about summary refs log tree commit diff
path: root/nptl/pthread_create.c
blob: 172f002d9b1984a93d872cdeab12a9aa88c7d1de (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
/* Copyright (C) 2002, 2003 Free Software Foundation, Inc.
   This file is part of the GNU C Library.
   Contributed by Ulrich Drepper <drepper@redhat.com>, 2002.

   The GNU C Library is free software; you can redistribute it and/or
   modify it under the terms of the GNU Lesser General Public
   License as published by the Free Software Foundation; either
   version 2.1 of the License, or (at your option) any later version.

   The GNU C Library is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public
   License along with the GNU C Library; if not, write to the Free
   Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
   02111-1307 USA.  */

#include <errno.h>
#include <stdbool.h>
#include <stdlib.h>
#include <string.h>
#include "pthreadP.h"
#include <hp-timing.h>
#include <ldsodefs.h>
#include <atomic.h>

#include <shlib-compat.h>


/* Local function to start thread and handle cleanup.  */
static int start_thread (void *arg);
/* Similar version used when debugging.  */
static int start_thread_debug (void *arg);


/* Nozero if debugging mode is enabled.  */
int __pthread_debug;

/* Globally enabled events.  */
static td_thr_events_t __nptl_threads_events;

/* Pointer to descriptor with the last event.  */
static struct pthread *__nptl_last_event;

/* Number of threads running.  */
unsigned int __nptl_nthreads = 1;


/* Code to allocate and deallocate a stack.  */
#define DEFINE_DEALLOC
#include "allocatestack.c"

/* Code to create the thread.  */
#include "createthread.c"


/* Table of the key information.  */
struct pthread_key_struct __pthread_keys[PTHREAD_KEYS_MAX]
  __attribute__ ((section (".bss")));
hidden_def (__pthread_keys)

/* This is for libthread_db only.  */
const int __pthread_pthread_sizeof_descr = sizeof (struct pthread);

struct pthread *
internal_function
__find_in_stack_list (pd)
     struct pthread *pd;
{
  list_t *entry;
  struct pthread *result = NULL;

  lll_lock (stack_cache_lock);

  list_for_each (entry, &stack_used)
    {
      struct pthread *curp;

      curp = list_entry (entry, struct pthread, header.data.list);
      if (curp == pd)
	{
	  result = curp;
	  break;
	}
    }

  if (result == NULL)
    list_for_each (entry, &__stack_user)
      {
	struct pthread *curp;

	curp = list_entry (entry, struct pthread, header.data.list);
	if (curp == pd)
	  {
	    result = curp;
	    break;
	  }
      }

  lll_unlock (stack_cache_lock);

  return result;
}


/* Deallocate POSIX thread-local-storage.  */
static void
deallocate_tsd (struct pthread *pd)
{
  /* Maybe no data was ever allocated.  This happens often so we have
     a flag for this.  */
  if (pd->specific_used)
    {
      size_t round;
      bool found_nonzero;

      for (round = 0, found_nonzero = true;
	   found_nonzero && round < PTHREAD_DESTRUCTOR_ITERATIONS;
	   ++round)
	{
	  size_t cnt;
	  size_t idx;

	  for (cnt = idx = 0; cnt < PTHREAD_KEY_1STLEVEL_SIZE; ++cnt)
	    if (pd->specific[cnt] != NULL)
	      {
		size_t inner;

		for (inner = 0; inner < PTHREAD_KEY_2NDLEVEL_SIZE;
		     ++inner, ++idx)
		  {
		    void *data = pd->specific[cnt][inner].data;

		    if (data != NULL
			/* Make sure the data corresponds to a valid
			   key.  This test fails if the key was
			   deallocated and also if it was
			   re-allocated.  It is the user's
			   responsibility to free the memory in this
			   case.  */
			&& (pd->specific[cnt][inner].seq
			    == __pthread_keys[idx].seq)
			/* It is not necessary to register a destructor
			   function.  */
			&& __pthread_keys[idx].destr != NULL)
		      {
			pd->specific[cnt][inner].data = NULL;
			__pthread_keys[idx].destr (data);
			found_nonzero = true;
		      }
		  }

