[PATCH v5 2/4] dax/bus: Use guard(device) in sysfs attribute helpers

[Vishal Verma]

Use the guard(device) macro to lock a 'struct device', and unlock it
automatically when going out of scope using Scope Based Resource
Management semantics. A lot of the sysfs attribute writes in
drivers/dax/bus.c benefit from a cleanup using these, so change these
where applicable.

Cc: Joao Martins <joao.m.martins@xxxxxxxxxx>
Cc: Dan Williams <dan.j.williams@xxxxxxxxx>
Signed-off-by: Vishal Verma <vishal.l.verma@xxxxxxxxx>
---
 drivers/dax/bus.c | 143 ++++++++++++++++++++++--------------------------------
 1 file changed, 59 insertions(+), 84 deletions(-)

diff --git a/drivers/dax/bus.c b/drivers/dax/bus.c
index 1ff1ab5fa105..6226de131d17 100644
--- a/drivers/dax/bus.c
+++ b/drivers/dax/bus.c
@@ -294,13 +294,10 @@ static ssize_t available_size_show(struct device *dev,
 		struct device_attribute *attr, char *buf)
 {
 	struct dax_region *dax_region = dev_get_drvdata(dev);
-	unsigned long long size;
 
-	device_lock(dev);
-	size = dax_region_avail_size(dax_region);
-	device_unlock(dev);
+	guard(device)(dev);
 
-	return sprintf(buf, "%llu\n", size);
+	return sprintf(buf, "%llu\n", dax_region_avail_size(dax_region));
 }
 static DEVICE_ATTR_RO(available_size);
 
@@ -309,17 +306,14 @@ static ssize_t seed_show(struct device *dev,
 {
 	struct dax_region *dax_region = dev_get_drvdata(dev);
 	struct device *seed;
-	ssize_t rc;
 
 	if (is_static(dax_region))
 		return -EINVAL;
 
-	device_lock(dev);
+	guard(device)(dev);
 	seed = dax_region->seed;
-	rc = sprintf(buf, "%s\n", seed ? dev_name(seed) : "");
-	device_unlock(dev);
 
-	return rc;
+	return sprintf(buf, "%s\n", seed ? dev_name(seed) : "");
 }
 static DEVICE_ATTR_RO(seed);
 
@@ -328,24 +322,28 @@ static ssize_t create_show(struct device *dev,
 {
 	struct dax_region *dax_region = dev_get_drvdata(dev);
 	struct device *youngest;
-	ssize_t rc;
 
 	if (is_static(dax_region))
 		return -EINVAL;
 
-	device_lock(dev);
+	guard(device)(dev);
 	youngest = dax_region->youngest;
-	rc = sprintf(buf, "%s\n", youngest ? dev_name(youngest) : "");
-	device_unlock(dev);
 
-	return rc;
+	return sprintf(buf, "%s\n", youngest ? dev_name(youngest) : "");
 }
 
 static ssize_t create_store(struct device *dev, struct device_attribute *attr,
 		const char *buf, size_t len)
 {
 	struct dax_region *dax_region = dev_get_drvdata(dev);
+	struct dev_dax_data data = {
+		.dax_region = dax_region,
+		.size = 0,
+		.id = -1,
+		.memmap_on_memory = false,
+	};
 	unsigned long long avail;
+	struct dev_dax *dev_dax;
 	ssize_t rc;
 	int val;
 
@@ -358,38 +356,25 @@ static ssize_t create_store(struct device *dev, struct device_attribute *attr,
 	if (val != 1)
 		return -EINVAL;
 
-	device_lock(dev);
+	guard(device)(dev);
 	avail = dax_region_avail_size(dax_region);
 	if (avail == 0)
-		rc = -ENOSPC;
-	else {
-		struct dev_dax_data data = {
-			.dax_region = dax_region,
-			.size = 0,
-			.id = -1,
-			.memmap_on_memory = false,
-		};
-		struct dev_dax *dev_dax = devm_create_dev_dax(&data);
+		return -ENOSPC;
 
-		if (IS_ERR(dev_dax))
-			rc = PTR_ERR(dev_dax);
-		else {
-			/*
-			 * In support of crafting multiple new devices
-			 * simultaneously multiple seeds can be created,
-			 * but only the first one that has not been
-			 * successfully bound is tracked as the region
-			 * seed.
-			 */
-			if (!dax_region->seed)
-				dax_region->seed = &dev_dax->dev;
-			dax_region->youngest = &dev_dax->dev;
-			rc = len;
-		}
-	}
-	device_unlock(dev);
+	dev_dax = devm_create_dev_dax(&data);
+	if (IS_ERR(dev_dax))
+		return PTR_ERR(dev_dax);
 
