padata: Disable BH when taking works lock on MT path

As the old padata code can execute in softirq context, disable
softirqs for the new padata_do_mutithreaded code too as otherwise
lockdep will get antsy.

Reported-by: [email protected]
Signed-off-by: Herbert Xu <[email protected]>
Acked-by: Daniel Jordan <[email protected]>
Signed-off-by: Herbert Xu <[email protected]>

Author: herbertx

kernel/padata.c

@@ -106,7 +106,7 @@ static int __init padata_work_alloc_mt(int nworks, void *data,
 {
 	int i;
 
-	spin_lock(&padata_works_lock);
+	spin_lock_bh(&padata_works_lock);
 	/* Start at 1 because the current task participates in the job. */
 	for (i = 1; i < nworks; ++i) {
 		struct padata_work *pw = padata_work_alloc();
@@ -116,7 +116,7 @@ static int __init padata_work_alloc_mt(int nworks, void *data,
 		padata_work_init(pw, padata_mt_helper, data, 0);
 		list_add(&pw->pw_list, head);
 	}
-	spin_unlock(&padata_works_lock);
+	spin_unlock_bh(&padata_works_lock);
 
 	return i;
 }
@@ -134,12 +134,12 @@ static void __init padata_works_free(struct list_head *works)
 	if (list_empty(works))
 		return;
 
-	spin_lock(&padata_works_lock);
+	spin_lock_bh(&padata_works_lock);
 	list_for_each_entry_safe(cur, next, works, pw_list) {
 		list_del(&cur->pw_list);
 		padata_work_free(cur);
 	}
-	spin_unlock(&padata_works_lock);
+	spin_unlock_bh(&padata_works_lock);
 }
 
 static void padata_parallel_worker(struct work_struct *parallel_work)