crypto/threads_*: remove CRYPTO_atomic_{read|write}.

CRYPTO_atomic_read was added with intention to read statistics counters,
but readings are effectively indistinguishable from regular load (even
in non-lock-free case). This is because you can get out-dated value in
both cases. CRYPTO_atomic_write was added for symmetry and was never used.

Reviewed-by: Kurt Roeckx <kurt@roeckx.be>
(Merged from https://github.com/openssl/openssl/pull/6883)

crypto/threads_none.c

@@ -128,18 +128,6 @@ int CRYPTO_atomic_add(int *val, int amount, int *ret, CRYPTO_RWLOCK *lock)
     return 1;
 }
 
-int CRYPTO_atomic_read(int *val, int *ret, CRYPTO_RWLOCK *lock)
-{
-    *ret = *val;
-    return 1;
-}
-
-int CRYPTO_atomic_write(int *val, int n, CRYPTO_RWLOCK *lock)
-{
-    *val = n;
-    return 1;
-}
-
 int openssl_init_fork_handlers(void)
 {
     return 0;

crypto/threads_pthread.c

@@ -175,44 +175,6 @@ int CRYPTO_atomic_add(int *val, int amount, int *ret, CRYPTO_RWLOCK *lock)
     return 1;
 }
 
-int CRYPTO_atomic_read(int *val, int *ret, CRYPTO_RWLOCK *lock)
-{
-# if defined(__GNUC__) && defined(__ATOMIC_ACQUIRE)
-    if (__atomic_is_lock_free(sizeof(*val), val)) {
-        __atomic_load(val, ret, __ATOMIC_ACQUIRE);
-        return 1;
-    }
-# endif
-    if (!CRYPTO_THREAD_read_lock(lock))
-        return 0;
-
-    *ret  = *val;
-
-    if (!CRYPTO_THREAD_unlock(lock))
-        return 0;
-
-    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;
 

crypto/threads_win.c

@@ -155,18 +155,6 @@ int CRYPTO_atomic_add(int *val, int amount, int *ret, CRYPTO_RWLOCK *lock)
     return 1;
 }
 
-int CRYPTO_atomic_read(int *val, int *ret, CRYPTO_RWLOCK *lock)
-{
-    *ret = InterlockedCompareExchange(val, 0, 0);
-    return 1;
-}
-
-int CRYPTO_atomic_write(int *val, int n, CRYPTO_RWLOCK *lock)
-{
-    InterlockedExchange(val, n);
-    return 1;
-}
-
 int openssl_init_fork_handlers(void)
 {
     return 0;

doc/man3/CRYPTO_THREAD_run_once.pod

@@ -4,8 +4,8 @@
 
 CRYPTO_THREAD_run_once,
 CRYPTO_THREAD_lock_new, CRYPTO_THREAD_read_lock, CRYPTO_THREAD_write_lock,
-CRYPTO_THREAD_unlock, CRYPTO_THREAD_lock_free, CRYPTO_atomic_add,
-CRYPTO_atomic_read, CRYPTO_atomic_write - OpenSSL thread support
+CRYPTO_THREAD_unlock, CRYPTO_THREAD_lock_free,
+CRYPTO_atomic_add - OpenSSL thread support
 
 =head1 SYNOPSIS
 
@@ -21,8 +21,6 @@ CRYPTO_atomic_read, CRYPTO_atomic_write - OpenSSL thread support
  void CRYPTO_THREAD_lock_free(CRYPTO_RWLOCK *lock);
 
  int CRYPTO_atomic_add(int *val, int amount, int *ret, CRYPTO_RWLOCK *lock);
- int CRYPTO_atomic_read(int *val, int *ret, CRYPTO_RWLOCK *lock);
- int CRYPTO_atomic_write(int *val, int n, CRYPTO_RWLOCK *lock);
 
 =head1 DESCRIPTION
 
@@ -77,17 +75,6 @@ operations are supported on the specific platform. Because of this, if a
 variable is modified by CRYPTO_atomic_add() then CRYPTO_atomic_add() must
 be the only way that the variable is modified.
 
-=item *
-
-CRYPTO_atomic_read() atomically reads B<val> and returns the result of
-the operation in B<ret>. B<lock> will be locked, unless atomic operations
-are supported on the specific platform.
-
-=item *
-
-CRYPTO_atomic_write() atomically writes B<n> to B<val>. B<lock> will be
-locked, unless atomic operations are supported on the specific platform.
-
 =back
 
 =head1 RETURN VALUES

include/openssl/crypto.h

@@ -73,8 +73,6 @@ int CRYPTO_THREAD_unlock(CRYPTO_RWLOCK *lock);
 void CRYPTO_THREAD_lock_free(CRYPTO_RWLOCK *lock);
 
 int CRYPTO_atomic_add(int *val, int amount, int *ret, CRYPTO_RWLOCK *lock);
-int CRYPTO_atomic_read(int *val, int *ret, CRYPTO_RWLOCK *lock);
-int CRYPTO_atomic_write(int *val, int n, CRYPTO_RWLOCK *lock);
 
 /*
  * The following can be used to detect memory leaks in the library. If

util/libcrypto.num

@@ -4396,8 +4396,6 @@ EVP_PKEY_meth_set_check                 4341	1_1_1	EXIST::FUNCTION:
 EVP_PKEY_meth_get_check                 4342	1_1_1	EXIST::FUNCTION:
 EVP_PKEY_meth_remove                    4343	1_1_1	EXIST::FUNCTION:
 OPENSSL_sk_reserve                      4344	1_1_1	EXIST::FUNCTION:
-CRYPTO_atomic_read                      4345	1_1_1	EXIST::FUNCTION:
-CRYPTO_atomic_write                     4346	1_1_1	EXIST::FUNCTION:
 EVP_PKEY_set1_engine                    4347	1_1_0g	EXIST::FUNCTION:ENGINE
 DH_new_by_nid                           4348	1_1_1	EXIST::FUNCTION:DH
 DH_get_nid                              4349	1_1_1	EXIST::FUNCTION:DH