On Fri, 2006-08-04 at 13:48 -0700, Cihula, Joseph wrote:
> Michael,
...
> I realize that working code is worth more than a proposal, but perhaps
> you could see if the advantages of this approach might be worth a little
> re-coding.
>
Thanks for the suggestions, I'll see what I can do to fit them in.
> Joe
>
> On Wednesday, August 02, 2006 5:18 AM, Michael LeMay <> wrote:
>
> > Hello,
> >
> > This patch allows userspace tools on a domU to setup a watch on
> > the xenstore. It does this by intercepting XS_WATCH requests written
> > to /proc/xen/xenbus and then re-submitting the request to the
> > in-kernel
> > xenstore interface, in
> > linux-2.6-xen-sparse/drivers/xen/xenbus/xenbus_xs.c. When a callback
> > occurs, an in-kernel function is invoked, which then reconstructs a
> > response in the format expected by userspace, and sends this response
> > through /proc/xen/xenbus.
> >
> > It was necessary to add some supporting infrastructure to
> > linux-2.6-xen-sparse/drivers/xen/xenbus/xenbus_dev.c, such as an
> > additional mutex to protect the response queue and a list of active
> > watches associated with each connection.
> >
> >
> > Signed-off-by: Michael LeMay <mdlemay@xxxxxxxxxxxxxx>
> >
> > ---
> >
> > linux-2.6-xen-sparse/drivers/xen/xenbus/xenbus_dev.c | 114
> > +++++++++++++++++++ 1 file changed, 114 insertions(+)
> >
> > diff -r eb8083d63198 -r 0c8a22ad7e46
> > linux-2.6-xen-sparse/drivers/xen/xenbus/xenbus_dev.c ---
> > a/linux-2.6-xen-sparse/drivers/xen/xenbus/xenbus_dev.c Tue Aug
> 01
> > 10:52:02 2006 -0400 +++
> > b/linux-2.6-xen-sparse/drivers/xen/xenbus/xenbus_dev.c Wed Aug
> 02
> > 08:20:06 2006 -0400 @@ -58,6 +58,9 @@ struct xenbus_dev_data {
> /*
> > In-progress transaction. */ struct list_head transactions;
> >
> > + /* Active watches. */
> > + struct list_head watches;
> > +
> > /* Partial request. */
> > unsigned int len;
> > union {
> > @@ -70,6 +73,8 @@ struct xenbus_dev_data {
> > char read_buffer[PAGE_SIZE];
> > unsigned int read_cons, read_prod;
> > wait_queue_head_t read_waitq;
> > +
> > + struct mutex reply_mutex;
> > };
> >
> > static struct proc_dir_entry *xenbus_dev_intf;
> > @@ -100,13 +105,59 @@ static void queue_reply(struct xenbus_de
> > {
> > int i;
> >
> > + mutex_lock(&u->reply_mutex);
> > +
> > for (i = 0; i < len; i++, u->read_prod++)
> > u->read_buffer[MASK_READ_IDX(u->read_prod)] = data[i];
> >
> > BUG_ON((u->read_prod - u->read_cons) > sizeof(u->read_buffer));
> >
> > + mutex_unlock(&u->reply_mutex);
> > +
> > wake_up(&u->read_waitq);
> > }
> > +
> > +struct watch_adapter
> > +{
> > + struct list_head list;
> > + struct xenbus_watch watch;
> > + struct xenbus_dev_data *dev_data;
> > + char *token;
> > +};
> > +
> > +static void free_watch_adapter (struct watch_adapter *watch)
> > +{
> > + kfree(watch->watch.node);
> > + kfree(watch->token);
> > + kfree(watch);
> > +}
> > +
> > +static void watch_fired(struct xenbus_watch *watch,
> > + const char **vec,
> > + unsigned int len)
> > +{
> > + struct watch_adapter *adap =
> > + container_of(watch, struct watch_adapter, watch);
> > + struct xsd_sockmsg hdr;
> > + const char *path, *token;
> > + int path_len, tok_len, body_len;
> > +
> > + path = vec[XS_WATCH_PATH];
> > + token = adap->token;
> > +
> > + path_len = strlen(path) + 1;
> > + tok_len = strlen(token) + 1;
> > + body_len = path_len + tok_len;
