diff options
Diffstat (limited to 'REORG.TODO/nptl/pthread_mutex_timedlock.c')
| -rw-r--r-- | REORG.TODO/nptl/pthread_mutex_timedlock.c | 636 |
1 files changed, 636 insertions, 0 deletions
diff --git a/REORG.TODO/nptl/pthread_mutex_timedlock.c b/REORG.TODO/nptl/pthread_mutex_timedlock.c new file mode 100644 index 0000000000..a4beb7b0dc --- /dev/null +++ b/REORG.TODO/nptl/pthread_mutex_timedlock.c @@ -0,0 +1,636 @@ +/* Copyright (C) 2002-2017 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, see + <http://www.gnu.org/licenses/>. */ + +#include <assert.h> +#include <errno.h> +#include <time.h> +#include <sys/param.h> +#include <sys/time.h> +#include "pthreadP.h" +#include <atomic.h> +#include <lowlevellock.h> +#include <not-cancel.h> + +#include <stap-probe.h> + +#ifndef lll_timedlock_elision +#define lll_timedlock_elision(a,dummy,b,c) lll_timedlock(a, b, c) +#endif + +#ifndef lll_trylock_elision +#define lll_trylock_elision(a,t) lll_trylock(a) +#endif + +#ifndef FORCE_ELISION +#define FORCE_ELISION(m, s) +#endif + +int +pthread_mutex_timedlock (pthread_mutex_t *mutex, + const struct timespec *abstime) +{ + int oldval; + pid_t id = THREAD_GETMEM (THREAD_SELF, tid); + int result = 0; + + LIBC_PROBE (mutex_timedlock_entry, 2, mutex, abstime); + + /* We must not check ABSTIME here. If the thread does not block + abstime must not be checked for a valid value. */ + + switch (__builtin_expect (PTHREAD_MUTEX_TYPE_ELISION (mutex), + PTHREAD_MUTEX_TIMED_NP)) + { + /* Recursive mutex. */ + case PTHREAD_MUTEX_RECURSIVE_NP|PTHREAD_MUTEX_ELISION_NP: + case PTHREAD_MUTEX_RECURSIVE_NP: + /* Check whether we already hold the mutex. */ + if (mutex->__data.__owner == id) + { + /* Just bump the counter. */ + if (__glibc_unlikely (mutex->__data.__count + 1 == 0)) + /* Overflow of the counter. */ + return EAGAIN; + + ++mutex->__data.__count; + + goto out; + } + + /* We have to get the mutex. */ + result = lll_timedlock (mutex->__data.__lock, abstime, + PTHREAD_MUTEX_PSHARED (mutex)); + + if (result != 0) + goto out; + + /* Only locked once so far. */ + mutex->__data.__count = 1; + break; + + /* Error checking mutex. */ + case PTHREAD_MUTEX_ERRORCHECK_NP: + /* Check whether we already hold the mutex. */ + if (__glibc_unlikely (mutex->__data.__owner == id)) + return EDEADLK; + + /* Don't do lock elision on an error checking mutex. */ + goto simple; + + case PTHREAD_MUTEX_TIMED_NP: + FORCE_ELISION (mutex, goto elision); + simple: + /* Normal mutex. */ + result = lll_timedlock (mutex->__data.__lock, abstime, + PTHREAD_MUTEX_PSHARED (mutex)); + break; + + case PTHREAD_MUTEX_TIMED_ELISION_NP: + elision: __attribute__((unused)) + /* Don't record ownership */ + return lll_timedlock_elision (mutex->__data.__lock, + mutex->__data.__spins, + abstime, + PTHREAD_MUTEX_PSHARED (mutex)); + + + case PTHREAD_MUTEX_ADAPTIVE_NP: + if (! __is_smp) + goto simple; + + if (lll_trylock (mutex->__data.__lock) != 0) + { + int cnt = 0; + int max_cnt = MIN (MAX_ADAPTIVE_COUNT, + mutex->__data.__spins * 2 + 10); + do + { + if (cnt++ >= max_cnt) + { + result = lll_timedlock (mutex->__data.__lock, abstime, + PTHREAD_MUTEX_PSHARED (mutex)); + break; + } + atomic_spin_nop (); + } + while (lll_trylock (mutex->__data.__lock) != 0); + + mutex->__data.__spins += (cnt - mutex->__data.__spins) / 8; + } + break; + + case PTHREAD_MUTEX_ROBUST_RECURSIVE_NP: + case PTHREAD_MUTEX_ROBUST_ERRORCHECK_NP: + case PTHREAD_MUTEX_ROBUST_NORMAL_NP: + case PTHREAD_MUTEX_ROBUST_ADAPTIVE_NP: + THREAD_SETMEM (THREAD_SELF, robust_head.list_op_pending, + &mutex->__data.__list.__next); + /* We need to set op_pending before starting the operation. Also + see comments at ENQUEUE_MUTEX. */ + __asm ("" ::: "memory"); + + oldval = mutex->__data.