From: kaf24@firebug.cl.cam.ac.uk Date: Thu, 31 Aug 2006 23:33:19 +0000 (+0100) Subject: [XENBUS] Introduce new "online" node for backend drivers. X-Git-Tag: archive/raspbian/4.8.0-1+rpi1~1^2~15673^2~7 X-Git-Url: https://dgit.raspbian.org/%22http://www.example.com/cgi/success//%22http:/www.example.com/cgi/success/?a=commitdiff_plain;h=5182367c40548e68ee1a6d68ad81e8efbab6e2f7;p=xen.git [XENBUS] Introduce new "online" node for backend drivers. Driver changes: Make backend drivers check it when entering Closed state, only unregister devices when the "online" node is either "0" or not present. The later maintains backward compatibility. Tools changes: Update "online" node when creating and hot-unplugging devices. Background: When kexec'ing a new kernel, the old kernel's frontend driver will shutdown, but the backend device should *NOT* disappear due to that, so the new kernel instance can reconnect. Signed-off-by: Gerd Hoffmann --- diff --git a/linux-2.6-xen-sparse/drivers/xen/blkback/xenbus.c b/linux-2.6-xen-sparse/drivers/xen/blkback/xenbus.c index 931f7bf4bc..02f90a6803 100644 --- a/linux-2.6-xen-sparse/drivers/xen/blkback/xenbus.c +++ b/linux-2.6-xen-sparse/drivers/xen/blkback/xenbus.c @@ -301,11 +301,11 @@ static void frontend_changed(struct xenbus_device *dev, struct backend_info *be = dev->dev.driver_data; int err; - DPRINTK(""); + DPRINTK("%s", xenbus_strstate(frontend_state)); switch (frontend_state) { case XenbusStateInitialising: - if (dev->state == XenbusStateClosing) { + if (dev->state == XenbusStateClosed) { printk("%s: %s: prepare for reconnect\n", __FUNCTION__, dev->nodename); xenbus_switch_state(dev, XenbusStateInitWait); @@ -331,8 +331,12 @@ static void frontend_changed(struct xenbus_device *dev, xenbus_switch_state(dev, XenbusStateClosing); break; - case XenbusStateUnknown: case XenbusStateClosed: + xenbus_switch_state(dev, XenbusStateClosed); + if (xenbus_dev_is_online(dev)) + break; + /* fall through if not online */ + case XenbusStateUnknown: device_unregister(&dev->dev); break; diff --git a/linux-2.6-xen-sparse/drivers/xen/blktap/common.h b/linux-2.6-xen-sparse/drivers/xen/blktap/common.h index e610bed9e4..56faca7a60 100644 --- a/linux-2.6-xen-sparse/drivers/xen/blktap/common.h +++ b/linux-2.6-xen-sparse/drivers/xen/blktap/common.h @@ -91,6 +91,7 @@ blkif_t *tap_alloc_blkif(domid_t domid); void tap_blkif_free(blkif_t *blkif); int tap_blkif_map(blkif_t *blkif, unsigned long shared_page, unsigned int evtchn); +void tap_blkif_unmap(blkif_t *blkif); #define blkif_get(_b) (atomic_inc(&(_b)->refcnt)) #define blkif_put(_b) \ diff --git a/linux-2.6-xen-sparse/drivers/xen/blktap/interface.c b/linux-2.6-xen-sparse/drivers/xen/blktap/interface.c index 19e0eda0a0..b0eccf4225 100644 --- a/linux-2.6-xen-sparse/drivers/xen/blktap/interface.c +++ b/linux-2.6-xen-sparse/drivers/xen/blktap/interface.c @@ -135,20 +135,25 @@ int tap_blkif_map(blkif_t *blkif, unsigned long shared_page, return 0; } -void tap_blkif_free(blkif_t *blkif) +void tap_blkif_unmap(blkif_t *blkif) { - atomic_dec(&blkif->refcnt); - wait_event(blkif->waiting_to_free, atomic_read(&blkif->refcnt) == 0); - - /* Already disconnected? */ - if (blkif->irq) + if (blkif->irq) { unbind_from_irqhandler(blkif->irq, blkif); - + blkif->irq = 0; + } if (blkif->blk_ring.sring) { unmap_frontend_page(blkif); free_vm_area(blkif->blk_ring_area); + blkif->blk_ring.sring = NULL; } +} + +void tap_blkif_free(blkif_t *blkif) +{ + atomic_dec(&blkif->refcnt); + wait_event(blkif->waiting_to_free, atomic_read(&blkif->refcnt) == 0); + tap_blkif_unmap(blkif); kmem_cache_free(blkif_cachep, blkif); } diff --git a/linux-2.6-xen-sparse/drivers/xen/blktap/xenbus.c b/linux-2.6-xen-sparse/drivers/xen/blktap/xenbus.c index e0158592cf..6c16a2e60b 100644 --- a/linux-2.6-xen-sparse/drivers/xen/blktap/xenbus.c +++ b/linux-2.6-xen-sparse/drivers/xen/blktap/xenbus.c @@ -247,6 +247,11 @@ static void tap_frontend_changed(struct xenbus_device *dev, switch (frontend_state) { case XenbusStateInitialising: + if (dev->state == XenbusStateClosed) { + printk("%s: %s: prepare for reconnect\n", + __FUNCTION__, dev->nodename); + xenbus_switch_state(dev, XenbusStateInitWait); + } break; case XenbusStateInitialised: @@ -264,11 +269,20 @@ static void tap_frontend_changed(struct xenbus_device *dev, break; case XenbusStateClosing: + if (be->blkif->xenblkd) { + kthread_stop(be->blkif->xenblkd); + be->blkif->xenblkd = NULL; + } + tap_blkif_unmap(be->blkif); xenbus_switch_state(dev, XenbusStateClosing); break; - case XenbusStateUnknown: case XenbusStateClosed: + xenbus_switch_state(dev, XenbusStateClosed); + if (xenbus_dev_is_online(dev)) + break; + /* fall through if not online */ + case XenbusStateUnknown: device_unregister(&dev->dev); break; diff --git a/linux-2.6-xen-sparse/drivers/xen/netback/xenbus.c b/linux-2.6-xen-sparse/drivers/xen/netback/xenbus.c index 9da8e3b4be..a8b19a65be 100644 --- a/linux-2.6-xen-sparse/drivers/xen/netback/xenbus.c +++ b/linux-2.6-xen-sparse/drivers/xen/netback/xenbus.c @@ -228,13 +228,13 @@ static void frontend_changed(struct xenbus_device *dev, { struct backend_info *be = dev->dev.driver_data; - DPRINTK(""); + DPRINTK("%s", xenbus_strstate(frontend_state)); be->frontend_state = frontend_state; switch (frontend_state) { case XenbusStateInitialising: - if (dev->state == XenbusStateClosing) { + if (dev->state == XenbusStateClosed) { printk("%s: %s: prepare for reconnect\n", __FUNCTION__, dev->nodename); if (be->netif) { @@ -260,8 +260,12 @@ static void frontend_changed(struct xenbus_device *dev, xenbus_switch_state(dev, XenbusStateClosing); break; - case XenbusStateUnknown: case XenbusStateClosed: + xenbus_switch_state(dev, XenbusStateClosed); + if (xenbus_dev_is_online(dev)) + break; + /* fall through if not online */ + case XenbusStateUnknown: if (be->netif != NULL) kobject_uevent(&dev->dev.kobj, KOBJ_OFFLINE); device_unregister(&dev->dev); diff --git a/linux-2.6-xen-sparse/drivers/xen/xenbus/xenbus_backend_client.c b/linux-2.6-xen-sparse/drivers/xen/xenbus/xenbus_backend_client.c index b99991cdab..cd8ba02383 100644 --- a/linux-2.6-xen-sparse/drivers/xen/xenbus/xenbus_backend_client.c +++ b/linux-2.6-xen-sparse/drivers/xen/xenbus/xenbus_backend_client.c @@ -132,4 +132,16 @@ int xenbus_unmap_ring(struct xenbus_device *dev, } EXPORT_SYMBOL_GPL(xenbus_unmap_ring); +int xenbus_dev_is_online(struct xenbus_device *dev) +{ + int rc, val; + + rc = xenbus_scanf(XBT_NIL, dev->nodename, "online", "%d", &val); + if (rc != 1) + val = 0; /* no online node present */ + + return val; +} +EXPORT_SYMBOL_GPL(xenbus_dev_is_online); + MODULE_LICENSE("Dual BSD/GPL"); diff --git a/linux-2.6-xen-sparse/include/xen/xenbus.h b/linux-2.6-xen-sparse/include/xen/xenbus.h index 993f317b7c..cd09eb8985 100644 --- a/linux-2.6-xen-sparse/include/xen/xenbus.h +++ b/linux-2.6-xen-sparse/include/xen/xenbus.h @@ -298,5 +298,6 @@ void xenbus_dev_fatal(struct xenbus_device *dev, int err, const char *fmt, int __init xenbus_dev_init(void); char *xenbus_strstate(enum xenbus_state state); +int xenbus_dev_is_online(struct xenbus_device *dev); #endif /* _XEN_XENBUS_H */ diff --git a/tools/python/xen/xend/server/DevController.py b/tools/python/xen/xend/server/DevController.py index 92e298c9df..e90008dbc0 100644 --- a/tools/python/xen/xend/server/DevController.py +++ b/tools/python/xen/xend/server/DevController.py @@ -207,6 +207,9 @@ class DevController: devid = int(devid) + # Modify online status /before/ updating state (latter is watched by + # drivers, so this ordering avoids a race). + self.writeBackend(devid, 'online', "0") self.writeBackend(devid, 'state', str(xenbusState['Closing'])) @@ -406,7 +409,8 @@ class DevController: 'domain' : self.vm.getName(), 'frontend' : frontpath, 'frontend-id' : "%i" % self.vm.getDomid(), - 'state' : str(xenbusState['Initialising']) + 'state' : str(xenbusState['Initialising']), + 'online' : "1" }) return (backpath, frontpath)