diff options
Diffstat (limited to 'REORG.TODO/nptl/pthread_mutex_setprioceiling.c')
| -rw-r--r-- | REORG.TODO/nptl/pthread_mutex_setprioceiling.c | 121 |
1 files changed, 121 insertions, 0 deletions
diff --git a/REORG.TODO/nptl/pthread_mutex_setprioceiling.c b/REORG.TODO/nptl/pthread_mutex_setprioceiling.c new file mode 100644 index 0000000000..18b0763ba1 --- /dev/null +++ b/REORG.TODO/nptl/pthread_mutex_setprioceiling.c @@ -0,0 +1,121 @@ +/* Set current priority ceiling of pthread_mutex_t. + Copyright (C) 2006-2017 Free Software Foundation, Inc. + This file is part of the GNU C Library. + Contributed by Jakub Jelinek <jakub@redhat.com>, 2006. + + 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 <stdbool.h> +#include <errno.h> +#include <pthreadP.h> +#include <atomic.h> + + +int +pthread_mutex_setprioceiling (pthread_mutex_t *mutex, int prioceiling, + int *old_ceiling) +{ + /* The low bits of __kind aren't ever changed after pthread_mutex_init, + so we don't need a lock yet. */ + if ((mutex->__data.__kind & PTHREAD_MUTEX_PRIO_PROTECT_NP) == 0) + return EINVAL; + + /* See __init_sched_fifo_prio. */ + if (atomic_load_relaxed (&__sched_fifo_min_prio) == -1 + || atomic_load_relaxed (&__sched_fifo_max_prio) == -1) + __init_sched_fifo_prio (); + + if (__glibc_unlikely (prioceiling + < atomic_load_relaxed (&__sched_fifo_min_prio)) + || __glibc_unlikely (prioceiling + > atomic_load_relaxed (&__sched_fifo_max_prio)) + || __glibc_unlikely ((prioceiling + & (PTHREAD_MUTEXATTR_PRIO_CEILING_MASK + >> PTHREAD_MUTEXATTR_PRIO_CEILING_SHIFT)) + != prioceiling)) + return EINVAL; + + /* Check whether we already hold the mutex. */ + bool locked = false; + int kind = PTHREAD_MUTEX_TYPE (mutex); + if (mutex->__data.__owner == THREAD_GETMEM (THREAD_SELF, tid)) + { + if (kind == PTHREAD_MUTEX_PP_ERRORCHECK_NP) + return EDEADLK; + + if (kind == PTHREAD_MUTEX_PP_RECURSIVE_NP) + locked = true; + } + + int oldval = mutex->__data.__lock; + if (! locked) + do + { + /* Need to lock the mutex, but without obeying the priority + protect protocol. */ + int ceilval = (oldval & PTHREAD_MUTEX_PRIO_CEILING_MASK); + + oldval = atomic_compare_and_exchange_val_acq (&mutex->__data.__lock, + ceilval | 1, ceilval); + if (oldval == ceilval) + break; + + do + { + oldval + = atomic_compare_and_exchange_val_acq (&mutex->__data.__lock, + ceilval | 2, + ceilval | 1); + + if ((oldval & PTHREAD_MUTEX_PRIO_CEILING_MASK) != ceilval) + break; + + if (oldval != ceilval) + lll_futex_wait (&mutex->__data.__lock, ceilval | 2, + PTHREAD_MUTEX_PSHARED (mutex)); + } + while (atomic_compare_and_exchange_val_acq (&mutex->__data.__lock, + ceilval | 2, ceilval) + != ceilval); + + if ((oldval & PTHREAD_MUTEX_PRIO_CEILING_MASK) != ceilval) + continue; + } + while (0); + + int oldprio = (oldval & PTHREAD_MUTEX_PRIO_CEILING_MASK) + >> PTHREAD_MUTEX_PRIO_CEILING_SHIFT; + if (locked) + { + int ret = __pthread_tpp_change_priority (oldprio, prioceiling); + if (ret) + return ret; + } + + if (old_ceiling != NULL) + *old_ceiling = oldprio; + + int newlock = 0; + if (locked) + newlock = (mutex->__data.__lock & ~PTHREAD_MUTEX_PRIO_CEILING_MASK); + mutex->__data.__lock = newlock + | (prioceiling << PTHREAD_MUTEX_PRIO_CEILING_SHIFT); + atomic_full_barrier (); + + lll_futex_wake (&mutex->__data.__lock, INT_MAX, + PTHREAD_MUTEX_PSHARED (mutex)); + + return 0; +} |