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glibc/nptl/pthread_mutex_unlock.c
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/* Copyright (C) 2002-2016 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, see | |
<http://www.gnu.org/licenses/>. */ | |
#include <assert.h> | |
#include <errno.h> | |
#include <stdlib.h> | |
#include "pthreadP.h" | |
#include <lowlevellock.h> | |
#include <stap-probe.h> | |
#ifndef lll_unlock_elision | |
#define lll_unlock_elision(a,b,c) ({ lll_unlock (a,c); 0; }) | |
#endif | |
static int | |
internal_function | |
__pthread_mutex_unlock_full (pthread_mutex_t *mutex, int decr) | |
__attribute_noinline__; | |
int | |
internal_function attribute_hidden | |
__pthread_mutex_unlock_usercnt (pthread_mutex_t *mutex, int decr) | |
{ | |
int type = PTHREAD_MUTEX_TYPE_ELISION (mutex); | |
if (__builtin_expect (type & | |
~(PTHREAD_MUTEX_KIND_MASK_NP|PTHREAD_MUTEX_ELISION_FLAGS_NP), 0)) | |
return __pthread_mutex_unlock_full (mutex, decr); | |
if (__builtin_expect (type, PTHREAD_MUTEX_TIMED_NP) | |
== PTHREAD_MUTEX_TIMED_NP) | |
{ | |
/* Always reset the owner field. */ | |
normal: | |
mutex->__data.__owner = 0; | |
if (decr) | |
/* One less user. */ | |
--mutex->__data.__nusers; | |
/* Unlock. */ | |
lll_unlock (mutex->__data.__lock, PTHREAD_MUTEX_PSHARED (mutex)); | |
LIBC_PROBE (mutex_release, 1, mutex); | |
return 0; | |
} | |
else if (__glibc_likely (type == PTHREAD_MUTEX_TIMED_ELISION_NP)) | |
{ | |
/* Don't reset the owner/users fields for elision. */ | |
return lll_unlock_elision (mutex->__data.__lock, mutex->__data.__elision, | |
PTHREAD_MUTEX_PSHARED (mutex)); | |
} | |
else if (__builtin_expect (PTHREAD_MUTEX_TYPE (mutex) | |
== PTHREAD_MUTEX_RECURSIVE_NP, 1)) | |
{ | |
/* Recursive mutex. */ | |
if (mutex->__data.__owner != THREAD_GETMEM (THREAD_SELF, tid)) | |
return EPERM; | |
if (--mutex->__data.__count != 0) | |
/* We still hold the mutex. */ | |
return 0; | |
goto normal; | |
} | |
else if (__builtin_expect (PTHREAD_MUTEX_TYPE (mutex) | |
== PTHREAD_MUTEX_ADAPTIVE_NP, 1)) | |
goto normal; | |
else | |
{ | |
/* Error checking mutex. */ | |
assert (type == PTHREAD_MUTEX_ERRORCHECK_NP); | |
if (mutex->__data.__owner != THREAD_GETMEM (THREAD_SELF, tid) | |
|| ! lll_islocked (mutex->__data.__lock)) | |
return EPERM; | |
goto normal; | |
} | |
} | |
static int | |
internal_function | |
__pthread_mutex_unlock_full (pthread_mutex_t *mutex, int decr) | |
{ | |
int newowner = 0; | |
switch (PTHREAD_MUTEX_TYPE (mutex)) | |
{ | |
case PTHREAD_MUTEX_ROBUST_RECURSIVE_NP: | |
/* Recursive mutex. */ | |
if ((mutex->__data.__lock & FUTEX_TID_MASK) | |
== THREAD_GETMEM (THREAD_SELF, tid) | |
&& __builtin_expect (mutex->__data.__owner | |
== PTHREAD_MUTEX_INCONSISTENT, 0)) | |
{ | |
if (--mutex->__data.__count != 0) | |
/* We still hold the mutex. */ | |
return ENOTRECOVERABLE; | |
goto notrecoverable; | |
} | |
if (mutex->__data.__owner != THREAD_GETMEM (THREAD_SELF, tid)) | |
return EPERM; | |
