Merge branch 'locking-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull locking fixes from Ingo Molnar:
"Two lockdep fixes for bugs introduced by the cross-release dependency
tracking feature - plus a commit that disables it because performance
regressed in an absymal fashion on some systems"
* 'locking-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
locking/lockdep: Disable cross-release features for now
locking/selftest: Avoid false BUG report
locking/lockdep: Fix stacktrace mess
diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c
index 44c8d0d..e36e652 100644
--- a/kernel/locking/lockdep.c
+++ b/kernel/locking/lockdep.c
@@ -1873,10 +1873,10 @@ check_prev_add(struct task_struct *curr, struct held_lock *prev,
struct held_lock *next, int distance, struct stack_trace *trace,
int (*save)(struct stack_trace *trace))
{
- struct lock_list *entry;
- int ret;
- struct lock_list this;
struct lock_list *uninitialized_var(target_entry);
+ struct lock_list *entry;
+ struct lock_list this;
+ int ret;
/*
* Prove that the new <prev> -> <next> dependency would not
@@ -1890,8 +1890,17 @@ check_prev_add(struct task_struct *curr, struct held_lock *prev,
this.class = hlock_class(next);
this.parent = NULL;
ret = check_noncircular(&this, hlock_class(prev), &target_entry);
- if (unlikely(!ret))
+ if (unlikely(!ret)) {
+ if (!trace->entries) {
+ /*
+ * If @save fails here, the printing might trigger
+ * a WARN but because of the !nr_entries it should
+ * not do bad things.
+ */
+ save(trace);
+ }
return print_circular_bug(&this, target_entry, next, prev, trace);
+ }
else if (unlikely(ret < 0))
return print_bfs_bug(ret);
@@ -1938,7 +1947,7 @@ check_prev_add(struct task_struct *curr, struct held_lock *prev,
return print_bfs_bug(ret);
- if (save && !save(trace))
+ if (!trace->entries && !save(trace))
return 0;
/*
@@ -1958,20 +1967,6 @@ check_prev_add(struct task_struct *curr, struct held_lock *prev,
if (!ret)
return 0;
- /*
- * Debugging printouts:
- */
- if (verbose(hlock_class(prev)) || verbose(hlock_class(next))) {
- graph_unlock();
- printk("\n new dependency: ");
- print_lock_name(hlock_class(prev));
- printk(KERN_CONT " => ");
- print_lock_name(hlock_class(next));
- printk(KERN_CONT "\n");
- dump_stack();
- if (!graph_lock())
- return 0;
- }
return 2;
}
@@ -1986,8 +1981,12 @@ check_prevs_add(struct task_struct *curr, struct held_lock *next)
{
int depth = curr->lockdep_depth;
struct held_lock *hlock;
- struct stack_trace trace;
- int (*save)(struct stack_trace *trace) = save_trace;
+ struct stack_trace trace = {
+ .nr_entries = 0,
+ .max_entries = 0,
+ .entries = NULL,
+ .skip = 0,
+ };
/*
* Debugging checks.
@@ -2018,18 +2017,11 @@ check_prevs_add(struct task_struct *curr, struct held_lock *next)
*/
if (hlock->read != 2 && hlock->check) {
int ret = check_prev_add(curr, hlock, next,
- distance, &trace, save);
+ distance, &trace, save_trace);
if (!ret)
return 0;
/*
- * Stop saving stack_trace if save_trace() was
- * called at least once:
- */
- if (save && ret == 2)
- save = NULL;
-
- /*
* Stop after the first non-trylock entry,
* as non-trylock entries have added their
* own direct dependencies already, so this
diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index c1e720a..dfdad67 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -1092,8 +1092,8 @@
select DEBUG_MUTEXES
select DEBUG_RT_MUTEXES if RT_MUTEXES
select DEBUG_LOCK_ALLOC
- select LOCKDEP_CROSSRELEASE
- select LOCKDEP_COMPLETIONS
+ select LOCKDEP_CROSSRELEASE if BROKEN
+ select LOCKDEP_COMPLETIONS if BROKEN
select TRACE_IRQFLAGS
default n
help
diff --git a/lib/locking-selftest.c b/lib/locking-selftest.c
index cd0b5c9..2b827b8 100644
--- a/lib/locking-selftest.c
+++ b/lib/locking-selftest.c
@@ -2031,11 +2031,13 @@ void locking_selftest(void)
print_testname("mixed read-lock/lock-write ABBA");
pr_cont(" |");
dotest(rlock_ABBA1, FAILURE, LOCKTYPE_RWLOCK);
+#ifdef CONFIG_PROVE_LOCKING
/*
* Lockdep does indeed fail here, but there's nothing we can do about
* that now. Don't kill lockdep for it.
*/
unexpected_testcase_failures--;
+#endif
pr_cont(" |");
dotest(rwsem_ABBA1, FAILURE, LOCKTYPE_RWSEM);