linux-kernel - Re: [PATCH] virtio-blk: fixup coccinelle warnings

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Date:   Thu, 21 Oct 2021 00:08:23 -0700
From:   Joe Perches <joe@...ches.com>
To:     cgel.zte@...il.com, mst@...hat.com,
        Denis Efremov <efremov@...ux.com>,
        Julia Lawall <Julia.Lawall@...ia.fr>,
        Gilles Muller <Gilles.Muller@...ia.fr>,
        Nicolas Palix <nicolas.palix@...g.fr>,
        Michal Marek <michal.lkml@...kovi.net>, cocci@...ia.fr
Cc:     jasowang@...hat.com, pbonzini@...hat.com, stefanha@...hat.com,
        axboe@...nel.dk, virtualization@...ts.linux-foundation.org,
        linux-block@...r.kernel.org, linux-kernel@...r.kernel.org,
        Ye Guojin <ye.guojin@....com.cn>,
        Zeal Robot <zealci@....com.cn>
Subject: Re: [PATCH] virtio-blk: fixup coccinelle warnings

On Thu, 2021-10-21 at 06:51 +0000, cgel.zte@...il.com wrote:
> From: Ye Guojin <ye.guojin@....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);
}