padata: use %*pb[l] to print bitmaps including cpumasks and nodemasks

printk and friends can now format bitmaps using '%*pb[l]'.  cpumask
and nodemask also provide cpumask_pr_args() and nodemask_pr_args()
respectively which can be used to generate the two printf arguments
necessary to format the specified cpu/nodemask.

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Steffen Klassert <steffen.klassert@secunet.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

kernel/padata.c

@@ -917,15 +917,10 @@ static ssize_t show_cpumask(struct padata_instance *pinst,
 	else
 		cpumask = pinst->cpumask.pcpu;
 
-	len = bitmap_scnprintf(buf, PAGE_SIZE, cpumask_bits(cpumask),
-			       nr_cpu_ids);
-	if (PAGE_SIZE - len < 2)
-		len = -EINVAL;
-	else
-		len += sprintf(buf + len, "\n");
-
+	len = snprintf(buf, PAGE_SIZE, "%*pb\n",
+		       nr_cpu_ids, cpumask_bits(cpumask));
 	mutex_unlock(&pinst->lock);
-	return len;
+	return len < PAGE_SIZE ? len : -EINVAL;
 }
 
 static ssize_t store_cpumask(struct padata_instance *pinst,