From: Yu Kuai <yukuai3@xxxxxxxxxx> There are following smatch warning: block/blk-wbt.c:843 wbt_init() warn: sleeping in atomic context ioc_qos_write() <- disables preempt -> wbt_enable_default() -> wbt_init() wbt_init() will be called from wbt_enable_default() if wbt is not initialized, currently this is only possible in blk_register_queue(), hence wbt_init() will never be called from iocost and this warning is false positive. However, we might support rq_qos destruction dynamically in the future, and it's better to prevent that, hence move wbt_enable_default() outside 'ioc->lock'. This is safe because queue is still freezed. Reported-by: Dan Carpenter <error27@xxxxxxxxx> Link: https://lore.kernel.org/lkml/Y+Ja5SRs886CEz7a@kadam/ Signed-off-by: Yu Kuai <yukuai3@xxxxxxxxxx> Reviewed-by: Christoph Hellwig <hch@xxxxxx> --- block/blk-iocost.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) diff --git a/block/blk-iocost.c b/block/blk-iocost.c index 285ced3467ab..eb57e7e4f2db 100644 --- a/block/blk-iocost.c +++ b/block/blk-iocost.c @@ -3300,11 +3300,9 @@ static ssize_t ioc_qos_write(struct kernfs_open_file *of, char *input, blk_stat_enable_accounting(disk->queue); blk_queue_flag_set(QUEUE_FLAG_RQ_ALLOC_TIME, disk->queue); ioc->enabled = true; - wbt_disable_default(disk); } else { blk_queue_flag_clear(QUEUE_FLAG_RQ_ALLOC_TIME, disk->queue); ioc->enabled = false; - wbt_enable_default(disk); } if (user) { @@ -3317,6 +3315,11 @@ static ssize_t ioc_qos_write(struct kernfs_open_file *of, char *input, ioc_refresh_params(ioc, true); spin_unlock_irq(&ioc->lock); + if (enable) + wbt_disable_default(disk); + else + wbt_enable_default(disk); + blk_mq_unquiesce_queue(disk->queue); blk_mq_unfreeze_queue(disk->queue); -- 2.39.2
