diff options
| author | SeongJae Park <sjpark@amazon.de> | 2020-01-27 09:18:09 +0100 |
|---|---|---|
| committer | Boris Ostrovsky <boris.ostrovsky@oracle.com> | 2020-01-29 07:35:49 -0600 |
| commit | 060eabe8fbe726aca341b518366da4d79e338100 (patch) | |
| tree | de0003cb6dc543be114115605aae0f3e518803ac | |
| parent | 8a105678fb3ec4763352db84745968bf2cb4aa65 (diff) | |
xenbus/backend: Protect xenbus callback with lock
A driver's 'reclaim_memory' callback can race with 'probe' or 'remove'
because it will be called whenever memory pressure is detected. To
avoid such race, this commit embeds a spinlock in each 'xenbus_device'
and make 'xenbus' to hold the lock while the corresponded callbacks are
running.
Reviewed-by: Juergen Gross <jgross@suse.com>
Signed-off-by: SeongJae Park <sjpark@amazon.de>
Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
| -rw-r--r-- | drivers/xen/xenbus/xenbus_probe.c | 8 | ||||
| -rw-r--r-- | drivers/xen/xenbus/xenbus_probe_backend.c | 10 | ||||
| -rw-r--r-- | include/xen/xenbus.h | 1 |
3 files changed, 16 insertions, 3 deletions
diff --git a/drivers/xen/xenbus/xenbus_probe.c b/drivers/xen/xenbus/xenbus_probe.c index 378486b79f96..66975da4f3b6 100644 --- a/drivers/xen/xenbus/xenbus_probe.c +++ b/drivers/xen/xenbus/xenbus_probe.c @@ -239,7 +239,9 @@ int xenbus_dev_probe(struct device *_dev) goto fail; } + spin_lock(&dev->reclaim_lock); err = drv->probe(dev, id); + spin_unlock(&dev->reclaim_lock); if (err) goto fail_put; @@ -268,8 +270,11 @@ int xenbus_dev_remove(struct device *_dev) free_otherend_watch(dev); - if (drv->remove) + if (drv->remove) { + spin_lock(&dev->reclaim_lock); drv->remove(dev); + spin_unlock(&dev->reclaim_lock); + } module_put(drv->driver.owner); @@ -468,6 +473,7 @@ int xenbus_probe_node(struct xen_bus_type *bus, goto fail; dev_set_name(&xendev->dev, "%s", devname); + spin_lock_init(&xendev->reclaim_lock); /* Register with generic device framework. */ err = device_register(&xendev->dev); diff --git a/drivers/xen/xenbus/xenbus_probe_backend.c b/drivers/xen/xenbus/xenbus_probe_backend.c index 3b5cb7a5a7e4..791f6fe01e91 100644 --- a/drivers/xen/xenbus/xenbus_probe_backend.c +++ b/drivers/xen/xenbus/xenbus_probe_backend.c @@ -250,12 +250,18 @@ static int backend_probe_and_watch(struct notifier_block *notifier, static int backend_reclaim_memory(struct device *dev, void *data) { const struct xenbus_driver *drv; + struct xenbus_device *xdev; if (!dev->driver) return 0; drv = to_xenbus_driver(dev->driver); - if (drv && drv->reclaim_memory) - drv->reclaim_memory(to_xenbus_device(dev)); + if (drv && drv->reclaim_memory) { + xdev = to_xenbus_device(dev); + if (!spin_trylock(&xdev->reclaim_lock)) + return 0; + drv->reclaim_memory(xdev); + spin_unlock(&xdev->reclaim_lock); + } return 0; } diff --git a/include/xen/xenbus.h b/include/xen/xenbus.h index 980952ea452b..89a889585ba0 100644 --- a/include/xen/xenbus.h +++ b/include/xen/xenbus.h @@ -76,6 +76,7 @@ struct xenbus_device { enum xenbus_state state; struct completion down; struct work_struct work; + spinlock_t reclaim_lock; }; static inline struct xenbus_device *to_xenbus_device(struct device *dev) |