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622 lines
18 KiB
C
622 lines
18 KiB
C
/* Copyright (C) 2002-2018 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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Contributed by Ulrich Drepper <drepper@redhat.com>, 2002.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, see
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<http://www.gnu.org/licenses/>. */
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#include <assert.h>
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#include <errno.h>
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#include <stdlib.h>
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#include <unistd.h>
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#include <sys/param.h>
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#include <not-cancel.h>
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#include "pthreadP.h"
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#include <atomic.h>
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#include <lowlevellock.h>
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#include <stap-probe.h>
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#ifndef lll_lock_elision
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#define lll_lock_elision(lock, try_lock, private) ({ \
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lll_lock (lock, private); 0; })
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#endif
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#ifndef lll_trylock_elision
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#define lll_trylock_elision(a,t) lll_trylock(a)
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#endif
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/* Some of the following definitions differ when pthread_mutex_cond_lock.c
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includes this file. */
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#ifndef LLL_MUTEX_LOCK
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# define LLL_MUTEX_LOCK(mutex) \
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lll_lock ((mutex)->__data.__lock, PTHREAD_MUTEX_PSHARED (mutex))
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# define LLL_MUTEX_TRYLOCK(mutex) \
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lll_trylock ((mutex)->__data.__lock)
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# define LLL_ROBUST_MUTEX_LOCK_MODIFIER 0
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# define LLL_MUTEX_LOCK_ELISION(mutex) \
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lll_lock_elision ((mutex)->__data.__lock, (mutex)->__data.__elision, \
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PTHREAD_MUTEX_PSHARED (mutex))
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# define LLL_MUTEX_TRYLOCK_ELISION(mutex) \
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lll_trylock_elision((mutex)->__data.__lock, (mutex)->__data.__elision, \
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PTHREAD_MUTEX_PSHARED (mutex))
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#endif
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#ifndef FORCE_ELISION
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#define FORCE_ELISION(m, s)
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#endif
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static int __pthread_mutex_lock_full (pthread_mutex_t *mutex)
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__attribute_noinline__;
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int
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__pthread_mutex_lock (pthread_mutex_t *mutex)
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{
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unsigned int type = PTHREAD_MUTEX_TYPE_ELISION (mutex);
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LIBC_PROBE (mutex_entry, 1, mutex);
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if (__builtin_expect (type & ~(PTHREAD_MUTEX_KIND_MASK_NP
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| PTHREAD_MUTEX_ELISION_FLAGS_NP), 0))
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return __pthread_mutex_lock_full (mutex);
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if (__glibc_likely (type == PTHREAD_MUTEX_TIMED_NP))
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{
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FORCE_ELISION (mutex, goto elision);
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simple:
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/* Normal mutex. */
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LLL_MUTEX_LOCK (mutex);
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assert (mutex->__data.__owner == 0);
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}
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#ifdef HAVE_ELISION
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else if (__glibc_likely (type == PTHREAD_MUTEX_TIMED_ELISION_NP))
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{
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elision: __attribute__((unused))
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/* This case can never happen on a system without elision,
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as the mutex type initialization functions will not
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allow to set the elision flags. */
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/* Don't record owner or users for elision case. This is a
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tail call. */
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return LLL_MUTEX_LOCK_ELISION (mutex);
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}
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#endif
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else if (__builtin_expect (PTHREAD_MUTEX_TYPE (mutex)
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== PTHREAD_MUTEX_RECURSIVE_NP, 1))
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{
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/* Recursive mutex. */
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pid_t id = THREAD_GETMEM (THREAD_SELF, tid);
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/* Check whether we already hold the mutex. */
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if (mutex->__data.__owner == id)
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{
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/* Just bump the counter. */
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if (__glibc_unlikely (mutex->__data.__count + 1 == 0))
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/* Overflow of the counter. */
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return EAGAIN;
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++mutex->__data.__count;
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return 0;
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}
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/* We have to get the mutex. */
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LLL_MUTEX_LOCK (mutex);
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assert (mutex->__data.__owner == 0);
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mutex->__data.__count = 1;
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}
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else if (__builtin_expect (PTHREAD_MUTEX_TYPE (mutex)
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== PTHREAD_MUTEX_ADAPTIVE_NP, 1))
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{
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if (! __is_smp)
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goto simple;
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if (LLL_MUTEX_TRYLOCK (mutex) != 0)
