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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: Peter Zijlstra (Intel) <peterz@infradead.org>
This commit is contained in:
Peter Zijlstra 2020-12-10 11:16:34 +01:00
parent bc2dd71b28
commit 175b1a60e8
1 changed files with 49 additions and 42 deletions
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91
kernel/locking/lockdep.c
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@ -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();