crypto: api - optimize algorithm registration when self-tests disabled

Currently, registering an algorithm with the crypto API always causes a
notification to be posted to the "cryptomgr", which then creates a
kthread to self-test the algorithm.  However, if self-tests are disabled
in the kconfig (as is the default option), then this kthread just
notifies waiters that the algorithm has been tested, then exits.

This causes a significant amount of overhead, especially in the kthread
creation and destruction, which is not necessary at all.  For example,
in a quick test I found that booting a "minimum" x86_64 kernel with all
the crypto options enabled (except for the self-tests) takes about 400ms
until PID 1 can start.  Of that, a full 13ms is spent just doing this
pointless dance, involving a kthread being created, run, and destroyed
over 200 times.  That's over 3% of the entire kernel start time.

Fix this by just skipping the creation of the test larval and the
posting of the registration notification entirely, when self-tests are
disabled.

Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

1 files changed, 0 insertions, 3 deletions

diff --git a/crypto/api.c b/crypto/api.c
index 64f2d365a8e9..52ce10a35366 100644
--- a/crypto/api.c
+++ b/crypto/api.c
@@ -172,9 +172,6 @@ void crypto_wait_for_test(struct crypto_larval *larval)
 
 	err = wait_for_completion_killable(&larval->completion);
 	WARN_ON(err);
-	if (!err)
-		crypto_notify(CRYPTO_MSG_ALG_LOADED, larval);
-
 out:
 	crypto_larval_kill(&larval->alg);
 }