Re: [PATCH]: Fix ALIGN() macro

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On Sep 23, 2006, at 16:36:33, Kyle Moffett wrote:
On Sep 23, 2006, at 10:40:41, Herbert Xu wrote:
diff --git a/crypto/hmac.c b/crypto/hmac.c
index f403b69..d52b234 100644
--- a/crypto/hmac.c
+++ b/crypto/hmac.c
@@ -98,7 +98,7 @@ static int hmac_init(struct hash_desc *p
 	sg_set_buf(&tmp, ipad, bs);

 	return unlikely(crypto_hash_init(&desc)) ?:
-	       crypto_hash_update(&desc, &tmp, 1);
+	       crypto_hash_update(&desc, &tmp, bs);
 }

 static int hmac_update(struct hash_desc *pdesc,

Quick question: does "crypto_hash_init()" ever return anything other than 0 or 1? If so this is a subtle bug, as "unlikely()" is implemented like this:

# define unlikely(x) __builtin_expect(!!(x), 0)

IMO any usage of likely/unlikely other than if(unlikely()), if (likely()) is probably a bug.

With a bit more contemplation, I think this is one place where (if the compiler or sparse are cooperative) we should really look at the _Bool type or similar. If we could cast likely()/unlikely() to return (_Bool), then these sorts of problems would be caught at compile time, and likewise for other functions which return boolean values.

Cheers,
Kyle Moffett

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