| Message ID | 1495236179-27776-4-git-send-email-sstabellini@kernel.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
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 + /* "1" means socket, connect, release, bind, listen, accept and poll*/ This comment is obsolete, or at least should refer to XENBUS_FUNCTIONS_CALLS (and is missing a space at the end).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; > } > >
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.
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" +#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 = 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*/ + 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; + } + + err = xenbus_switch_state(dev, XenbusStateInitWait); + if (err) + return err; + return 0; } +static void set_backend_state(struct xenbus_device *dev, + enum xenbus_state state) +{ + while (dev->state != state) { + switch (dev->state) { + case XenbusStateClosed: + switch (state) { + case XenbusStateInitWait: + case XenbusStateConnected: + xenbus_switch_state(dev, XenbusStateInitWait); + break; + case XenbusStateClosing: + xenbus_switch_state(dev, XenbusStateClosing); + break; + default: + __WARN(); + } + break; + case XenbusStateInitWait: + case XenbusStateInitialised: + switch (state) { + case XenbusStateConnected: + backend_connect(dev); + xenbus_switch_state(dev, XenbusStateConnected); + break; + case XenbusStateClosing: + case XenbusStateClosed: + xenbus_switch_state(dev, XenbusStateClosing); + break; + default: + __WARN(); + } + break; + case XenbusStateConnected: + switch (state) { + case XenbusStateInitWait: + case XenbusStateClosing: + case XenbusStateClosed: + down(&pvcalls_back_global.frontends_lock); + backend_disconnect(dev); + up(&pvcalls_back_global.frontends_lock); + xenbus_switch_state(dev, XenbusStateClosing); + break; + default: + __WARN(); + } + break; + case XenbusStateClosing: + switch (state) { + case XenbusStateInitWait: + case XenbusStateConnected: + case XenbusStateClosed: + xenbus_switch_state(dev, XenbusStateClosed); + break; + default: + __WARN(); + } + break; + default: + __WARN(); + } + } +} + static void pvcalls_back_changed(struct xenbus_device *dev, enum xenbus_state frontend_state) { + switch (frontend_state) { + case XenbusStateInitialising: + set_backend_state(dev, XenbusStateInitWait); + break; + + case XenbusStateInitialised: + case XenbusStateConnected: + set_backend_state(dev, XenbusStateConnected); + break; + + case XenbusStateClosing: + set_backend_state(dev, XenbusStateClosing); + break; + + case XenbusStateClosed: + set_backend_state(dev, XenbusStateClosed); + if (xenbus_dev_is_online(dev)) + break; + device_unregister(&dev->dev); + break; + case XenbusStateUnknown: + set_backend_state(dev, XenbusStateClosed); + device_unregister(&dev->dev); + break; + + default: + xenbus_dev_fatal(dev, -EINVAL, "saw state %d at frontend", + frontend_state); + break; + } } static int pvcalls_back_remove(struct xenbus_device *dev)
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(+)