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Subject[PATCH v3 01/18] locking/lockdep: Change all print_*() return type to void
Date
Since none of the print_*() function's return value is necessary, change
their return type to void. No functional change.

In cases where an invariable return value is used, this change slightly
improves readability, i.e.:

print_x();
return 0;

is definitely better than:

return print_x(); /* where print_x() always returns 0 */

Signed-off-by: Yuyang Du <duyuyang@gmail.com>
---
kernel/locking/lockdep.c | 203 ++++++++++++++++++++++++-----------------------
1 file changed, 103 insertions(+), 100 deletions(-)

diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c
index 34cdcbe..41137ad 100644
--- a/kernel/locking/lockdep.c
+++ b/kernel/locking/lockdep.c
@@ -1430,17 +1430,15 @@ static inline int __bfs_backwards(struct lock_list *src_entry,
* Print a dependency chain entry (this is only done when a deadlock
* has been detected):
*/
-static noinline int
+static noinline void
print_circular_bug_entry(struct lock_list *target, int depth)
{
if (debug_locks_silent)
- return 0;
+ return;
printk("\n-> #%u", depth);
print_lock_name(target->class);
printk(KERN_CONT ":\n");
print_stack_trace(&target->trace, 6);
-
- return 0;
}

static void
@@ -1497,7 +1495,7 @@ static inline int __bfs_backwards(struct lock_list *src_entry,
* When a circular dependency is detected, print the
* header first:
*/
-static noinline int
+static noinline void
print_circular_bug_header(struct lock_list *entry, unsigned int depth,
struct held_lock *check_src,
struct held_lock *check_tgt)
@@ -1505,7 +1503,7 @@ static inline int __bfs_backwards(struct lock_list *src_entry,
struct task_struct *curr = current;

if (debug_locks_silent)
- return 0;
+ return;

pr_warn("\n");
pr_warn("======================================================\n");
@@ -1523,8 +1521,6 @@ static inline int __bfs_backwards(struct lock_list *src_entry,
pr_warn("\nthe existing dependency chain (in reverse order) is:\n");

print_circular_bug_entry(entry, depth);
-
- return 0;
}

static inline int class_equal(struct lock_list *entry, void *data)
@@ -1532,11 +1528,11 @@ static inline int class_equal(struct lock_list *entry, void *data)
return entry->class == data;
}

-static noinline int print_circular_bug(struct lock_list *this,
- struct lock_list *target,
- struct held_lock *check_src,
- struct held_lock *check_tgt,
- struct stack_trace *trace)
+static noinline void print_circular_bug(struct lock_list *this,
+ struct lock_list *target,
+ struct held_lock *check_src,
+ struct held_lock *check_tgt,
+ struct stack_trace *trace)
{
struct task_struct *curr = current;
struct lock_list *parent;
@@ -1544,10 +1540,10 @@ static noinline int print_circular_bug(struct lock_list *this,
int depth;

if (!debug_locks_off_graph_unlock() || debug_locks_silent)
- return 0;
+ return;

if (!save_trace(&this->trace))
- return 0;
+ return;

depth = get_lock_depth(target);

@@ -1569,21 +1565,17 @@ static noinline int print_circular_bug(struct lock_list *this,

printk("\nstack backtrace:\n");
dump_stack();
-
- return 0;
}

-static noinline int print_bfs_bug(int ret)
+static noinline void print_bfs_bug(int ret)
{
if (!debug_locks_off_graph_unlock())
- return 0;
+ return;

/*
* Breadth-first-search failed, graph got corrupted?
*/
WARN(1, "lockdep bfs error:%d\n", ret);
-
- return 0;
}

static int noop_count(struct lock_list *entry, void *data)
@@ -1766,7 +1758,7 @@ static void print_lock_class_header(struct lock_class *class, int depth)
*/
static void __used
print_shortest_lock_dependencies(struct lock_list *leaf,
- struct lock_list *root)
+ struct lock_list *root)
{
struct lock_list *entry = leaf;
int depth;
@@ -1788,8 +1780,6 @@ static void print_lock_class_header(struct lock_class *class, int depth)
entry = get_lock_parent(entry);
depth--;
} while (entry && (depth >= 0));
-
- return;
}

static void
@@ -1848,7 +1838,7 @@ static void print_lock_class_header(struct lock_class *class, int depth)
printk("\n *** DEADLOCK ***\n\n");
}

