summaryrefslogtreecommitdiff
diff options
context:
space:
mode:
authorLinus Torvalds <torvalds@linux-foundation.org>2015-06-14 14:03:11 -1000
committerLinus Torvalds <torvalds@linux-foundation.org>2015-06-14 14:03:11 -1000
commit5bd2c2867ffc0f4beeac5b94b0f674969f24c883 (patch)
tree0c6d5efb41a7df1530fe4cf566475c876da1dc6b
parentd37479aac53d9e3d6e4b628a727a84021cbb4bd5 (diff)
parentcee34d88cabd1ba5fc93e09b5b12232bc9338c7c (diff)
Merge branch 'locking-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull lockdep fix from Ingo Molnar: "A lockdep/modules unload race fix that can oops" * 'locking-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: lockdep: Fix a race between /proc/lock_stat and module unload
-rw-r--r--kernel/locking/lockdep.c3
-rw-r--r--kernel/locking/lockdep_proc.c22
2 files changed, 19 insertions, 6 deletions
diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c
index a0831e1b99f4..aaeae885d9af 100644
--- a/kernel/locking/lockdep.c
+++ b/kernel/locking/lockdep.c
@@ -3900,7 +3900,8 @@ static void zap_class(struct lock_class *class)
list_del_rcu(&class->hash_entry);
list_del_rcu(&class->lock_entry);
- class->key = NULL;
+ RCU_INIT_POINTER(class->key, NULL);
+ RCU_INIT_POINTER(class->name, NULL);
}
static inline int within(const void *addr, void *start, unsigned long size)
diff --git a/kernel/locking/lockdep_proc.c b/kernel/locking/lockdep_proc.c
index ef43ac4bafb5..d83d798bef95 100644
--- a/kernel/locking/lockdep_proc.c
+++ b/kernel/locking/lockdep_proc.c
@@ -426,10 +426,12 @@ static void seq_lock_time(struct seq_file *m, struct lock_time *lt)
static void seq_stats(struct seq_file *m, struct lock_stat_data *data)
{
- char name[39];
- struct lock_class *class;
+ struct lockdep_subclass_key *ckey;
struct lock_class_stats *stats;
+ struct lock_class *class;
+ const char *cname;
int i, namelen;
+ char name[39];
class = data->class;
stats = &data->stats;
@@ -440,15 +442,25 @@ static void seq_stats(struct seq_file *m, struct lock_stat_data *data)
if (class->subclass)
namelen -= 2;
- if (!class->name) {
+ rcu_read_lock_sched();
+ cname = rcu_dereference_sched(class->name);
+ ckey = rcu_dereference_sched(class->key);
+
+ if (!cname && !ckey) {
+ rcu_read_unlock_sched();
+ return;
+
+ } else if (!cname) {
char str[KSYM_NAME_LEN];
const char *key_name;
- key_name = __get_key_name(class->key, str);
+ key_name = __get_key_name(ckey, str);
snprintf(name, namelen, "%s", key_name);
} else {
- snprintf(name, namelen, "%s", class->name);
+ snprintf(name, namelen, "%s", cname);
}
+ rcu_read_unlock_sched();
+
namelen = strlen(name);
if (class->name_version > 1) {
snprintf(name+namelen, 3, "#%d", class->name_version);