__lock; + /* This is set to FUTEX_WAITERS iff we might have shared the + FUTEX_WAITERS flag with other threads, and therefore need to keep it + set to avoid lost wake-ups. We have the same requirement in the + simple mutex algorithm. */ + unsigned int assume_other_futex_waiters = 0; + while (1) + { + /* Try to acquire the lock through a CAS from 0 (not acquired) to + our TID | assume_other_futex_waiters. */ + if (__glibc_likely ((oldval == 0) + && (atomic_compare_and_exchange_bool_acq + (&mutex->__data.__lock, + id | assume_other_futex_waiters, 0) == 0))) + break; + + if ((oldval & FUTEX_OWNER_DIED) != 0) + { + /* The previous owner died. Try locking the mutex. */ + int newval = id | (oldval & FUTEX_WAITERS) + | assume_other_futex_waiters; + + newval + = atomic_compare_and_exchange_val_acq (&mutex->__data.__lock, + newval, oldval); + if (newval != oldval) + { + oldval = newval; + continue; + } + + /* We got the mutex. */ + mutex->__data.__count = 1; + /* But it is inconsistent unless marked otherwise. */ + mutex->__data.__owner = PTHREAD_MUTEX_INCONSISTENT; + + /* We must not enqueue the mutex before we have acquired it. + Also see comments at ENQUEUE_MUTEX. */ + __asm ("" ::: "memory"); + ENQUEUE_MUTEX (mutex); + /* We need to clear op_pending after we enqueue the mutex. */ + __asm ("" ::: "memory"); + THREAD_SETMEM (THREAD_SELF, robust_head.list_op_pending, NULL); + + /* Note that we deliberately exit here. If we fall + through to the end of the function __nusers would be + incremented which is not correct because the old + owner has to be discounted. */ + return EOWNERDEAD; + } + + /* Check whether we already hold the mutex. */ + if (__glibc_unlikely ((oldval & FUTEX_TID_MASK) == id)) + { + int kind = PTHREAD_MUTEX_TYPE (mutex); + if (kind == PTHREAD_MUTEX_ROBUST_ERRORCHECK_NP) + { + /* We do not need to ensure ordering wrt another memory + access. Also see comments at ENQUEUE_MUTEX. */ + THREAD_SETMEM (THREAD_SELF, robust_head.list_op_pending, + NULL); + return EDEADLK; + } + + if (kind == PTHREAD_MUTEX_ROBUST_RECURSIVE_NP) + { + /* We do not need to ensure ordering wrt another memory + access. */ + THREAD_SETMEM (THREAD_SELF, robust_head.list_op_pending, + NULL); + + /* Just bump the counter. */ + if (__glibc_unlikely (mutex->__data.__count + 1 == 0)) + /* Overflow of the counter. */ + return EAGAIN; + + ++mutex->__data.__count; + + LIBC_PROBE (mutex_timedlock_acquired, 1, mutex); + + return 0; + } + } + + /* We are about to block; check whether the timeout is invalid. */ + if (abstime->tv_nsec < 0 || abstime->tv_nsec >= 1000000000) + return EINVAL; + /* Work around the fact that the kernel rejects negative timeout + values despite them being valid. */ + if (__glibc_unlikely (abstime->tv_sec < 0)) + return ETIMEDOUT; +#if (!defined __ASSUME_FUTEX_CLOCK_REALTIME \ + || !defined lll_futex_timed_wait_bitset) + struct timeval tv; + struct timespec rt; + + /* Get the current time. */ + (void) __gettimeofday (&tv, NULL); + + /* Compute relative timeout. */ + rt.tv_sec = abstime->tv_sec - tv.tv_sec; + rt.tv_nsec = abstime->tv_nsec - tv.tv_usec * 1000; + if (rt.tv_nsec < 0) + { + rt.tv_nsec += 1000000000; + --rt.tv_sec; + } + + /* Already timed out? */ + if (rt.tv_sec < 0) + return ETIMEDOUT; +#endif + + /* We cannot acquire the mutex nor has its owner died. Thus, try + to block using futexes. Set FUTEX_WAITERS if necessary so that + other threads are aware that there are potentially threads + blocked on the futex. Restart if oldval changed in the + meantime. */ + if ((oldval & FUTEX_WAITERS) == 0) + { + if (atomic_compare_and_exchange_bool_acq (&mutex->__data.__lock, + oldval | FUTEX_WAITERS, + oldval) + != 0) + { + oldval = mutex->__data.