5.4-stable review patch. If anyone has any objections, please let me know.
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From: Peter Zijlstra peterz@infradead.org
commit 248efb2158f1e23750728e92ad9db3ab60c14485 upstream.
A few sites want to assert we own the graph_lock/lockdep_lock, provide a more conventional lock interface for it with a number of trivial debug checks.
Signed-off-by: Peter Zijlstra (Intel) peterz@infradead.org Link: https://lkml.kernel.org/r/20200313102107.GX12561@hirez.programming.kicks-ass... Signed-off-by: Carlos Llamas cmllamas@google.com Signed-off-by: Sasha Levin sashal@kernel.org --- kernel/locking/lockdep.c | 89 ++++++++++++++++++++++------------------ 1 file changed, 48 insertions(+), 41 deletions(-)
diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c index 0a2be60e4aa7b..b9fabbab39183 100644 --- a/kernel/locking/lockdep.c +++ b/kernel/locking/lockdep.c @@ -84,12 +84,39 @@ module_param(lock_stat, int, 0644); * to use a raw spinlock - we really dont want the spinlock * code to recurse back into the lockdep code... */ -static arch_spinlock_t lockdep_lock = (arch_spinlock_t)__ARCH_SPIN_LOCK_UNLOCKED; +static arch_spinlock_t __lock = (arch_spinlock_t)__ARCH_SPIN_LOCK_UNLOCKED; +static struct task_struct *__owner; + +static inline void lockdep_lock(void) +{ + DEBUG_LOCKS_WARN_ON(!irqs_disabled()); + + arch_spin_lock(&__lock); + __owner = current; + current->lockdep_recursion++; +} + +static inline void lockdep_unlock(void) +{ + if (debug_locks && DEBUG_LOCKS_WARN_ON(__owner != current)) + return; + + current->lockdep_recursion--; + __owner = NULL; + arch_spin_unlock(&__lock); +} + +static inline bool lockdep_assert_locked(void) +{ + return DEBUG_LOCKS_WARN_ON(__owner != current); +} + static struct task_struct *lockdep_selftest_task_struct;
+ static int graph_lock(void) { - arch_spin_lock(&lockdep_lock); + lockdep_lock(); /* * Make sure that if another CPU detected a bug while * walking the graph we dont change it (while the other @@ -97,27 +124,15 @@ static int graph_lock(void) * dropped already) */ if (!debug_locks) { - arch_spin_unlock(&lockdep_lock); + lockdep_unlock(); return 0; } - /* prevent any recursions within lockdep from causing deadlocks */ - current->lockdep_recursion++; return 1; }
-static inline int graph_unlock(void) +static inline void graph_unlock(void) { - if (debug_locks && !arch_spin_is_locked(&lockdep_lock)) { - /* - * The lockdep graph lock isn't locked while we expect it to - * be, we're confused now, bye! - */ - return DEBUG_LOCKS_WARN_ON(1); - } - - current->lockdep_recursion--; - arch_spin_unlock(&lockdep_lock); - return 0; + lockdep_unlock(); }
/* @@ -128,7 +143,7 @@ static inline int debug_locks_off_graph_unlock(void) { int ret = debug_locks_off();
- arch_spin_unlock(&lockdep_lock); + lockdep_unlock();
return ret; } @@ -1476,6 +1491,8 @@ static int __bfs(struct lock_list *source_entry, struct circular_queue *cq = &lock_cq; int ret = 1;
+ lockdep_assert_locked(); + if (match(source_entry, data)) { *target_entry = source_entry; ret = 0; @@ -1498,8 +1515,6 @@ static int __bfs(struct lock_list *source_entry,
head = get_dep_list(lock, offset);
- DEBUG_LOCKS_WARN_ON(!irqs_disabled()); - list_for_each_entry_rcu(entry, head, entry) { if (!lock_accessed(entry)) { unsigned int cq_depth; @@ -1726,11 +1741,9 @@ unsigned long lockdep_count_forward_deps(struct lock_class *class) this.class = class;
raw_local_irq_save(flags); - current->lockdep_recursion++; - arch_spin_lock(&lockdep_lock); + lockdep_lock(); ret = __lockdep_count_forward_deps(&this); - arch_spin_unlock(&lockdep_lock); - current->lockdep_recursion--; + lockdep_unlock(); raw_local_irq_restore(flags);
return ret; @@ -1755,11 +1768,9 @@ unsigned long lockdep_count_backward_deps(struct lock_class *class) this.class = class;
raw_local_irq_save(flags); - current->lockdep_recursion++; - arch_spin_lock(&lockdep_lock); + lockdep_lock(); ret = __lockdep_count_backward_deps(&this); - arch_spin_unlock(&lockdep_lock); - current->lockdep_recursion--; + lockdep_unlock(); raw_local_irq_restore(flags);
return ret; @@ -2930,7 +2941,7 @@ static inline int add_chain_cache(struct task_struct *curr, * disabled to make this an IRQ-safe lock.. for recursion reasons * lockdep won't complain about its own locking errors. */ - if (DEBUG_LOCKS_WARN_ON(!irqs_disabled())) + if (lockdep_assert_locked()) return 0;
chain = alloc_lock_chain(); @@ -5092,8 +5103,7 @@ static void free_zapped_rcu(struct rcu_head *ch) return;
raw_local_irq_save(flags); - arch_spin_lock(&lockdep_lock); - current->lockdep_recursion++; + lockdep_lock();
/* closed head */ pf = delayed_free.pf + (delayed_free.index ^ 1); @@ -5105,8 +5115,7 @@ static void free_zapped_rcu(struct rcu_head *ch) */ call_rcu_zapped(delayed_free.pf + delayed_free.index);
- current->lockdep_recursion--; - arch_spin_unlock(&lockdep_lock); + lockdep_unlock(); raw_local_irq_restore(flags); }
@@ -5151,13 +5160,11 @@ static void lockdep_free_key_range_reg(void *start, unsigned long size) init_data_structures_once();
raw_local_irq_save(flags); - arch_spin_lock(&lockdep_lock); - current->lockdep_recursion++; + lockdep_lock(); pf = get_pending_free(); __lockdep_free_key_range(pf, start, size); call_rcu_zapped(pf); - current->lockdep_recursion--; - arch_spin_unlock(&lockdep_lock); + lockdep_unlock(); raw_local_irq_restore(flags);
/* @@ -5179,10 +5186,10 @@ static void lockdep_free_key_range_imm(void *start, unsigned long size) init_data_structures_once();
raw_local_irq_save(flags); - arch_spin_lock(&lockdep_lock); + lockdep_lock(); __lockdep_free_key_range(pf, start, size); __free_zapped_classes(pf); - arch_spin_unlock(&lockdep_lock); + lockdep_unlock(); raw_local_irq_restore(flags); }
@@ -5278,10 +5285,10 @@ static void lockdep_reset_lock_imm(struct lockdep_map *lock) unsigned long flags;
raw_local_irq_save(flags); - arch_spin_lock(&lockdep_lock); + lockdep_lock(); __lockdep_reset_lock(pf, lock); __free_zapped_classes(pf); - arch_spin_unlock(&lockdep_lock); + lockdep_unlock(); raw_local_irq_restore(flags); }