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{
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int cnt = 0;
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int max_cnt = MIN (MAX_ADAPTIVE_COUNT,
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mutex->__data.__spins * 2 + 10);
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do
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{
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if (cnt++ >= max_cnt)
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{
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LLL_MUTEX_LOCK (mutex);
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break;
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}
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atomic_spin_nop ();
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}
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while (LLL_MUTEX_TRYLOCK (mutex) != 0);
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mutex->__data.__spins += (cnt - mutex->__data.__spins) / 8;
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}
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assert (mutex->__data.__owner == 0);
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}
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else
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{
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pid_t id = THREAD_GETMEM (THREAD_SELF, tid);
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assert (PTHREAD_MUTEX_TYPE (mutex) == PTHREAD_MUTEX_ERRORCHECK_NP);
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/* Check whether we already hold the mutex. */
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if (__glibc_unlikely (mutex->__data.__owner == id))
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return EDEADLK;
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goto simple;
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}
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pid_t id = THREAD_GETMEM (THREAD_SELF, tid);
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/* Record the ownership. */
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mutex->__data.__owner = id;
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#ifndef NO_INCR
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++mutex->__data.__nusers;
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#endif
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LIBC_PROBE (mutex_acquired, 1, mutex);
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return 0;
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}
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static int
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__pthread_mutex_lock_full (pthread_mutex_t *mutex)
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{
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int oldval;
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pid_t id = THREAD_GETMEM (THREAD_SELF, tid);
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switch (PTHREAD_MUTEX_TYPE (mutex))
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{
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case PTHREAD_MUTEX_ROBUST_RECURSIVE_NP:
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case PTHREAD_MUTEX_ROBUST_ERRORCHECK_NP:
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case PTHREAD_MUTEX_ROBUST_NORMAL_NP:
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case PTHREAD_MUTEX_ROBUST_ADAPTIVE_NP:
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THREAD_SETMEM (THREAD_SELF, robust_head.list_op_pending,
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&mutex->__data.__list.__next);
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/* We need to set op_pending before starting the operation. Also
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see comments at ENQUEUE_MUTEX. */
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__asm ("" ::: "memory");
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oldval = mutex->__data.__lock;
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/* This is set to FUTEX_WAITERS iff we might have shared the
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FUTEX_WAITERS flag with other threads, and therefore need to keep it
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set to avoid lost wake-ups. We have the same requirement in the
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simple mutex algorithm.
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We start with value zero for a normal mutex, and FUTEX_WAITERS if we
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are building the special case mutexes for use from within condition
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variables. */
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unsigned int assume_other_futex_waiters = LLL_ROBUST_MUTEX_LOCK_MODIFIER;
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while (1)
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{
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/* Try to acquire the lock through a CAS from 0 (not acquired) to
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our TID | assume_other_futex_waiters. */
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if (__glibc_likely (oldval == 0))
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{
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oldval
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= atomic_compare_and_exchange_val_acq (&mutex->__data.__lock,
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id | assume_other_futex_waiters, 0);
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if (__glibc_likely (oldval == 0))
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break;
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}
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if ((oldval & FUTEX_OWNER_DIED) != 0)
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{
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/* The previous owner died. Try locking the mutex. */
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int newval = id;
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#ifdef NO_INCR
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/* We are not taking assume_other_futex_waiters into accoount
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here simply because we'll set FUTEX_WAITERS anyway. */
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newval |= FUTEX_WAITERS;
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#else
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newval |= (oldval & FUTEX_WAITERS) | assume_other_futex_waiters;
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#endif
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newval
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= atomic_compare_and_exchange_val_acq (&mutex->__data.__lock,
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newval, oldval);
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if (newval != oldval)
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{
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oldval = newval;
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continue;
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}
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/* We got the mutex. */
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mutex->__data.__count = 1;
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/* But it is inconsistent unless marked otherwise. */
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mutex->__data.__owner = PTHREAD_MUTEX_INCONSISTENT;
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/* We must not enqueue the mutex before we have acquired it.
