On Thu, 25 Sep 2014 15:28:34 +0800 Chao Yu <chao2.yu@xxxxxxxxxxx> wrote:
> printk may cause long time lapse if value of printk_delay in sysctl is
> configured large by user. If register_md_personality takes long time to print in
> spinlock pers_lock, we may encounter high CPU usage rate when there are other
> pers_lock competitors who may be blocked to spin.
> We can avoid this condition by moving printk out of coverage of pers_lock
> spinlock.
>
> Signed-off-by: Chao Yu <chao2.yu@xxxxxxxxxxx>
> ---
> drivers/md/md.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/md/md.c b/drivers/md/md.c
> index e02de05..5fcf215 100644
> --- a/drivers/md/md.c
> +++ b/drivers/md/md.c
> @@ -7200,9 +7200,10 @@ static const struct file_operations md_seq_fops = {
>
> int register_md_personality(struct md_personality *p)
> {
> + printk(KERN_INFO "md: %s personality registered for level %d\n",
> + p->name, p->level);
> spin_lock(&pers_lock);
> list_add_tail(&p->list, &pers_list);
> - printk(KERN_INFO "md: %s personality registered for level %d\n", p->name, p->level);
> spin_unlock(&pers_lock);
> return 0;
> }
I'm not sure I see the pressing need for this - have you noticed actual
problems?
However it seems to make sense so I've applied it.
Thanks,
NeilBrown
Attachment:
signature.asc
Description: PGP signature
