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Merge branch 'locking-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

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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
This commit is contained in:
Linus Torvalds 2017-10-14 15:14:20 -04:00
commit 60a6ca6c94
3 changed files with 25 additions and 31 deletions
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50
kernel/locking/lockdep.c
View File

@ -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.
@ -2018,17 +2017,10 @@ 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

4
lib/Kconfig.debug
View File

@ -1092,8 +1092,8 @@ config PROVE_LOCKING
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

2
lib/locking-selftest.c
View File

@ -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);