drd_semaphore.c revision 62ada3f31afe602f7c9a651530d16b06655400ff 
1/*
2  This file is part of drd, a data race detector.
3
4  Copyright (C) 2006-2008 Bart Van Assche
5  bart.vanassche@gmail.com
6
7  This program is free software; you can redistribute it and/or
8  modify it under the terms of the GNU General Public License as
9  published by the Free Software Foundation; either version 2 of the
10  License, or (at your option) any later version.
11
12  This program is distributed in the hope that it will be useful, but
13  WITHOUT ANY WARRANTY; without even the implied warranty of
14  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
15  General Public License for more details.
16
17  You should have received a copy of the GNU General Public License
18  along with this program; if not, write to the Free Software
19  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
20  02111-1307, USA.
21
22  The GNU General Public License is contained in the file COPYING.
23*/
24
25
26#include "drd_clientobj.h"
27#include "drd_error.h"
28#include "drd_semaphore.h"
29#include "drd_suppression.h"
30#include "pub_tool_errormgr.h"    // VG_(maybe_record_error)()
31#include "pub_tool_libcassert.h"  // tl_assert()
32#include "pub_tool_libcprint.h"   // VG_(printf)()
33#include "pub_tool_machine.h"     // VG_(get_IP)()
34#include "pub_tool_mallocfree.h"  // VG_(malloc), VG_(free)
35#include "pub_tool_threadstate.h" // VG_(get_running_tid)()
36
37
38// Local functions.
39
40static void semaphore_cleanup(struct semaphore_info* p);
41
42
43// Local variables.
44
45static Bool s_trace_semaphore;
46static ULong s_semaphore_segment_creation_count;
47
48
49// Function definitions.
50
51static void segment_push(struct semaphore_info* p, Segment* sg)
52{
53  Word n;
54
55  tl_assert(sg);
56  n = VG_(addToXA)(p->last_sem_post_seg, &sg);
57#if 0
58  VG_(message)(Vg_UserMsg, "0x%lx push: added at position %ld/%ld",
59               p->a1, n, VG_(sizeXA)(p->last_sem_post_seg));
60#endif
61  tl_assert(*(Segment**)VG_(indexXA)(p->last_sem_post_seg, n) == sg);
62}
63
64static Segment* segment_pop(struct semaphore_info* p)
65{
66  Word sz;
67  Segment* sg;
68
69  sz = VG_(sizeXA)(p->last_sem_post_seg);
70#if 0
71  VG_(message)(Vg_UserMsg, "0x%lx pop:  removed from position %ld/%ld",
72               p->a1, sz - 1, sz);
73#endif
74  sg = 0;
75  if (sz > 0)
76  {
77    sg = *(Segment**)VG_(indexXA)(p->last_sem_post_seg, sz - 1);
78    tl_assert(sg);
79    VG_(dropTailXA)(p->last_sem_post_seg, 1);
80  }
81  return sg;
82}
83
84void semaphore_set_trace(const Bool trace_semaphore)
85{
86  s_trace_semaphore = trace_semaphore;
87}
88
89static
90void semaphore_initialize(struct semaphore_info* const p, const Addr semaphore)
91{
92  tl_assert(semaphore != 0);
93  tl_assert(p->a1 == semaphore);
94  tl_assert(p->type == ClientSemaphore);
95
96  p->cleanup           = (void(*)(DrdClientobj*))semaphore_cleanup;
97  p->waits_to_skip     = 0;
98  p->value             = 0;
99  p->waiters           = 0;
100  p->last_sem_post_tid = DRD_INVALID_THREADID;
101  p->last_sem_post_seg = VG_(newXA)(VG_(malloc), "drd.sg-stack",
102                                    VG_(free), sizeof(Segment*));
103}
104
105/** Free the memory that was allocated by semaphore_initialize(). Called by
106 *  clientobj_remove().
