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Add and use new glibc-internal futex API.

Browse Source 
This adds new functions for futex operations, starting with wait,
abstimed_wait, reltimed_wait, wake.  They add documentation and error
checking according to the current draft of the Linux kernel futex manpage.

Waiting with absolute or relative timeouts is split into separate functions.
This allows for removing a few cases of code duplication in pthreads code,
which uses absolute timeouts; also, it allows us to put platform-specific
code to go from an absolute to a relative timeout into the platform-specific
futex abstractions..

Futex operations that can be canceled are also split out into separate
functions suffixed by "_cancelable".

There are separate versions for both Linux and NaCl; while they currently
differ only slightly, my expectation is that the separate versions of
lowlevellock-futex.h will eventually be merged into futex-internal.h
when we get to move the lll_ functions over to the new futex API.
This commit is contained in:
Torvald Riegel 2014-12-04 14:12:23 +01:00
parent 203c1a898d
commit a2f0363f81
40 changed files with 963 additions and 492 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

70
ChangeLog
View File

@ -1,3 +1,73 @@
2015-07-10 Torvald Riegel <triegel@redhat.com>
* sysdeps/nptl/futex-internal.h: New file.
* sysdeps/nacl/futex-internal.h: New file.
* sysdeps/unix/sysv/linux/futex-internal.h: New file.
* nptl/allocatestack.c (setxid_mark_thread): Use futex wrappers with
error checking.
(setxid_unmark_thread): Likewise.
(__nptl_setxid): Likewise.
(__wait_lookup_done): Likewise.
* nptl/cancellation.c (__pthread_disable_asynccancel): Likewise.
* nptl/nptl-init.c (sighandler_setxid): Likewise.
* nptl/pthread_create.c (START_THREAD_DEFN): Likewise.
* nptl/pthread_once.c (clear_once_control): Likewise.
(__pthread_once_slow): Likewise.
* nptl/unregister-atfork.c (__unregister_atfork): Likewise.
* sysdeps/nacl/exit-thread.h (__exit_thread): Likewise.
* sysdeps/nptl/aio_misc.h (AIO_MISC_NOTIFY, AIO_MISC_WAIT): Likewise.
* sysdeps/nptl/fork.c (__libc_fork): Likewise.
* sysdeps/nptl/gai_misc.h (GAI_MISC_NOTIFY, GAI_MISC_WAIT): Likewise.
* nptl/pthread_rwlock_rdlock.c (__pthread_rwlock_rdlock_slow):
Likewise.
(__pthread_rwlock_rdlock): Likewise.
* nptl/pthread_rwlock_timedrdlock.c (pthread_rwlock_timedrdlock):
Likewise.
* nptl/pthread_rwlock_timedwrlock.c (pthread_rwlock_timedwrlock):
Likewise.
* nptl/pthread_rwlock_tryrdlock.c (__pthread_rwlock_tryrdlock):
Likewise.
* nptl/pthread_rwlock_unlock.c (__pthread_rwlock_unlock): Likewise.
* nptl/pthread_rwlock_wrlock.c (__pthread_rwlock_wrlock_slow:
Likewise.
* nptl/pthread_rwlock_init (__pthread_rwlock_init): Remove
__ASSUME_PRIVATE_FUTEX check.
* nptl/pthread_rwlockattr_setpshared (pthread_rwlockattr_setpshared):
Check that shared futexes are supported.
* nptl/pthread_barrier_wait.c (pthread_barrier_wait): Use futex
wrappers with error checking.
* nptl/pthread_barrier_init.c (pthread_barrier_init): Add comments,
remove attribute sanity check and __ASSUME_PRIVATE_FUTEX check.
* nptl/pthread_barrierattr_setpshared.c
(pthread_barrierattr_setpshared): Check that shared futexes are
supported.
* nptl/pthread_condattr_setpshared.c (pthread_condattr_setpshared):
Likewise.
* nptl/pthread_mutexattr_setpshared.c (pthread_mutexattr_setpshared):
Likewise.
* nptl/sem_init.c (futex_private_if_supported): Remove.
(__new_sem_init): Adapt and check that shared futexes are supported.
* nptl/sem_open.c (sem_open): Likewise.
* nptl/sem_post.c (futex_wake): Remove.
* nptl/sem_waitcommon.c (futex_abstimed_wait, futex_wake): Remove.
(do_futex_wait): Use futex wrappers with error checking.
* nptl/sem_wait.c: Include lowlevellock.h.
* sysdeps/sparc/nptl/pthread_barrier_init.c (__pthread_barrier_init):
Use futex_supports_pshared.
* sysdeps/sparc/nptl/pthread_barrier_wait.c (pthread_barrier_wait):
Use futex wrappers with error checking.
* sysdeps/sparc/sparc32/pthread_barrier_wait.c (pthread_barrier_wait):
Likewise.
* sysdeps/sparc/sparc32/sem_init.c (futex_private_if_supported): Remove.
* sysdeps/sparc/sparc32/sem_post.c (futex_wake): Likewise.
* sysdeps/sparc/sparc32/sem_open.c (sem_open): Use FUTEX_SHARED.
* sysdeps/sparc/sparc32/sem_waitcommon.c (futex_abstimed_wait): Remove.
(futex_wake): Likewise.
(sem_assume_only_signals_cause_futex_EINTR): Likewise.
(do_futex_wait): Use futex wrappers with error checking.
(__new_sem_wait_slow): Update EINTR handling.
* sysdeps/sparc/sparc32/sem_wait.c: Include lowlevellock.h.
2015-07-09 Martin Sebor <msebor@redhat.com>
[BZ #18435]

