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>

diff --git a/crypto/algapi.c b/crypto/algapi.c
index 5c69ff8..950195e 100644 (file)
--- a/crypto/algapi.c
+++ b/crypto/algapi.c
@@ -222,12 +222,64 @@ void crypto_remove_spawns(struct crypto_alg *alg, struct list_head *list,
 }
 EXPORT_SYMBOL_GPL(crypto_remove_spawns);
 
+static void crypto_alg_finish_registration(struct crypto_alg *alg,
+                                          bool fulfill_requests,
+                                          struct list_head *algs_to_put)
+{
+       struct crypto_alg *q;
+
+       list_for_each_entry(q, &crypto_alg_list, cra_list) {
+               if (q == alg)
+                       continue;
+
+               if (crypto_is_moribund(q))
+                       continue;
+
+               if (crypto_is_larval(q)) {
+                       struct crypto_larval *larval = (void *)q;
+
+                       /*
+                        * Check to see if either our generic name or
+                        * specific name can satisfy the name requested
+                        * by the larval entry q.
+                        */
+                       if (strcmp(alg->cra_name, q->cra_name) &&
+                           strcmp(alg->cra_driver_name, q->cra_name))
+                               continue;
+
+                       if (larval->adult)
+                               continue;
+                       if ((q->cra_flags ^ alg->cra_flags) & larval->mask)
+                               continue;
+
+                       if (fulfill_requests && crypto_mod_get(alg))
+                               larval->adult = alg;
+                       else
+                               larval->adult = ERR_PTR(-EAGAIN);
+
+                       continue;
+               }
+
+               if (strcmp(alg->cra_name, q->cra_name))
+                       continue;
+
+               if (strcmp(alg->cra_driver_name, q->cra_driver_name) &&
+                   q->cra_priority > alg->cra_priority)
+                       continue;
+
+               crypto_remove_spawns(q, algs_to_put, alg);
+       }
+
+       crypto_notify(CRYPTO_MSG_ALG_LOADED, alg);
+}
+
 static struct crypto_larval *crypto_alloc_test_larval(struct crypto_alg *alg)
 {
        struct crypto_larval *larval;
 
-       if (!IS_ENABLED(CONFIG_CRYPTO_MANAGER))
-               return NULL;
+       if (!IS_ENABLED(CONFIG_CRYPTO_MANAGER) ||
+           IS_ENABLED(CONFIG_CRYPTO_MANAGER_DISABLE_TESTS))
+               return NULL; /* No self-test needed */
 
        larval = crypto_larval_alloc(alg->cra_name,
                                     alg->cra_flags | CRYPTO_ALG_TESTED, 0);
@@ -248,7 +300,8 @@ static struct crypto_larval *crypto_alloc_test_larval(struct crypto_alg *alg)
        return larval;
 }
 
-static struct crypto_larval *__crypto_register_alg(struct crypto_alg *alg)
+static struct crypto_larval *
+__crypto_register_alg(struct crypto_alg *alg, struct list_head *algs_to_put)
 {
        struct crypto_alg *q;
        struct crypto_larval *larval;
@@ -259,9 +312,6 @@ static struct crypto_larval *__crypto_register_alg(struct crypto_alg *alg)
 
        INIT_LIST_HEAD(&alg->cra_users);
 
-       /* No cheating! */
-       alg->cra_flags &= ~CRYPTO_ALG_TESTED;
-
        ret = -EEXIST;
 
        list_for_each_entry(q, &crypto_alg_list, cra_list) {
@@ -288,12 +338,17 @@ static struct crypto_larval *__crypto_register_alg(struct crypto_alg *alg)
 
        list_add(&alg->cra_list, &crypto_alg_list);
 
-       if (larval)
+       crypto_stats_init(alg);
+
+       if (larval) {
+               /* No cheating! */
+               alg->cra_flags &= ~CRYPTO_ALG_TESTED;
+
                list_add(&larval->alg.cra_list, &crypto_alg_list);
-       else
+       } else {
                alg->cra_flags |= CRYPTO_ALG_TESTED;
-
-       crypto_stats_init(alg);
+               crypto_alg_finish_registration(alg, true, algs_to_put);
+       }
 
 out:
        return larval;
@@ -341,7 +396,10 @@ found:
 
        alg->cra_flags |= CRYPTO_ALG_TESTED;
 
