diff options
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/locking/lockdep.c | 35 | ||||
| -rw-r--r-- | kernel/locking/lockdep_internals.h | 2 |
2 files changed, 31 insertions, 6 deletions
diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c index 54b74fabf40c..2facbbd146ec 100644 --- a/kernel/locking/lockdep.c +++ b/kernel/locking/lockdep.c @@ -3969,13 +3969,18 @@ static int separate_irq_context(struct task_struct *curr, static int mark_lock(struct task_struct *curr, struct held_lock *this, enum lock_usage_bit new_bit) { - unsigned int new_mask = 1 << new_bit, ret = 1; + unsigned int old_mask, new_mask, ret = 1; if (new_bit >= LOCK_USAGE_STATES) { DEBUG_LOCKS_WARN_ON(1); return 0; } + if (new_bit == LOCK_USED && this->read) + new_bit = LOCK_USED_READ; + + new_mask = 1 << new_bit; + /* * If already set then do not dirty the cacheline, * nor do any checks: @@ -3988,13 +3993,22 @@ static int mark_lock(struct task_struct *curr, struct held_lock *this, /* * Make sure we didn't race: */ - if (unlikely(hlock_class(this)->usage_mask & new_mask)) { - graph_unlock(); - return 1; - } + if (unlikely(hlock_class(this)->usage_mask & new_mask)) + goto unlock; + old_mask = hlock_class(this)->usage_mask; hlock_class(this)->usage_mask |= new_mask; + /* + * Save one usage_traces[] entry and map both LOCK_USED and + * LOCK_USED_READ onto the same entry. + */ + if (new_bit == LOCK_USED || new_bit == LOCK_USED_READ) { + if (old_mask & (LOCKF_USED | LOCKF_USED_READ)) + goto unlock; + new_bit = LOCK_USED; + } + if (!(hlock_class(this)->usage_traces[new_bit] = save_trace())) return 0; @@ -4008,6 +4022,7 @@ static int mark_lock(struct task_struct *curr, struct held_lock *this, return 0; } +unlock: graph_unlock(); /* @@ -4942,12 +4957,20 @@ static void verify_lock_unused(struct lockdep_map *lock, struct held_lock *hlock { #ifdef CONFIG_PROVE_LOCKING struct lock_class *class = look_up_lock_class(lock, subclass); + unsigned long mask = LOCKF_USED; /* if it doesn't have a class (yet), it certainly hasn't been used yet */ if (!class) return; - if (!(class->usage_mask & LOCK_USED)) + /* + * READ locks only conflict with USED, such that if we only ever use + * READ locks, there is no deadlock possible -- RCU. + */ + if (!hlock->read) + mask |= LOCKF_USED_READ; + + if (!(class->usage_mask & mask)) return; hlock->class_idx = class - lock_classes; diff --git a/kernel/locking/lockdep_internals.h b/kernel/locking/lockdep_internals.h index baca699b94e9..b0be1560ed17 100644 --- a/kernel/locking/lockdep_internals.h +++ b/kernel/locking/lockdep_internals.h @@ -19,6 +19,7 @@ enum lock_usage_bit { #include "lockdep_states.h" #undef LOCKDEP_STATE LOCK_USED, + LOCK_USED_READ, LOCK_USAGE_STATES }; @@ -40,6 +41,7 @@ enum { #include "lockdep_states.h" #undef LOCKDEP_STATE __LOCKF(USED) + __LOCKF(USED_READ) }; #define LOCKDEP_STATE(__STATE) LOCKF_ENABLED_##__STATE | |