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| -rw-r--r-- | linuxthreads/sysdeps/s390/pspinlock.c | 91 |
1 files changed, 91 insertions, 0 deletions
diff --git a/linuxthreads/sysdeps/s390/pspinlock.c b/linuxthreads/sysdeps/s390/pspinlock.c new file mode 100644 index 0000000..08231bf --- /dev/null +++ b/linuxthreads/sysdeps/s390/pspinlock.c @@ -0,0 +1,91 @@ +/* POSIX spinlock implementation. S/390 version. + Copyright (C) 2000 Free Software Foundation, Inc. + Contributed by Martin Schwidefsky (schwidefsky@de.ibm.com). + This file is part of the GNU C Library. + + The GNU C Library is free software; you can redistribute it and/or + modify it under the terms of the GNU Library General Public License as + published by the Free Software Foundation; either version 2 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 + Library General Public License for more details. + + You should have received a copy of the GNU Library General Public + License along with the GNU C Library; see the file COPYING.LIB. If not, + write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330, + Boston, MA 02111-1307, USA. */ + +#include <errno.h> +#include <pthread.h> + + +/* This implementation is similar to the one used in the Linux kernel. + But the kernel is byte instructions for the memory access. This is + faster but unusable here. The problem is that only 128 + threads/processes could use the spinlock at the same time. If (by + a design error in the program) a thread/process would hold the + spinlock for a time long enough to accumulate 128 waiting + processes, the next one will find a positive value in the spinlock + and assume it is unlocked. We cannot accept that. */ + +int +__pthread_spin_lock (pthread_spinlock_t *lock) +{ + asm volatile(" basr 1,0\n" + "0: slr 0,0\n" + " cs 0,1,%1\n" + " jl 0b\n" + : "=m" (*lock) + : "0" (*lock) : "0", "1", "cc" ); + return 0; +} +weak_alias (__pthread_spin_lock, pthread_spin_lock) + +int +__pthread_spin_trylock (pthread_spinlock_t *lock) +{ + int oldval; + + asm volatile(" slr %1,%1\n" + " basr 1,0\n" + "0: cs %1,1,%0" + : "=m" (*lock), "=&d" (oldval) + : "0" (*lock) : "1", "cc" ); + return oldval == 0 ? 0 : EBUSY; +} +weak_alias (__pthread_spin_trylock, pthread_spin_trylock) + + +int +__pthread_spin_unlock (pthread_spinlock_t *lock) +{ + asm volatile(" xc 0(4,%0),0(%0)\n" + " bcr 15,0" + : "=a" (lock) ); + return 0; +} +weak_alias (__pthread_spin_unlock, pthread_spin_unlock) + + +int +__pthread_spin_init (pthread_spinlock_t *lock, int pshared) +{ + /* We can ignore the `pshared' parameter. Since we are busy-waiting + all processes which can access the memory location `lock' points + to can use the spinlock. */ + *lock = 0; + return 0; +} +weak_alias (__pthread_spin_init, pthread_spin_init) + + +int +__pthread_spin_destroy (pthread_spinlock_t *lock) +{ + /* Nothing to do. */ + return 0; +} +weak_alias (__pthread_spin_destroy, pthread_spin_destroy) |