1/* Private libc-internal interface for mutex locks. NPTL version.
2 Copyright (C) 1996-2019 Free Software Foundation, Inc.
3 This file is part of the GNU C Library.
4
5 The GNU C Library is free software; you can redistribute it and/or
6 modify it under the terms of the GNU Lesser General Public License as
7 published by the Free Software Foundation; either version 2.1 of the
8 License, or (at your option) any later version.
9
10 The GNU C Library is distributed in the hope that it will be useful,
11 but WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 Lesser General Public License for more details.
14
15 You should have received a copy of the GNU Lesser General Public
16 License along with the GNU C Library; see the file COPYING.LIB. If
17 not, see <http://www.gnu.org/licenses/>. */
18
19#ifndef _LIBC_LOCKP_H
20#define _LIBC_LOCKP_H 1
21
22#include <pthread.h>
23#define __need_NULL
24#include <stddef.h>
25
26
27/* Fortunately Linux now has a mean to do locking which is realtime
28 safe without the aid of the thread library. We also need no fancy
29 options like error checking mutexes etc. We only need simple
30 locks, maybe recursive. This can be easily and cheaply implemented
31 using futexes. We will use them everywhere except in ld.so since
32 ld.so might be used on old kernels with a different libc.so. */
33#include <lowlevellock.h>
34#include <tls.h>
35#include <pthread-functions.h>
36
37#if IS_IN (libpthread)
38/* This gets us the declarations of the __pthread_* internal names,
39 and hidden_proto for them. */
40# include <nptl/pthreadP.h>
41#endif
42
43/* Mutex type. */
44#if !IS_IN (libc) && !IS_IN (libpthread)
45typedef pthread_mutex_t __libc_lock_t;
46#else
47typedef int __libc_lock_t;
48#endif
49typedef struct { pthread_mutex_t mutex; } __rtld_lock_recursive_t;
50typedef pthread_rwlock_t __libc_rwlock_t;
51
52/* Type for key to thread-specific data. */
53typedef pthread_key_t __libc_key_t;
54
55/* Define a lock variable NAME with storage class CLASS. The lock must be
56 initialized with __libc_lock_init before it can be used (or define it
57 with __libc_lock_define_initialized, below). Use `extern' for CLASS to
58 declare a lock defined in another module. In public structure
59 definitions you must use a pointer to the lock structure (i.e., NAME
60 begins with a `*'), because its storage size will not be known outside
61 of libc. */
62#define __libc_lock_define(CLASS,NAME) \
63 CLASS __libc_lock_t NAME;
64#define __libc_rwlock_define(CLASS,NAME) \
65 CLASS __libc_rwlock_t NAME;
66#define __rtld_lock_define_recursive(CLASS,NAME) \
67 CLASS __rtld_lock_recursive_t NAME;
68
69/* Define an initialized lock variable NAME with storage class CLASS.