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Also see comments at ENQUEUE_MUTEX. */
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__asm ("" ::: "memory");
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ENQUEUE_MUTEX (mutex);
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/* We need to clear op_pending after we enqueue the mutex. */
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__asm ("" ::: "memory");
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THREAD_SETMEM (THREAD_SELF, robust_head.list_op_pending, NULL);
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/* Note that we deliberately exit here. If we fall
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through to the end of the function __nusers would be
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incremented which is not correct because the old
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owner has to be discounted. If we are not supposed
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to increment __nusers we actually have to decrement
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it here. */
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#ifdef NO_INCR
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--mutex->__data.__nusers;
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#endif
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return EOWNERDEAD;
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}
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/* Check whether we already hold the mutex. */
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if (__glibc_unlikely ((oldval & FUTEX_TID_MASK) == id))
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{
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int kind = PTHREAD_MUTEX_TYPE (mutex);
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if (kind == PTHREAD_MUTEX_ROBUST_ERRORCHECK_NP)
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{
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/* We do not need to ensure ordering wrt another memory
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access. Also see comments at ENQUEUE_MUTEX. */
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THREAD_SETMEM (THREAD_SELF, robust_head.list_op_pending,
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NULL);
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return EDEADLK;
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}
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if (kind == PTHREAD_MUTEX_ROBUST_RECURSIVE_NP)
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{
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/* We do not need to ensure ordering wrt another memory
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access. */
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THREAD_SETMEM (THREAD_SELF, robust_head.list_op_pending,
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NULL);
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/* Just bump the counter. */
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if (__glibc_unlikely (mutex->__data.__count + 1 == 0))
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/* Overflow of the counter. */
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return EAGAIN;
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++mutex->__data.__count;
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return 0;
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}
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}
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/* We cannot acquire the mutex nor has its owner died. Thus, try
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to block using futexes. Set FUTEX_WAITERS if necessary so that
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other threads are aware that there are potentially threads
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blocked on the futex. Restart if oldval changed in the
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meantime. */
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if ((oldval & FUTEX_WAITERS) == 0)
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{
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if (atomic_compare_and_exchange_bool_acq (&mutex->__data.__lock,
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oldval | FUTEX_WAITERS,
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oldval)
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!= 0)
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{
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oldval = mutex->__data.__lock;
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continue;
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}
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oldval |= FUTEX_WAITERS;
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}
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/* It is now possible that we share the FUTEX_WAITERS flag with
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another thread; therefore, update assume_other_futex_waiters so
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that we do not forget about this when handling other cases
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above and thus do not cause lost wake-ups. */
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assume_other_futex_waiters |= FUTEX_WAITERS;
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/* Block using the futex and reload current lock value. */
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lll_futex_wait (&mutex->__data.__lock, oldval,
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PTHREAD_ROBUST_MUTEX_PSHARED (mutex));
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oldval = mutex->__data.__lock;
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}
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/* We have acquired the mutex; check if it is still consistent. */
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if (__builtin_expect (mutex->__data.__owner
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== PTHREAD_MUTEX_NOTRECOVERABLE, 0))
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{
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/* This mutex is now not recoverable. */
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mutex->__data.__count = 0;
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int private = PTHREAD_ROBUST_MUTEX_PSHARED (mutex);
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lll_unlock (mutex->__data.__lock, private);
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/* FIXME This violates the mutex destruction requirements. See
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__pthread_mutex_unlock_full. */
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THREAD_SETMEM (THREAD_SELF, robust_head.list_op_pending, NULL);
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return ENOTRECOVERABLE;
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}
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mutex->__data.__count = 1;
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/* We must not enqueue the mutex before we have acquired it.
