crypto: crct10dif - Add fallback for broken initrds

Unfortunately, even with a softdep some distros fail to include
the necessary modules in the initrd.  Therefore this patch adds
a fallback path to restore existing behaviour where we cannot
load the new crypto crct10dif algorithm.

In order to do this, the underlying crct10dif has been split out
from the crypto implementation so that it can be used on the
fallback path.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

1 files changed, 10 insertions, 1 deletions

diff --git a/lib/crc-t10dif.c b/lib/crc-t10dif.c
index 43bc5b0..dfe6ec1 100644
--- a/lib/crc-t10dif.c
+++ b/lib/crc-t10dif.c
@@ -14,8 +14,10 @@
 #include <linux/err.h>
 #include <linux/init.h>
 #include <crypto/hash.h>
+#include <linux/static_key.h>
 
 static struct crypto_shash *crct10dif_tfm;
+static struct static_key crct10dif_fallback __read_mostly;
 
 __u16 crc_t10dif(const unsigned char *buffer, size_t len)
 {
@@ -25,6 +27,9 @@ __u16 crc_t10dif(const unsigned char *buffer, size_t len)
 	} desc;
 	int err;
 
+	if (static_key_false(&crct10dif_fallback))
+		return crc_t10dif_generic(0, buffer, len);
+
 	desc.shash.tfm = crct10dif_tfm;
 	desc.shash.flags = 0;
 	*(__u16 *)desc.ctx = 0;
@@ -39,7 +44,11 @@ EXPORT_SYMBOL(crc_t10dif);
 static int __init crc_t10dif_mod_init(void)
 {
 	crct10dif_tfm = crypto_alloc_shash("crct10dif", 0, 0);
-	return PTR_RET(crct10dif_tfm);
+	if (IS_ERR(crct10dif_tfm)) {
+		static_key_slow_inc(&crct10dif_fallback);
+		crct10dif_tfm = NULL;
+	}
+	return 0;
 }
 
 static void __exit crc_t10dif_mod_fini(void)