70
71 For the C library we take a deeper look at the initializer. For
72 this implementation all fields are initialized to zero. Therefore
73 we don't initialize the variable which allows putting it into the
74 BSS section. (Except on PA-RISC and other odd architectures, where
75 initialized locks must be set to one due to the lack of normal
76 atomic operations.) */
77
78#define _LIBC_LOCK_INITIALIZER LLL_LOCK_INITIALIZER
79#if IS_IN (libc) || IS_IN (libpthread)
80# if LLL_LOCK_INITIALIZER == 0
81# define __libc_lock_define_initialized(CLASS,NAME) \
82 CLASS __libc_lock_t NAME;
83# else
84# define __libc_lock_define_initialized(CLASS,NAME) \
85 CLASS __libc_lock_t NAME = LLL_LOCK_INITIALIZER;
86# endif
87#else
88# define __libc_lock_define_initialized(CLASS,NAME) \
89 CLASS __libc_lock_t NAME;
90#endif
91
92#define __libc_rwlock_define_initialized(CLASS,NAME) \
93 CLASS __libc_rwlock_t NAME = PTHREAD_RWLOCK_INITIALIZER;
94
95#define __rtld_lock_define_initialized_recursive(CLASS,NAME) \
96 CLASS __rtld_lock_recursive_t NAME = _RTLD_LOCK_RECURSIVE_INITIALIZER;
97#define _RTLD_LOCK_RECURSIVE_INITIALIZER \
98 {PTHREAD_RECURSIVE_MUTEX_INITIALIZER_NP}
99
100#define __rtld_lock_initialize(NAME) \
101 (void) ((NAME) = (__rtld_lock_recursive_t) _RTLD_LOCK_RECURSIVE_INITIALIZER)
102
103/* If we check for a weakly referenced symbol and then perform a
104 normal jump to it te code generated for some platforms in case of
105 PIC is unnecessarily slow. What would happen is that the function
106 is first referenced as data and then it is called indirectly
107 through the PLT. We can make this a direct jump. */
108#ifdef __PIC__
109# define __libc_maybe_call(FUNC, ARGS, ELSE) \
110 (__extension__ ({ __typeof (FUNC) *_fn = (FUNC); \
111 _fn != NULL ? (*_fn) ARGS : ELSE; }))
112#else
113# define __libc_maybe_call(FUNC, ARGS, ELSE) \
114 (FUNC != NULL ? FUNC ARGS : ELSE)
115#endif
116
117/* Call thread functions through the function pointer table. */
118#if defined SHARED && IS_IN (libc)
119# define PTFAVAIL(NAME) __libc_pthread_functions_init
120# define __libc_ptf_call(FUNC, ARGS, ELSE) \
121 (__libc_pthread_functions_init ? PTHFCT_CALL (ptr_##FUNC, ARGS) : ELSE)
122# define __libc_ptf_call_always(FUNC, ARGS) \
123 PTHFCT_CALL (ptr_##FUNC, ARGS)
124#elif IS_IN (libpthread)
125# define PTFAVAIL(NAME) 1
126# define __libc_ptf_call(FUNC, ARGS, ELSE) \
127 FUNC ARGS
128# define __libc_ptf_call_always(FUNC, ARGS) \
129 FUNC ARGS
130#else
131# define PTFAVAIL(NAME) (NAME != NULL)
132# define __libc_ptf_call(FUNC, ARGS, ELSE) \
133 __libc_maybe_call (FUNC, ARGS, ELSE)
134# define __libc_ptf_call_always(FUNC, ARGS) \
135 FUNC ARGS
136#endif
137
138
139/* Initialize the named lock variable, leaving it in a consistent, unlocked
140 state. */
141#if IS_IN (libc) || IS_IN (libpthread)
142# define __libc_lock_init(NAME) \
143 ((void) ((NAME) = LLL_LOCK_INITIALIZER))
144#else
145# define __libc_lock_init(NAME) \
146 __libc_maybe_call (__pthread_mutex_init, (&(NAME), NULL), 0)
147#endif
148#if defined SHARED && IS_IN (libc)
149/* ((NAME) = (__libc_rwlock_t) PTHREAD_RWLOCK_INITIALIZER) is inefficient. */
150# define __libc_rwlock_init(NAME) \
151 ((void) __builtin_memset (&(NAME), '\0', sizeof (NAME)))
152#else
153# define __libc_rwlock_init(NAME) \
154 __libc_maybe_call (__pthread_rwlock_init, (&(NAME), NULL), 0)
155#endif
