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Commit 2113caed authored by Linus Torvalds's avatar Linus Torvalds
Browse files

Merge branch 'locking-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 

Pull locking fixes from Ingo Molnar:
 "Two lockdep fixes"

* 'locking-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  lockdep: Fix lock_chain::base size
  locking/lockdep: Fix ->irq_context calculation
parents 8f3603a2 75dd602a

include/linux/lockdep.h

+5 −3
Original line number Diff line number Diff line
@@ -196,9 +196,11 @@ struct lock_list { 
 * We record lock dependency chains, so that we can cache them:

 */

struct lock_chain {

	u8				irq_context;

	u8				depth;

	u16				base;

	/* see BUILD_BUG_ON()s in lookup_chain_cache() */

	unsigned int			irq_context :  2,

					depth       :  6,

					base	    : 24;

	/* 4 byte hole */

	struct hlist_node		entry;

	u64				chain_key;

};

kernel/locking/lockdep.c

+34 −3
Original line number Diff line number Diff line
@@ -2176,15 +2176,37 @@ static inline int lookup_chain_cache(struct task_struct *curr, 
	chain->irq_context = hlock->irq_context;

	i = get_first_held_lock(curr, hlock);

	chain->depth = curr->lockdep_depth + 1 - i;



	BUILD_BUG_ON((1UL << 24) <= ARRAY_SIZE(chain_hlocks));

	BUILD_BUG_ON((1UL << 6)  <= ARRAY_SIZE(curr->held_locks));

	BUILD_BUG_ON((1UL << 8*sizeof(chain_hlocks[0])) <= ARRAY_SIZE(lock_classes));



	if (likely(nr_chain_hlocks + chain->depth <= MAX_LOCKDEP_CHAIN_HLOCKS)) {

		chain->base = nr_chain_hlocks;

		nr_chain_hlocks += chain->depth;

		for (j = 0; j < chain->depth - 1; j++, i++) {

			int lock_id = curr->held_locks[i].class_idx - 1;

			chain_hlocks[chain->base + j] = lock_id;

		}

		chain_hlocks[chain->base + j] = class - lock_classes;

	}



	if (nr_chain_hlocks < MAX_LOCKDEP_CHAIN_HLOCKS)

		nr_chain_hlocks += chain->depth;



#ifdef CONFIG_DEBUG_LOCKDEP

	/*

	 * Important for check_no_collision().

	 */

	if (unlikely(nr_chain_hlocks > MAX_LOCKDEP_CHAIN_HLOCKS)) {

		if (debug_locks_off_graph_unlock())

			return 0;



		print_lockdep_off("BUG: MAX_LOCKDEP_CHAIN_HLOCKS too low!");

		dump_stack();

		return 0;

	}

#endif



	hlist_add_head_rcu(&chain->entry, hash_head);

	debug_atomic_inc(chain_lookup_misses);

	inc_chains();
@@ -2932,6 +2954,11 @@ static int mark_irqflags(struct task_struct *curr, struct held_lock *hlock) 
	return 1;

}



static inline unsigned int task_irq_context(struct task_struct *task)

{

	return 2 * !!task->hardirq_context + !!task->softirq_context;

}



static int separate_irq_context(struct task_struct *curr,

		struct held_lock *hlock)

{
@@ -2940,8 +2967,6 @@ static int separate_irq_context(struct task_struct *curr, 
	/*

	 * Keep track of points where we cross into an interrupt context:

	 */

	hlock->irq_context = 2*(curr->hardirq_context ? 1 : 0) +

				curr->softirq_context;

	if (depth) {

		struct held_lock *prev_hlock;
@@ -2973,6 +2998,11 @@ static inline int mark_irqflags(struct task_struct *curr, 
	return 1;

}



static inline unsigned int task_irq_context(struct task_struct *task)

{

	return 0;

}



static inline int separate_irq_context(struct task_struct *curr,

		struct held_lock *hlock)

{
@@ -3241,6 +3271,7 @@ static int __lock_acquire(struct lockdep_map *lock, unsigned int subclass, 
	hlock->acquire_ip = ip;

	hlock->instance = lock;

	hlock->nest_lock = nest_lock;

	hlock->irq_context = task_irq_context(curr);

	hlock->trylock = trylock;

	hlock->read = read;

	hlock->check = check;

kernel/locking/lockdep_proc.c

+2 −0
Original line number Diff line number Diff line
@@ -141,6 +141,8 @@ static int lc_show(struct seq_file *m, void *v) 
	int i;



	if (v == SEQ_START_TOKEN) {

		if (nr_chain_hlocks > MAX_LOCKDEP_CHAIN_HLOCKS)

			seq_printf(m, "(buggered) ");

		seq_printf(m, "all lock chains:\n");

		return 0;

	}