padata: add pd get/put refcnt helper

[ Upstream commit ae15420 ]

Add helpers for pd to get/put refcnt to make code consice.

Signed-off-by: Chen Ridong <chenridong@huawei.com>
Acked-by: Daniel Jordan <daniel.m.jordan@oracle.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Stable-dep-of: dd7d37c ("padata: avoid UAF for reorder_work")
Signed-off-by: Sasha Levin <sashal@kernel.org>
(cherry picked from commit 9634c4761eaea1df9bb3bebfb739ce04de8dad56)

Author: Chen Ridong

kernel/padata.c

@@ -47,6 +47,22 @@ struct padata_mt_job_state {
 static void padata_free_pd(struct parallel_data *pd);
 static void __init padata_mt_helper(struct work_struct *work);
 
+static inline void padata_get_pd(struct parallel_data *pd)
+{
+	refcount_inc(&pd->refcnt);
+}
+
+static inline void padata_put_pd_cnt(struct parallel_data *pd, int cnt)
+{
+	if (refcount_sub_and_test(cnt, &pd->refcnt))
+		padata_free_pd(pd);
+}
+
+static inline void padata_put_pd(struct parallel_data *pd)
+{
+	padata_put_pd_cnt(pd, 1);
+}
+
 static int padata_index_to_cpu(struct parallel_data *pd, int cpu_index)
 {
 	int cpu, target_cpu;
@@ -206,7 +222,7 @@ int padata_do_parallel(struct padata_shell *ps,
 	if ((pinst->flags & PADATA_RESET))
 		goto out;
 
-	refcount_inc(&pd->refcnt);
+	padata_get_pd(pd);
 	padata->pd = pd;
 	padata->cb_cpu = *cb_cpu;
 
@@ -380,8 +396,7 @@ static void padata_serial_worker(struct work_struct *serial_work)
 	}
 	local_bh_enable();
 
-	if (refcount_sub_and_test(cnt, &pd->refcnt))
-		padata_free_pd(pd);
+	padata_put_pd_cnt(pd, cnt);
 }
 
 /**
@@ -678,8 +693,7 @@ static int padata_replace(struct padata_instance *pinst)
 	synchronize_rcu();
 
 	list_for_each_entry_continue_reverse(ps, &pinst->pslist, list)
-		if (refcount_dec_and_test(&ps->opd->refcnt))
-			padata_free_pd(ps->opd);
+		padata_put_pd(ps->opd);
 
 	pinst->flags &= ~PADATA_RESET;
 
@@ -1127,8 +1141,7 @@ void padata_free_shell(struct padata_shell *ps)
 	mutex_lock(&ps->pinst->lock);
 	list_del(&ps->list);
 	pd = rcu_dereference_protected(ps->pd, 1);
-	if (refcount_dec_and_test(&pd->refcnt))
-		padata_free_pd(pd);
+	padata_put_pd(pd);
 	mutex_unlock(&ps->pinst->lock);
 
 	kfree(ps);