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Also see comments at ENQUEUE_MUTEX. */
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__asm ("" ::: "memory");
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ENQUEUE_MUTEX (mutex);
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/* We need to clear op_pending after we enqueue the mutex. */
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__asm ("" ::: "memory");
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THREAD_SETMEM (THREAD_SELF, robust_head.list_op_pending, NULL);
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break;
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/* The PI support requires the Linux futex system call. If that's not
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available, pthread_mutex_init should never have allowed the type to
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be set. So it will get the default case for an invalid type. */
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#ifdef __NR_futex
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case PTHREAD_MUTEX_PI_RECURSIVE_NP:
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case PTHREAD_MUTEX_PI_ERRORCHECK_NP:
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case PTHREAD_MUTEX_PI_NORMAL_NP:
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case PTHREAD_MUTEX_PI_ADAPTIVE_NP:
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case PTHREAD_MUTEX_PI_ROBUST_RECURSIVE_NP:
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case PTHREAD_MUTEX_PI_ROBUST_ERRORCHECK_NP:
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case PTHREAD_MUTEX_PI_ROBUST_NORMAL_NP:
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case PTHREAD_MUTEX_PI_ROBUST_ADAPTIVE_NP:
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{
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int kind = mutex->__data.__kind & PTHREAD_MUTEX_KIND_MASK_NP;
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int robust = mutex->__data.__kind & PTHREAD_MUTEX_ROBUST_NORMAL_NP;
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if (robust)
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{
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/* Note: robust PI futexes are signaled by setting bit 0. */
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THREAD_SETMEM (THREAD_SELF, robust_head.list_op_pending,
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(void *) (((uintptr_t) &mutex->__data.__list.__next)
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| 1));
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/* We need to set op_pending before starting the operation. Also
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see comments at ENQUEUE_MUTEX. */
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__asm ("" ::: "memory");
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}
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oldval = mutex->__data.__lock;
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/* Check whether we already hold the mutex. */
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if (__glibc_unlikely ((oldval & FUTEX_TID_MASK) == id))
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{
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if (kind == PTHREAD_MUTEX_ERRORCHECK_NP)
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{
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/* We do not need to ensure ordering wrt another memory
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access. */
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THREAD_SETMEM (THREAD_SELF, robust_head.list_op_pending, NULL);
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return EDEADLK;
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}
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if (kind == PTHREAD_MUTEX_RECURSIVE_NP)
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{
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/* We do not need to ensure ordering wrt another memory
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access. */
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THREAD_SETMEM (THREAD_SELF, robust_head.list_op_pending, NULL);
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/* Just bump the counter. */
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if (__glibc_unlikely (mutex->__data.__count + 1 == 0))
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/* Overflow of the counter. */
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return EAGAIN;
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++mutex->__data.__count;
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return 0;
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}
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}
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int newval = id;
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# ifdef NO_INCR
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newval |= FUTEX_WAITERS;
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# endif
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oldval = atomic_compare_and_exchange_val_acq (&mutex->__data.__lock,
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newval, 0);
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if (oldval != 0)
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{
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/* The mutex is locked. The kernel will now take care of