107 */
108static void semaphore_cleanup(struct semaphore_info* p)
109{
110  Segment* sg;
111
112  if (p->waiters > 0)
113  {
114    SemaphoreErrInfo sei = { p->a1 };
115    VG_(maybe_record_error)(VG_(get_running_tid)(),
116                            SemaphoreErr,
117                            VG_(get_IP)(VG_(get_running_tid)()),
118                            "Destruction of semaphore that is being waited"
119                            " upon",
120                            &sei);
121  }
122  while ((sg = segment_pop(p)))
123    DRD_(sg_put)(sg);
124  VG_(deleteXA)(p->last_sem_post_seg);
125}
126
127static
128struct semaphore_info*
129semaphore_get_or_allocate(const Addr semaphore)
130{
131  struct semaphore_info *p;
132
133  tl_assert(offsetof(DrdClientobj, semaphore) == 0);
134  p = &clientobj_get(semaphore, ClientSemaphore)->semaphore;
135  if (p == 0)
136  {
137    tl_assert(offsetof(DrdClientobj, semaphore) == 0);
138    p = &clientobj_add(semaphore, ClientSemaphore)->semaphore;
139    semaphore_initialize(p, semaphore);
140  }
141  return p;
142}
143
144static struct semaphore_info* semaphore_get(const Addr semaphore)
145{
146  tl_assert(offsetof(DrdClientobj, semaphore) == 0);
147  return &clientobj_get(semaphore, ClientSemaphore)->semaphore;
148}
149
150/** Called before sem_init(). */
151struct semaphore_info* semaphore_init(const Addr semaphore,
152                                      const Word pshared, const UInt value)
153{
154  struct semaphore_info* p;
155  Segment* sg;
156
157  if (s_trace_semaphore)
158  {
159    VG_(message)(Vg_UserMsg,
160                 "[%d/%d] semaphore_init      0x%lx value %u",
161                 VG_(get_running_tid)(),
162                 thread_get_running_tid(),
163                 semaphore,
164                 value);
165  }
166  p = semaphore_get(semaphore);
167  if (p)
168  {
169    const ThreadId vg_tid = VG_(get_running_tid)();
170    SemaphoreErrInfo SEI = { semaphore };
171    VG_(maybe_record_error)(vg_tid,
172                            SemaphoreErr,
173                            VG_(get_IP)(vg_tid),
174                            "Semaphore reinitialization",
175                            &SEI);
176    // Remove all segments from the segment stack.
177    while ((sg = segment_pop(p)))
178    {
179      DRD_(sg_put)(sg);
180    }
181  }
182  else
183  {
184    p = semaphore_get_or_allocate(semaphore);
185  }
186  tl_assert(p);
187  p->waits_to_skip = value;
188  p->value         = value;
189  return p;
190}
191
192/** Called after sem_destroy(). */
193void semaphore_destroy(const Addr semaphore)
194{
195  struct semaphore_info* p;
196
197  p = semaphore_get(semaphore);
198
199  if (s_trace_semaphore)
200  {
201    VG_(message)(Vg_UserMsg,
202                 "[%d/%d] semaphore_destroy   0x%lx value %u",
203                 VG_(get_running_tid)(),
204                 thread_get_running_tid(),
205                 semaphore,
206                 p ? p->value : 0);
207  }
208
209  if (p == 0)
210  {
211    GenericErrInfo GEI;
212    VG_(maybe_record_error)(VG_(get_running_tid)(),
213                            GenericErr,
214                            VG_(get_IP)(VG_(get_running_tid)()),
215                            "Not a semaphore",
216                            &GEI);
217    return;
218  }
219
220  clientobj_remove(semaphore, ClientSemaphore);
221}
222
223/** Called before sem_wait(). */
224void semaphore_pre_wait(const Addr semaphore)
225{
226  struct semaphore_info* p;
227
228  p = semaphore_get_or_allocate(semaphore);
229  tl_assert(p);
230  tl_assert((int)p->waiters >= 0);
231  p->waiters++;
232  tl_assert(p->waiters > 0);
233}
234
235/** Called after sem_wait() finished.
