1 files changed, 55 insertions, 2 deletions

diff --git a/lib/crc-t10dif.c b/lib/crc-t10dif.c
index 1ad33e555805..4d0d47c1ffbd 100644
--- a/lib/crc-t10dif.c
+++ b/lib/crc-t10dif.c
@@ -14,10 +14,47 @@
 #include <linux/err.h>
 #include <linux/init.h>
 #include <crypto/hash.h>
+#include <crypto/algapi.h>
 #include <linux/static_key.h>
+#include <linux/notifier.h>
 
-static struct crypto_shash *crct10dif_tfm;
+static struct crypto_shash __rcu *crct10dif_tfm;
 static struct static_key crct10dif_fallback __read_mostly;
+static DEFINE_MUTEX(crc_t10dif_mutex);
+
+static int crc_t10dif_rehash(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;
+
+        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;
+        }
+        new = crypto_alloc_shash("crct10dif", 0, 0);
+        if (IS_ERR(new)) {
+                mutex_unlock(&crc_t10dif_mutex);
+                return 0;
+        }
+        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,
+};
 
 __u16 crc_t10dif_update(__u16 crc, const unsigned char *buffer, size_t len)
 {
@@ -30,11 +67,14 @@ __u16 crc_t10dif_update(__u16 crc, const unsigned char *buffer, size_t len)
         if (static_key_false(&crct10dif_fallback))
                 return crc_t10dif_generic(crc, buffer, len);
 
-        desc.shash.tfm = crct10dif_tfm;
+        rcu_read_lock();
+        desc.shash.tfm = rcu_dereference(crct10dif_tfm);
         desc.shash.flags = 0;
         *(__u16 *)desc.ctx = crc;
 
         err = crypto_shash_update(&desc.shash, buffer, len);
+        rcu_read_unlock();
+
         BUG_ON(err);
 
         return *(__u16 *)desc.ctx;
@@ -49,6 +89,7 @@ EXPORT_SYMBOL(crc_t10dif);
 
 static int __init crc_t10dif_mod_init(void)
 {
+        crypto_register_notifier(&crc_t10dif_nb);
         crct10dif_tfm = crypto_alloc_shash("crct10dif", 0, 0);
         if (IS_ERR(crct10dif_tfm)) {
                 static_key_slow_inc(&crct10dif_fallback);
@@ -59,12 +100,24 @@ static int __init crc_t10dif_mod_init(void)
 
 static void __exit crc_t10dif_mod_fini(void)
 {
+        crypto_unregister_notifier(&crc_t10dif_nb);
         crypto_free_shash(crct10dif_tfm);
 }
 
 module_init(crc_t10dif_mod_init);
 module_exit(crc_t10dif_mod_fini);
 
+static int crc_t10dif_transform_show(char *buffer, const struct kernel_param *kp)
+{
+        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)));
+}
+
+module_param_call(transform, NULL, crc_t10dif_transform_show, NULL, 0644);
+
 MODULE_DESCRIPTION("T10 DIF CRC calculation");
 MODULE_LICENSE("GPL");
 MODULE_SOFTDEP("pre: crct10dif");