		if (cnt != 0)
		  {
		    /* The first block is allocated as part of the thread
		       descriptor.  */
		    free (pd->specific[cnt]);
		    pd->specific[cnt] = NULL;
		  }
		else
		  /* Clear the memory of the first block for reuse.  */
		  memset (pd->specific[0], '\0',
			  sizeof (struct pthread_key_data));
	      }
	    else
	      idx += PTHREAD_KEY_1STLEVEL_SIZE;
	}

      pd->specific_used = false;
    }
}


/* Deallocate a thread's stack after optionally making sure the thread
   descriptor is still valid.  */
void
internal_function
__free_tcb (struct pthread *pd)
{
  /* The thread is exiting now.  */
  if (atomic_bit_test_set (&pd->cancelhandling, TERMINATED_BIT) == 0)
    {
      /* Remove the descriptor from the list.  */
      if (DEBUGGING_P && __find_in_stack_list (pd) == NULL)
	/* Something is really wrong.  The descriptor for a still
	   running thread is gone.  */
	abort ();

      /* Run the destructor for the thread-local data.  */
      deallocate_tsd (pd);

      /* Queue the stack memory block for reuse and exit the process.  The
	 kernel will signal via writing to the address returned by
	 QUEUE-STACK when the stack is available.  */
      __deallocate_stack (pd);
    }
}


static int
start_thread (void *arg)
{
  /* One more thread.  */
  atomic_increment (&__nptl_nthreads);

  struct pthread *pd = (struct pthread *) arg;

#if HP_TIMING_AVAIL
  /* Remember the time when the thread was started.  */
  hp_timing_t now;
  HP_TIMING_NOW (now);
  THREAD_SETMEM (pd, cpuclock_offset, now);
#endif

  /* This is where the try/finally block should be created.  For
     compilers without that support we do use setjmp.  */
  if (setjmp (pd->cancelbuf) == 0)
    {
      /* Run the code the user provided.  */
      pd->result = pd->start_routine (pd->arg);
    }


  /* If this is the last thread we terminate the process now.  We
     do not notify the debugger, it might just irritate it if there
     is no thread left.  */
  if (__builtin_expect (atomic_decrement_and_test (&__nptl_nthreads), 0))
    /* This was the last thread.  */
    exit (0);


  /* Report the death of the thread if this is wanted.  */
  if (__builtin_expect (pd->report_events, 0))
    {
      /* See whether TD_DEATH is in any of the mask.  */
      const int idx = __td_eventword (TD_DEATH);
      const uint32_t mask = __td_eventmask (TD_DEATH);

      if ((mask & (__nptl_threads_events.event_bits[idx]
		   | pd->eventbuf.eventmask.event_bits[idx])) != 0)
	{
	  /* Yep, we have to signal the death.  Add the descriptor to
	     the list but only if it is not already on it.  */
	  if (pd->nextevent == NULL)
	    {
	      pd->eventbuf.eventnum = TD_DEATH;
	      pd->eventbuf.eventdata = pd;

	      do
		pd->nextevent = __nptl_last_event;
	      while (atomic_compare_and_exchange_acq (&__nptl_last_event, pd,
						      pd->nextevent) != 0);
	    }

	  /* Now call the function to signal the event.  */
	  __nptl_death_event ();
	}
    }


  /* The thread is exiting now.  */
  atomic_bit_set (&pd->cancelhandling, EXITING_BIT);

  /* If the thread is detached free the TCB.  */
  if (IS_DETACHED (pd))
    /* Free the TCB.  */
    __free_tcb (pd);

  /* We cannot call '_exit' here.  '_exit' will terminate the process.

     The 'exit' implementation in the kernel will signal when the
     process is really dead since 'clone' got passed the CLONE_CLEARTID
     flag.  The 'tid' field in the TCB will be set to zero.

     The exit code is zero since in case all threads exit by calling
     'pthread_exit' the exit status must be 0 (zero).  */
  __exit_thread_inline (0);

  /* NOTREACHED */
  return 0;
}


/* Just list start_thread but we do some more things needed for a run
   with a debugger attached.  */
static int
start_thread_debug (void *arg)
{
  struct pthread *pd = (struct pthread *) arg;

  /* Get the lock the parent locked to force synchronization.  */
  lll_lock (pd->lock);
  /* And give it up right away.  */
  lll_unlock (pd->lock);

