Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]
Groups > linux.kernel > #1650984 > unrolled thread
| Started by | Boris Ostrovsky <boris.ostrovsky@oracle.com> |
|---|---|
| First post | 2017-05-26 02:20 +0200 |
| Last post | 2017-06-01 23:00 +0200 |
| Articles | 2 — 2 participants |
Back to article view | Back to linux.kernel
This discussion starts older than the indexed window; earlier articles aren't shown. The article labeled Started by
below is the oldest one visible, not the original post.
Re: [PATCH v2 04/18] xen/pvcalls: xenbus state handling Boris Ostrovsky <boris.ostrovsky@oracle.com> - 2017-05-26 02:20 +0200
Re: [PATCH v2 04/18] xen/pvcalls: xenbus state handling Stefano Stabellini <sstabellini@kernel.org> - 2017-06-01 23:00 +0200
| From | Boris Ostrovsky <boris.ostrovsky@oracle.com> |
|---|---|
| Date | 2017-05-26 02:20 +0200 |
| Subject | Re: [PATCH v2 04/18] xen/pvcalls: xenbus state handling |
| Message-ID | <tLb8Z-6VX-7@gated-at.bofh.it> |
On 05/19/2017 07:22 PM, Stefano Stabellini wrote:
> Introduce the code to handle xenbus state changes.
>
> Implement the probe function for the pvcalls backend. Write the
> supported versions, max-page-order and function-calls nodes to xenstore,
> as required by the protocol.
>
> Introduce stub functions for disconnecting/connecting to a frontend.
>
> Signed-off-by: Stefano Stabellini <stefano@aporeto.com>
> CC: boris.ostrovsky@oracle.com
> CC: jgross@suse.com
> ---
> drivers/xen/pvcalls-back.c | 135 +++++++++++++++++++++++++++++++++++++++++++++
> 1 file changed, 135 insertions(+)
>
> diff --git a/drivers/xen/pvcalls-back.c b/drivers/xen/pvcalls-back.c
> index 9044cf2..b4da138 100644
> --- a/drivers/xen/pvcalls-back.c
> +++ b/drivers/xen/pvcalls-back.c
> @@ -25,20 +25,155 @@
> #include <xen/xenbus.h>
> #include <xen/interface/io/pvcalls.h>
>
> +#define PVCALLS_VERSIONS "1"
Shouldn't this be in a header file that will be shared with frontends?
> +#define MAX_RING_ORDER XENBUS_MAX_RING_GRANT_ORDER
> +
> struct pvcalls_back_global {
> struct list_head frontends;
> struct semaphore frontends_lock;
> } pvcalls_back_global;
>
> +static int backend_connect(struct xenbus_device *dev)
> +{
> + return 0;
> +}
> +
> +static int backend_disconnect(struct xenbus_device *dev)
> +{
> + return 0;
> +}
> +
> static int pvcalls_back_probe(struct xenbus_device *dev,
> const struct xenbus_device_id *id)
> {
> + int err;
> +
> + err = xenbus_printf(XBT_NIL, dev->nodename, "versions", "%s",
> + PVCALLS_VERSIONS);
> + if (err) {
> + pr_warn("%s write out 'version' failed\n", __func__);
> + return -EINVAL;
err?
> + }
> +
> + err = xenbus_printf(XBT_NIL, dev->nodename, "max-page-order", "%u",
> + MAX_RING_ORDER);
> + if (err) {
> + pr_warn("%s write out 'max-page-order' failed\n", __func__);
> + return err;
> + }
> +
> + /* "1" means socket, connect, release, bind, listen, accept and poll*/
This comment is obsolete, or at least should refer to
XENBUS_FUNCTIONS_CALLS (and is missing a space at the end).
> + err = xenbus_printf(XBT_NIL, dev->nodename, "function-calls",
> + XENBUS_FUNCTIONS_CALLS);
> + if (err) {
> + pr_warn("%s write out 'function-calls' failed\n", __func__);
> + return err;
> + }
In case of errors we will end up with all previous entries. I think this
should be done as a transaction which would be aborted in case of an error.
> +
> + err = xenbus_switch_state(dev, XenbusStateInitWait);
> + if (err)
> + return err;
Not sure what to do on an error here (wrt xenstore entries).
xenbus_switch_state() itself uses transactions. Are we allowed to have
nested transactions?