-static int
+static void
print_bad_irq_dependency(struct task_struct *curr,
struct lock_list *prev_root,
struct lock_list *next_root,
@@ -1861,7 +1851,7 @@ static void print_lock_class_header(struct lock_class *class, int depth)
const char *irqclass)
{
if (!debug_locks_off_graph_unlock() || debug_locks_silent)
- return 0;
+ return;

pr_warn("\n");
pr_warn("=====================================================\n");
@@ -1907,19 +1897,17 @@ static void print_lock_class_header(struct lock_class *class, int depth)

pr_warn("\nthe dependencies between %s-irq-safe lock and the holding lock:\n", irqclass);
if (!save_trace(&prev_root->trace))
- return 0;
+ return;
print_shortest_lock_dependencies(backwards_entry, prev_root);

pr_warn("\nthe dependencies between the lock to be acquired");
pr_warn(" and %s-irq-unsafe lock:\n", irqclass);
if (!save_trace(&next_root->trace))
- return 0;
+ return;
print_shortest_lock_dependencies(forwards_entry, next_root);

pr_warn("\nstack backtrace:\n");
dump_stack();
-
- return 0;
}

static int
@@ -1936,23 +1924,28 @@ static void print_lock_class_header(struct lock_class *class, int depth)

this.class = hlock_class(prev);
ret = find_usage_backwards(&this, bit_backwards, &target_entry);
- if (ret < 0)
- return print_bfs_bug(ret);
+ if (ret < 0) {
+ print_bfs_bug(ret);
+ return 0;
+ }
if (ret == 1)
return ret;

that.parent = NULL;
that.class = hlock_class(next);
ret = find_usage_forwards(&that, bit_forwards, &target_entry1);
- if (ret < 0)
- return print_bfs_bug(ret);
+ if (ret < 0) {
+ print_bfs_bug(ret);
+ return 0;
+ }
if (ret == 1)
return ret;

- return print_bad_irq_dependency(curr, &this, &that,
- target_entry, target_entry1,
- prev, next,
- bit_backwards, bit_forwards, irqclass);
+ print_bad_irq_dependency(curr, &this, &that,
+ target_entry, target_entry1,
+ prev, next,
+ bit_backwards, bit_forwards, irqclass);
+ return 0;
}

static const char *state_names[] = {
@@ -2055,8 +2048,7 @@ static inline void inc_chains(void)
#endif

static void
-print_deadlock_scenario(struct held_lock *nxt,
- struct held_lock *prv)
+print_deadlock_scenario(struct held_lock *nxt, struct held_lock *prv)
{
struct lock_class *next = hlock_class(nxt);
struct lock_class *prev = hlock_class(prv);
@@ -2074,12 +2066,12 @@ static inline void inc_chains(void)
printk(" May be due to missing lock nesting notation\n\n");
}

-static int
+static void
print_deadlock_bug(struct task_struct *curr, struct held_lock *prev,
struct held_lock *next)
{
if (!debug_locks_off_graph_unlock() || debug_locks_silent)
- return 0;
+ return;

pr_warn("\n");
pr_warn("============================================\n");
@@ -2098,8 +2090,6 @@ static inline void inc_chains(void)

pr_warn("\nstack backtrace:\n");
dump_stack();
-
- return 0;
}

/*
@@ -2141,7 +2131,8 @@ static inline void inc_chains(void)
if (nest)
return 2;

- return print_deadlock_bug(curr, prev, next);
+ print_deadlock_bug(curr, prev, next);
+ return 0;
}
return 1;
}
@@ -2217,10 +2208,13 @@ static inline void inc_chains(void)
*/
save(trace);
}
- return print_circular_bug(&this, target_entry, next, prev, trace);
+ print_circular_bug(&this, target_entry, next, prev, trace);
+ return 0;
+ }
+ else if (unlikely(ret < 0)) {
+ print_bfs_bug(ret);
+ return 0;
}
- else if (unlikely(ret < 0))
- return print_bfs_bug(ret);

if (!check_prev_add_irq(curr, prev, next))
return 0;
@@ -2261,8 +2255,10 @@ static inline void inc_chains(void)
debug_atomic_inc(nr_redundant);
return 2;
}
- if (ret < 0)
- return print_bfs_bug(ret);
+ if (ret < 0) {
+ print_bfs_bug(ret);
+ return 0;
+ }


if (!trace->entries && !save(trace))
@@ -2784,8 +2780,7 @@ static void check_chain_key(struct task_struct *curr)
#endif
}

-static void
-print_usage_bug_scenario(struct held_lock *lock)
+static void print_usage_bug_scenario(struct held_lock *lock)
{
struct lock_class *class = hlock_class(lock);