-       /* Only satisfy larval waiters if we are the best. */
+       /*
+        * If a higher-priority implementation of the same algorithm is
+        * currently being tested, then don't fulfill request larvals.
+        */
        best = true;
        list_for_each_entry(q, &crypto_alg_list, cra_list) {
                if (crypto_is_moribund(q) || !crypto_is_larval(q))
@@ -356,47 +414,7 @@ found:
                }
        }
 
-       list_for_each_entry(q, &crypto_alg_list, cra_list) {
-               if (q == alg)
-                       continue;
-
-               if (crypto_is_moribund(q))
-                       continue;
-
-               if (crypto_is_larval(q)) {
-                       struct crypto_larval *larval = (void *)q;
-
-                       /*
-                        * Check to see if either our generic name or
-                        * specific name can satisfy the name requested
-                        * by the larval entry q.
-                        */
-                       if (strcmp(alg->cra_name, q->cra_name) &&
-                           strcmp(alg->cra_driver_name, q->cra_name))
-                               continue;
-
-                       if (larval->adult)
-                               continue;
-                       if ((q->cra_flags ^ alg->cra_flags) & larval->mask)
-                               continue;
-
-                       if (best && crypto_mod_get(alg))
-                               larval->adult = alg;
-                       else
-                               larval->adult = ERR_PTR(-EAGAIN);
-
-                       continue;
-               }
-
-               if (strcmp(alg->cra_name, q->cra_name))
-                       continue;
-
-               if (strcmp(alg->cra_driver_name, q->cra_driver_name) &&
-                   q->cra_priority > alg->cra_priority)
-                       continue;
-
-               crypto_remove_spawns(q, &list, alg);
-       }
+       crypto_alg_finish_registration(alg, best, &list);
 
 complete:
        complete_all(&test->completion);
@@ -423,7 +441,8 @@ EXPORT_SYMBOL_GPL(crypto_remove_final);
 int crypto_register_alg(struct crypto_alg *alg)
 {
        struct crypto_larval *larval;
-       bool test_started;
+       LIST_HEAD(algs_to_put);
+       bool test_started = false;
        int err;
 
        alg->cra_flags &= ~CRYPTO_ALG_DEAD;
@@ -432,17 +451,18 @@ int crypto_register_alg(struct crypto_alg *alg)
                return err;
 
        down_write(&crypto_alg_sem);
-       larval = __crypto_register_alg(alg);
-       test_started = static_key_enabled(&crypto_boot_test_finished);
-       if (!IS_ERR_OR_NULL(larval))
+       larval = __crypto_register_alg(alg, &algs_to_put);
+       if (!IS_ERR_OR_NULL(larval)) {
+               test_started = static_key_enabled(&crypto_boot_test_finished);
                larval->test_started = test_started;
+       }
        up_write(&crypto_alg_sem);
 
-       if (IS_ERR_OR_NULL(larval))
+       if (IS_ERR(larval))
                return PTR_ERR(larval);
-
        if (test_started)
                crypto_wait_for_test(larval);
+       crypto_remove_final(&algs_to_put);
        return 0;
 }
 EXPORT_SYMBOL_GPL(crypto_register_alg);
@@ -619,6 +639,7 @@ int crypto_register_instance(struct crypto_template *tmpl,
        struct crypto_larval *larval;
        struct crypto_spawn *spawn;
        u32 fips_internal = 0;
+       LIST_HEAD(algs_to_put);
        int err;
 
        err = crypto_check_alg(&inst->alg);
@@ -650,7 +671,7 @@ int crypto_register_instance(struct crypto_template *tmpl,
 
        inst->alg.cra_flags |= (fips_internal & CRYPTO_ALG_FIPS_INTERNAL);
 
-       larval = __crypto_register_alg(&inst->alg);
+       larval = __crypto_register_alg(&inst->alg, &algs_to_put);
        if (IS_ERR(larval))
                goto unlock;
        else if (larval)
@@ -662,15 +683,12 @@ int crypto_register_instance(struct crypto_template *tmpl,
 unlock:
        up_write(&crypto_alg_sem);
 
-       err = PTR_ERR(larval);
-       if (IS_ERR_OR_NULL(larval))
-               goto err;
-
-       crypto_wait_for_test(larval);
-       err = 0;
-
-err:
-       return err;
+       if (IS_ERR(larval))
+               return PTR_ERR(larval);
+       if (larval)
+               crypto_wait_for_test(larval);
+       crypto_remove_final(&algs_to_put);
+       return 0;
 }
 EXPORT_SYMBOL_GPL(crypto_register_instance);
 

diff --git a/crypto/api.c b/crypto/api.c
index 64f2d36..52ce10a 100644 (file)
--- 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);
 }