diff options
Diffstat (limited to 'nptl/lowlevellock.h')
-rw-r--r-- | nptl/lowlevellock.h | 90 |
1 files changed, 0 insertions, 90 deletions
diff --git a/nptl/lowlevellock.h b/nptl/lowlevellock.h deleted file mode 100644 index 338da39990..0000000000 --- a/nptl/lowlevellock.h +++ /dev/null @@ -1,90 +0,0 @@ -/* Low level locking macros used in NPTL implementation. Stub version. - Copyright (C) 2002 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 <atomic.h> - - -/* Implement generic mutex. Basic futex syscall support is required: - - lll_futex_wait(futex, value) - call sys_futex with FUTEX_WAIT - and third parameter VALUE - - lll_futex_wake(futex, value) - call sys_futex with FUTEX_WAKE - and third parameter VALUE -*/ - - -/* Mutex lock counter: - bit 31 clear means unlocked; - bit 31 set means locked. - - All code that looks at bit 31 first increases the 'number of - interested threads' usage counter, which is in bits 0-30. - - All negative mutex values indicate that the mutex is still locked. */ - - -static inline void -__generic_mutex_lock (int *mutex) -{ - unsigned int v; - - /* Bit 31 was clear, we got the mutex. (this is the fastpath). */ - if (atomic_bit_test_set (mutex, 31) == 0) - return; - - atomic_increment (mutex); - - while (1) - { - if (atomic_bit_test_set (mutex, 31) == 0) - { - atomic_decrement (mutex); - return; - } - - /* We have to wait now. First make sure the futex value we are - monitoring is truly negative (i.e. locked). */ - v = *mutex; - if (v >= 0) - continue; - - lll_futex_wait (mutex, v); - } -} - - -static inline void -__generic_mutex_unlock (int *mutex) -{ - /* Adding 0x80000000 to the counter results in 0 if and only if - there are not other interested threads - we can return (this is - the fastpath). */ - if (atomic_add_zero (mutex, 0x80000000)) - return; - - /* There are other threads waiting for this mutex, wake one of them - up. */ - lll_futex_wake (mutex, 1); -} - - -#define lll_mutex_lock(futex) __generic_mutex_lock (&(futex)) -#define lll_mutex_unlock(futex) __generic_mutex_unlock (&(futex)) |