16
nptl/allocatestack.c
View File

@ -29,6 +29,7 @@
#include <tls.h>
#include <list.h>
#include <lowlevellock.h>
#include <futex-internal.h>
#include <kernel-features.h>
#include <stack-aliasing.h>
@ -987,7 +988,7 @@ setxid_mark_thread (struct xid_command *cmdp, struct pthread *t)
if (t->setxid_futex == -1
&& ! atomic_compare_and_exchange_bool_acq (&t->setxid_futex, -2, -1))
do
lll_futex_wait (&t->setxid_futex, -2, LLL_PRIVATE);
futex_wait_simple (&t->setxid_futex, -2, FUTEX_PRIVATE);
while (t->setxid_futex == -2);
/* Don't let the thread exit before the setxid handler runs. */
@ -1005,7 +1006,7 @@ setxid_mark_thread (struct xid_command *cmdp, struct pthread *t)
if ((ch & SETXID_BITMASK) == 0)
{
t->setxid_futex = 1;
lll_futex_wake (&t->setxid_futex, 1, LLL_PRIVATE);
futex_wake (&t->setxid_futex, 1, FUTEX_PRIVATE);
}
return;
}
@ -1032,7 +1033,7 @@ setxid_unmark_thread (struct xid_command *cmdp, struct pthread *t)
/* Release the futex just in case. */
t->setxid_futex = 1;
lll_futex_wake (&t->setxid_futex, 1, LLL_PRIVATE);
futex_wake (&t->setxid_futex, 1, FUTEX_PRIVATE);
}
@ -1141,7 +1142,8 @@ __nptl_setxid (struct xid_command *cmdp)
int cur = cmdp->cntr;
while (cur != 0)
{
lll_futex_wait (&cmdp->cntr, cur, LLL_PRIVATE);
futex_wait_simple ((unsigned int *) &cmdp->cntr, cur,
FUTEX_PRIVATE);
cur = cmdp->cntr;
}
}
@ -1251,7 +1253,8 @@ __wait_lookup_done (void)
continue;
do
lll_futex_wait (gscope_flagp, THREAD_GSCOPE_FLAG_WAIT, LLL_PRIVATE);
futex_wait_simple ((unsigned int *) gscope_flagp,
THREAD_GSCOPE_FLAG_WAIT, FUTEX_PRIVATE);
while (*gscope_flagp == THREAD_GSCOPE_FLAG_WAIT);
}
@ -1273,7 +1276,8 @@ __wait_lookup_done (void)
continue;
do
lll_futex_wait (gscope_flagp, THREAD_GSCOPE_FLAG_WAIT, LLL_PRIVATE);
futex_wait_simple ((unsigned int *) gscope_flagp,
THREAD_GSCOPE_FLAG_WAIT, FUTEX_PRIVATE);
while (*gscope_flagp == THREAD_GSCOPE_FLAG_WAIT);
}

