From: Richard Levitte <levitte@openssl.org>
Date: Wed, 24 Aug 2016 07:14:44 +0000 (+0200)
Subject: CRYPTO_atomic_add(): check that the object is lock free
X-Git-Tag: OpenSSL_1_1_0~13
X-Git-Url: https://git.openssl.org/?p=openssl.git;a=commitdiff_plain;h=1beca67688189f6542c7d08233c28e8fab73dba7

CRYPTO_atomic_add(): check that the object is lock free

If not, fall back to our own code, using the given mutex

Reviewed-by: Andy Polyakov <appro@openssl.org>
---

diff --git a/crypto/threads_pthread.c b/crypto/threads_pthread.c
index 9f4ae76bf8..5cc48afb16 100644
--- a/crypto/threads_pthread.c
+++ b/crypto/threads_pthread.c
@@ -110,8 +110,11 @@ int CRYPTO_THREAD_compare_id(CRYPTO_THREAD_ID a, CRYPTO_THREAD_ID b)
 int CRYPTO_atomic_add(int *val, int amount, int *ret, CRYPTO_RWLOCK *lock)
 {
 # if defined(__GNUC__) && defined(__ATOMIC_ACQ_REL)
-    *ret = __atomic_add_fetch(val, amount, __ATOMIC_ACQ_REL);
-# else
+    if (__atomic_is_lock_free(sizeof(*val), val)) {
+        *ret = __atomic_add_fetch(val, amount, __ATOMIC_ACQ_REL);
+        return 1;
+    }
+# endif
     if (!CRYPTO_THREAD_write_lock(lock))
         return 0;
 
@@ -120,7 +123,6 @@ int CRYPTO_atomic_add(int *val, int amount, int *ret, CRYPTO_RWLOCK *lock)
 
     if (!CRYPTO_THREAD_unlock(lock))
         return 0;
-# endif
 
     return 1;
 }