Bug#16736461: ATOMIC OPERATIONS USING LOCKS ARE BROKEN, WON'T COMPILE

jhauglid · jhauglid · commit 8a987b476978 · 2013-06-04T08:48:27.000+02:00
Post-push fix: Change my_atomic_rwlock_t back to contain pthread_mutex_t
and not mysql_mutex_t to avoid risk of recursion. Instead change SAFE_MUTEX
versions of my_atomic_rwlock_* macros to accept pthread_mutex_t parameter.
Issue noticed by Marc Alff.
diff --git a/include/atomic/rwlock.h b/include/atomic/rwlock.h
@@ -38,52 +38,19 @@ typedef char my_atomic_rwlock_t;
 #define MY_ATOMIC_MODE "dummy (non-atomic)"
 #else /* not MY_ATOMIC_MODE_DUMMY */
 
-typedef struct {mysql_mutex_t rw;} my_atomic_rwlock_t;
-
-#ifndef SAFE_MUTEX
+typedef struct {pthread_mutex_t rw;} my_atomic_rwlock_t;
 
 /*
   we're using read-write lock macros but map them to mutex locks, and they're
   faster. Still, having semantically rich API we can change the
   underlying implementation, if necessary.
 */
-#define my_atomic_rwlock_destroy(name)     pthread_mutex_destroy(& (name)->rw.m_mutex)
-#define my_atomic_rwlock_init(name)        pthread_mutex_init(& (name)->rw.m_mutex, 0)
-#define my_atomic_rwlock_rdlock(name)      pthread_mutex_lock(& (name)->rw.m_mutex)
-#define my_atomic_rwlock_wrlock(name)      pthread_mutex_lock(& (name)->rw.m_mutex)
-#define my_atomic_rwlock_rdunlock(name)    pthread_mutex_unlock(& (name)->rw.m_mutex)
-#define my_atomic_rwlock_wrunlock(name)    pthread_mutex_unlock(& (name)->rw.m_mutex)
-
-#else /* SAFE_MUTEX */
-
-/*
-  SAFE_MUTEX pollutes the compiling name space with macros
-  that alter pthread_mutex_t, pthread_mutex_init, etc.
-  Atomic operations should never use the safe mutex wrappers.
-  Unfortunately, there is no way to have both:
-  - safe mutex macros expanding pthread_mutex_lock to safe_mutex_lock
-  - my_atomic macros expanding to unmodified pthread_mutex_lock
-  inlined in the same compilation unit.
-  So, in case of SAFE_MUTEX, a function call is required.
-  Given that SAFE_MUTEX is a debugging facility,
-  this extra function call is not a performance concern for
-  production builds.
-*/
-C_MODE_START
-extern void plain_pthread_mutex_init(safe_mutex_t *);
-extern void plain_pthread_mutex_destroy(safe_mutex_t *);
-extern void plain_pthread_mutex_lock(safe_mutex_t *);
-extern void plain_pthread_mutex_unlock(safe_mutex_t *);
-C_MODE_END
-
-#define my_atomic_rwlock_destroy(name)     plain_pthread_mutex_destroy(&(name)->rw.m_mutex)
-#define my_atomic_rwlock_init(name)        plain_pthread_mutex_init(&(name)->rw.m_mutex)
-#define my_atomic_rwlock_rdlock(name)      plain_pthread_mutex_lock(&(name)->rw.m_mutex)
-#define my_atomic_rwlock_wrlock(name)      plain_pthread_mutex_lock(&(name)->rw.m_mutex)
-#define my_atomic_rwlock_rdunlock(name)    plain_pthread_mutex_unlock(&(name)->rw.m_mutex)
-#define my_atomic_rwlock_wrunlock(name)    plain_pthread_mutex_unlock(&(name)->rw.m_mutex)
-
-#endif /* SAFE_MUTEX */
+#define my_atomic_rwlock_destroy(name)     pthread_mutex_destroy(& (name)->rw)
+#define my_atomic_rwlock_init(name)        pthread_mutex_init(& (name)->rw, 0)
+#define my_atomic_rwlock_rdlock(name)      pthread_mutex_lock(& (name)->rw)
+#define my_atomic_rwlock_wrlock(name)      pthread_mutex_lock(& (name)->rw)
+#define my_atomic_rwlock_rdunlock(name)    pthread_mutex_unlock(& (name)->rw)
+#define my_atomic_rwlock_wrunlock(name)    pthread_mutex_unlock(& (name)->rw)
 
 #define MY_ATOMIC_MODE "mutex"
 #ifndef MY_ATOMIC_MODE_RWLOCKS
diff --git a/mysys/my_atomic.c b/mysys/my_atomic.c
@@ -1,4 +1,4 @@
-/* Copyright (c) 2006, 2010, Oracle and/or its affiliates. All rights reserved.
+/* Copyright (c) 2006, 2013, Oracle and/or its affiliates. All rights reserved.
 
    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
@@ -35,33 +35,3 @@ int my_atomic_initialize()
   return MY_ATOMIC_OK;
 #endif
 }
-
-#ifdef SAFE_MUTEX
-#undef pthread_mutex_init
-#undef pthread_mutex_destroy
-#undef pthread_mutex_lock
-#undef pthread_mutex_unlock
-
-void plain_pthread_mutex_init(safe_mutex_t *m)
-{
-  pthread_mutex_init(& m->mutex, NULL);
-}
-
-void plain_pthread_mutex_destroy(safe_mutex_t *m)
-{
-  pthread_mutex_destroy(& m->mutex);
-}
-
-void plain_pthread_mutex_lock(safe_mutex_t *m)
-{
-  pthread_mutex_lock(& m->mutex);
-}
-
-void plain_pthread_mutex_unlock(safe_mutex_t *m)
-{
-  pthread_mutex_unlock(& m->mutex);
-}
-
-#endif
-
-
