Add atomic write call

Reviewed-by: Rich Salz <rsalz@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/4414)

1 files changed, 19 insertions, 0 deletions

diff --git a/crypto/threads_pthread.c b/crypto/threads_pthread.c
index 3f8ada2c37..34be314f1f 100644
--- a/crypto/threads_pthread.c
+++ b/crypto/threads_pthread.c
@@ -188,6 +188,25 @@ int CRYPTO_atomic_read(int *val, int *ret, CRYPTO_RWLOCK *lock)
     return 1;
 }
 
+int CRYPTO_atomic_write(int *val, int n, CRYPTO_RWLOCK *lock)
+{
+# if defined(__GNUC__) && defined(__ATOMIC_RELEASE)
+    if (__atomic_is_lock_free(sizeof(*val), val)) {
+        __atomic_store(val, &n, __ATOMIC_RELEASE);
+        return 1;
+    }
+# endif
+    if (!CRYPTO_THREAD_write_lock(lock))
+        return 0;
+
+    *val = n;
+
+    if (!CRYPTO_THREAD_unlock(lock))
+        return 0;
+
+    return 1;
+}
+
 # ifdef OPENSSL_SYS_UNIX
 static pthread_once_t fork_once_control = PTHREAD_ONCE_INIT;