if (--mutex->__data.__count != 0) | |
/* We still hold the mutex. */ | |
return 0; | |
goto robust; | |
case PTHREAD_MUTEX_ROBUST_ERRORCHECK_NP: | |
case PTHREAD_MUTEX_ROBUST_NORMAL_NP: | |
case PTHREAD_MUTEX_ROBUST_ADAPTIVE_NP: | |
if ((mutex->__data.__lock & FUTEX_TID_MASK) | |
!= THREAD_GETMEM (THREAD_SELF, tid) | |
|| ! lll_islocked (mutex->__data.__lock)) | |
return EPERM; | |
/* If the previous owner died and the caller did not succeed in | |
making the state consistent, mark the mutex as unrecoverable | |
and make all waiters. */ | |
if (__builtin_expect (mutex->__data.__owner | |
== PTHREAD_MUTEX_INCONSISTENT, 0)) | |
notrecoverable: | |
newowner = PTHREAD_MUTEX_NOTRECOVERABLE; | |
robust: | |
/* Remove mutex from the list. */ | |
THREAD_SETMEM (THREAD_SELF, robust_head.list_op_pending, | |
&mutex->__data.__list.__next); | |
DEQUEUE_MUTEX (mutex); | |
mutex->__data.__owner = newowner; | |
if (decr) | |
/* One less user. */ | |
--mutex->__data.__nusers; | |
/* Unlock. */ | |
lll_robust_unlock (mutex->__data.__lock, | |
PTHREAD_ROBUST_MUTEX_PSHARED (mutex)); | |
THREAD_SETMEM (THREAD_SELF, robust_head.list_op_pending, NULL); | |
break; | |
/* The PI support requires the Linux futex system call. If that's not | |
available, pthread_mutex_init should never have allowed the type to | |
be set. So it will get the default case for an invalid type. */ | |
#ifdef __NR_futex | |
case PTHREAD_MUTEX_PI_RECURSIVE_NP: | |
/* Recursive mutex. */ | |
if (mutex->__data.__owner != THREAD_GETMEM (THREAD_SELF, tid)) | |
return EPERM; | |
if (--mutex->__data.__count != 0) | |
/* We still hold the mutex. */ | |
return 0; | |
goto continue_pi_non_robust; | |
case PTHREAD_MUTEX_PI_ROBUST_RECURSIVE_NP: | |
/* Recursive mutex. */ | |
if ((mutex->__data.__lock & FUTEX_TID_MASK) | |
== THREAD_GETMEM (THREAD_SELF, tid) | |
&& __builtin_expect (mutex->__data.__owner | |
== PTHREAD_MUTEX_INCONSISTENT, 0)) | |
{ | |
if (--mutex->__data.__count != 0) | |
/* We still hold the mutex. */ | |
return ENOTRECOVERABLE; | |
goto pi_notrecoverable; | |
} | |
if (mutex->__data.__owner != THREAD_GETMEM (THREAD_SELF, tid)) | |
return EPERM; | |
if (--mutex->__data.__count != 0) | |
/* We still hold the mutex. */ | |
return 0; | |
goto continue_pi_robust; | |
case PTHREAD_MUTEX_PI_ERRORCHECK_NP: | |
case PTHREAD_MUTEX_PI_NORMAL_NP: | |
case PTHREAD_MUTEX_PI_ADAPTIVE_NP: | |
case PTHREAD_MUTEX_PI_ROBUST_ERRORCHECK_NP: | |
case PTHREAD_MUTEX_PI_ROBUST_NORMAL_NP: | |
case PTHREAD_MUTEX_PI_ROBUST_ADAPTIVE_NP: | |
if ((mutex->__data.__lock & FUTEX_TID_MASK) | |
!= THREAD_GETMEM (THREAD_SELF, tid) | |
|| ! lll_islocked (mutex->__data.__lock)) | |
return EPERM; | |
/* If the previous owner died and the caller did not succeed in | |
making the state consistent, mark the mutex as unrecoverable | |
and make all waiters. */ | |
if ((mutex->__data.__kind & PTHREAD_MUTEX_ROBUST_NORMAL_NP) != 0 | |
&& __builtin_expect (mutex->__data.__owner | |
== PTHREAD_MUTEX_INCONSISTENT, 0)) | |
