[lvc-project] [PATCH] crypto: drbg - simplify drbg_get_random_bytes()

[Sergey Shtylyov]

To begin with, drbg_fips_continuous_test() only returns 0 and -EAGAIN,
so an early return from the *do/while* loop in drbg_get_random_bytes()
just isn't possible.  Then, the loop condition needs to be adjusted to
only continue the loop while -EAGAIN is returned and the final *return*
statement needs to be adjusted as well, in order to be prepared for the
case of drbg_fips_continuous_test() starting to return some other error
codes...

Found by Linux Verification Center (linuxtesting.org) with the Svace static
analysis tool.

Suggested-by: Yann Droneaud <yann at droneaud.fr>
Signed-off-by: Sergey Shtylyov <s.shtylyov at omp.ru>

---
The patch is against the master branch of Herbert Xu's cryptodev-2.6.git repo.

 crypto/drbg.c |    6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

Index: cryptodev-2.6/crypto/drbg.c
===================================================================
--- cryptodev-2.6.orig/crypto/drbg.c
+++ cryptodev-2.6/crypto/drbg.c
@@ -854,11 +854,9 @@ static inline int drbg_get_random_bytes(
 	do {
 		get_random_bytes(entropy, entropylen);
 		ret = drbg_fips_continuous_test(drbg, entropy);
-		if (ret && ret != -EAGAIN)
-			return ret;
-	} while (ret);
+	} while (ret == -EAGAIN);
 
-	return 0;
+	return ret;
 }
 
 static int drbg_seed_from_random(struct drbg_state *drbg)