@@ -2802,12 +2797,12 @@ static void check_chain_key(struct task_struct *curr)
printk("\n *** DEADLOCK ***\n\n");
}

-static int
+static void
print_usage_bug(struct task_struct *curr, struct held_lock *this,
enum lock_usage_bit prev_bit, enum lock_usage_bit new_bit)
{
if (!debug_locks_off_graph_unlock() || debug_locks_silent)
- return 0;
+ return;

pr_warn("\n");
pr_warn("================================\n");
@@ -2837,8 +2832,6 @@ static void check_chain_key(struct task_struct *curr)

pr_warn("\nstack backtrace:\n");
dump_stack();
-
- return 0;
}

/*
@@ -2848,8 +2841,10 @@ static void check_chain_key(struct task_struct *curr)
valid_state(struct task_struct *curr, struct held_lock *this,
enum lock_usage_bit new_bit, enum lock_usage_bit bad_bit)
{
- if (unlikely(hlock_class(this)->usage_mask & (1 << bad_bit)))
- return print_usage_bug(curr, this, bad_bit, new_bit);
+ if (unlikely(hlock_class(this)->usage_mask & (1 << bad_bit))) {
+ print_usage_bug(curr, this, bad_bit, new_bit);
+ return 0;
+ }
return 1;
}

@@ -2861,7 +2856,7 @@ static int mark_lock(struct task_struct *curr, struct held_lock *this,
/*
* print irq inversion bug:
*/
-static int
+static void
print_irq_inversion_bug(struct task_struct *curr,
struct lock_list *root, struct lock_list *other,
struct held_lock *this, int forwards,
@@ -2872,7 +2867,7 @@ static int mark_lock(struct task_struct *curr, struct held_lock *this,
int depth;

if (!debug_locks_off_graph_unlock() || debug_locks_silent)
- return 0;
+ return;

pr_warn("\n");
pr_warn("========================================================\n");
@@ -2913,13 +2908,11 @@ static int mark_lock(struct task_struct *curr, struct held_lock *this,

pr_warn("\nthe shortest dependencies between 2nd lock and 1st lock:\n");
if (!save_trace(&root->trace))
- return 0;
+ return;
print_shortest_lock_dependencies(other, root);

pr_warn("\nstack backtrace:\n");
dump_stack();
-
- return 0;
}

/*
@@ -2937,13 +2930,16 @@ static int mark_lock(struct task_struct *curr, struct held_lock *this,
root.parent = NULL;
root.class = hlock_class(this);
ret = find_usage_forwards(&root, bit, &target_entry);
- if (ret < 0)
- return print_bfs_bug(ret);
+ if (ret < 0) {
+ print_bfs_bug(ret);
+ return 0;
+ }
if (ret == 1)
return ret;

- return print_irq_inversion_bug(curr, &root, target_entry,
- this, 1, irqclass);
+ print_irq_inversion_bug(curr, &root, target_entry,
+ this, 1, irqclass);
+ return 0;
}

/*
@@ -2961,13 +2957,16 @@ static int mark_lock(struct task_struct *curr, struct held_lock *this,
root.parent = NULL;
root.class = hlock_class(this);
ret = find_usage_backwards(&root, bit, &target_entry);
- if (ret < 0)
- return print_bfs_bug(ret);
+ if (ret < 0) {
+ print_bfs_bug(ret);
+ return 0;
+ }
if (ret == 1)
return ret;

- return print_irq_inversion_bug(curr, &root, target_entry,
- this, 0, irqclass);
+ print_irq_inversion_bug(curr, &root, target_entry,
+ this, 0, irqclass);
+ return 0;
}

void print_irqtrace_events(struct task_struct *curr)
@@ -3510,15 +3509,15 @@ void lockdep_init_map(struct lockdep_map *lock, const char *name,
struct lock_class_key __lockdep_no_validate__;
EXPORT_SYMBOL_GPL(__lockdep_no_validate__);

-static int
+static void
print_lock_nested_lock_not_held(struct task_struct *curr,
struct held_lock *hlock,
unsigned long ip)
{
if (!debug_locks_off())
- return 0;
+ return;
if (debug_locks_silent)
- return 0;
+ return;

pr_warn("\n");
pr_warn("==================================\n");
@@ -3540,8 +3539,6 @@ void lockdep_init_map(struct lockdep_map *lock, const char *name,

pr_warn("\nstack backtrace:\n");
dump_stack();
-
- return 0;
}

static int __lock_is_held(const struct lockdep_map *lock, int read);
@@ -3690,8 +3687,10 @@ static int __lock_acquire(struct lockdep_map *lock, unsigned int subclass,
}
chain_key = iterate_chain_key(chain_key, class_idx);

