crypto: qat - Don't attempt to register algorithm multiple times

When multiple devices are present in the system the driver attempts
to register the same algorithm many times.

Changes in v2:
 - use proper synchronization mechanizm between register and unregister
Signed-off-by: Tadeusz Struk <tadeusz.struk@intel.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

drivers/crypto/qat/qat_common/qat_asym_algs.c

@@ -58,6 +58,9 @@
 #include "adf_common_drv.h"
 #include "qat_crypto.h"
 
+static DEFINE_MUTEX(algs_lock);
+static unsigned int active_devs;
+
 struct qat_rsa_input_params {
 	union {
 		struct {
@@ -629,11 +632,21 @@ static struct akcipher_alg rsa = {
 
 int qat_asym_algs_register(void)
 {
-	rsa.base.cra_flags = 0;
-	return crypto_register_akcipher(&rsa);
+	int ret = 0;
+
+	mutex_lock(&algs_lock);
+	if (++active_devs == 1) {
+		rsa.base.cra_flags = 0;
+		ret = crypto_register_akcipher(&rsa);
+	}
+	mutex_unlock(&algs_lock);
+	return ret;
 }
 
 void qat_asym_algs_unregister(void)
 {
-	crypto_unregister_akcipher(&rsa);
+	mutex_lock(&algs_lock);
+	if (--active_devs == 0)
+		crypto_unregister_akcipher(&rsa);
+	mutex_unlock(&algs_lock);
 }