From 4b1c7840b7d01b14a1a00fa0e61b761d4391ba67 Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Tue, 6 Nov 2012 09:16:53 -0800 Subject: [PATCH] device_cgroup: add lockdep asserts device_cgroup uses RCU safe ->exceptions list which is write-protected by devcgroup_mutex and has had some issues using locking correctly. Add lockdep asserts to utility functions so that future errors can be easily detected. Signed-off-by: Tejun Heo Acked-by: Serge E. Hallyn Cc: Aristeu Rozanski Cc: Li Zefan --- security/device_cgroup.c | 12 ++++++++++++ 1 file changed, 12 insertions(+) diff --git a/security/device_cgroup.c b/security/device_cgroup.c index b08d20c66c2e..78a16f5b7275 100644 --- a/security/device_cgroup.c +++ b/security/device_cgroup.c @@ -82,6 +82,8 @@ static int dev_exceptions_copy(struct list_head *dest, struct list_head *orig) { struct dev_exception_item *ex, *tmp, *new; + lockdep_assert_held(&devcgroup_mutex); + list_for_each_entry(ex, orig, list) { new = kmemdup(ex, sizeof(*ex), GFP_KERNEL); if (!new) @@ -107,6 +109,8 @@ static int dev_exception_add(struct dev_cgroup *dev_cgroup, { struct dev_exception_item *excopy, *walk; + lockdep_assert_held(&devcgroup_mutex); + excopy = kmemdup(ex, sizeof(*ex), GFP_KERNEL); if (!excopy) return -ENOMEM; @@ -137,6 +141,8 @@ static void dev_exception_rm(struct dev_cgroup *dev_cgroup, { struct dev_exception_item *walk, *tmp; + lockdep_assert_held(&devcgroup_mutex); + list_for_each_entry_safe(walk, tmp, &dev_cgroup->exceptions, list) { if (walk->type != ex->type) continue; @@ -163,6 +169,8 @@ static void dev_exception_clean(struct dev_cgroup *dev_cgroup) { struct dev_exception_item *ex, *tmp; + lockdep_assert_held(&devcgroup_mutex); + list_for_each_entry_safe(ex, tmp, &dev_cgroup->exceptions, list) { list_del_rcu(&ex->list); kfree_rcu(ex, rcu); @@ -298,6 +306,10 @@ static int may_access(struct dev_cgroup *dev_cgroup, struct dev_exception_item *ex; bool match = false; + rcu_lockdep_assert(rcu_read_lock_held() || + lockdep_is_held(&devcgroup_mutex), + "device_cgroup::may_access() called without proper synchronization"); + list_for_each_entry_rcu(ex, &dev_cgroup->exceptions, list) { if ((refex->type & DEV_BLOCK) && !(ex->type & DEV_BLOCK)) continue; -- 2.20.1