156
157/* Finalize the named lock variable, which must be locked. It cannot be
158 used again until __libc_lock_init is called again on it. This must be
159 called on a lock variable before the containing storage is reused. */
160#if IS_IN (libc) || IS_IN (libpthread)
161# define __libc_lock_fini(NAME) ((void) 0)
162#else
163# define __libc_lock_fini(NAME) \
164 __libc_maybe_call (__pthread_mutex_destroy, (&(NAME)), 0)
165#endif
166#if defined SHARED && IS_IN (libc)
167# define __libc_rwlock_fini(NAME) ((void) 0)
168#else
169# define __libc_rwlock_fini(NAME) \
170 __libc_maybe_call (__pthread_rwlock_destroy, (&(NAME)), 0)
171#endif
172
173/* Lock the named lock variable. */
174#if IS_IN (libc) || IS_IN (libpthread)
175# ifndef __libc_lock_lock
176# define __libc_lock_lock(NAME) \
177 ({ lll_lock (NAME, LLL_PRIVATE); 0; })
178# endif
179#else
180# undef __libc_lock_lock
181# define __libc_lock_lock(NAME) \
182 __libc_maybe_call (__pthread_mutex_lock, (&(NAME)), 0)
183#endif
184#define __libc_rwlock_rdlock(NAME) \
185 __libc_ptf_call (__pthread_rwlock_rdlock, (&(NAME)), 0)
186#define __libc_rwlock_wrlock(NAME) \
187 __libc_ptf_call (__pthread_rwlock_wrlock, (&(NAME)), 0)
188
189/* Try to lock the named lock variable. */
190#if IS_IN (libc) || IS_IN (libpthread)
191# ifndef __libc_lock_trylock
192# define __libc_lock_trylock(NAME) \
193 lll_trylock (NAME)
194# endif
195#else
196# undef __libc_lock_trylock
197# define __libc_lock_trylock(NAME) \
198 __libc_maybe_call (__pthread_mutex_trylock, (&(NAME)), 0)
199#endif
200#define __libc_rwlock_tryrdlock(NAME) \
201 __libc_maybe_call (__pthread_rwlock_tryrdlock, (&(NAME)), 0)
202#define __libc_rwlock_trywrlock(NAME) \
203 __libc_maybe_call (__pthread_rwlock_trywrlock, (&(NAME)), 0)
204
205#define __rtld_lock_trylock_recursive(NAME) \
206 __libc_maybe_call (__pthread_mutex_trylock, (&(NAME).mutex), 0)
207
208/* Unlock the named lock variable. */
209#if IS_IN (libc) || IS_IN (libpthread)
210# define __libc_lock_unlock(NAME) \
211 lll_unlock (NAME, LLL_PRIVATE)
212#else
213# define __libc_lock_unlock(NAME) \
214 __libc_maybe_call (__pthread_mutex_unlock, (&(NAME)), 0)
215#endif
216#define __libc_rwlock_unlock(NAME) \
217 __libc_ptf_call (__pthread_rwlock_unlock, (&(NAME)), 0)
218
219#ifdef SHARED
220# define __rtld_lock_default_lock_recursive(lock) \
221 ++((pthread_mutex_t *)(lock))->__data.__count;
222
223# define __rtld_lock_default_unlock_recursive(lock) \
224 --((pthread_mutex_t *)(lock))->__data.__count;
225
226# define __rtld_lock_lock_recursive(NAME) \
227 GL(dl_rtld_lock_recursive) (&(NAME).mutex)
228
229# define __rtld_lock_unlock_recursive(NAME) \
230 GL(dl_rtld_unlock_recursive) (&(NAME).mutex)
231#else
232# define __rtld_lock_lock_recursive(NAME) \
233 __libc_maybe_call (__pthread_mutex_lock, (&(NAME).mutex), 0)
234
235# define __rtld_lock_unlock_recursive(NAME) \
236 __libc_maybe_call (__pthread_mutex_unlock, (&(NAME).mutex), 0)
237#endif
238
239/* Define once control variable. */
240#if PTHREAD_ONCE_INIT == 0
241/* Special case for static variables where we can avoid the initialization
242 if it is zero. */
243# define __libc_once_define(CLASS, NAME) \
244 CLASS pthread_once_t NAME
245#else
246# define __libc_once_define(CLASS, NAME) \
247 CLASS pthread_once_t NAME = PTHREAD_ONCE_INIT
248#endif
249
250/* Call handler iff the first call. */