- if (nest_lock && !__lock_is_held(nest_lock, -1))
- return print_lock_nested_lock_not_held(curr, hlock, ip);
+ if (nest_lock && !__lock_is_held(nest_lock, -1)) {
+ print_lock_nested_lock_not_held(curr, hlock, ip);
+ return 0;
+ }

if (!debug_locks_silent) {
WARN_ON_ONCE(depth && !hlock_class(hlock - 1)->key);
@@ -3727,14 +3726,14 @@ static int __lock_acquire(struct lockdep_map *lock, unsigned int subclass,
return 1;
}

-static int
-print_unlock_imbalance_bug(struct task_struct *curr, struct lockdep_map *lock,
- unsigned long ip)
+static void print_unlock_imbalance_bug(struct task_struct *curr,
+ struct lockdep_map *lock,
+ unsigned long ip)
{
if (!debug_locks_off())
- return 0;
+ return;
if (debug_locks_silent)
- return 0;
+ return;

pr_warn("\n");
pr_warn("=====================================\n");
@@ -3752,8 +3751,6 @@ static int __lock_acquire(struct lockdep_map *lock, unsigned int subclass,

pr_warn("\nstack backtrace:\n");
dump_stack();
-
- return 0;
}

static int match_held_lock(const struct held_lock *hlock,
@@ -3872,8 +3869,10 @@ static int reacquire_held_locks(struct task_struct *curr, unsigned int depth,
return 0;

hlock = find_held_lock(curr, lock, depth, &i);
- if (!hlock)
- return print_unlock_imbalance_bug(curr, lock, ip);
+ if (!hlock) {
+ print_unlock_imbalance_bug(curr, lock, ip);
+ return 0;
+ }

lockdep_init_map(lock, name, key, 0);
class = register_lock_class(lock, subclass, 0);
@@ -3913,8 +3912,10 @@ static int __lock_downgrade(struct lockdep_map *lock, unsigned long ip)
return 0;

hlock = find_held_lock(curr, lock, depth, &i);
- if (!hlock)
- return print_unlock_imbalance_bug(curr, lock, ip);
+ if (!hlock) {
+ print_unlock_imbalance_bug(curr, lock, ip);
+ return 0;
+ }

curr->lockdep_depth = i;
curr->curr_chain_key = hlock->prev_chain_key;
@@ -3958,16 +3959,20 @@ static int __lock_downgrade(struct lockdep_map *lock, unsigned long ip)
* So we're all set to release this lock.. wait what lock? We don't
* own any locks, you've been drinking again?
*/
- if (DEBUG_LOCKS_WARN_ON(depth <= 0))
- return print_unlock_imbalance_bug(curr, lock, ip);
+ if (DEBUG_LOCKS_WARN_ON(depth <= 0)) {
+ print_unlock_imbalance_bug(curr, lock, ip);
+ return 0;
+ }

/*
* Check whether the lock exists in the current stack
* of held locks:
*/
hlock = find_held_lock(curr, lock, depth, &i);
- if (!hlock)
- return print_unlock_imbalance_bug(curr, lock, ip);
+ if (!hlock) {
+ print_unlock_imbalance_bug(curr, lock, ip);
+ return 0;
+ }

if (hlock->instance == lock)
lock_release_holdtime(hlock);
@@ -4310,14 +4315,14 @@ void lock_unpin_lock(struct lockdep_map *lock, struct pin_cookie cookie)
EXPORT_SYMBOL_GPL(lock_unpin_lock);

#ifdef CONFIG_LOCK_STAT
-static int
-print_lock_contention_bug(struct task_struct *curr, struct lockdep_map *lock,
- unsigned long ip)
+static void print_lock_contention_bug(struct task_struct *curr,
+ struct lockdep_map *lock,
+ unsigned long ip)
{
if (!debug_locks_off())
- return 0;
+ return;
if (debug_locks_silent)
- return 0;
+ return;

pr_warn("\n");
pr_warn("=================================\n");
@@ -4335,8 +4340,6 @@ void lock_unpin_lock(struct lockdep_map *lock, struct pin_cookie cookie)

pr_warn("\nstack backtrace:\n");
dump_stack();
-
- return 0;
}

static void
--
1.8.3.1
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