diff options
author | Paul Mackerras <paulus@samba.org> | 2007-02-07 14:05:13 +1100 |
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committer | Paul Mackerras <paulus@samba.org> | 2007-02-07 14:05:13 +1100 |
commit | 8423200553113cc031caa9b147f6150a8e26545c (patch) | |
tree | 752c93a200c9ba056c7469c96f7e27d02c99291d /kernel/sys.c | |
parent | f03e64f2ca6ee3d0b7824536b1940497701fe766 (diff) | |
parent | 62d0cfcb27cf755cebdc93ca95dabc83608007cd (diff) |
Merge branch 'linux-2.6'
Diffstat (limited to 'kernel/sys.c')
-rw-r--r-- | kernel/sys.c | 15 |
1 files changed, 11 insertions, 4 deletions
diff --git a/kernel/sys.c b/kernel/sys.c index c7675c1bfdf..6e2101dec0f 100644 --- a/kernel/sys.c +++ b/kernel/sys.c @@ -323,11 +323,18 @@ EXPORT_SYMBOL_GPL(blocking_notifier_chain_unregister); int blocking_notifier_call_chain(struct blocking_notifier_head *nh, unsigned long val, void *v) { - int ret; + int ret = NOTIFY_DONE; - down_read(&nh->rwsem); - ret = notifier_call_chain(&nh->head, val, v); - up_read(&nh->rwsem); + /* + * We check the head outside the lock, but if this access is + * racy then it does not matter what the result of the test + * is, we re-check the list after having taken the lock anyway: + */ + if (rcu_dereference(nh->head)) { + down_read(&nh->rwsem); + ret = notifier_call_chain(&nh->head, val, v); + up_read(&nh->rwsem); + } return ret; } |