newlib/libc/stdlib/mlock.c

   1 #ifndef MALLOC_PROVIDED
   2 /*
   3 FUNCTION
   4 <<__malloc_lock>>, <<__malloc_unlock>>---lock malloc pool
   5
   6 INDEX
   7         __malloc_lock
   8 INDEX
   9         __malloc_unlock
  10
  11 SYNOPSIS
  12         #include <malloc.h>
  13         void __malloc_lock (struct _reent *<[reent]>);
  14         void __malloc_unlock (struct _reent *<[reent]>);
  15
  16 DESCRIPTION
  17 The <<malloc>> family of routines call these functions when they need to lock
  18 the memory pool.  The version of these routines supplied in the library use
  19 the lock API defined in sys/lock.h.  If multiple threads of execution can
  20 call <<malloc>>, or if <<malloc>> can be called reentrantly, then you need to
  21 define your own versions of these functions in order to safely lock the
  22 memory pool during a call.  If you do not, the memory pool may become
  23 corrupted.
  24
  25 A call to <<malloc>> may call <<__malloc_lock>> recursively; that is,
  26 the sequence of calls may go <<__malloc_lock>>, <<__malloc_lock>>,
  27 <<__malloc_unlock>>, <<__malloc_unlock>>.  Any implementation of these
  28 routines must be careful to avoid causing a thread to wait for a lock
  29 that it already holds.
  30 */
  31
  32 #include <malloc.h>
  33 #include <sys/lock.h>
  34
  35 #ifndef __SINGLE_THREAD__
  36 __LOCK_INIT_RECURSIVE(static, __malloc_recursive_mutex);
  37 #endif
  38
  39 void
  40 __malloc_lock (ptr)
  41      struct _reent *ptr;
  42 {
  43 #ifndef __SINGLE_THREAD__
  44   __lock_acquire_recursive (__malloc_recursive_mutex);
  45 #endif
  46 }
  47
  48 void
  49 __malloc_unlock (ptr)
  50      struct _reent *ptr;
  51 {
  52 #ifndef __SINGLE_THREAD__
  53   __lock_release_recursive (__malloc_recursive_mutex);
  54 #endif
  55 }
  56
  57 #endif