locking/lockdep: Add new check to lock_downgrade() (6419c4af) · Commits · 戴 / test

include/linux/lockdep.h

+3 −0

Original line number	Diff line number	Diff line
		@@ -361,6 +361,8 @@ static inline void lock_set_subclass(struct lockdep_map *lock,
		lock_set_class(lock, lock->name, lock->key, subclass, ip);
		}

		extern void lock_downgrade(struct lockdep_map *lock, unsigned long ip);

		extern void lockdep_set_current_reclaim_state(gfp_t gfp_mask);
		extern void lockdep_clear_current_reclaim_state(void);
		extern void lockdep_trace_alloc(gfp_t mask);
		@@ -411,6 +413,7 @@ static inline void lockdep_on(void)

		# define lock_acquire(l, s, t, r, c, n, i) do { } while (0)
		# define lock_release(l, n, i) do { } while (0)
		# define lock_downgrade(l, i) do { } while (0)
		# define lock_set_class(l, n, k, s, i) do { } while (0)
		# define lock_set_subclass(l, s, i) do { } while (0)
		# define lockdep_set_current_reclaim_state(g) do { } while (0)

kernel/locking/lockdep.c

+55 −0

Original line number	Diff line number	Diff line
		@@ -3533,6 +3533,44 @@ __lock_set_class(struct lockdep_map lock, const char name,
		return 1;
		}

		static int __lock_downgrade(struct lockdep_map *lock, unsigned long ip)
		{
		struct task_struct *curr = current;
		struct held_lock *hlock;
		unsigned int depth;
		int i;

		depth = curr->lockdep_depth;
		/*
		* This function is about (re)setting the class of a held lock,
		* yet we're not actually holding any locks. Naughty user!
		*/
		if (DEBUG_LOCKS_WARN_ON(!depth))
		return 0;

		hlock = find_held_lock(curr, lock, depth, &i);
		if (!hlock)
		return print_unlock_imbalance_bug(curr, lock, ip);

		curr->lockdep_depth = i;
		curr->curr_chain_key = hlock->prev_chain_key;

		WARN(hlock->read, "downgrading a read lock");
		hlock->read = 1;
		hlock->acquire_ip = ip;

		if (reacquire_held_locks(curr, depth, i))
		return 0;

		/*
		* I took it apart and put it back together again, except now I have
		* these 'spare' parts.. where shall I put them.
		*/
		if (DEBUG_LOCKS_WARN_ON(curr->lockdep_depth != depth))
		return 0;
		return 1;
		}

		/*
		* Remove the lock to the list of currently held locks - this gets
		* called on mutex_unlock()/spin_unlock*() (or on a failed
		@@ -3759,6 +3797,23 @@ void lock_set_class(struct lockdep_map lock, const char name,
		}
		EXPORT_SYMBOL_GPL(lock_set_class);

		void lock_downgrade(struct lockdep_map *lock, unsigned long ip)
		{
		unsigned long flags;

		if (unlikely(current->lockdep_recursion))
		return;

		raw_local_irq_save(flags);
		current->lockdep_recursion = 1;
		check_flags(flags);
		if (__lock_downgrade(lock, ip))
		check_chain_key(current);
		current->lockdep_recursion = 0;
		raw_local_irq_restore(flags);
		}
		EXPORT_SYMBOL_GPL(lock_downgrade);

		/*
		* We are not always called with irqs disabled - do that here,
		* and also avoid lockdep recursion:

kernel/locking/rwsem.c

+2 −4

Original line number	Diff line number	Diff line
		@@ -124,10 +124,8 @@ EXPORT_SYMBOL(up_write);
		*/
		void downgrade_write(struct rw_semaphore *sem)
		{
		/*
		* lockdep: a downgraded write will live on as a write
		* dependency.
		*/
		lock_downgrade(&sem->dep_map, _RET_IP_);

		rwsem_set_reader_owned(sem);
		__downgrade_write(sem);
		}

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