linux-kernel - [PATCH 1/2] dmaengine: Cleanups for the slave <-> channel symlink support

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Date:   Thu, 30 Jan 2020 13:42:19 +0200
From:   Peter Ujfalusi <peter.ujfalusi@...com>
To:     <vkoul@...nel.org>
CC:     <dmaengine@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <dan.j.williams@...el.com>, <geert@...ux-m68k.org>
Subject: [PATCH 1/2] dmaengine: Cleanups for the slave <-> channel symlink support

No need to use goto to jump over the
return chan ? chan : ERR_PTR(-EPROBE_DEFER);
We can just revert the check and return right there.

Do not fail the channel request if the chan->name allocation fails, but
print a warning about it.

Change the dev_err to dev_warn if sysfs_create_link() fails as it is not
fatal.

Only attempt to remove the DMA_SLAVE_NAME symlink if it is created - or it
was attempted to be created.

Signed-off-by: Peter Ujfalusi <peter.ujfalusi@...com>
---
 drivers/dma/dmaengine.c | 23 +++++++++++++----------
 1 file changed, 13 insertions(+), 10 deletions(-)

diff --git a/drivers/dma/dmaengine.c b/drivers/dma/dmaengine.c
index 7b1cefc3213a..75516f9fbab4 100644
--- a/drivers/dma/dmaengine.c
+++ b/drivers/dma/dmaengine.c
@@ -756,22 +756,24 @@ struct dma_chan *dma_request_chan(struct device *dev, const char *name)
 	}
 	mutex_unlock(&dma_list_mutex);
 
-	if (!IS_ERR_OR_NULL(chan))
-		goto found;
-
-	return chan ? chan : ERR_PTR(-EPROBE_DEFER);
+	if (IS_ERR_OR_NULL(chan))
+		return chan ? chan : ERR_PTR(-EPROBE_DEFER);
 
 found:
-	chan->slave = dev;
 	chan->name = kasprintf(GFP_KERNEL, "dma:%s", name);
-	if (!chan->name)
-		return ERR_PTR(-ENOMEM);
+	if (!chan->name) {
+		dev_warn(dev,
+			 "Cannot allocate memory for slave symlink name\n");
+		return chan;
+	}
+	chan->slave = dev;
 
 	if (sysfs_create_link(&chan->dev->device.kobj, &dev->kobj,
 			      DMA_SLAVE_NAME))
-		dev_err(dev, "Cannot create DMA %s symlink\n", DMA_SLAVE_NAME);
+		dev_warn(dev, "Cannot create DMA %s symlink\n", DMA_SLAVE_NAME);
 	if (sysfs_create_link(&dev->kobj, &chan->dev->device.kobj, chan->name))
-		dev_err(dev, "Cannot create DMA %s symlink\n", chan->name);
+		dev_warn(dev, "Cannot create DMA %s symlink\n", chan->name);
+
 	return chan;
 }
 EXPORT_SYMBOL_GPL(dma_request_chan);
@@ -830,13 +832,14 @@ void dma_release_channel(struct dma_chan *chan)
 	/* drop PRIVATE cap enabled by __dma_request_channel() */
 	if (--chan->device->privatecnt == 0)
 		dma_cap_clear(DMA_PRIVATE, chan->device->cap_mask);
+
 	if (chan->slave) {
+		sysfs_remove_link(&chan->dev->device.kobj, DMA_SLAVE_NAME);
 		sysfs_remove_link(&chan->slave->kobj, chan->name);
 		kfree(chan->name);
 		chan->name = NULL;
 		chan->slave = NULL;
 	}
-	sysfs_remove_link(&chan->dev->device.kobj, DMA_SLAVE_NAME);
 	mutex_unlock(&dma_list_mutex);
 }
 EXPORT_SYMBOL_GPL(dma_release_channel);
-- 
Peter

Texas Instruments Finland Oy, Porkkalankatu 22, 00180 Helsinki.
Y-tunnus/Business ID: 0615521-4. Kotipaikka/Domicile: Helsinki