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-rw-r--r--kernel/locking/lockdep.c27
-rw-r--r--kernel/locking/lockdep_internals.h2
-rw-r--r--kernel/locking/lockdep_proc.c4
3 files changed, 33 insertions, 0 deletions
diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c
index 986f2fa79dbb..b2dd313951ce 100644
--- a/kernel/locking/lockdep.c
+++ b/kernel/locking/lockdep.c
@@ -1307,6 +1307,19 @@ check_noncircular(struct lock_list *root, struct lock_class *target,
return result;
}
+static noinline int
+check_redundant(struct lock_list *root, struct lock_class *target,
+ struct lock_list **target_entry)
+{
+ int result;
+
+ debug_atomic_inc(nr_redundant_checks);
+
+ result = __bfs_forwards(root, target, class_equal, target_entry);
+
+ return result;
+}
+
#if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)
/*
* Forwards and backwards subgraph searching, for the purposes of
@@ -1872,6 +1885,20 @@ check_prev_add(struct task_struct *curr, struct held_lock *prev,
}
}
+ /*
+ * Is the <prev> -> <next> link redundant?
+ */
+ this.class = hlock_class(prev);
+ this.parent = NULL;
+ ret = check_redundant(&this, hlock_class(next), &target_entry);
+ if (!ret) {
+ debug_atomic_inc(nr_redundant);
+ return 2;
+ }
+ if (ret < 0)
+ return print_bfs_bug(ret);
+
+
if (!*stack_saved) {
if (!save_trace(&trace))
return 0;
diff --git a/kernel/locking/lockdep_internals.h b/kernel/locking/lockdep_internals.h
index c08fbd2f5ba9..1da4669d57a7 100644
--- a/kernel/locking/lockdep_internals.h
+++ b/kernel/locking/lockdep_internals.h
@@ -143,6 +143,8 @@ struct lockdep_stats {
int redundant_softirqs_on;
int redundant_softirqs_off;
int nr_unused_locks;
+ int nr_redundant_checks;
+ int nr_redundant;
int nr_cyclic_checks;
int nr_cyclic_check_recursions;
int nr_find_usage_forwards_checks;
diff --git a/kernel/locking/lockdep_proc.c b/kernel/locking/lockdep_proc.c
index 6d1fcc786081..68d9e267ccd4 100644
--- a/kernel/locking/lockdep_proc.c
+++ b/kernel/locking/lockdep_proc.c
@@ -201,6 +201,10 @@ static void lockdep_stats_debug_show(struct seq_file *m)
debug_atomic_read(chain_lookup_hits));
seq_printf(m, " cyclic checks: %11llu\n",
debug_atomic_read(nr_cyclic_checks));
+ seq_printf(m, " redundant checks: %11llu\n",
+ debug_atomic_read(nr_redundant_checks));
+ seq_printf(m, " redundant links: %11llu\n",
+ debug_atomic_read(nr_redundant));
seq_printf(m, " find-mask forwards checks: %11llu\n",
debug_atomic_read(nr_find_usage_forwards_checks));
seq_printf(m, " find-mask backwards checks: %11llu\n",