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 cf507a7d200ce34326e091cbbda82c8b30e73543..4c5be85016b640926c31434788d8eed90e819c0e 100644 (file)
--- a/drivers/base/core.c
+++ b/drivers/base/core.c
@@ -559,6 +559,7 @@ void device_initialize(struct device *dev)
        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 a03977a96d7eed76fbd9eb94da21e4954b0b0d13..06aed8305bf3bc38061dc42c168c3b9d83f29492 100644 (file)
--- a/include/linux/lockdep.h
+++ b/include/linux/lockdep.h
@@ -44,6 +44,8 @@ struct lock_class_key {
        struct lockdep_subclass_key     subkeys[MAX_LOCKDEP_SUBCLASSES];
 };
 
+extern struct lock_class_key __lockdep_no_validate__;
+
 #define LOCKSTAT_POINTS                4
 
 /*
@@ -270,6 +272,9 @@ extern void lockdep_init_map(struct lockdep_map *lock, const char *name,
 #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 @@ static inline void lockdep_on(void)
 #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 ec21304856d102814a796ef511f02d728f58a380..54286798c37b8e060078adbd7444c3f2c8da9847 100644 (file)
--- a/kernel/lockdep.c
+++ b/kernel/lockdep.c
@@ -2711,6 +2711,8 @@ void lockdep_init_map(struct lockdep_map *lock, const char *name,
 }
 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 @@ static int __lock_acquire(struct lockdep_map *lock, unsigned int subclass,
                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 a4d74344d805610a67e0e7e0bbf1674875f555a7..f2bbea9007006e0549d1c8ece31274a15153326c 100755 (executable)
--- a/scripts/checkpatch.pl
+++ b/scripts/checkpatch.pl
@@ -2656,6 +2656,7 @@ sub process {
 # 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 @@ sub process {
                                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