pi_notrecoverable: | |
newowner = PTHREAD_MUTEX_NOTRECOVERABLE; | |
if ((mutex->__data.__kind & PTHREAD_MUTEX_ROBUST_NORMAL_NP) != 0) | |
{ | |
continue_pi_robust: | |
/* Remove mutex from the list. | |
Note: robust PI futexes are signaled by setting bit 0. */ | |
THREAD_SETMEM (THREAD_SELF, robust_head.list_op_pending, | |
(void *) (((uintptr_t) &mutex->__data.__list.__next) | |
| 1)); | |
DEQUEUE_MUTEX (mutex); | |
} | |
continue_pi_non_robust: | |
mutex->__data.__owner = newowner; | |
if (decr) | |
/* One less user. */ | |
--mutex->__data.__nusers; | |
/* Unlock. Load all necessary mutex data before releasing the mutex | |
to not violate the mutex destruction requirements (see | |
lll_unlock). */ | |
int robust = mutex->__data.__kind & PTHREAD_MUTEX_ROBUST_NORMAL_NP; | |
int private = (robust | |
? PTHREAD_ROBUST_MUTEX_PSHARED (mutex) | |
: PTHREAD_MUTEX_PSHARED (mutex)); | |
if ((mutex->__data.__lock & FUTEX_WAITERS) != 0 | |
|| atomic_compare_and_exchange_bool_rel (&mutex->__data.__lock, 0, | |
THREAD_GETMEM (THREAD_SELF, | |
tid))) | |
{ | |
INTERNAL_SYSCALL_DECL (__err); | |
INTERNAL_SYSCALL (futex, __err, 2, &mutex->__data.__lock, | |
__lll_private_flag (FUTEX_UNLOCK_PI, private)); | |
} | |
THREAD_SETMEM (THREAD_SELF, robust_head.list_op_pending, NULL); | |
break; | |
#endif /* __NR_futex. */ | |
case PTHREAD_MUTEX_PP_RECURSIVE_NP: | |
/* Recursive mutex. */ | |
if (mutex->__data.__owner != THREAD_GETMEM (THREAD_SELF, tid)) | |
return EPERM; | |
if (--mutex->__data.__count != 0) | |
/* We still hold the mutex. */ | |
return 0; | |
goto pp; | |
case PTHREAD_MUTEX_PP_ERRORCHECK_NP: | |
/* Error checking mutex. */ | |
if (mutex->__data.__owner != THREAD_GETMEM (THREAD_SELF, tid) | |
|| (mutex->__data.__lock & ~ PTHREAD_MUTEX_PRIO_CEILING_MASK) == 0) | |
return EPERM; | |
/* FALLTHROUGH */ | |
case PTHREAD_MUTEX_PP_NORMAL_NP: | |
case PTHREAD_MUTEX_PP_ADAPTIVE_NP: | |
/* Always reset the owner field. */ | |
pp: | |
mutex->__data.__owner = 0; | |
if (decr) | |
/* One less user. */ | |
--mutex->__data.__nusers; | |
/* Unlock. */ | |
int newval, oldval; | |
do | |
{ | |
oldval = mutex->__data.__lock; | |
newval = oldval & PTHREAD_MUTEX_PRIO_CEILING_MASK; | |
} | |
while (atomic_compare_and_exchange_bool_rel (&mutex->__data.__lock, | |
newval, oldval)); | |
if ((oldval & ~PTHREAD_MUTEX_PRIO_CEILING_MASK) > 1) | |
lll_futex_wake (&mutex->__data.__lock, 1, | |
PTHREAD_MUTEX_PSHARED (mutex)); | |
int oldprio = newval >> PTHREAD_MUTEX_PRIO_CEILING_SHIFT; | |
LIBC_PROBE (mutex_release, 1, mutex); | |
return __pthread_tpp_change_priority (oldprio, -1); | |
default: | |
/* Correct code cannot set any other type. */ | |
return EINVAL; | |
} | |
LIBC_PROBE (mutex_release, 1, mutex); | |
return 0; | |
} | |
int | |
__pthread_mutex_unlock (pthread_mutex_t *mutex) | |
{ | |
return __pthread_mutex_unlock_usercnt (mutex, 1); | |
} | |
strong_alias (__pthread_mutex_unlock, pthread_mutex_unlock) | |
hidden_def (__pthread_mutex_unlock) |