251#define __libc_once(ONCE_CONTROL, INIT_FUNCTION) \
252 do { \
253 if (PTFAVAIL (__pthread_once)) \
254 __libc_ptf_call_always (__pthread_once, (&(ONCE_CONTROL), \
255 INIT_FUNCTION)); \
256 else if ((ONCE_CONTROL) == PTHREAD_ONCE_INIT) { \
257 INIT_FUNCTION (); \
258 (ONCE_CONTROL) |= 2; \
259 } \
260 } while (0)
261
262/* Get once control variable. */
263#define __libc_once_get(ONCE_CONTROL) ((ONCE_CONTROL) != PTHREAD_ONCE_INIT)
264
265/* Note that for I/O cleanup handling we are using the old-style
266 cancel handling. It does not have to be integrated with C++ snce
267 no C++ code is called in the middle. The old-style handling is
268 faster and the support is not going away. */
269extern void _pthread_cleanup_push (struct _pthread_cleanup_buffer *buffer,
270 void (*routine) (void *), void *arg);
271extern void _pthread_cleanup_pop (struct _pthread_cleanup_buffer *buffer,
272 int execute);
273extern void _pthread_cleanup_push_defer (struct _pthread_cleanup_buffer *buffer,
274 void (*routine) (void *), void *arg);
275extern void _pthread_cleanup_pop_restore (struct _pthread_cleanup_buffer *buffer,
276 int execute);
277
278/* Sometimes we have to exit the block in the middle. */
279#define __libc_cleanup_end(DOIT) \
280 if (_avail) { \
281 __libc_ptf_call_always (_pthread_cleanup_pop_restore, (&_buffer, DOIT));\
282 } else if (DOIT) \
283 _buffer.__routine (_buffer.__arg)
284
285
286/* Normal cleanup handling, based on C cleanup attribute. */
287__extern_inline void
288__libc_cleanup_routine (struct __pthread_cleanup_frame *f)
289{
290 if (f->__do_it)
291 f->__cancel_routine (f->__cancel_arg);
292}
293
294#define __libc_cleanup_push(fct, arg) \
295 do { \
296 struct __pthread_cleanup_frame __clframe \
297 __attribute__ ((__cleanup__ (__libc_cleanup_routine))) \
298 = { .__cancel_routine = (fct), .__cancel_arg = (arg), \
299 .__do_it = 1 };
300
301#define __libc_cleanup_pop(execute) \
302 __clframe.__do_it = (execute); \
303 } while (0)
304
305
306/* Create thread-specific key. */
307#define __libc_key_create(KEY, DESTRUCTOR) \
308 __libc_ptf_call (__pthread_key_create, (KEY, DESTRUCTOR), 1)
309
310/* Get thread-specific data. */
311#define __libc_getspecific(KEY) \
312 __libc_ptf_call (__pthread_getspecific, (KEY), NULL)
313
314/* Set thread-specific data. */
315#define __libc_setspecific(KEY, VALUE) \
316 __libc_ptf_call (__pthread_setspecific, (KEY, VALUE), 0)
317
318
319/* Register handlers to execute before and after `fork'. Note that the
320 last parameter is NULL. The handlers registered by the libc are
321 never removed so this is OK. */
322extern int __register_atfork (void (*__prepare) (void),
323 void (*__parent) (void),
324 void (*__child) (void),
325 void *__dso_handle);
326
327/* Functions that are used by this file and are internal to the GNU C
328 library. */
329
330extern int __pthread_mutex_init (pthread_mutex_t *__mutex,
331 const pthread_mutexattr_t *__mutex_attr);
332
333extern int __pthread_mutex_destroy (pthread_mutex_t *__mutex);
334
335extern int __pthread_mutex_trylock (pthread_mutex_t *__mutex);
336
337extern int __pthread_mutex_lock (pthread_mutex_t *__mutex);
338
339extern int __pthread_mutex_unlock (pthread_mutex_t *__mutex);
340
341extern int __pthread_mutexattr_init (pthread_mutexattr_t *__attr);
342
343extern int __pthread_mutexattr_destroy (pthread_mutexattr_t *__attr);