__lock; + continue; + } + oldval |= FUTEX_WAITERS; + } + + /* It is now possible that we share the FUTEX_WAITERS flag with + another thread; therefore, update assume_other_futex_waiters so + that we do not forget about this when handling other cases + above and thus do not cause lost wake-ups. */ + assume_other_futex_waiters |= FUTEX_WAITERS; + + /* Block using the futex. */ +#if (!defined __ASSUME_FUTEX_CLOCK_REALTIME \ + || !defined lll_futex_timed_wait_bitset) + lll_futex_timed wait (&mutex->__data.__lock, oldval, + &rt, PTHREAD_ROBUST_MUTEX_PSHARED (mutex)); +#else + int err = lll_futex_timed_wait_bitset (&mutex->__data.__lock, + oldval, abstime, FUTEX_CLOCK_REALTIME, + PTHREAD_ROBUST_MUTEX_PSHARED (mutex)); + /* The futex call timed out. */ + if (err == -ETIMEDOUT) + return -err; +#endif + /* Reload current lock value. */ + oldval = mutex->__data.__lock; + } + + /* We have acquired the mutex; check if it is still consistent. */ + if (__builtin_expect (mutex->__data.__owner + == PTHREAD_MUTEX_NOTRECOVERABLE, 0)) + { + /* This mutex is now not recoverable. */ + mutex->__data.__count = 0; + int private = PTHREAD_ROBUST_MUTEX_PSHARED (mutex); + lll_unlock (mutex->__data.__lock, private); + /* FIXME This violates the mutex destruction requirements. See + __pthread_mutex_unlock_full. */ + THREAD_SETMEM (THREAD_SELF, robust_head.list_op_pending, NULL); + return ENOTRECOVERABLE; + } + + mutex->__data.__count = 1; + /* We must not enqueue the mutex before we have acquired it. + Also see comments at ENQUEUE_MUTEX. */ + __asm ("" ::: "memory"); + ENQUEUE_MUTEX (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; + + /* The PI support requires the Linux futex system call. If that's not + available, pthread_mutex_init should never have allowed the type to + be set. So it will get the default case for an invalid type. */ +#ifdef __NR_futex + case PTHREAD_MUTEX_PI_RECURSIVE_NP: + case PTHREAD_MUTEX_PI_ERRORCHECK_NP: + case PTHREAD_MUTEX_PI_NORMAL_NP: + case PTHREAD_MUTEX_PI_ADAPTIVE_NP: + case PTHREAD_MUTEX_PI_ROBUST_RECURSIVE_NP: + case PTHREAD_MUTEX_PI_ROBUST_ERRORCHECK_NP: + case PTHREAD_MUTEX_PI_ROBUST_NORMAL_NP: + case PTHREAD_MUTEX_PI_ROBUST_ADAPTIVE_NP: + { + int kind = mutex->__data.__kind & PTHREAD_MUTEX_KIND_MASK_NP; + int robust = mutex->__data.__kind & PTHREAD_MUTEX_ROBUST_NORMAL_NP; + + if (robust) + { + /* Note: robust PI futexes are signaled by setting bit 0. */ + THREAD_SETMEM (THREAD_SELF, robust_head.list_op_pending, + (void *) (((uintptr_t) &mutex->__data.__list.__next) + | 1)); + /* We need to set op_pending before starting the operation. Also + see comments at ENQUEUE_MUTEX. */ + __asm ("" ::: "memory"); + } + + oldval = mutex->__data.__lock; + + /* Check whether we already hold the mutex. */ + if (__glibc_unlikely ((oldval & FUTEX_TID_MASK) == id)) + { + if (kind == PTHREAD_MUTEX_ERRORCHECK_NP) + { + /* We do not need to ensure ordering wrt another memory + access. */ + THREAD_SETMEM (THREAD_SELF, robust_head.list_op_pending, NULL); + return EDEADLK; + } + + if (kind == PTHREAD_MUTEX_RECURSIVE_NP) + { + /* We do not need to ensure ordering wrt another memory + access. */ + THREAD_SETMEM (THREAD_SELF, robust_head.list_op_pending, NULL); + + /* Just bump the counter. */ + if (__glibc_unlikely (mutex->__data.__count + 1 == 0)) + /* Overflow of the counter. */ + return EAGAIN; + + ++mutex->__data.__count; + + LIBC_PROBE (mutex_timedlock_acquired, 1, mutex); + + return 0; + } + } + + oldval = atomic_compare_and_exchange_val_acq (&mutex->__data.__lock, + id, 0); + + if (oldval != 0) + { + /* The mutex is locked. The kernel will now take care of + everything. The timeout value must be a relative value. + Convert it. */ + int private = (robust + ? PTHREAD_ROBUST_MUTEX_PSHARED (mutex) + : PTHREAD_MUTEX_PSHARED (mutex)); + INTERNAL_SYSCALL_DECL (__err); + + int e = INTERNAL_SYSCALL (futex, __err, 4, &mutex->__data.