-	return rc;
+	/*
+	 * In support of crafting multiple new devices simultaneously multiple
+	 * seeds can be created, but only the first one that has not been
+	 * successfully bound is tracked as the region seed.
+	 */
+	if (!dax_region->seed)
+		dax_region->seed = &dev_dax->dev;
+	dax_region->youngest = &dev_dax->dev;
+
+	return len;
 }
 static DEVICE_ATTR_RW(create);
 
@@ -481,12 +466,9 @@ static int __free_dev_dax_id(struct dev_dax *dev_dax)
 static int free_dev_dax_id(struct dev_dax *dev_dax)
 {
 	struct device *dev = &dev_dax->dev;
-	int rc;
 
-	device_lock(dev);
-	rc = __free_dev_dax_id(dev_dax);
-	device_unlock(dev);
-	return rc;
+	guard(device)(dev);
+	return __free_dev_dax_id(dev_dax);
 }
 
 static int alloc_dev_dax_id(struct dev_dax *dev_dax)
@@ -908,9 +890,8 @@ static ssize_t size_show(struct device *dev,
 	struct dev_dax *dev_dax = to_dev_dax(dev);
 	unsigned long long size;
 
-	device_lock(dev);
+	guard(device)(dev);
 	size = dev_dax_size(dev_dax);
-	device_unlock(dev);
 
 	return sprintf(buf, "%llu\n", size);
 }
@@ -1080,17 +1061,16 @@ static ssize_t size_store(struct device *dev, struct device_attribute *attr,
 		return -EINVAL;
 	}
 
-	device_lock(dax_region->dev);
-	if (!dax_region->dev->driver) {
-		device_unlock(dax_region->dev);
+	guard(device)(dax_region->dev);
+	if (!dax_region->dev->driver)
 		return -ENXIO;
-	}
-	device_lock(dev);
+
+	guard(device)(dev);
 	rc = dev_dax_resize(dax_region, dev_dax, val);
-	device_unlock(dev);
-	device_unlock(dax_region->dev);
+	if (rc)
+		return rc;
 
-	return rc == 0 ? len : rc;
+	return len;
 }
 static DEVICE_ATTR_RW(size);
 
@@ -1137,21 +1117,20 @@ static ssize_t mapping_store(struct device *dev, struct device_attribute *attr,
 	if (rc)
 		return rc;
 
-	rc = -ENXIO;
-	device_lock(dax_region->dev);
-	if (!dax_region->dev->driver) {
-		device_unlock(dax_region->dev);
-		return rc;
-	}
-	device_lock(dev);
+	guard(device)(dax_region->dev);
+	if (!dax_region->dev->driver)
+		return -ENXIO;
 
+	guard(device)(dev);
 	to_alloc = range_len(&r);
-	if (alloc_is_aligned(dev_dax, to_alloc))
-		rc = alloc_dev_dax_range(dev_dax, r.start, to_alloc);
-	device_unlock(dev);
-	device_unlock(dax_region->dev);
+	if (!alloc_is_aligned(dev_dax, to_alloc))
+		return -ENXIO;
 
-	return rc == 0 ? len : rc;
+	rc = alloc_dev_dax_range(dev_dax, r.start, to_alloc);
+	if (rc)
+		return rc;
+
+	return len;
 }
 static DEVICE_ATTR_WO(mapping);
 
@@ -1196,27 +1175,23 @@ static ssize_t align_store(struct device *dev, struct device_attribute *attr,
 	if (!dax_align_valid(val))
 		return -EINVAL;
 
-	device_lock(dax_region->dev);
-	if (!dax_region->dev->driver) {
-		device_unlock(dax_region->dev);
+	guard(device)(dax_region->dev);
+	if (!dax_region->dev->driver)
 		return -ENXIO;
-	}
 
-	device_lock(dev);
-	if (dev->driver) {
-		rc = -EBUSY;
-		goto out_unlock;
-	}
+	guard(device)(dev);
+	if (dev->driver)
+		return -EBUSY;
 
 	align_save = dev_dax->align;
 	dev_dax->align = val;
 	rc = dev_dax_validate_align(dev_dax);
-	if (rc)
+	if (rc) {
 		dev_dax->align = align_save;
-out_unlock:
-	device_unlock(dev);
-	device_unlock(dax_region->dev);
-	return rc == 0 ? len : rc;
+		return rc;
+	}
+
+	return len;
 }
 static DEVICE_ATTR_RW(align);
 

-- 
2.41.0