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authorJuergen Gross <jgross@suse.com>2020-03-05 11:03:23 +0100
committerBoris Ostrovsky <boris.ostrovsky@oracle.com>2020-03-05 09:42:23 -0600
commit2f69a110e7bba3ec6bc089a2f736ca0941d887ed (patch)
tree57ffc62e0497d2f1be6ad89f9abd7c8adbdde722 /drivers/xen
parent8130b9d5b5abf26f9927b487c15319a187775f34 (diff)
downloadlinux-2f69a110e7bba3ec6bc089a2f736ca0941d887ed.tar.bz2
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>
Diffstat (limited to 'drivers/xen')
-rw-r--r--drivers/xen/xenbus/xenbus_probe.c10
-rw-r--r--drivers/xen/xenbus/xenbus_probe_backend.c5
2 files changed, 8 insertions, 7 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;
}