diff options
Diffstat (limited to 'nptl/sysdeps/unix/sysv/linux/s390/pthread_once.c')
| -rw-r--r-- | nptl/sysdeps/unix/sysv/linux/s390/pthread_once.c | 111 |
1 files changed, 111 insertions, 0 deletions
diff --git a/nptl/sysdeps/unix/sysv/linux/s390/pthread_once.c b/nptl/sysdeps/unix/sysv/linux/s390/pthread_once.c new file mode 100644 index 0000000000..f29e23fd4b --- /dev/null +++ b/nptl/sysdeps/unix/sysv/linux/s390/pthread_once.c @@ -0,0 +1,111 @@ +/* Copyright (C) 2003 Free Software Foundation, Inc. + This file is part of the GNU C Library. + Contributed by Martin Schwidefsky <schwidefsky@de.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 "pthreadP.h" +#include <lowlevellock.h> + + +unsigned long int __fork_generation attribute_hidden; + + +static void +clear_once_control (void *arg) +{ + pthread_once_t *once_control = (pthread_once_t *) arg; + + *once_control = 0; + lll_futex_wake (once_control, INT_MAX); +} + + +int +__pthread_once (once_control, init_routine) + pthread_once_t *once_control; + void (*init_routine) (void); +{ + while (1) + { + int oldval; + int newval; + + /* Pseudo code: + oldval = *once_control; + if ((oldval & 2) == 0) + { + newval = (oldval & 3) | __fork_generation | 1; + *once_control = newval; + } + Do this atomically. */ + __asm __volatile (" l %1,%0\n" + "0: lhi %2,2\n" + " tml %1,2\n" + " jnz 1f\n" + " nr %2,%1\n" + " ahi %2,1\n" + " o %2,%3\n" + " cs %1,%2,%0\n" + " jl 0b\n" + "1:" + : "=Q" (*once_control), "=&d" (oldval), "=&d" (newval) + : "m" (__fork_generation), "m" (*once_control) + : "cc" ); + /* Check if the initialized has already been done. */ + if ((oldval & 2) != 0) + break; + /* Check if another thread already runs the initializer. */ + if ((oldval & 1) != 0) + { + /* Check whether the initializer execution was interrupted + by a fork. */ + if (((oldval ^ newval) & -4) == 0) + { + /* Same generation, some other thread was faster. Wait. */ + lll_futex_wait (once_control, newval); + continue; + } + } + + /* This thread is the first here. Do the initialization. + Register a cleanup handler so that in case the thread gets + interrupted the initialization can be restarted. */ + pthread_cleanup_push (clear_once_control, once_control); + + init_routine (); + + pthread_cleanup_pop (0); + + + /* Add one to *once_control. */ + __asm __volatile (" l %1,%0\n" + "0: lr %2,%1\n" + " ahi %2,1\n" + " cs %1,%2,%0\n" + " jl 0b\n" + : "=Q" (*once_control), "=&d" (oldval), "=&d" (newval) + : "m" (*once_control) : "cc" ); + + /* Wake up all other threads. */ + lll_futex_wake (once_control, INT_MAX); + break; + } + + return 0; +} +weak_alias (__pthread_once, pthread_once) +strong_alias (__pthread_once, __pthread_once_internal) |