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everything. */
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int private = (robust
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? PTHREAD_ROBUST_MUTEX_PSHARED (mutex)
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: PTHREAD_MUTEX_PSHARED (mutex));
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INTERNAL_SYSCALL_DECL (__err);
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int e = INTERNAL_SYSCALL (futex, __err, 4, &mutex->__data.__lock,
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__lll_private_flag (FUTEX_LOCK_PI,
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private), 1, 0);
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if (INTERNAL_SYSCALL_ERROR_P (e, __err)
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&& (INTERNAL_SYSCALL_ERRNO (e, __err) == ESRCH
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|| INTERNAL_SYSCALL_ERRNO (e, __err) == EDEADLK))
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{
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assert (INTERNAL_SYSCALL_ERRNO (e, __err) != EDEADLK
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|| (kind != PTHREAD_MUTEX_ERRORCHECK_NP
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&& kind != PTHREAD_MUTEX_RECURSIVE_NP));
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/* ESRCH can happen only for non-robust PI mutexes where
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the owner of the lock died. */
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assert (INTERNAL_SYSCALL_ERRNO (e, __err) != ESRCH || !robust);
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/* Delay the thread indefinitely. */
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while (1)
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__pause_nocancel ();
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}
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oldval = mutex->__data.__lock;
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assert (robust || (oldval & FUTEX_OWNER_DIED) == 0);
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}
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if (__glibc_unlikely (oldval & FUTEX_OWNER_DIED))
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{
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atomic_and (&mutex->__data.__lock, ~FUTEX_OWNER_DIED);
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/* We got the mutex. */
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mutex->__data.__count = 1;
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/* But it is inconsistent unless marked otherwise. */
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mutex->__data.__owner = PTHREAD_MUTEX_INCONSISTENT;
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/* We must not enqueue the mutex before we have acquired it.
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Also see comments at ENQUEUE_MUTEX. */
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__asm ("" ::: "memory");
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ENQUEUE_MUTEX_PI (mutex);
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/* We need to clear op_pending after we enqueue the mutex. */
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__asm ("" ::: "memory");
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THREAD_SETMEM (THREAD_SELF, robust_head.list_op_pending, NULL);
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/* Note that we deliberately exit here. If we fall
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through to the end of the function __nusers would be
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incremented which is not correct because the old owner
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has to be discounted. If we are not supposed to
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increment __nusers we actually have to decrement it here. */
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# ifdef NO_INCR
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--mutex->__data.__nusers;
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# endif
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return EOWNERDEAD;
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}
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if (robust
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&& __builtin_expect (mutex->__data.__owner
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== PTHREAD_MUTEX_NOTRECOVERABLE, 0))
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{
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/* This mutex is now not recoverable. */
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mutex->__data.__count = 0;
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INTERNAL_SYSCALL_DECL (__err);
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INTERNAL_SYSCALL (futex, __err, 4, &mutex->__data.__lock,
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__lll_private_flag (FUTEX_UNLOCK_PI,
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PTHREAD_ROBUST_MUTEX_PSHARED (mutex)),
|
|
0, 0);
|
|
|
|
/* To the kernel, this will be visible after the kernel has
|
|
acquired the mutex in the syscall. */
|
|
THREAD_SETMEM (THREAD_SELF, robust_head.list_op_pending, NULL);
|
|
return ENOTRECOVERABLE;
|
|
}
|
|
|
|
mutex->__data.__count = 1;
|
|
if (robust)
|
|
{
|
|
/* We must not enqueue the mutex before we have acquired it.
