Virtualization - Oct 2021 - [PATCH] virtio-blk: fixup coccinelle warnings

On Thu, 2021-10-21 at 06:51 +0000, cgel.zte at gmail.com
wrote:
> From: Ye Guojin <ye.guojin at zte.com.cn>
> 
> coccicheck complains about the use of snprintf() in sysfs show
> functions:
> WARNING  use scnprintf or sprintf
> 
> Use sysfs_emit instead of scnprintf or sprintf makes more sense.
[]
> diff --git a/drivers/block/virtio_blk.c b/drivers/block/virtio_blk.c
[]
> @@ -624,7 +624,7 @@ cache_type_show(struct device *dev, struct
device_attribute *attr, char *buf)
> -	return snprintf(buf, 40, "%s\n",
virtblk_cache_types[writeback]);
> +	return sysfs_emit(buf, "%s\n", virtblk_cache_types[writeback]);
Perhaps scripts/coccinelle/api/device_attr_show.cocci should be updated
to be more like the script used in commit 1c7fd72687d6

@@
identifier d_show;
identifier dev, attr, buf;
@@

ssize_t d_show(struct device *dev, struct device_attribute *attr, char *buf)
{
	<...
	return
-	sprintf(buf,
+	sysfs_emit(buf,
	...);
	...>
}

@@
identifier d_show;
identifier dev, attr, buf;
@@

ssize_t d_show(struct device *dev, struct device_attribute *attr, char *buf)
{
	<...
	return
-	snprintf(buf, PAGE_SIZE,
+	sysfs_emit(buf,
	...);
	...>
}

@@
identifier d_show;
identifier dev, attr, buf;
@@

ssize_t d_show(struct device *dev, struct device_attribute *attr, char *buf)
{
	<...
	return
-	scnprintf(buf, PAGE_SIZE,
+	sysfs_emit(buf,
	...);
	...>
}

@@
identifier d_show;
identifier dev, attr, buf;
expression chr;
@@

ssize_t d_show(struct device *dev, struct device_attribute *attr, char *buf)
{
	<...
	return
-	strcpy(buf, chr);
+	sysfs_emit(buf, chr);
	...>
}

@@
identifier d_show;
identifier dev, attr, buf;
identifier len;
@@

ssize_t d_show(struct device *dev, struct device_attribute *attr, char *buf)
{
	<...
	len -	sprintf(buf,
+	sysfs_emit(buf,
	...);
	...>
	return len;
}

@@
identifier d_show;
identifier dev, attr, buf;
identifier len;
@@

ssize_t d_show(struct device *dev, struct device_attribute *attr, char *buf)
{
	<...
	len -	snprintf(buf, PAGE_SIZE,
+	sysfs_emit(buf,
	...);
	...>
	return len;
}

@@
identifier d_show;
identifier dev, attr, buf;
identifier len;
@@

ssize_t d_show(struct device *dev, struct device_attribute *attr, char *buf)
{
	<...
	len -	scnprintf(buf, PAGE_SIZE,
+	sysfs_emit(buf,
	...);
	...>
	return len;
}

@@
identifier d_show;
identifier dev, attr, buf;
identifier len;
@@

ssize_t d_show(struct device *dev, struct device_attribute *attr, char *buf)
{
	<...
-	len += scnprintf(buf + len, PAGE_SIZE - len,
+	len += sysfs_emit_at(buf, len,
	...);
	...>
	return len;
}

@@
identifier d_show;
identifier dev, attr, buf;
expression chr;
@@

ssize_t d_show(struct device *dev, struct device_attribute *attr, char *buf)
{
	...
-	strcpy(buf, chr);
-	return strlen(buf);
+	return sysfs_emit(buf, chr);
}

On Thu, Oct 21, 2021 at 12:08:23AM -0700, Joe Perches
wrote:
> On Thu, 2021-10-21 at 06:51 +0000, cgel.zte at gmail.com wrote:
> > From: Ye Guojin <ye.guojin at zte.com.cn>
> > 
> > coccicheck complains about the use of snprintf() in sysfs show
> > functions:
> > WARNING  use scnprintf or sprintf
> > 
> > Use sysfs_emit instead of scnprintf or sprintf makes more sense.
> []
> > diff --git a/drivers/block/virtio_blk.c b/drivers/block/virtio_blk.c
> []
> > @@ -624,7 +624,7 @@ cache_type_show(struct device *dev, struct
device_attribute *attr, char *buf)
> > -	return snprintf(buf, 40, "%s\n",
virtblk_cache_types[writeback]);
> > +	return sysfs_emit(buf, "%s\n",
virtblk_cache_types[writeback]);
> 
> Perhaps scripts/coccinelle/api/device_attr_show.cocci should be updated
> to be more like the script used in commit 1c7fd72687d6
This won't catch the case covered by the patch because it's
"snprintf(buf, 40" instead of "snprintf(buf, PAGE_SIZE",
although
any size that's not PAGE_SIZE needs to be reviewed carefully in case the
intent of the statement is to truncate the output.

Stefan
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