[PATCH v2] net/9p/trans_virtio.c: add null terminal for mount tag

[piaojun]

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 <piao...@huawei.com>
---
 net/9p/trans_virtio.c | 15 +++++----------
 1 file changed, 5 insertions(+), 10 deletions(-)

diff --git a/net/9p/trans_virtio.c b/net/9p/trans_virtio.c
index d422bfc..0fe9c37 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;

@@ -529,10 +527,9 @@ static ssize_t p9_mount_tag_show(struct device *dev,
        vdev = dev_to_virtio(dev);
        chan = vdev->priv;

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

-       return chan->tag_len + 1;
+       return strlen(chan->tag) + 1;
 }

 static DEVICE_ATTR(mount_tag, 0444, p9_mount_tag_show, NULL);
@@ -585,7 +582,7 @@ 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 +591,6 @@ 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 +650,7 @@ 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 (!strncmp(devname, chan->tag, strlen(chan->tag) + 1)) {
                        if (!chan->inuse) {
                                chan->inuse = true;
                                found = 1;
--