OTOH, xenbus_switch_state() never returns an error, at least now. In
fact, in most cases we ignore return value.
-boris
> +
> return 0;
> }
>
>
[toc] | [next] | [standalone]
| From | Stefano Stabellini <sstabellini@kernel.org> |
|---|---|
| Date | 2017-06-01 23:00 +0200 |
| Message-ID | <tNFmi-7IJ-19@gated-at.bofh.it> |
| In reply to | #1650984 |
On Thu, 25 May 2017, Boris Ostrovsky wrote:
> On 05/19/2017 07:22 PM, Stefano Stabellini wrote:
> > Introduce the code to handle xenbus state changes.
> >
> > Implement the probe function for the pvcalls backend. Write the
> > supported versions, max-page-order and function-calls nodes to xenstore,
> > as required by the protocol.
> >
> > Introduce stub functions for disconnecting/connecting to a frontend.
> >
> > Signed-off-by: Stefano Stabellini <stefano@aporeto.com>
> > CC: boris.ostrovsky@oracle.com
> > CC: jgross@suse.com
> > ---
> > drivers/xen/pvcalls-back.c | 135 +++++++++++++++++++++++++++++++++++++++++++++
> > 1 file changed, 135 insertions(+)
> >
> > diff --git a/drivers/xen/pvcalls-back.c b/drivers/xen/pvcalls-back.c
> > index 9044cf2..b4da138 100644
> > --- a/drivers/xen/pvcalls-back.c
> > +++ b/drivers/xen/pvcalls-back.c
> > @@ -25,20 +25,155 @@
> > #include <xen/xenbus.h>
> > #include <xen/interface/io/pvcalls.h>
> >
> > +#define PVCALLS_VERSIONS "1"
>
> Shouldn't this be in a header file that will be shared with frontends?
I don't think it should: different backends could implement a different
pvcalls version. There is an handshake mechanism to agree on a version
of the protocol to use. It is probably not a good idea to expose this
specific version in the generic pvcalls header.
> > +#define MAX_RING_ORDER XENBUS_MAX_RING_GRANT_ORDER
> > +
> > struct pvcalls_back_global {
> > struct list_head frontends;
> > struct semaphore frontends_lock;
> > } pvcalls_back_global;
> >
> > +static int backend_connect(struct xenbus_device *dev)
> > +{
> > + return 0;
> > +}
> > +
> > +static int backend_disconnect(struct xenbus_device *dev)
> > +{
> > + return 0;
> > +}
> > +
> > static int pvcalls_back_probe(struct xenbus_device *dev,
> > const struct xenbus_device_id *id)
> > {
> > + int err;
> > +
> > + err = xenbus_printf(XBT_NIL, dev->nodename, "versions", "%s",
> > + PVCALLS_VERSIONS);
> > + if (err) {
> > + pr_warn("%s write out 'version' failed\n", __func__);
> > + return -EINVAL;
>
> err?
OK
> > + }
> > +
> > + err = xenbus_printf(XBT_NIL, dev->nodename, "max-page-order", "%u",
> > + MAX_RING_ORDER);
> > + if (err) {
> > + pr_warn("%s write out 'max-page-order' failed\n", __func__);
> > + return err;
> > + }
> > +
> > + /* "1" means socket, connect, release, bind, listen, accept and poll*/
>
> This comment is obsolete, or at least should refer to
> XENBUS_FUNCTIONS_CALLS (and is missing a space at the end).
OK
> > + err = xenbus_printf(XBT_NIL, dev->nodename, "function-calls",
> > + XENBUS_FUNCTIONS_CALLS);
> > + if (err) {
> > + pr_warn("%s write out 'function-calls' failed\n", __func__);
> > + return err;
> > + }
>
>
> In case of errors we will end up with all previous entries. I think this
> should be done as a transaction which would be aborted in case of an error.
OK
> > +
> > + err = xenbus_switch_state(dev, XenbusStateInitWait);
> > + if (err)
> > + return err;
>
>
> Not sure what to do on an error here (wrt xenstore entries).
> xenbus_switch_state() itself uses transactions. Are we allowed to have
> nested transactions?
>
> OTOH, xenbus_switch_state() never returns an error, at least now. In
> fact, in most cases we ignore return value.
I don't think we can have nested transactions. For simplicity, I'll
ignore errors from xenbus_switch_state.
[toc] | [prev] | [standalone]
Back to top | Article view | linux.kernel
csiph-web