Re: [PATCH 2/2] iio: Avoid unnecessary kasprintf

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On 14/02/14 14:19, Lars-Peter Clausen wrote:
name_format already contains the final name and no format characters. So the
code basically reads:

	dev_attr->attr.name = kstrdup(GFP_KERNEL, name_format);
	if (dev_attr->attr.name == NULL)
		...
	kfree(name_format);

Which means we can save one alloc and free pair per attribute name if we
directly assign name_format to dev_attr->attr.name.

The patch also renames name_format to name to denote that this is indeed the
final name and has no format characters in it.

Signed-off-by: Lars-Peter Clausen <lars@xxxxxxxxxx>
---
I went back through the log and it looks like it has always been like this.
name_format never actually contained a format string.
oops ;)

It did in my mind at some point.

Good spot.  Applied to the togreg branch of iio.git.
---
  drivers/iio/industrialio-core.c | 39 +++++++++++++--------------------------
  1 file changed, 13 insertions(+), 26 deletions(-)

diff --git a/drivers/iio/industrialio-core.c b/drivers/iio/industrialio-core.c
index fd96e8b..85a2a07 100644
--- a/drivers/iio/industrialio-core.c
+++ b/drivers/iio/industrialio-core.c
@@ -540,7 +540,7 @@ int __iio_device_attr_init(struct device_attribute *dev_attr,
  			   enum iio_shared_by shared_by)
  {
  	int ret = 0;
-	char *name_format = NULL;
+	char *name = NULL;
  	char *full_postfix;
  	sysfs_attr_init(&dev_attr->attr);

@@ -572,16 +572,15 @@ int __iio_device_attr_init(struct device_attribute *dev_attr,
  	if (chan->differential) { /* Differential can not have modifier */
  		switch (shared_by) {
  		case IIO_SHARED_BY_ALL:
-			name_format = kasprintf(GFP_KERNEL, "%s", full_postfix);
+			name = kasprintf(GFP_KERNEL, "%s", full_postfix);
  			break;
  		case IIO_SHARED_BY_DIR:
-			name_format = kasprintf(GFP_KERNEL, "%s_%s",
+			name = kasprintf(GFP_KERNEL, "%s_%s",
  						iio_direction[chan->output],
  						full_postfix);
  			break;
  		case IIO_SHARED_BY_TYPE:
-			name_format
-				= kasprintf(GFP_KERNEL, "%s_%s-%s_%s",
+			name = kasprintf(GFP_KERNEL, "%s_%s-%s_%s",
  					    iio_direction[chan->output],
  					    iio_chan_type_name_spec[chan->type],
  					    iio_chan_type_name_spec[chan->type],
@@ -593,8 +592,7 @@ int __iio_device_attr_init(struct device_attribute *dev_attr,
  				ret = -EINVAL;
  				goto error_free_full_postfix;
  			}
-			name_format
-				= kasprintf(GFP_KERNEL,
+			name = kasprintf(GFP_KERNEL,
  					    "%s_%s%d-%s%d_%s",
  					    iio_direction[chan->output],
  					    iio_chan_type_name_spec[chan->type],
@@ -607,16 +605,15 @@ int __iio_device_attr_init(struct device_attribute *dev_attr,
  	} else { /* Single ended */
  		switch (shared_by) {
  		case IIO_SHARED_BY_ALL:
-			name_format = kasprintf(GFP_KERNEL, "%s", full_postfix);
+			name = kasprintf(GFP_KERNEL, "%s", full_postfix);
  			break;
  		case IIO_SHARED_BY_DIR:
-			name_format = kasprintf(GFP_KERNEL, "%s_%s",
+			name = kasprintf(GFP_KERNEL, "%s_%s",
  						iio_direction[chan->output],
  						full_postfix);
  			break;
  		case IIO_SHARED_BY_TYPE:
-			name_format
-				= kasprintf(GFP_KERNEL, "%s_%s_%s",
+			name = kasprintf(GFP_KERNEL, "%s_%s_%s",
  					    iio_direction[chan->output],
  					    iio_chan_type_name_spec[chan->type],
  					    full_postfix);
@@ -624,33 +621,24 @@ int __iio_device_attr_init(struct device_attribute *dev_attr,

  		case IIO_SEPARATE:
  			if (chan->indexed)
-				name_format
-					= kasprintf(GFP_KERNEL, "%s_%s%d_%s",
+				name = kasprintf(GFP_KERNEL, "%s_%s%d_%s",
  						    iio_direction[chan->output],
  						    iio_chan_type_name_spec[chan->type],
  						    chan->channel,
  						    full_postfix);
  			else
-				name_format
-					= kasprintf(GFP_KERNEL, "%s_%s_%s",
+				name = kasprintf(GFP_KERNEL, "%s_%s_%s",
  						    iio_direction[chan->output],
  						    iio_chan_type_name_spec[chan->type],
  						    full_postfix);
  			break;
  		}
  	}
-	if (name_format == NULL) {
+	if (name == NULL) {
  		ret = -ENOMEM;
  		goto error_free_full_postfix;
  	}
-	dev_attr->attr.name = kasprintf(GFP_KERNEL,
-					name_format,
-					chan->channel,
-					chan->channel2);
-	if (dev_attr->attr.name == NULL) {
-		ret = -ENOMEM;
-		goto error_free_name_format;
-	}
+	dev_attr->attr.name = name;

  	if (readfunc) {
  		dev_attr->attr.mode |= S_IRUGO;
@@ -661,8 +649,7 @@ int __iio_device_attr_init(struct device_attribute *dev_attr,
  		dev_attr->attr.mode |= S_IWUSR;
  		dev_attr->store = writefunc;
  	}
-error_free_name_format:
-	kfree(name_format);
+
  error_free_full_postfix:
  	kfree(full_postfix);



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