1 files changed, 42 insertions, 12 deletions

diff --git a/lib/crc-t10dif.c b/lib/crc-t10dif.c
index 8cc01a603416..c9acf1c12cfc 100644
--- a/lib/crc-t10dif.c
+++ b/lib/crc-t10dif.c
@@ -19,39 +19,46 @@
 static struct crypto_shash __rcu *crct10dif_tfm;
 static struct static_key crct10dif_fallback __read_mostly;
 static DEFINE_MUTEX(crc_t10dif_mutex);
+static struct work_struct crct10dif_rehash_work;
 
-static int crc_t10dif_rehash(struct notifier_block *self, unsigned long val, void *data)
+static int crc_t10dif_notify(struct notifier_block *self, unsigned long val, void *data)
 {
 	struct crypto_alg *alg = data;
-	struct crypto_shash *new, *old;
 
 	if (val != CRYPTO_MSG_ALG_LOADED ||
 	    static_key_false(&crct10dif_fallback) ||
 	    strncmp(alg->cra_name, CRC_T10DIF_STRING, strlen(CRC_T10DIF_STRING)))
 		return 0;
 
+	schedule_work(&crct10dif_rehash_work);
+	return 0;
+}
+
+static void crc_t10dif_rehash(struct work_struct *work)
+{
+	struct crypto_shash *new, *old;
+
 	mutex_lock(&crc_t10dif_mutex);
 	old = rcu_dereference_protected(crct10dif_tfm,
 					lockdep_is_held(&crc_t10dif_mutex));
 	if (!old) {
 		mutex_unlock(&crc_t10dif_mutex);
-		return 0;
+		return;
 	}
 	new = crypto_alloc_shash("crct10dif", 0, 0);
 	if (IS_ERR(new)) {
 		mutex_unlock(&crc_t10dif_mutex);
-		return 0;
+		return;
 	}
 	rcu_assign_pointer(crct10dif_tfm, new);
 	mutex_unlock(&crc_t10dif_mutex);
 
 	synchronize_rcu();
 	crypto_free_shash(old);
-	return 0;
 }
 
 static struct notifier_block crc_t10dif_nb = {
-	.notifier_call = crc_t10dif_rehash,
+	.notifier_call = crc_t10dif_notify,
 };
 
 __u16 crc_t10dif_update(__u16 crc, const unsigned char *buffer, size_t len)
@@ -86,19 +93,26 @@ EXPORT_SYMBOL(crc_t10dif);
 
 static int __init crc_t10dif_mod_init(void)
 {
+	struct crypto_shash *tfm;
+
+	INIT_WORK(&crct10dif_rehash_work, crc_t10dif_rehash);
 	crypto_register_notifier(&crc_t10dif_nb);
-	crct10dif_tfm = crypto_alloc_shash("crct10dif", 0, 0);
-	if (IS_ERR(crct10dif_tfm)) {
+	mutex_lock(&crc_t10dif_mutex);
+	tfm = crypto_alloc_shash("crct10dif", 0, 0);
+	if (IS_ERR(tfm)) {
 		static_key_slow_inc(&crct10dif_fallback);
-		crct10dif_tfm = NULL;
+		tfm = NULL;
 	}
+	RCU_INIT_POINTER(crct10dif_tfm, tfm);
+	mutex_unlock(&crc_t10dif_mutex);
 	return 0;
 }
 
 static void __exit crc_t10dif_mod_fini(void)
 {
 	crypto_unregister_notifier(&crc_t10dif_nb);
-	crypto_free_shash(crct10dif_tfm);
+	cancel_work_sync(&crct10dif_rehash_work);
+	crypto_free_shash(rcu_dereference_protected(crct10dif_tfm, 1));
 }
 
 module_init(crc_t10dif_mod_init);
@@ -106,11 +120,27 @@ module_exit(crc_t10dif_mod_fini);
 
 static int crc_t10dif_transform_show(char *buffer, const struct kernel_param *kp)
 {
+	struct crypto_shash *tfm;
+	const char *name;
+	int len;
+
 	if (static_key_false(&crct10dif_fallback))
 		return sprintf(buffer, "fallback\n");
 
-	return sprintf(buffer, "%s\n",
-		crypto_tfm_alg_driver_name(crypto_shash_tfm(crct10dif_tfm)));
+	rcu_read_lock();
+	tfm = rcu_dereference(crct10dif_tfm);
+	if (!tfm) {
+		len = sprintf(buffer, "init\n");
+		goto unlock;
+	}
+
+	name = crypto_tfm_alg_driver_name(crypto_shash_tfm(tfm));
+	len = sprintf(buffer, "%s\n", name);
+
+unlock:
+	rcu_read_unlock();
+
+	return len;
 }
 
 module_param_call(transform, NULL, crc_t10dif_transform_show, NULL, 0644);