2018-08-03 09:24:34

by piaojun

Subject: [PATCH v3] net/9p/trans_virtio.c: add null terminal for mount tag

chan->tag is Non-null terminated which will result in printing messy code
when debugging code. So we should add '\0' for tag to make the code more
convenient and robust. In addition, I drop char->tag_len to simplify the
code.

Signed-off-by: Jun Piao <[email protected]>
---
net/9p/trans_virtio.c | 17 +++++++----------
1 file changed, 7 insertions(+), 10 deletions(-)

diff --git a/net/9p/trans_virtio.c b/net/9p/trans_virtio.c
index d422bfc..46a5ab2 100644
--- a/net/9p/trans_virtio.c
+++ b/net/9p/trans_virtio.c
@@ -89,10 +89,8 @@ struct virtio_chan {
unsigned long p9_max_pages;
/* Scatterlist: can be too big for stack. */
struct scatterlist sg[VIRTQUEUE_NUM];
-
- int tag_len;
/*
- * tag name to identify a mount Non-null terminated
+ * tag name to identify a mount null terminated
*/
char *tag;

@@ -525,14 +523,15 @@ static ssize_t p9_mount_tag_show(struct device *dev,
{
struct virtio_chan *chan;
struct virtio_device *vdev;
+ int tag_len;

vdev = dev_to_virtio(dev);
chan = vdev->priv;
+ tag_len = strlen(chan->tag);

- memcpy(buf, chan->tag, chan->tag_len);
- buf[chan->tag_len] = 0;
+ memcpy(buf, chan->tag, tag_len + 1);

- return chan->tag_len + 1;
+ return tag_len + 1;
}

static DEVICE_ATTR(mount_tag, 0444, p9_mount_tag_show, NULL);
@@ -585,7 +584,7 @@ static int p9_virtio_probe(struct virtio_device *vdev)
err = -EINVAL;
goto out_free_vq;
}
- tag = kmalloc(tag_len, GFP_KERNEL);
+ tag = kzalloc(tag_len + 1, GFP_KERNEL);
if (!tag) {
err = -ENOMEM;
goto out_free_vq;
@@ -594,7 +593,6 @@ static int p9_virtio_probe(struct virtio_device *vdev)
virtio_cread_bytes(vdev, offsetof(struct virtio_9p_config, tag),
tag, tag_len);
chan->tag = tag;
- chan->tag_len = tag_len;
err = sysfs_create_file(&(vdev->dev.kobj), &dev_attr_mount_tag.attr);
if (err) {
goto out_free_tag;
@@ -654,8 +652,7 @@ static int p9_virtio_probe(struct virtio_device *vdev)

mutex_lock(&virtio_9p_lock);
list_for_each_entry(chan, &virtio_chan_list, chan_list) {
- if (!strncmp(devname, chan->tag, chan->tag_len) &&
- strlen(devname) == chan->tag_len) {
+ if (!strcmp(devname, chan->tag)) {
if (!chan->inuse) {
chan->inuse = true;
found = 1;
--

2018-08-03 09:45:01

by Dominique Martinet

Subject: Re: [PATCH v3] net/9p/trans_virtio.c: add null terminal for mount tag

piaojun wrote on Fri, Aug 03, 2018:
> chan->tag is Non-null terminated which will result in printing messy code
> when debugging code. So we should add '\0' for tag to make the code more
> convenient and robust. In addition, I drop char->tag_len to simplify the
> code.

LGTM, I'll pick this up.

Thanks for the rework

> Signed-off-by: Jun Piao <[email protected]>
> ---
> net/9p/trans_virtio.c | 17 +++++++----------
> 1 file changed, 7 insertions(+), 10 deletions(-)
>
> diff --git a/net/9p/trans_virtio.c b/net/9p/trans_virtio.c
> index d422bfc..46a5ab2 100644
> --- a/net/9p/trans_virtio.c
> +++ b/net/9p/trans_virtio.c
> @@ -89,10 +89,8 @@ struct virtio_chan {
> unsigned long p9_max_pages;
> /* Scatterlist: can be too big for stack. */
> struct scatterlist sg[VIRTQUEUE_NUM];
> -
> - int tag_len;
> /*
> - * tag name to identify a mount Non-null terminated
> + * tag name to identify a mount null terminated
> */
> char *tag;
>
> @@ -525,14 +523,15 @@ static ssize_t p9_mount_tag_show(struct device *dev,
> {
> struct virtio_chan *chan;
> struct virtio_device *vdev;
> + int tag_len;
>
> vdev = dev_to_virtio(dev);
> chan = vdev->priv;
> + tag_len = strlen(chan->tag);
>
> - memcpy(buf, chan->tag, chan->tag_len);
> - buf[chan->tag_len] = 0;
> + memcpy(buf, chan->tag, tag_len + 1);
>
> - return chan->tag_len + 1;
> + return tag_len + 1;
> }
>
> static DEVICE_ATTR(mount_tag, 0444, p9_mount_tag_show, NULL);
> @@ -585,7 +584,7 @@ static int p9_virtio_probe(struct virtio_device *vdev)
> err = -EINVAL;
> goto out_free_vq;
> }
> - tag = kmalloc(tag_len, GFP_KERNEL);
> + tag = kzalloc(tag_len + 1, GFP_KERNEL);
> if (!tag) {
> err = -ENOMEM;
> goto out_free_vq;
> @@ -594,7 +593,6 @@ static int p9_virtio_probe(struct virtio_device *vdev)
> virtio_cread_bytes(vdev, offsetof(struct virtio_9p_config, tag),
> tag, tag_len);
> chan->tag = tag;
> - chan->tag_len = tag_len;
> err = sysfs_create_file(&(vdev->dev.kobj), &dev_attr_mount_tag.attr);
> if (err) {
> goto out_free_tag;
> @@ -654,8 +652,7 @@ static int p9_virtio_probe(struct virtio_device *vdev)
>
> mutex_lock(&virtio_9p_lock);
> list_for_each_entry(chan, &virtio_chan_list, chan_list) {
> - if (!strncmp(devname, chan->tag, chan->tag_len) &&
> - strlen(devname) == chan->tag_len) {
> + if (!strcmp(devname, chan->tag)) {
> if (!chan->inuse) {
> chan->inuse = true;
> found = 1;
> --