From 30b03d05e07467b8c6ec683ea96b5bffcbcd3931 Mon Sep 17 00:00:00 2001 From: =?utf8?q?Marek=20Marczykowski-G=C3=B3recki?= Date: Fri, 26 Jun 2015 03:28:24 +0200 Subject: [PATCH] xen/gntdevt: Fix race condition in gntdev_release() MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit While gntdev_release() is called the MMU notifier is still registered and can traverse priv->maps list even if no pages are mapped (which is the case -- gntdev_release() is called after all). But gntdev_release() will clear that list, so make sure that only one of those things happens at the same time. Signed-off-by: Marek Marczykowski-Górecki Cc: Signed-off-by: David Vrabel --- drivers/xen/gntdev.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/drivers/xen/gntdev.c b/drivers/xen/gntdev.c index 67b9163db718..0dbb222daaf1 100644 --- a/drivers/xen/gntdev.c +++ b/drivers/xen/gntdev.c @@ -568,12 +568,14 @@ static int gntdev_release(struct inode *inode, struct file *flip) pr_debug("priv %p\n", priv); + mutex_lock(&priv->lock); while (!list_empty(&priv->maps)) { map = list_entry(priv->maps.next, struct grant_map, next); list_del(&map->next); gntdev_put_map(NULL /* already removed */, map); } WARN_ON(!list_empty(&priv->freeable_maps)); + mutex_unlock(&priv->lock); if (use_ptemod) mmu_notifier_unregister(&priv->mn, priv->mm); -- 2.20.1