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md: avoid potential long delay under pers_lock 

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@samsung.com>
Signed-off-by: NeilBrown <neilb@suse.de>
This commit is contained in:
Chao Yu 2014-09-25 15:28:34 +08:00 committed by NeilBrown
parent 0638bb0e73
commit 50bd377405
1 changed files with 2 additions and 1 deletions
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3
drivers/md/md.c
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@ -7187,9 +7187,10 @@ 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;
}