From: Coly Li <colyli@xxxxxxx> This patch changes the asynchronous registration kworker to a delayed kworker. There is probability queue_work() queues the async registration kworker to the same CPU (even though very little), then the process which writing sysfs interface to reigster bcache device may won't return immeidately. queue_delayed_work() in this patch will delay 10 jiffies before insert the kworker to run queue, which makes sure the registering process may always returns to user space in time. Fixes: 9e23ccf8f0a22 ("bcache: asynchronous devices registration") Signed-off-by: Coly Li <colyli@xxxxxxx> Cc: Hannes Reinecke <hare@xxxxxxx> --- drivers/md/bcache/super.c | 14 ++++++++------ 1 file changed, 8 insertions(+), 6 deletions(-) diff --git a/drivers/md/bcache/super.c b/drivers/md/bcache/super.c index 904ea9bbb5c4..a6e79083010a 100644 --- a/drivers/md/bcache/super.c +++ b/drivers/md/bcache/super.c @@ -19,6 +19,7 @@ #include <linux/genhd.h> #include <linux/idr.h> #include <linux/kthread.h> +#include <linux/workqueue.h> #include <linux/module.h> #include <linux/random.h> #include <linux/reboot.h> @@ -2380,7 +2381,7 @@ static bool bch_is_open(struct block_device *bdev) } struct async_reg_args { - struct work_struct reg_work; + struct delayed_work reg_work; char *path; struct cache_sb *sb; struct cache_sb_disk *sb_disk; @@ -2391,7 +2392,7 @@ static void register_bdev_worker(struct work_struct *work) { int fail = false; struct async_reg_args *args = - container_of(work, struct async_reg_args, reg_work); + container_of(work, struct async_reg_args, reg_work.work); struct cached_dev *dc; dc = kzalloc(sizeof(*dc), GFP_KERNEL); @@ -2421,7 +2422,7 @@ static void register_cache_worker(struct work_struct *work) { int fail = false; struct async_reg_args *args = - container_of(work, struct async_reg_args, reg_work); + container_of(work, struct async_reg_args, reg_work.work); struct cache *ca; ca = kzalloc(sizeof(*ca), GFP_KERNEL); @@ -2449,11 +2450,12 @@ static void register_cache_worker(struct work_struct *work) static void register_device_aync(struct async_reg_args *args) { if (SB_IS_BDEV(args->sb)) - INIT_WORK(&args->reg_work, register_bdev_worker); + INIT_DELAYED_WORK(&args->reg_work, register_bdev_worker); else - INIT_WORK(&args->reg_work, register_cache_worker); + INIT_DELAYED_WORK(&args->reg_work, register_cache_worker); - queue_work(system_wq, &args->reg_work); + /* 10 jiffies is enough for a delay */ + queue_delayed_work(system_wq, &args->reg_work, 10); } static ssize_t register_bcache(struct kobject *k, struct kobj_attribute *attr, -- 2.25.0