236 *  @note Do not rely on the value of 'waited' -- some glibc versions do
237 *        not set it correctly.
238 */
239void semaphore_post_wait(const DrdThreadId tid, const Addr semaphore,
240                         const Bool waited)
241{
242  struct semaphore_info* p;
243  Segment* sg;
244
245  p = semaphore_get(semaphore);
246  if (s_trace_semaphore)
247  {
248    VG_(message)(Vg_UserMsg,
249                 "[%d/%d] semaphore_wait      0x%lx value %u -> %u",
250                 VG_(get_running_tid)(),
251                 thread_get_running_tid(),
252                 semaphore,
253                 p ? p->value : 0,
254                 p ? p->value - 1 : 0);
255  }
256  tl_assert(p);
257  tl_assert(p->waiters > 0);
258  p->waiters--;
259  tl_assert((int)p->waiters >= 0);
260  tl_assert((int)p->value >= 0);
261  if (p->value == 0)
262  {
263    SemaphoreErrInfo sei = { semaphore };
264    VG_(maybe_record_error)(VG_(get_running_tid)(),
265                            SemaphoreErr,
266                            VG_(get_IP)(VG_(get_running_tid)()),
267                            "Invalid semaphore",
268                            &sei);
269    return;
270  }
271  p->value--;
272  tl_assert((int)p->value >= 0);
273  if (p->waits_to_skip > 0)
274    p->waits_to_skip--;
275  else
276  {
277    sg = segment_pop(p);
278    tl_assert(sg);
279    if (sg)
280    {
281      if (p->last_sem_post_tid != tid
282          && p->last_sem_post_tid != DRD_INVALID_THREADID)
283      {
284        thread_combine_vc2(tid, &sg->vc);
285      }
286      DRD_(sg_put)(sg);
287      thread_new_segment(tid);
288      s_semaphore_segment_creation_count++;
289    }
290  }
291}
292
293/** Called before sem_post(). */
294void semaphore_pre_post(const DrdThreadId tid, const Addr semaphore)
295{
296  struct semaphore_info* p;
297  Segment* sg;
298
299  p = semaphore_get_or_allocate(semaphore);
300  p->value++;
301
302  if (s_trace_semaphore)
303  {
304    VG_(message)(Vg_UserMsg,
305                 "[%d/%d] semaphore_post      0x%lx value %u -> %u",
306                 VG_(get_running_tid)(),
307                 thread_get_running_tid(),
308                 semaphore,
309                 p->value - 1, p->value);
310  }
311
312  p->last_sem_post_tid = tid;
313  thread_new_segment(tid);
314  sg = 0;
315  thread_get_latest_segment(&sg, tid);
316  tl_assert(sg);
317  segment_push(p, sg);
318  s_semaphore_segment_creation_count++;
319}
320
321/** Called after sem_post() finished successfully. */
322void semaphore_post_post(const DrdThreadId tid, const Addr semaphore,
323                         const Bool waited)
324{
325  /* Note: it is hard to implement the sem_post() wrapper correctly in     */
326  /* case sem_post() returns an error code. This is because handling this  */
327  /* case correctly requires restoring the vector clock associated with    */
328  /* the semaphore to its original value here. In order to do that without */
329  /* introducing a race condition, extra locking has to be added around    */
330  /* each semaphore call. Such extra locking would have to be added in     */
331  /* drd_intercepts.c. However, it is hard to implement synchronization    */
332  /* in drd_intercepts.c in a portable way without calling already         */
333  /* redirected functions.                                                 */
334}
335
336void semaphore_thread_delete(const DrdThreadId threadid)
337{ }
338
339ULong get_semaphore_segment_creation_count(void)
340{
341  return s_semaphore_segment_creation_count;
342}
343