Commit 175b1a60 authored by Peter Zijlstra's avatar Peter Zijlstra
Browse files

locking/lockdep: Clean up check_redundant() a bit 



In preparation for adding an TRACE_IRQFLAGS dependent skip function to
check_redundant(), move it below the TRACE_IRQFLAGS #ifdef.

While there, provide a stub function to reduce #ifdef usage.

Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
parent bc2dd71b

kernel/locking/lockdep.c

+49 −42
Original line number Diff line number Diff line
@@ -2130,46 +2130,6 @@ check_noncircular(struct held_lock *src, struct held_lock *target, 
	return ret;

}



#ifdef CONFIG_LOCKDEP_SMALL

/*

 * Check that the dependency graph starting at <src> can lead to

 * <target> or not. If it can, <src> -> <target> dependency is already

 * in the graph.

 *

 * Return BFS_RMATCH if it does, or BFS_RMATCH if it does not, return BFS_E* if

 * any error appears in the bfs search.

 */

static noinline enum bfs_result

check_redundant(struct held_lock *src, struct held_lock *target)

{

	enum bfs_result ret;

	struct lock_list *target_entry;

	struct lock_list src_entry;



	bfs_init_root(&src_entry, src);

	/*

	 * Special setup for check_redundant().

	 *

	 * To report redundant, we need to find a strong dependency path that

	 * is equal to or stronger than <src> -> <target>. So if <src> is E,

	 * we need to let __bfs() only search for a path starting at a -(E*)->,

	 * we achieve this by setting the initial node's ->only_xr to true in

	 * that case. And if <prev> is S, we set initial ->only_xr to false

	 * because both -(S*)-> (equal) and -(E*)-> (stronger) are redundant.

	 */

	src_entry.only_xr = src->read == 0;



	debug_atomic_inc(nr_redundant_checks);



	ret = check_path(target, &src_entry, hlock_equal, NULL, &target_entry);



	if (ret == BFS_RMATCH)

		debug_atomic_inc(nr_redundant);



	return ret;

}

#endif



#ifdef CONFIG_TRACE_IRQFLAGS



/*
@@ -2706,6 +2666,55 @@ static inline int check_irq_usage(struct task_struct *curr, 
}

#endif /* CONFIG_TRACE_IRQFLAGS */



#ifdef CONFIG_LOCKDEP_SMALL

/*

 * Check that the dependency graph starting at <src> can lead to

 * <target> or not. If it can, <src> -> <target> dependency is already

 * in the graph.

 *

 * Return BFS_RMATCH if it does, or BFS_RMATCH if it does not, return BFS_E* if

 * any error appears in the bfs search.

 */

static noinline enum bfs_result

check_redundant(struct held_lock *src, struct held_lock *target)

{

	enum bfs_result ret;

	struct lock_list *target_entry;

	struct lock_list src_entry;



	bfs_init_root(&src_entry, src);

	/*

	 * Special setup for check_redundant().

	 *

	 * To report redundant, we need to find a strong dependency path that

	 * is equal to or stronger than <src> -> <target>. So if <src> is E,

	 * we need to let __bfs() only search for a path starting at a -(E*)->,

	 * we achieve this by setting the initial node's ->only_xr to true in

	 * that case. And if <prev> is S, we set initial ->only_xr to false

	 * because both -(S*)-> (equal) and -(E*)-> (stronger) are redundant.

	 */

	src_entry.only_xr = src->read == 0;



	debug_atomic_inc(nr_redundant_checks);



	ret = check_path(target, &src_entry, hlock_equal, NULL, &target_entry);



	if (ret == BFS_RMATCH)

		debug_atomic_inc(nr_redundant);



	return ret;

}



#else



static inline enum bfs_result

check_redundant(struct held_lock *src, struct held_lock *target)

{

	return BFS_RNOMATCH;

}



#endif



static void inc_chains(int irq_context)

{

	if (irq_context & LOCK_CHAIN_HARDIRQ_CONTEXT)
@@ -2926,7 +2935,6 @@ check_prev_add(struct task_struct *curr, struct held_lock *prev, 
		}

	}



#ifdef CONFIG_LOCKDEP_SMALL

	/*

	 * Is the <prev> -> <next> link redundant?

	 */
@@ -2935,7 +2943,6 @@ check_prev_add(struct task_struct *curr, struct held_lock *prev, 
		return 0;

	else if (ret == BFS_RMATCH)

		return 2;

#endif



	if (!*trace) {

		*trace = save_trace();