4
nptl/cancellation.c
View File

@ -19,6 +19,7 @@
#include <setjmp.h>
#include <stdlib.h>
#include "pthreadP.h"
#include <futex-internal.h>
/* The next two functions are similar to pthread_setcanceltype() but
@ -93,7 +94,8 @@ __pthread_disable_asynccancel (int oldtype)
while (__builtin_expect ((newval & (CANCELING_BITMASK | CANCELED_BITMASK))
== CANCELING_BITMASK, 0))
{
lll_futex_wait (&self->cancelhandling, newval, LLL_PRIVATE);
futex_wait_simple ((unsigned int *) &self->cancelhandling, newval,
FUTEX_PRIVATE);
newval = THREAD_GETMEM (self, cancelhandling);
}
}

5
nptl/nptl-init.c
View File

@ -34,6 +34,7 @@
#include <shlib-compat.h>
#include <smp.h>
#include <lowlevellock.h>
#include <futex-internal.h>
#include <kernel-features.h>
#include <libc-internal.h>
#include <pthread-pids.h>
@ -279,10 +280,10 @@ sighandler_setxid (int sig, siginfo_t *si, void *ctx)
/* And release the futex. */
self->setxid_futex = 1;
lll_futex_wake (&self->setxid_futex, 1, LLL_PRIVATE);
futex_wake (&self->setxid_futex, 1, FUTEX_PRIVATE);
if (atomic_decrement_val (&__xidcmd->cntr) == 0)
lll_futex_wake (&__xidcmd->cntr, 1, LLL_PRIVATE);
futex_wake ((unsigned int *) &__xidcmd->cntr, 1, FUTEX_PRIVATE);
}
#endif

14
nptl/pthread_barrier_init.c
View File

@ -36,6 +36,7 @@ __pthread_barrier_init (barrier, attr, count)
{
struct pthread_barrier *ibarrier;
/* XXX EINVAL is not specified by POSIX as a possible error code. */
if (__glibc_unlikely (count == 0))
return EINVAL;
@ -44,11 +45,6 @@ __pthread_barrier_init (barrier, attr, count)
? iattr = (struct pthread_barrierattr *) attr
: &default_barrierattr);
if (iattr->pshared != PTHREAD_PROCESS_PRIVATE
&& __builtin_expect (iattr->pshared != PTHREAD_PROCESS_SHARED, 0))
/* Invalid attribute. */
return EINVAL;
ibarrier = (struct pthread_barrier *) barrier;
/* Initialize the individual fields. */
@ -57,14 +53,10 @@ __pthread_barrier_init (barrier, attr, count)
ibarrier->init_count = count;
ibarrier->curr_event = 0;
#ifdef __ASSUME_PRIVATE_FUTEX
/* XXX Don't use FUTEX_SHARED or FUTEX_PRIVATE as long as there are still
assembly implementations that expect the value determined below. */
ibarrier->private = (iattr->pshared != PTHREAD_PROCESS_PRIVATE
? 0 : FUTEX_PRIVATE_FLAG);
#else
ibarrier->private = (iattr->pshared != PTHREAD_PROCESS_PRIVATE
? 0 : THREAD_GETMEM (THREAD_SELF,
header.private_futex));
#endif
return 0;
}

16
nptl/pthread_barrier_wait.c
View File

@ -19,6 +19,7 @@
#include <errno.h>
#include <sysdep.h>
#include <lowlevellock.h>
#include <futex-internal.h>
#include <pthreadP.h>
@ -29,9 +30,12 @@ __pthread_barrier_wait (barrier)
{
struct pthread_barrier *ibarrier = (struct pthread_barrier *) barrier;
int result = 0;
int lll_private = ibarrier->private ^ FUTEX_PRIVATE_FLAG;
int futex_private = (lll_private == LLL_PRIVATE
? FUTEX_PRIVATE : FUTEX_SHARED);
/* Make sure we are alone. */
lll_lock (ibarrier->lock, ibarrier->private ^ FUTEX_PRIVATE_FLAG);
lll_lock (ibarrier->lock, lll_private);
/* One more arrival. */
--ibarrier->left;
@ -44,8 +48,7 @@ __pthread_barrier_wait (barrier)
++ibarrier->curr_event;
/* Wake up everybody. */
lll_futex_wake (&ibarrier->curr_event, INT_MAX,
ibarrier->private ^ FUTEX_PRIVATE_FLAG);
futex_wake (&ibarrier->curr_event, INT_MAX, futex_private);
/* This is the thread which finished the serialization. */
result = PTHREAD_BARRIER_SERIAL_THREAD;
@ -57,12 +60,11 @@ __pthread_barrier_wait (barrier)
unsigned int event = ibarrier->curr_event;
/* Before suspending, make the barrier available to others. */
lll_unlock (ibarrier->lock, ibarrier->private ^ FUTEX_PRIVATE_FLAG);
lll_unlock (ibarrier->lock, lll_private);
/* Wait for the event counter of the barrier to change. */
do
lll_futex_wait (&ibarrier->curr_event, event,
ibarrier->private ^ FUTEX_PRIVATE_FLAG);
futex_wait_simple (&ibarrier->curr_event, event, futex_private);
while (event == ibarrier->curr_event);
}
@ -72,7 +74,7 @@ __pthread_barrier_wait (barrier)
/* If this was the last woken thread, unlock. */
if (atomic_increment_val (&ibarrier->left) == init_count)
/* We are done. */
lll_unlock (ibarrier->lock, ibarrier->private ^ FUTEX_PRIVATE_FLAG);
lll_unlock (ibarrier->lock, lll_private);
return result;
}

