diff options
| author | Juergen Gross <jgross@suse.com> | 2020-03-05 11:03:23 +0100 |
|---|---|---|
| committer | Boris Ostrovsky <boris.ostrovsky@oracle.com> | 2020-03-05 16:42:23 +0100 |
| commit | 2f69a110e7bba3ec6bc089a2f736ca0941d887ed (patch) | |
| tree | 57ffc62e0497d2f1be6ad89f9abd7c8adbdde722 | |
| parent | xenbus: req->err should be updated before req->state (diff) | |
| download | linux-2f69a110e7bba3ec6bc089a2f736ca0941d887ed.tar.xz linux-2f69a110e7bba3ec6bc089a2f736ca0941d887ed.zip | |
xen/xenbus: fix locking
Commit 060eabe8fbe726 ("xenbus/backend: Protect xenbus callback with
lock") introduced a bug by holding a lock while calling a function
which might schedule.
Fix that by using a semaphore instead.
Fixes: 060eabe8fbe726 ("xenbus/backend: Protect xenbus callback with lock")
Signed-off-by: Juergen Gross <jgross@suse.com>
Link: https://lore.kernel.org/r/20200305100323.16736-1-jgross@suse.com
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
| -rw-r--r-- | drivers/xen/xenbus/xenbus_probe.c | 10 | ||||
| -rw-r--r-- | drivers/xen/xenbus/xenbus_probe_backend.c | 5 | ||||
| -rw-r--r-- | include/xen/xenbus.h | 3 |
3 files changed, 10 insertions, 8 deletions
diff --git a/drivers/xen/xenbus/xenbus_probe.c b/drivers/xen/xenbus/xenbus_probe.c index 66975da4f3b6..8c4d05b687b7 100644 --- a/drivers/xen/xenbus/xenbus_probe.c +++ b/drivers/xen/xenbus/xenbus_probe.c @@ -239,9 +239,9 @@ int xenbus_dev_probe(struct device *_dev) goto fail; } - spin_lock(&dev->reclaim_lock); + down(&dev->reclaim_sem); err = drv->probe(dev, id); - spin_unlock(&dev->reclaim_lock); + up(&dev->reclaim_sem); if (err) goto fail_put; @@ -271,9 +271,9 @@ int xenbus_dev_remove(struct device *_dev) free_otherend_watch(dev); if (drv->remove) { - spin_lock(&dev->reclaim_lock); + down(&dev->reclaim_sem); drv->remove(dev); - spin_unlock(&dev->reclaim_lock); + up(&dev->reclaim_sem); } module_put(drv->driver.owner); @@ -473,7 +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); + sema_init(&xendev->reclaim_sem, 1); /* 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 791f6fe01e91..9b2fbe69bccc 100644 --- a/drivers/xen/xenbus/xenbus_probe_backend.c +++ b/drivers/xen/xenbus/xenbus_probe_backend.c @@ -45,6 +45,7 @@ #include <linux/mm.h> #include <linux/notifier.h> #include <linux/export.h> +#include <linux/semaphore.h> #include <asm/page.h> #include <asm/pgtable.h> @@ -257,10 +258,10 @@ static int backend_reclaim_memory(struct device *dev, void *data) drv = to_xenbus_driver(dev->driver); if (drv && drv->reclaim_memory) { xdev = to_xenbus_device(dev); - if (!spin_trylock(&xdev->reclaim_lock)) + if (down_trylock(&xdev->reclaim_sem)) return 0; drv->reclaim_memory(xdev); - spin_unlock(&xdev->reclaim_lock); + up(&xdev->reclaim_sem); } return 0; } diff --git a/include/xen/xenbus.h b/include/xen/xenbus.h index 89a889585ba0..850a43bd69d3 100644 --- a/include/xen/xenbus.h +++ b/include/xen/xenbus.h @@ -42,6 +42,7 @@ #include <linux/completion.h> #include <linux/init.h> #include <linux/slab.h> +#include <linux/semaphore.h> #include <xen/interface/xen.h> #include <xen/interface/grant_table.h> #include <xen/interface/io/xenbus.h> @@ -76,7 +77,7 @@ struct xenbus_device { enum xenbus_state state; struct completion down; struct work_struct work; - spinlock_t reclaim_lock; + struct semaphore reclaim_sem; }; static inline struct xenbus_device *to_xenbus_device(struct device *dev) |