  /* Now do the actual startup.  */
  return start_thread (arg);
}


/* Default thread attributes for the case when the user does not
   provide any.  */
static const struct pthread_attr default_attr =
  {
    /* Just some value > 0 which gets rounded to the nearest page size.  */
    .guardsize = 1,
  };


int
__pthread_create_2_1 (newthread, attr, start_routine, arg)
     pthread_t *newthread;
     const pthread_attr_t *attr;
     void *(*start_routine) (void *);
     void *arg;
{
  STACK_VARIABLES;
  const struct pthread_attr *iattr;
  struct pthread *pd;
  int err;

  iattr = (struct pthread_attr *) attr;
  if (iattr == NULL)
    /* Is this the best idea?  On NUMA machines this could mean
       accessing far-away memory.  */
    iattr = &default_attr;

  err = ALLOCATE_STACK (iattr, &pd);
  if (__builtin_expect (err != 0, 0))
    /* Something went wrong.  Maybe a parameter of the attributes is
       invalid or we could not allocate memory.  */
    return err;


  /* Initialize the TCB.  All initializations with zero should be
     performed in 'get_cached_stack'.  This way we avoid doing this if
     the stack freshly allocated with 'mmap'.  */

  /* Reference to the TCB itself.  */
  pd->header.data.self = pd;

#ifdef TLS_TCB_AT_TP
  /* Self-reference.  */
  pd->header.data.tcb = pd;
#endif

  /* Store the address of the start routine and the parameter.  Since
     we do not start the function directly the stillborn thread will
     get the information from its thread descriptor.  */
  pd->start_routine = start_routine;
  pd->arg = arg;

  /* Copy the thread attribute flags.  */
  pd->flags = iattr->flags;

  /* Initialize the field for the ID of the thread which is waiting
     for us.  This is a self-reference in case the thread is created
     detached.  */
  pd->joinid = iattr->flags & ATTR_FLAG_DETACHSTATE ? pd : NULL;

  /* The debug events are inherited from the parent.  */
  pd->eventbuf = THREAD_SELF->eventbuf;


  /* Determine scheduling parameters for the thread.
     XXX How to determine whether scheduling handling is needed?  */
  if (0 && attr != NULL)
    {
      if (iattr->flags & ATTR_FLAG_NOTINHERITSCHED)
	{
	  /* Use the scheduling parameters the user provided.  */
	  pd->schedpolicy = iattr->schedpolicy;
	  memcpy (&pd->schedparam, &iattr->schedparam,
		  sizeof (struct sched_param));
	}
      else
	{
	  /* Just store the scheduling attributes of the parent.  */
	  pd->schedpolicy = __sched_getscheduler (0);
	  __sched_getparam (0, &pd->schedparam);
	}
    }

  /* Pass the descriptor to the caller.  */
  *newthread = (pthread_t) pd;

  /* Start the thread.  */
  err = create_thread (pd, STACK_VARIABLES_ARGS);
  if (err != 0)
    {
      /* Something went wrong.  Free the resources.  */
      __deallocate_stack (pd);
      return err;
    }

  return 0;
}
versioned_symbol (libpthread, __pthread_create_2_1, pthread_create, GLIBC_2_1);


#if SHLIB_COMPAT(libpthread, GLIBC_2_0, GLIBC_2_1)
int
__pthread_create_2_0 (newthread, attr, start_routine, arg)
     pthread_t *newthread;
     const pthread_attr_t *attr;
     void *(*start_routine) (void *);
     void *arg;
{
  /* The ATTR attribute is not really of type `pthread_attr_t *'.  It has
     the old size and access to the new members might crash the program.
     We convert the struct now.  */
  struct pthread_attr new_attr;

  if (attr != NULL)
    {
      struct pthread_attr *iattr = (struct pthread_attr *) attr;
      size_t ps = __getpagesize ();

      /* Copy values from the user-provided attributes.  */
      new_attr.schedparam = iattr->schedparam;
      new_attr.schedpolicy = iattr->schedpolicy;
      new_attr.flags = iattr->flags;

      /* Fill in default values for the fields not present in the old
	 implementation.  */
      new_attr.guardsize = ps;
      new_attr.stackaddr = NULL;
      new_attr.stacksize = 0;

      /* We will pass this value on to the real implementation.  */
      attr = (pthread_attr_t *) &new_attr;
    }

  return __pthread_create_2_1 (newthread, attr, start_routine, arg);
}
compat_symbol (libpthread, __pthread_create_2_0, pthread_create,
	       GLIBC_2_0);
#endif