From d7c36d6350b5a4b27256eaeeea3b72621a819c9a Mon Sep 17 00:00:00 2001 From: Arnd Bergmann Date: Tue, 10 Jun 2025 11:29:21 +0200 Subject: [PATCH] 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 Signed-off-by: Boqun Feng Link: https://lore.kernel.org/r/20250610092941.2642847-1-arnd@kernel.org --- include/linux/lockdep_types.h | 2 +- kernel/locking/lockdep.c | 27 ++++++++++++--------------- kernel/locking/lockdep_proc.c | 2 +- 3 files changed, 14 insertions(+), 17 deletions(-) diff --git a/include/linux/lockdep_types.h b/include/linux/lockdep_types.h index 9f361d3ab9d95..eae115a264885 100644 --- a/include/linux/lockdep_types.h +++ b/include/linux/lockdep_types.h @@ -175,7 +175,7 @@ struct lock_class_stats { 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); #endif diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c index dd2bbf73718b0..0c941418a2159 100644 --- a/kernel/locking/lockdep.c +++ b/kernel/locking/lockdep.c @@ -297,33 +297,30 @@ static inline void lock_time_add(struct lock_time *src, struct lock_time *dst) 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; - memset(&stats, 0, sizeof(struct lock_class_stats)); + memset(stats, 0, sizeof(struct lock_class_stats)); for_each_possible_cpu(cpu) { struct lock_class_stats *pcs = &per_cpu(cpu_lock_stats, cpu)[class - lock_classes]; - for (i = 0; i < ARRAY_SIZE(stats.contention_point); i++) - stats.contention_point[i] += pcs->contention_point[i]; + for (i = 0; i < ARRAY_SIZE(stats->contention_point); i++) + stats->contention_point[i] += pcs->contention_point[i]; - for (i = 0; i < ARRAY_SIZE(stats.contending_point); i++) - stats.contending_point[i] += pcs->contending_point[i]; + for (i = 0; i < ARRAY_SIZE(stats->contending_point); i++) + stats->contending_point[i] += pcs->contending_point[i]; - lock_time_add(&pcs->read_waittime, &stats.read_waittime); - lock_time_add(&pcs->write_waittime, &stats.write_waittime); + lock_time_add(&pcs->read_waittime, &stats->read_waittime); + lock_time_add(&pcs->write_waittime, &stats->write_waittime); - lock_time_add(&pcs->read_holdtime, &stats.read_holdtime); - lock_time_add(&pcs->write_holdtime, &stats.write_holdtime); + lock_time_add(&pcs->read_holdtime, &stats->read_holdtime); + lock_time_add(&pcs->write_holdtime, &stats->write_holdtime); - for (i = 0; i < ARRAY_SIZE(stats.bounces); i++) - stats.bounces[i] += pcs->bounces[i]; + for (i = 0; i < ARRAY_SIZE(stats->bounces); i++) + stats->bounces[i] += pcs->bounces[i]; } - - return stats; } void clear_lock_stats(struct lock_class *class) diff --git a/kernel/locking/lockdep_proc.c b/kernel/locking/lockdep_proc.c index b52c07c4707cd..1916db9aa46b6 100644 --- a/kernel/locking/lockdep_proc.c +++ b/kernel/locking/lockdep_proc.c @@ -657,7 +657,7 @@ static int lock_stat_open(struct inode *inode, struct file *file) if (!test_bit(idx, lock_classes_in_use)) continue; iter->class = class; - iter->stats = lock_stats(class); + lock_stats(class, &iter->stats); iter++; } -- 2.47.2