lockdep: Add novalidate class for dev->mutex conversion
The conversion of device->sem to device->mutex resulted in lockdep
warnings. Create a novalidate class for now until the driver folks
come up with separate classes. That way we have at least the basic
mutex debugging coverage.
Add a checkpatch error so the usage is reserved for device->mutex.
[ tglx: checkpatch and compile fix for LOCKDEP=n ]
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
diff --git a/drivers/base/core.c b/drivers/base/core.c
index cf507a7..4c5be85 100644
--- a/drivers/base/core.c
+++ b/drivers/base/core.c
@@ -559,6 +559,7 @@
kobject_init(&dev->kobj, &device_ktype);
INIT_LIST_HEAD(&dev->dma_pools);
mutex_init(&dev->mutex);
+ lockdep_set_novalidate_class(&dev->mutex);
spin_lock_init(&dev->devres_lock);
INIT_LIST_HEAD(&dev->devres_head);
device_pm_init(dev);
diff --git a/include/linux/lockdep.h b/include/linux/lockdep.h
index a03977a9..06aed83 100644
--- a/include/linux/lockdep.h
+++ b/include/linux/lockdep.h
@@ -44,6 +44,8 @@
struct lockdep_subclass_key subkeys[MAX_LOCKDEP_SUBCLASSES];
};
+extern struct lock_class_key __lockdep_no_validate__;
+
#define LOCKSTAT_POINTS 4
/*
@@ -270,6 +272,9 @@
#define lockdep_set_subclass(lock, sub) \
lockdep_init_map(&(lock)->dep_map, #lock, \
(lock)->dep_map.key, sub)
+
+#define lockdep_set_novalidate_class(lock) \
+ lockdep_set_class(lock, &__lockdep_no_validate__)
/*
* Compare locking classes
*/
@@ -354,6 +359,9 @@
#define lockdep_set_class_and_subclass(lock, key, sub) \
do { (void)(key); } while (0)
#define lockdep_set_subclass(lock, sub) do { } while (0)
+
+#define lockdep_set_novalidate_class(lock) do { } while (0)
+
/*
* We don't define lockdep_match_class() and lockdep_match_key() for !LOCKDEP
* case since the result is not well defined and the caller should rather
diff --git a/kernel/lockdep.c b/kernel/lockdep.c
index ec21304..5428679 100644
--- a/kernel/lockdep.c
+++ b/kernel/lockdep.c
@@ -2711,6 +2711,8 @@
}
EXPORT_SYMBOL_GPL(lockdep_init_map);
+struct lock_class_key __lockdep_no_validate__;
+
/*
* This gets called for every mutex_lock*()/spin_lock*() operation.
* We maintain the dependency maps and validate the locking attempt:
@@ -2745,6 +2747,9 @@
return 0;
}
+ if (lock->key == &__lockdep_no_validate__)
+ check = 1;
+
if (!subclass)
class = lock->class_cache;
/*
diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
index a4d7434..f2bbea9 100755
--- a/scripts/checkpatch.pl
+++ b/scripts/checkpatch.pl
@@ -2656,6 +2656,7 @@
# check for semaphores used as mutexes
if ($line =~ /^.\s*init_MUTEX_LOCKED\s*\(/) {
WARN("consider using a completion\n" . $herecurr);
+
}
# recommend strict_strto* over simple_strto*
if ($line =~ /\bsimple_(strto.*?)\s*\(/) {
@@ -2740,6 +2741,16 @@
WARN("use of in_atomic() is incorrect outside core kernel code\n" . $herecurr);
}
}
+
+# check for lockdep_set_novalidate_class
+ if ($line =~ /^.\s*lockdep_set_novalidate_class\s*\(/ ||
+ $line =~ /__lockdep_no_validate__\s*\)/ ) {
+ if ($realfile !~ m@^kernel/lockdep@ &&
+ $realfile !~ m@^include/linux/lockdep@ &&
+ $realfile !~ m@^drivers/base/core@) {
+ ERROR("lockdep_no_validate class is reserved for device->mutex.\n" . $herecurr);
+ }
+ }
}
# If we have no input at all, then there is nothing to report on