__lock, + __lll_private_flag (FUTEX_LOCK_PI, + private), 1, + abstime); + if (INTERNAL_SYSCALL_ERROR_P (e, __err)) + { + if (INTERNAL_SYSCALL_ERRNO (e, __err) == ETIMEDOUT) + return ETIMEDOUT; + + if (INTERNAL_SYSCALL_ERRNO (e, __err) == ESRCH + || INTERNAL_SYSCALL_ERRNO (e, __err) == EDEADLK) + { + assert (INTERNAL_SYSCALL_ERRNO (e, __err) != EDEADLK + || (kind != PTHREAD_MUTEX_ERRORCHECK_NP + && kind != PTHREAD_MUTEX_RECURSIVE_NP)); + /* ESRCH can happen only for non-robust PI mutexes where + the owner of the lock died. */ + assert (INTERNAL_SYSCALL_ERRNO (e, __err) != ESRCH + || !robust); + + /* Delay the thread until the timeout is reached. + Then return ETIMEDOUT. */ + struct timespec reltime; + struct timespec now; + + INTERNAL_SYSCALL (clock_gettime, __err, 2, CLOCK_REALTIME, + &now); + reltime.tv_sec = abstime->tv_sec - now.tv_sec; + reltime.tv_nsec = abstime->tv_nsec - now.tv_nsec; + if (reltime.tv_nsec < 0) + { + reltime.tv_nsec += 1000000000; + --reltime.tv_sec; + } + if (reltime.tv_sec >= 0) + while (nanosleep_not_cancel (&reltime, &reltime) != 0) + continue; + + return ETIMEDOUT; + } + + return INTERNAL_SYSCALL_ERRNO (e, __err); + } + + oldval = mutex->__data.__lock; + + assert (robust || (oldval & FUTEX_OWNER_DIED) == 0); + } + + if (__glibc_unlikely (oldval & FUTEX_OWNER_DIED)) + { + atomic_and (&mutex->__data.__lock, ~FUTEX_OWNER_DIED); + + /* We got the mutex. */ + mutex->__data.__count = 1; + /* But it is inconsistent unless marked otherwise. */ + mutex->__data.__owner = PTHREAD_MUTEX_INCONSISTENT; + + /* 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); + + /* Note that we deliberately exit here. If we fall + through to the end of the function __nusers would be + incremented which is not correct because the old owner + has to be discounted. */ + return EOWNERDEAD; + } + + if (robust + && __builtin_expect (mutex->__data.__owner + == PTHREAD_MUTEX_NOTRECOVERABLE, 0)) + { + /* This mutex is now not recoverable. */ + mutex->__data.__count = 0; + + INTERNAL_SYSCALL_DECL (__err); + INTERNAL_SYSCALL (futex, __err, 4, &mutex->__data.__lock, + __lll_private_flag (FUTEX_UNLOCK_PI, + 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; + + LIBC_PROBE (mutex_timedlock_acquired, 1, mutex); + + 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) + { + result = EINVAL; + failpp: + if (oldprio != -1) + __pthread_tpp_change_priority (oldprio, -1); + return result; + } + + result = __pthread_tpp_change_priority (oldprio, ceiling); + if (result) + return result; + + ceilval = ceiling << PTHREAD_MUTEX_PRIO_CEILING_SHIFT; + oldprio = ceiling; + + 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) + { + /* Reject invalid timeouts. */ + if (abstime->tv_nsec < 0 || abstime->tv_nsec >= 1000000000) + { + result = EINVAL; + goto failpp; + } + + struct timeval tv; + struct timespec rt; + + /* Get the current time. */ + (void) __gettimeofday (&tv, NULL); + + /* Compute relative timeout. */ + rt.tv_sec = abstime->tv_sec - tv.tv_sec; + rt.tv_nsec = abstime->tv_nsec - tv.tv_usec * 1000; + if (rt.tv_nsec < 0) + { + rt.tv_nsec += 1000000000; + --rt.tv_sec; + } + + /* Already timed out? */ + if (rt.tv_sec < 0) + { + result = ETIMEDOUT; + goto failpp; + } + + lll_futex_timed_wait (&mutex->__data.__lock, + ceilval | 2, &rt, + 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; + } + + if (result == 0) + { + /* Record the ownership. */ + mutex->__data.__owner = id; + ++mutex->__data.__nusers; + + LIBC_PROBE (mutex_timedlock_acquired, 1, mutex); + } + + out: + return result; +} |