padata: Check for valid padata instance on start

This patch introduces the PADATA_INVALID flag which is
checked on padata start. This will be used to mark a padata
instance as invalid, if the padata cpumask does not intersect
with the active cpumask. we change padata_start to return an
error if the PADATA_INVALID is set. Also we adapt the only
padata user, pcrypt to this change.

Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

crypto/pcrypt.c

@@ -385,6 +385,7 @@ static struct crypto_template pcrypt_tmpl = {
 
 static int __init pcrypt_init(void)
 {
+	int err = -ENOMEM;
 	encwq = create_workqueue("pencrypt");
 	if (!encwq)
 		goto err;
@@ -400,14 +401,22 @@ static int __init pcrypt_init(void)
 
 	pcrypt_dec_padata = padata_alloc(cpu_possible_mask, decwq);
 	if (!pcrypt_dec_padata)
-		goto err_free_padata;
+		goto err_free_enc_padata;
 
-	padata_start(pcrypt_enc_padata);
-	padata_start(pcrypt_dec_padata);
+	err = padata_start(pcrypt_enc_padata);
+	if (err)
+		goto err_free_dec_padata;
+
+	err = padata_start(pcrypt_dec_padata);
+	if (err)
+		goto err_free_dec_padata;
 
 	return crypto_register_template(&pcrypt_tmpl);
 
-err_free_padata:
+err_free_dec_padata:
+	padata_free(pcrypt_dec_padata);
+
+err_free_enc_padata:
 	padata_free(pcrypt_enc_padata);
 
 err_destroy_decwq:
@@ -417,7 +426,7 @@ err_destroy_encwq:
 	destroy_workqueue(encwq);
 
 err:
-	return -ENOMEM;
+	return err;
 }
 
 static void __exit pcrypt_exit(void)

include/linux/padata.h

@@ -126,6 +126,7 @@ struct padata_instance {
 	u8			flags;
 #define	PADATA_INIT		1
 #define	PADATA_RESET		2
+#define	PADATA_INVALID		4
 };
 
 extern struct padata_instance *padata_alloc(const struct cpumask *cpumask,
@@ -138,6 +139,6 @@ extern int padata_set_cpumask(struct padata_instance *pinst,
 			      cpumask_var_t cpumask);
 extern int padata_add_cpu(struct padata_instance *pinst, int cpu);
 extern int padata_remove_cpu(struct padata_instance *pinst, int cpu);
-extern void padata_start(struct padata_instance *pinst);
+extern int padata_start(struct padata_instance *pinst);
 extern void padata_stop(struct padata_instance *pinst);
 #endif

kernel/padata.c

@@ -485,6 +485,11 @@ static void padata_flush_queues(struct parallel_data *pd)
 	BUG_ON(atomic_read(&pd->refcnt) != 0);
 }
 
+static void __padata_start(struct padata_instance *pinst)
+{
+	pinst->flags |= PADATA_INIT;
+}
+
 /* Replace the internal control stucture with a new one. */
 static void padata_replace(struct padata_instance *pinst,
 			   struct parallel_data *pd_new)
@@ -619,11 +624,20 @@ EXPORT_SYMBOL(padata_remove_cpu);
  *
  * @pinst: padata instance to start
  */
-void padata_start(struct padata_instance *pinst)
+int padata_start(struct padata_instance *pinst)
 {
+	int err = 0;
+
 	mutex_lock(&pinst->lock);
-	pinst->flags |= PADATA_INIT;
+
+	if (pinst->flags & PADATA_INVALID)
+		err =-EINVAL;
+
+	 __padata_start(pinst);
+
 	mutex_unlock(&pinst->lock);
+
+	return err;
 }
 EXPORT_SYMBOL(padata_start);