1*062c5bc4SJason Schmidlapp /*
2*062c5bc4SJason Schmidlapp * pthread_mutex_trylock.c
3*062c5bc4SJason Schmidlapp *
4*062c5bc4SJason Schmidlapp * Description:
5*062c5bc4SJason Schmidlapp * This translation unit implements mutual exclusion (mutex) primitives.
6*062c5bc4SJason Schmidlapp *
7*062c5bc4SJason Schmidlapp * --------------------------------------------------------------------------
8*062c5bc4SJason Schmidlapp *
9*062c5bc4SJason Schmidlapp * Pthreads-embedded (PTE) - POSIX Threads Library for embedded systems
10*062c5bc4SJason Schmidlapp * Copyright(C) 2008 Jason Schmidlapp
11*062c5bc4SJason Schmidlapp *
12*062c5bc4SJason Schmidlapp * Contact Email: jschmidlapp@users.sourceforge.net
13*062c5bc4SJason Schmidlapp *
14*062c5bc4SJason Schmidlapp *
15*062c5bc4SJason Schmidlapp * Based upon Pthreads-win32 - POSIX Threads Library for Win32
16*062c5bc4SJason Schmidlapp * Copyright(C) 1998 John E. Bossom
17*062c5bc4SJason Schmidlapp * Copyright(C) 1999,2005 Pthreads-win32 contributors
18*062c5bc4SJason Schmidlapp *
19*062c5bc4SJason Schmidlapp * Contact Email: rpj@callisto.canberra.edu.au
20*062c5bc4SJason Schmidlapp *
21*062c5bc4SJason Schmidlapp * The original list of contributors to the Pthreads-win32 project
22*062c5bc4SJason Schmidlapp * is contained in the file CONTRIBUTORS.ptw32 included with the
23*062c5bc4SJason Schmidlapp * source code distribution. The list can also be seen at the
24*062c5bc4SJason Schmidlapp * following World Wide Web location:
25*062c5bc4SJason Schmidlapp * http://sources.redhat.com/pthreads-win32/contributors.html
26*062c5bc4SJason Schmidlapp *
27*062c5bc4SJason Schmidlapp * This library is free software; you can redistribute it and/or
28*062c5bc4SJason Schmidlapp * modify it under the terms of the GNU Lesser General Public
29*062c5bc4SJason Schmidlapp * License as published by the Free Software Foundation; either
30*062c5bc4SJason Schmidlapp * version 2 of the License, or (at your option) any later version.
31*062c5bc4SJason Schmidlapp *
32*062c5bc4SJason Schmidlapp * This library is distributed in the hope that it will be useful,
33*062c5bc4SJason Schmidlapp * but WITHOUT ANY WARRANTY; without even the implied warranty of
34*062c5bc4SJason Schmidlapp * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
35*062c5bc4SJason Schmidlapp * Lesser General Public License for more details.
36*062c5bc4SJason Schmidlapp *
37*062c5bc4SJason Schmidlapp * You should have received a copy of the GNU Lesser General Public
38*062c5bc4SJason Schmidlapp * License along with this library in the file COPYING.LIB;
39*062c5bc4SJason Schmidlapp * if not, write to the Free Software Foundation, Inc.,
40*062c5bc4SJason Schmidlapp * 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
41*062c5bc4SJason Schmidlapp */
42*062c5bc4SJason Schmidlapp
43*062c5bc4SJason Schmidlapp #include "pthread.h"
44*062c5bc4SJason Schmidlapp #include "implement.h"
45*062c5bc4SJason Schmidlapp
46*062c5bc4SJason Schmidlapp
47*062c5bc4SJason Schmidlapp int
pthread_mutex_trylock(pthread_mutex_t * mutex)48*062c5bc4SJason Schmidlapp pthread_mutex_trylock (pthread_mutex_t * mutex)
49*062c5bc4SJason Schmidlapp {
50*062c5bc4SJason Schmidlapp int result = 0;
51*062c5bc4SJason Schmidlapp pthread_mutex_t mx;
52*062c5bc4SJason Schmidlapp
53*062c5bc4SJason Schmidlapp /*
54*062c5bc4SJason Schmidlapp * Let the system deal with invalid pointers.
55*062c5bc4SJason Schmidlapp */
56*062c5bc4SJason Schmidlapp
57*062c5bc4SJason Schmidlapp /*
58*062c5bc4SJason Schmidlapp * We do a quick check to see if we need to do more work
59*062c5bc4SJason Schmidlapp * to initialise a static mutex. We check
60*062c5bc4SJason Schmidlapp * again inside the guarded section of pte_mutex_check_need_init()
61*062c5bc4SJason Schmidlapp * to avoid race conditions.
62*062c5bc4SJason Schmidlapp */
63*062c5bc4SJason Schmidlapp if (*mutex >= PTHREAD_ERRORCHECK_MUTEX_INITIALIZER)
64*062c5bc4SJason Schmidlapp {
65*062c5bc4SJason Schmidlapp if ((result = pte_mutex_check_need_init (mutex)) != 0)
66*062c5bc4SJason Schmidlapp {
67*062c5bc4SJason Schmidlapp return (result);
68*062c5bc4SJason Schmidlapp }
69*062c5bc4SJason Schmidlapp }
70*062c5bc4SJason Schmidlapp
71*062c5bc4SJason Schmidlapp mx = *mutex;
72*062c5bc4SJason Schmidlapp
73*062c5bc4SJason Schmidlapp if (0 == PTE_ATOMIC_COMPARE_EXCHANGE (&mx->lock_idx,1,0))
74*062c5bc4SJason Schmidlapp {
75*062c5bc4SJason Schmidlapp if (mx->kind != PTHREAD_MUTEX_NORMAL)
76*062c5bc4SJason Schmidlapp {
77*062c5bc4SJason Schmidlapp mx->recursive_count = 1;
78*062c5bc4SJason Schmidlapp mx->ownerThread = pthread_self ();
79*062c5bc4SJason Schmidlapp }
80*062c5bc4SJason Schmidlapp }
81*062c5bc4SJason Schmidlapp else
82*062c5bc4SJason Schmidlapp {
83*062c5bc4SJason Schmidlapp if (mx->kind == PTHREAD_MUTEX_RECURSIVE &&
84*062c5bc4SJason Schmidlapp pthread_equal (mx->ownerThread, pthread_self ()))
85*062c5bc4SJason Schmidlapp {
86*062c5bc4SJason Schmidlapp mx->recursive_count++;
87*062c5bc4SJason Schmidlapp }
88*062c5bc4SJason Schmidlapp else
89*062c5bc4SJason Schmidlapp {
90*062c5bc4SJason Schmidlapp result = EBUSY;
91*062c5bc4SJason Schmidlapp }
92*062c5bc4SJason Schmidlapp }
93*062c5bc4SJason Schmidlapp
94*062c5bc4SJason Schmidlapp return (result);
95*062c5bc4SJason Schmidlapp }
96