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locking/lockdep: Avoid struct return in lock_stats() 

Returning a large structure from the lock_stats() function causes clang
to have multiple copies of it on the stack and copy between them, which
can end up exceeding the frame size warning limit:

kernel/locking/lockdep.c:300:25: error: stack frame size (1464) exceeds limit (1280) in 'lock_stats' [-Werror,-Wframe-larger-than]
  300 | struct lock_class_stats lock_stats(struct lock_class *class)

Change the calling conventions to directly operate on the caller's copy,
which apparently is what gcc does already.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Boqun Feng <boqun.feng@gmail.com>
Link: https://lore.kernel.org/r/20250610092941.2642847-1-arnd@kernel.org
This commit is contained in:
Arnd Bergmann 2025-06-10 11:29:21 +02:00 committed by Boqun Feng
parent f84a15b90d
commit d7c36d6350
3 changed files with 14 additions and 17 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
include/linux/lockdep_types.h
View File

@ -175,7 +175,7 @@ struct lock_class_stats {
unsigned long bounces[nr_bounce_types]; unsigned long bounces[nr_bounce_types];
}; };
struct lock_class_stats lock_stats(struct lock_class *class); void lock_stats(struct lock_class *class, struct lock_class_stats *stats);
void clear_lock_stats(struct lock_class *class); void clear_lock_stats(struct lock_class *class);
#endif #endif

27
kernel/locking/lockdep.c
View File

@ -297,33 +297,30 @@ static inline void lock_time_add(struct lock_time *src, struct lock_time *dst)
dst->nr += src->nr; dst->nr += src->nr;
} }
struct lock_class_stats lock_stats(struct lock_class *class) void lock_stats(struct lock_class *class, struct lock_class_stats *stats)
{ {
struct lock_class_stats stats;
int cpu, i; int cpu, i;
memset(&stats, 0, sizeof(struct lock_class_stats)); memset(stats, 0, sizeof(struct lock_class_stats));
for_each_possible_cpu(cpu) { for_each_possible_cpu(cpu) {
struct lock_class_stats *pcs = struct lock_class_stats *pcs =
&per_cpu(cpu_lock_stats, cpu)[class - lock_classes]; &per_cpu(cpu_lock_stats, cpu)[class - lock_classes];
for (i = 0; i < ARRAY_SIZE(stats.contention_point); i++) for (i = 0; i < ARRAY_SIZE(stats->contention_point); i++)
stats.contention_point[i] += pcs->contention_point[i]; stats->contention_point[i] += pcs->contention_point[i];
for (i = 0; i < ARRAY_SIZE(stats.contending_point); i++) for (i = 0; i < ARRAY_SIZE(stats->contending_point); i++)
stats.contending_point[i] += pcs->contending_point[i]; stats->contending_point[i] += pcs->contending_point[i];
lock_time_add(&pcs->read_waittime, &stats.read_waittime); lock_time_add(&pcs->read_waittime, &stats->read_waittime);
lock_time_add(&pcs->write_waittime, &stats.write_waittime); lock_time_add(&pcs->write_waittime, &stats->write_waittime);
lock_time_add(&pcs->read_holdtime, &stats.read_holdtime); lock_time_add(&pcs->read_holdtime, &stats->read_holdtime);
lock_time_add(&pcs->write_holdtime, &stats.write_holdtime); lock_time_add(&pcs->write_holdtime, &stats->write_holdtime);
for (i = 0; i < ARRAY_SIZE(stats.bounces); i++) for (i = 0; i < ARRAY_SIZE(stats->bounces); i++)
stats.bounces[i] += pcs->bounces[i]; stats->bounces[i] += pcs->bounces[i];
} }
return stats;
} }
void clear_lock_stats(struct lock_class *class) void clear_lock_stats(struct lock_class *class)

2
kernel/locking/lockdep_proc.c
View File

@ -657,7 +657,7 @@ static int lock_stat_open(struct inode *inode, struct file *file)
if (!test_bit(idx, lock_classes_in_use)) if (!test_bit(idx, lock_classes_in_use))
continue; continue;
iter->class = class; iter->class = class;
iter->stats = lock_stats(class); lock_stats(class, &iter->stats);
iter++; iter++;
} }