7
nptl/pthread_barrierattr_setpshared.c
View File

@ -18,6 +18,7 @@
#include <errno.h>
#include "pthreadP.h"
#include <futex-internal.h>
int
@ -27,9 +28,9 @@ pthread_barrierattr_setpshared (attr, pshared)
{
struct pthread_barrierattr *iattr;
if (pshared != PTHREAD_PROCESS_PRIVATE
&& __builtin_expect (pshared != PTHREAD_PROCESS_SHARED, 0))
return EINVAL;
int err = futex_supports_pshared (pshared);
if (err != 0)
return err;
iattr = (struct pthread_barrierattr *) attr;

7
nptl/pthread_condattr_setpshared.c
View File

@ -18,15 +18,16 @@
#include <errno.h>
#include <pthreadP.h>
#include <futex-internal.h>
int
pthread_condattr_setpshared (attr, pshared)
pthread_condattr_t *attr;
int pshared;
{
if (pshared != PTHREAD_PROCESS_PRIVATE
&& __builtin_expect (pshared != PTHREAD_PROCESS_SHARED, 0))
return EINVAL;
int err = futex_supports_pshared (pshared);
if (err != 0)
return err;
int *valuep = &((struct pthread_condattr *) attr)->value;

14
nptl/pthread_create.c
View File

@ -31,6 +31,7 @@
#include <kernel-features.h>
#include <exit-thread.h>
#include <default-sched.h>
#include <futex-internal.h>
#include <shlib-compat.h>
@ -269,7 +270,7 @@ START_THREAD_DEFN
/* Allow setxid from now onwards. */
if (__glibc_unlikely (atomic_exchange_acq (&pd->setxid_futex, 0) == -2))
lll_futex_wake (&pd->setxid_futex, 1, LLL_PRIVATE);
futex_wake (&pd->setxid_futex, 1, FUTEX_PRIVATE);
#ifdef __NR_set_robust_list
# ifndef __ASSUME_SET_ROBUST_LIST
@ -414,7 +415,8 @@ START_THREAD_DEFN
this->__list.__next = NULL;
atomic_or (&this->__lock, FUTEX_OWNER_DIED);
lll_futex_wake (&this->__lock, 1, /* XYZ */ LLL_SHARED);
futex_wake ((unsigned int *) &this->__lock, 1,
/* XYZ */ FUTEX_SHARED);
}
while (robust != (void *) &pd->robust_head);
}
@ -442,7 +444,11 @@ START_THREAD_DEFN
/* Some other thread might call any of the setXid functions and expect
us to reply. In this case wait until we did that. */
do
lll_futex_wait (&pd->setxid_futex, 0, LLL_PRIVATE);
/* XXX This differs from the typical futex_wait_simple pattern in that
the futex_wait condition (setxid_futex) is different from the
condition used in the surrounding loop (cancelhandling). We need
to check and document why this is correct. */
futex_wait_simple (&pd->setxid_futex, 0, FUTEX_PRIVATE);
while (pd->cancelhandling & SETXID_BITMASK);
/* Reset the value so that the stack can be reused. */
@ -683,7 +689,7 @@ __pthread_create_2_1 (newthread, attr, start_routine, arg)
stillborn thread. */
if (__glibc_unlikely (atomic_exchange_acq (&pd->setxid_futex, 0)
== -2))
lll_futex_wake (&pd->setxid_futex, 1, LLL_PRIVATE);
futex_wake (&pd->setxid_futex, 1, FUTEX_PRIVATE);
/* Free the resources. */
__deallocate_stack (pd);

