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locking/lockdep: Refactorize check_noncircular and check_redundant 

These two functions now handle different check results themselves. A new
check_path function is added to check whether there is a path in the
dependency graph. No functional change.

Signed-off-by: Yuyang Du <duyuyang@gmail.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: bvanassche@acm.org
Cc: frederic@kernel.org
Cc: ming.lei@redhat.com
Cc: will.deacon@arm.com
Link: https://lkml.kernel.org/r/20190506081939.74287-20-duyuyang@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Yuyang Du 2019-05-06 16:19:35 +08:00 committed by Ingo Molnar
parent b4adfe8e05
commit 8c2c2b449a
1 changed files with 74 additions and 44 deletions
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118
kernel/locking/lockdep.c
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@ -1683,33 +1683,90 @@ unsigned long lockdep_count_backward_deps(struct lock_class *class)
}
/*
* Prove that the dependency graph starting at <entry> can not
* lead to <target>. Print an error and return 0 if it does.
* Check that the dependency graph starting at <src> can lead to
* <target> or not. Print an error and return 0 if it does.
*/
static noinline int
check_noncircular(struct lock_list *root, struct lock_class *target,
struct lock_list **target_entry)
check_path(struct lock_class *target, struct lock_list *src_entry,
struct lock_list **target_entry)
{
int result;
int ret;
ret = __bfs_forwards(src_entry, (void *)target, class_equal,
target_entry);
if (unlikely(ret < 0))
print_bfs_bug(ret);
return ret;
}
/*
* Prove that the dependency graph starting at <src> can not
* lead to <target>. If it can, there is a circle when adding
* <target> -> <src> dependency.
*
* Print an error and return 0 if it does.
*/
static noinline int
check_noncircular(struct held_lock *src, struct held_lock *target,
struct lock_trace *trace)
{
int ret;
struct lock_list *uninitialized_var(target_entry);
struct lock_list src_entry = {
.class = hlock_class(src),
.parent = NULL,
};
debug_atomic_inc(nr_cyclic_checks);
result = __bfs_forwards(root, target, class_equal, target_entry);
ret = check_path(hlock_class(target), &src_entry, &target_entry);
return result;
if (unlikely(!ret)) {
if (!trace->nr_entries) {
/*
* If save_trace fails here, the printing might
* trigger a WARN but because of the !nr_entries it
* should not do bad things.
*/
save_trace(trace);
}
print_circular_bug(&src_entry, target_entry, src, target);
}
return ret;
}
/*
* 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.
*
* Print an error and return 2 if it does or 1 if it does not.
*/
static noinline int
check_redundant(struct lock_list *root, struct lock_class *target,
struct lock_list **target_entry)
check_redundant(struct held_lock *src, struct held_lock *target)
{
int result;
int ret;
struct lock_list *uninitialized_var(target_entry);
struct lock_list src_entry = {
.class = hlock_class(src),
.parent = NULL,
};
debug_atomic_inc(nr_redundant_checks);
result = __bfs_forwards(root, target, class_equal, target_entry);
ret = check_path(hlock_class(target), &src_entry, &target_entry);
return result;
if (!ret) {
debug_atomic_inc(nr_redundant);
ret = 2;
} else if (ret < 0)
ret = 0;
return ret;
}
#ifdef CONFIG_TRACE_IRQFLAGS
@ -2307,9 +2364,7 @@ static int
check_prev_add(struct task_struct *curr, struct held_lock *prev,
struct held_lock *next, int distance, struct lock_trace *trace)
{
struct lock_list *uninitialized_var(target_entry);
struct lock_list *entry;
struct lock_list this;
int ret;
if (!hlock_class(prev)->key || !hlock_class(next)->key) {
@ -2340,25 +2395,9 @@ check_prev_add(struct task_struct *curr, struct held_lock *prev,
* MAX_CIRCULAR_QUEUE_SIZE) which keeps track of a breadth of nodes
* in the graph whose neighbours are to be checked.
*/
this.class = hlock_class(next);
this.parent = NULL;
ret = check_noncircular(&this, hlock_class(prev), &target_entry);
if (unlikely(!ret)) {
if (!trace->nr_entries) {
/*
* If save_trace fails here, the printing might
* trigger a WARN but because of the !nr_entries it
* should not do bad things.
*/
save_trace(trace);
}
print_circular_bug(&this, target_entry, next, prev);
ret = check_noncircular(next, prev, trace);
if (unlikely(ret <= 0))
return 0;
}
else if (unlikely(ret < 0)) {
print_bfs_bug(ret);
return 0;
}
if (!check_irq_usage(curr, prev, next))
return 0;
@ -2392,18 +2431,9 @@ check_prev_add(struct task_struct *curr, struct held_lock *prev,
/*
* Is the <prev> -> <next> link redundant?
*/
this.class = hlock_class(prev);
this.parent = NULL;
ret = check_redundant(&this, hlock_class(next), &target_entry);
if (!ret) {
debug_atomic_inc(nr_redundant);
return 2;
}
if (ret < 0) {
print_bfs_bug(ret);
return 0;
}
ret = check_redundant(prev, next);
if (ret != 1)
return ret;
if (!trace->nr_entries && !save_trace(trace))
return 0;