> > +
> > + hdr.type = XS_WATCH_EVENT;
> > + hdr.len = body_len;
> > +
> > + queue_reply(adap->dev_data, (char *)&hdr, sizeof(hdr));
> > + queue_reply(adap->dev_data, (char *)path, path_len);
> > + queue_reply(adap->dev_data, (char *)token, tok_len);
> > +}
> > +
> > +static LIST_HEAD(watch_list);
> >
> > static ssize_t xenbus_dev_write(struct file *filp,
> > const char __user *ubuf,
> > @@ -116,6 +167,9 @@ static ssize_t xenbus_dev_write(struct f
> > struct xenbus_dev_transaction *trans = NULL;
> > uint32_t msg_type;
> > void *reply;
> > + char *path, *token;
> > + struct watch_adapter *watch, *tmp_watch;
> > + int err;
> >
> > if ((len + u->len) > sizeof(u->u.buffer))
> > return -EINVAL;
> > @@ -169,6 +223,56 @@ static ssize_t xenbus_dev_write(struct f
> > kfree(reply);
> > break;
> >
> > + case XS_WATCH:
> > + case XS_UNWATCH:
> > + path = u->u.buffer + sizeof(u->u.msg);
> > + token = memchr(path, 0, u->u.msg.len);
> > + if (token == NULL)
> > + return -EILSEQ;
> > + token++;
> > +
> > + if (msg_type == XS_WATCH) {
> > + static const char * XS_WATCH_RESP = "OK";
> > + struct xsd_sockmsg hdr;
> > +
> > + watch = kmalloc(sizeof(*watch), GFP_KERNEL);
> > + watch->watch.node = kmalloc(strlen(path)+1,
> > + GFP_KERNEL);
> > + strcpy((char *)watch->watch.node, path);
> > + watch->watch.callback = watch_fired;
> > + watch->token = kmalloc(strlen(token)+1,
> GFP_KERNEL);
> > + strcpy(watch->token, token);
> > + watch->dev_data = u;
> > +
> > + err = register_xenbus_watch(&watch->watch);
> > + if (err) {
> > + free_watch_adapter(watch);
> > + return err;
> > + }
> > +
> > + list_add(&watch->list, &u->watches);
> > +
> > + hdr.type = XS_WATCH;
> > + hdr.len = strlen(XS_WATCH_RESP) + 1;
> > + queue_reply(u, (char *)&hdr, sizeof(hdr));
> > + queue_reply(u, (char *)XS_WATCH_RESP, hdr.len);
> > + } else {
> > + list_for_each_entry_safe(watch, tmp_watch,
> > + &u->watches, list) {
> > + if (!strcmp(watch->token, token) &&
> > + !strcmp(watch->watch.node, path))
> > + break;
> > + {
> > +
> unregister_xenbus_watch(&watch->watch);
> > + list_del(&watch->list);
> > + free_watch_adapter(watch);
> > + break;
> > + }
> > + }
> > + }
> > +
> > + break;
> > +
> > default:
> > return -EINVAL;
> > }
> > @@ -191,7 +295,10 @@ static int xenbus_dev_open(struct inode
> > return -ENOMEM;
> >
> > INIT_LIST_HEAD(&u->transactions);
> > + INIT_LIST_HEAD(&u->watches);
> > init_waitqueue_head(&u->read_waitq);
> > +
> > + mutex_init(&u->reply_mutex);
> >
> > filp->private_data = u;
> >
> > @@ -202,11 +309,18 @@ static int xenbus_dev_release(struct ino
> > {
> > struct xenbus_dev_data *u = filp->private_data;
> > struct xenbus_dev_transaction *trans, *tmp;
> > + struct watch_adapter *watch, *tmp_watch;
> >
> > list_for_each_entry_safe(trans, tmp, &u->transactions, list) {
> > xenbus_transaction_end(trans->handle, 1);
> > list_del(&trans->list);
> > kfree(trans);
> > + }
> > +
> > + list_for_each_entry_safe(watch, tmp_watch, &u->watches, list) {
> > + unregister_xenbus_watch(&watch->watch);
> > + list_del(&watch->list);
> > + free_watch_adapter(watch);
> > }
> >
> > kfree(u);
> >
> >
> >
> > _______________________________________________
> > Xen-devel mailing list
> > Xen-devel@xxxxxxxxxxxxxxxxxxx
> > http://lists.xensource.com/xen-devel
_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-devel
|
Home