344
345extern int __pthread_mutexattr_settype (pthread_mutexattr_t *__attr,
346 int __kind);
347
348extern int __pthread_rwlock_init (pthread_rwlock_t *__rwlock,
349 const pthread_rwlockattr_t *__attr);
350
351extern int __pthread_rwlock_destroy (pthread_rwlock_t *__rwlock);
352
353extern int __pthread_rwlock_rdlock (pthread_rwlock_t *__rwlock);
354
355extern int __pthread_rwlock_tryrdlock (pthread_rwlock_t *__rwlock);
356
357extern int __pthread_rwlock_wrlock (pthread_rwlock_t *__rwlock);
358
359extern int __pthread_rwlock_trywrlock (pthread_rwlock_t *__rwlock);
360
361extern int __pthread_rwlock_unlock (pthread_rwlock_t *__rwlock);
362
363extern int __pthread_key_create (pthread_key_t *__key,
364 void (*__destr_function) (void *));
365
366extern int __pthread_setspecific (pthread_key_t __key,
367 const void *__pointer);
368
369extern void *__pthread_getspecific (pthread_key_t __key);
370
371extern int __pthread_once (pthread_once_t *__once_control,
372 void (*__init_routine) (void));
373
374extern int __pthread_atfork (void (*__prepare) (void),
375 void (*__parent) (void),
376 void (*__child) (void));
377
378extern int __pthread_setcancelstate (int state, int *oldstate);
379
380
381/* Make the pthread functions weak so that we can elide them from
382 single-threaded processes. */
383#ifndef __NO_WEAK_PTHREAD_ALIASES
384# ifdef weak_extern
385weak_extern (__pthread_mutex_init)
386weak_extern (__pthread_mutex_destroy)
387weak_extern (__pthread_mutex_lock)
388weak_extern (__pthread_mutex_trylock)
389weak_extern (__pthread_mutex_unlock)
390weak_extern (__pthread_mutexattr_init)
391weak_extern (__pthread_mutexattr_destroy)
392weak_extern (__pthread_mutexattr_settype)
393weak_extern (__pthread_rwlock_init)
394weak_extern (__pthread_rwlock_destroy)
395weak_extern (__pthread_rwlock_rdlock)
396weak_extern (__pthread_rwlock_tryrdlock)
397weak_extern (__pthread_rwlock_wrlock)
398weak_extern (__pthread_rwlock_trywrlock)
399weak_extern (__pthread_rwlock_unlock)
400weak_extern (__pthread_key_create)
401weak_extern (__pthread_setspecific)
402weak_extern (__pthread_getspecific)
403weak_extern (__pthread_once)
404weak_extern (__pthread_initialize)
405weak_extern (__pthread_atfork)
406weak_extern (__pthread_setcancelstate)
407weak_extern (_pthread_cleanup_push_defer)
408weak_extern (_pthread_cleanup_pop_restore)
409# else
410# pragma weak __pthread_mutex_init
411# pragma weak __pthread_mutex_destroy
412# pragma weak __pthread_mutex_lock
413# pragma weak __pthread_mutex_trylock
414# pragma weak __pthread_mutex_unlock
415# pragma weak __pthread_mutexattr_init
416# pragma weak __pthread_mutexattr_destroy
417# pragma weak __pthread_mutexattr_settype
418# pragma weak __pthread_rwlock_destroy
419# pragma weak __pthread_rwlock_rdlock
420# pragma weak __pthread_rwlock_tryrdlock
421# pragma weak __pthread_rwlock_wrlock
422# pragma weak __pthread_rwlock_trywrlock
423# pragma weak __pthread_rwlock_unlock
424# pragma weak __pthread_key_create
425# pragma weak __pthread_setspecific
426# pragma weak __pthread_getspecific
427# pragma weak __pthread_once
428# pragma weak __pthread_initialize
429# pragma weak __pthread_atfork
430# pragma weak __pthread_setcancelstate
431# pragma weak _pthread_cleanup_push_defer
432# pragma weak _pthread_cleanup_pop_restore
433# endif
434#endif
435
436#endif /* libc-lockP.h */
437