| /* sem_wait -- wait on a semaphore. Generic futex-using version. |
| Copyright (C) 2003, 2007 Free Software Foundation, Inc. |
| This file is part of the GNU C Library. |
| Contributed by Paul Mackerras <paulus@au.ibm.com>, 2003. |
| |
| 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 <sysdep.h> |
| #include <lowlevellock.h> |
| #include <internaltypes.h> |
| #include <semaphore.h> |
| |
| #include <pthreadP.h> |
| #include <shlib-compat.h> |
| |
| |
| void |
| attribute_hidden |
| __sem_wait_cleanup (void *arg) |
| { |
| struct new_sem *isem = (struct new_sem *) arg; |
| |
| atomic_decrement (&isem->nwaiters); |
| } |
| |
| |
| int |
| __new_sem_wait (sem_t *sem) |
| { |
| struct new_sem *isem = (struct new_sem *) sem; |
| int err; |
| |
| if (atomic_decrement_if_positive (&isem->value) > 0) |
| return 0; |
| |
| atomic_increment (&isem->nwaiters); |
| |
| pthread_cleanup_push (__sem_wait_cleanup, isem); |
| |
| while (1) |
| { |
| /* Enable asynchronous cancellation. Required by the standard. */ |
| int oldtype = __pthread_enable_asynccancel (); |
| |
| err = lll_futex_wait (&isem->value, 0, |
| isem->private ^ FUTEX_PRIVATE_FLAG); |
| |
| /* Disable asynchronous cancellation. */ |
| __pthread_disable_asynccancel (oldtype); |
| |
| if (err != 0 && err != -EWOULDBLOCK) |
| { |
| __set_errno (-err); |
| err = -1; |
| break; |
| } |
| |
| if (atomic_decrement_if_positive (&isem->value) > 0) |
| { |
| err = 0; |
| break; |
| } |
| } |
| |
| pthread_cleanup_pop (0); |
| |
| atomic_decrement (&isem->nwaiters); |
| |
| return err; |
| } |
| versioned_symbol (libpthread, __new_sem_wait, sem_wait, GLIBC_2_1); |
| |
| |
| #if SHLIB_COMPAT (libpthread, GLIBC_2_0, GLIBC_2_1) |
| int |
| attribute_compat_text_section |
| __old_sem_wait (sem_t *sem) |
| { |
| int *futex = (int *) sem; |
| int err; |
| |
| do |
| { |
| if (atomic_decrement_if_positive (futex) > 0) |
| return 0; |
| |
| /* Enable asynchronous cancellation. Required by the standard. */ |
| int oldtype = __pthread_enable_asynccancel (); |
| |
| /* Always assume the semaphore is shared. */ |
| err = lll_futex_wait (futex, 0, LLL_SHARED); |
| |
| /* Disable asynchronous cancellation. */ |
| __pthread_disable_asynccancel (oldtype); |
| } |
| while (err == 0 || err == -EWOULDBLOCK); |
| |
| __set_errno (-err); |
| return -1; |
| } |
| |
| compat_symbol (libpthread, __old_sem_wait, sem_wait, GLIBC_2_0); |
| #endif |