2 files changed, 32 insertions, 4 deletions

diff --git a/crypto/rng.c b/crypto/rng.c
index 13155058b193..b81cffb13bab 100644
--- a/crypto/rng.c
+++ b/crypto/rng.c
@@ -155,14 +155,33 @@ EXPORT_SYMBOL_GPL(crypto_get_default_rng);
 void crypto_put_default_rng(void)
 {
         mutex_lock(&crypto_default_rng_lock);
-        if (!--crypto_default_rng_refcnt) {
-                crypto_free_rng(crypto_default_rng);
-                crypto_default_rng = NULL;
-        }
+        crypto_default_rng_refcnt--;
         mutex_unlock(&crypto_default_rng_lock);
 }
 EXPORT_SYMBOL_GPL(crypto_put_default_rng);
 
+#if defined(CONFIG_CRYPTO_RNG) || defined(CONFIG_CRYPTO_RNG_MODULE)
+int crypto_del_default_rng(void)
+{
+        int err = -EBUSY;
+
+        mutex_lock(&crypto_default_rng_lock);
+        if (crypto_default_rng_refcnt)
+                goto out;
+
+        crypto_free_rng(crypto_default_rng);
+        crypto_default_rng = NULL;
+
+        err = 0;
+
+out:
+        mutex_unlock(&crypto_default_rng_lock);
+
+        return err;
+}
+EXPORT_SYMBOL_GPL(crypto_del_default_rng);
+#endif
+
 int crypto_register_rng(struct rng_alg *alg)
 {
         struct crypto_alg *base = &alg->base;
diff --git a/include/crypto/internal/rng.h b/include/crypto/internal/rng.h
index 263f1a5eebc7..a52ef3483dd7 100644
--- a/include/crypto/internal/rng.h
+++ b/include/crypto/internal/rng.h
@@ -22,6 +22,15 @@ void crypto_unregister_rng(struct rng_alg *alg);
 int crypto_register_rngs(struct rng_alg *algs, int count);
 void crypto_unregister_rngs(struct rng_alg *algs, int count);
 
+#if defined(CONFIG_CRYPTO_RNG) || defined(CONFIG_CRYPTO_RNG_MODULE)
+int crypto_del_default_rng(void);
+#else
+static inline int crypto_del_default_rng(void)
+{
+        return 0;
+}
+#endif
+
 static inline void *crypto_rng_ctx(struct crypto_rng *tfm)
 {
         return crypto_tfm_ctx(&tfm->base);