malloc: Remove NO_THREADS

No functional change.  It was not possible to build without
threading support before.

ChangeLog

@@ -1,3 +1,10 @@
+2016-02-19  Florian Weimer  <fweimer@redhat.com>
+
+	* sysdeps/generic/malloc-machine.h: Assume mutex_init is always
+	available.  Do not define NO_THREADS.
+	* malloc/malloc.c: Do not check NO_THREADS.
+	* malloc/arena.c: Likewise.
+
 2016-02-19  Florian Weimer  <fweimer@redhat.com>
 
 	* malloc/malloc.c (__libc_mallinfo): Update comment.

malloc/arena.c

@@ -127,8 +127,6 @@ int __malloc_initialized = -1;
 
 /**************************************************************************/
 
-#ifndef NO_THREADS
-
 /* atfork support.  */
 
 static void *(*save_malloc_hook)(size_t __size, const void *);
@@ -327,7 +325,6 @@ ptmalloc_unlock_all2 (void)
 
 #  define ptmalloc_unlock_all2 ptmalloc_unlock_all
 # endif
-#endif  /* !NO_THREADS */
 
 /* Initialization routine. */
 #include <string.h>

malloc/malloc.c

@@ -1073,10 +1073,8 @@ static void*   realloc_check(void* oldmem, size_t bytes,
 			       const void *caller);
 static void*   memalign_check(size_t alignment, size_t bytes,
 				const void *caller);
-#ifndef NO_THREADS
 static void*   malloc_atfork(size_t sz, const void *caller);
 static void      free_atfork(void* mem, const void *caller);
-#endif
 
 /* ------------------ MMAP support ------------------  */
 

sysdeps/generic/malloc-machine.h

@@ -22,25 +22,6 @@
 
 #include <atomic.h>
 
-#ifndef mutex_init /* No threads, provide dummy macros */
-
-# define NO_THREADS
-
-/* The mutex functions used to do absolutely nothing, i.e. lock,
-   trylock and unlock would always just return 0.  However, even
-   without any concurrently active threads, a mutex can be used
-   legitimately as an `in use' flag.  To make the code that is
-   protected by a mutex async-signal safe, these macros would have to
-   be based on atomic test-and-set operations, for example. */
-typedef int mutex_t;
-
-# define mutex_init(m)          (*(m) = 0)
-# define mutex_lock(m)          ({ *(m) = 1; 0; })
-# define mutex_trylock(m)       (*(m) ? 1 : ((*(m) = 1), 0))
-# define mutex_unlock(m)        (*(m) = 0)
-
-#endif /* !defined mutex_init */
-
 #ifndef atomic_full_barrier
 # define atomic_full_barrier() __asm ("" ::: "memory")
 #endif