|
|
Also see comments at ENQUEUE_MUTEX. */
|
|
__asm ("" ::: "memory");
|
|
ENQUEUE_MUTEX_PI (mutex);
|
|
/* We need to clear op_pending after we enqueue the mutex. */
|
|
__asm ("" ::: "memory");
|
|
THREAD_SETMEM (THREAD_SELF, robust_head.list_op_pending, NULL);
|
|
}
|
|
}
|
|
break;
|
|
#endif /* __NR_futex. */
|
|
|
|
case PTHREAD_MUTEX_PP_RECURSIVE_NP:
|
|
case PTHREAD_MUTEX_PP_ERRORCHECK_NP:
|
|
case PTHREAD_MUTEX_PP_NORMAL_NP:
|
|
case PTHREAD_MUTEX_PP_ADAPTIVE_NP:
|
|
{
|
|
int kind = mutex->__data.__kind & PTHREAD_MUTEX_KIND_MASK_NP;
|
|
|
|
oldval = mutex->__data.__lock;
|
|
|
|
/* Check whether we already hold the mutex. */
|
|
if (mutex->__data.__owner == id)
|
|
{
|
|
if (kind == PTHREAD_MUTEX_ERRORCHECK_NP)
|
|
return EDEADLK;
|
|
|
|
if (kind == PTHREAD_MUTEX_RECURSIVE_NP)
|
|
{
|
|
/* Just bump the counter. */
|
|
if (__glibc_unlikely (mutex->__data.__count + 1 == 0))
|
|
/* Overflow of the counter. */
|
|
return EAGAIN;
|
|
|
|
++mutex->__data.__count;
|
|
|
|
return 0;
|
|
}
|
|
}
|
|
|
|
int oldprio = -1, ceilval;
|
|
do
|
|
{
|
|
int ceiling = (oldval & PTHREAD_MUTEX_PRIO_CEILING_MASK)
|
|
>> PTHREAD_MUTEX_PRIO_CEILING_SHIFT;
|
|
|
|
if (__pthread_current_priority () > ceiling)
|
|
{
|
|
if (oldprio != -1)
|
|
__pthread_tpp_change_priority (oldprio, -1);
|
|
return EINVAL;
|
|
}
|
|
|
|
int retval = __pthread_tpp_change_priority (oldprio, ceiling);
|
|
if (retval)
|
|
return retval;
|
|
|
|
ceilval = ceiling << PTHREAD_MUTEX_PRIO_CEILING_SHIFT;
|
|
oldprio = ceiling;
|
|
|
|
oldval
|
|
= atomic_compare_and_exchange_val_acq (&mutex->__data.__lock,
|
|
#ifdef NO_INCR
|
|
ceilval | 2,
|
|
#else
|
|
ceilval | 1,
|
|
#endif
|
|
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);
|
|
}
|
|
while ((oldval & PTHREAD_MUTEX_PRIO_CEILING_MASK) != ceilval);
|
|
|
|
assert (mutex->__data.__owner == 0);
|
|
mutex->__data.__count = 1;
|
|
}
|
|
break;
|
|
|
|
default:
|
|
/* Correct code cannot set any other type. */
|
|
return EINVAL;
|
|
}
|
|
|
|
/* Record the ownership. */
|
|
mutex->__data.__owner = id;
|
|
#ifndef NO_INCR
|
|
++mutex->__data.__nusers;
|
|
#endif
|
|
|
|
LIBC_PROBE (mutex_acquired, 1, mutex);
|
|
|
|
return 0;
|
|
}
|
|
#ifndef __pthread_mutex_lock
|
|
weak_alias (__pthread_mutex_lock, pthread_mutex_lock)
|
|
hidden_def (__pthread_mutex_lock)
|
|
#endif
|
|
|
|
|
|
#ifdef NO_INCR
|
|
void
|
|
__pthread_mutex_cond_lock_adjust (pthread_mutex_t *mutex)
|
|
{
|
|
assert ((mutex->__data.__kind & PTHREAD_MUTEX_PRIO_INHERIT_NP) != 0);
|
|
assert ((mutex->__data.__kind & PTHREAD_MUTEX_ROBUST_NORMAL_NP) == 0);
|
|
assert ((mutex->__data.__kind & PTHREAD_MUTEX_PSHARED_BIT) == 0);
|
|
|
|
/* Record the ownership. */
|
|
pid_t id = THREAD_GETMEM (THREAD_SELF, tid);
|
|
mutex->__data.__owner = id;
|
|
|
|
if (mutex->__data.__kind == PTHREAD_MUTEX_PI_RECURSIVE_NP)
|
|
++mutex->__data.__count;
|
|
}
|
|
#endif
|