blk-iocost calls blk_stat_enable_accounting() while holding an irqsafe lock which triggers a lockdep splat because q->stats->lock isn't irqsafe. Let's make it irqsafe.

Signed-off-by: Tejun Heo tj@kernel.org Fixes: cd006509b0a9 ("blk-iocost: account for IO size when testing latencies") Cc: stable@vger.kernel.org # v5.8+ --- block/blk-stat.c | 17 +++++++++++------ 1 file changed, 11 insertions(+), 6 deletions(-)

diff --git a/block/blk-stat.c b/block/blk-stat.c index 7da302ff88d0..ae3dd1fb8e61 100644 --- a/block/blk-stat.c +++ b/block/blk-stat.c @@ -137,6 +137,7 @@ void blk_stat_add_callback(struct request_queue *q, struct blk_stat_callback *cb) { unsigned int bucket; + unsigned long flags; int cpu;

for_each_possible_cpu(cpu) { @@ -147,20 +148,22 @@ void blk_stat_add_callback(struct request_queue *q, blk_rq_stat_init(&cpu_stat[bucket]); }

- spin_lock(&q->stats->lock); + spin_lock_irqsave(&q->stats->lock, flags); list_add_tail_rcu(&cb->list, &q->stats->callbacks); blk_queue_flag_set(QUEUE_FLAG_STATS, q); - spin_unlock(&q->stats->lock); + spin_unlock_irqrestore(&q->stats->lock, flags); }

void blk_stat_remove_callback(struct request_queue *q, struct blk_stat_callback *cb) { - spin_lock(&q->stats->lock); + unsigned long flags; + + spin_lock_irqsave(&q->stats->lock, flags); list_del_rcu(&cb->list); if (list_empty(&q->stats->callbacks) && !q->stats->enable_accounting) blk_queue_flag_clear(QUEUE_FLAG_STATS, q); - spin_unlock(&q->stats->lock); + spin_unlock_irqrestore(&q->stats->lock, flags);

del_timer_sync(&cb->timer); } @@ -183,10 +186,12 @@ void blk_stat_free_callback(struct blk_stat_callback *cb)

void blk_stat_enable_accounting(struct request_queue *q) { - spin_lock(&q->stats->lock); + unsigned long flags; + + spin_lock_irqsave(&q->stats->lock, flags); q->stats->enable_accounting = true; blk_queue_flag_set(QUEUE_FLAG_STATS, q); - spin_unlock(&q->stats->lock); + spin_unlock_irqrestore(&q->stats->lock, flags); } EXPORT_SYMBOL_GPL(blk_stat_enable_accounting);