7
nptl/pthread_mutexattr_setpshared.c
View File

@ -18,6 +18,7 @@
#include <errno.h>
#include <pthreadP.h>
#include <futex-internal.h>
int
@ -27,9 +28,9 @@ pthread_mutexattr_setpshared (attr, pshared)
{
struct pthread_mutexattr *iattr;
if (pshared != PTHREAD_PROCESS_PRIVATE
&& __builtin_expect (pshared != PTHREAD_PROCESS_SHARED, 0))
return EINVAL;
int err = futex_supports_pshared (pshared);
if (err != 0)
return err;
iattr = (struct pthread_mutexattr *) attr;

12
nptl/pthread_once.c
View File

@ -17,7 +17,7 @@
<http://www.gnu.org/licenses/>. */
#include "pthreadP.h"
#include <lowlevellock.h>
#include <futex-internal.h>
#include <atomic.h>
@ -35,7 +35,7 @@ clear_once_control (void *arg)
get interrupted (see __pthread_once), so all we need to relay to other
threads is the state being reset again. */
atomic_store_relaxed (once_control, 0);
lll_futex_wake (once_control, INT_MAX, LLL_PRIVATE);
futex_wake ((unsigned int *) once_control, INT_MAX, FUTEX_PRIVATE);
}
@ -100,8 +100,10 @@ __pthread_once_slow (pthread_once_t *once_control, void (*init_routine) (void))
is set and __PTHREAD_ONCE_DONE is not. */
if (val == newval)
{
/* Same generation, some other thread was faster. Wait. */
lll_futex_wait (once_control, newval, LLL_PRIVATE);
/* Same generation, some other thread was faster. Wait and
retry. */
futex_wait_simple ((unsigned int *) once_control,
(unsigned int) newval, FUTEX_PRIVATE);
continue;
}
}
@ -122,7 +124,7 @@ __pthread_once_slow (pthread_once_t *once_control, void (*init_routine) (void))
atomic_store_release (once_control, __PTHREAD_ONCE_DONE);
/* Wake up all other threads. */
lll_futex_wake (once_control, INT_MAX, LLL_PRIVATE);
futex_wake ((unsigned int *) once_control, INT_MAX, FUTEX_PRIVATE);
break;
}

7
nptl/pthread_rwlock_init.c
View File

@ -58,15 +58,8 @@ __pthread_rwlock_init (rwlock, attr)
If the pshared value is in locking functions XORed with avail
we get the expected result. */
#ifdef __ASSUME_PRIVATE_FUTEX
rwlock->__data.__shared = (iattr->pshared == PTHREAD_PROCESS_PRIVATE
? 0 : FUTEX_PRIVATE_FLAG);
#else
rwlock->__data.__shared = (iattr->pshared == PTHREAD_PROCESS_PRIVATE
? 0
: THREAD_GETMEM (THREAD_SELF,
header.private_futex));
#endif
return 0;
}

18
nptl/pthread_rwlock_rdlock.c
View File

@ -19,6 +19,7 @@
#include <errno.h>
#include <sysdep.h>
#include <lowlevellock.h>
#include <futex-internal.h>
#include <pthread.h>
#include <pthreadP.h>
#include <stap-probe.h>
@ -32,6 +33,8 @@ __pthread_rwlock_rdlock_slow (pthread_rwlock_t *rwlock)
{
int result = 0;
bool wake = false;
int futex_shared =
rwlock->__data.__shared == LLL_PRIVATE ? FUTEX_PRIVATE : FUTEX_SHARED;
/* Lock is taken in caller. */
@ -60,9 +63,10 @@ __pthread_rwlock_rdlock_slow (pthread_rwlock_t *rwlock)
/* Free the lock. */
lll_unlock (rwlock->__data.__lock, rwlock->__data.__shared);
/* Wait for the writer to finish. */
lll_futex_wait (&rwlock->__data.__readers_wakeup, waitval,
rwlock->__data.__shared);
/* Wait for the writer to finish. We do not check the return value
because we decide how to continue based on the state of the rwlock. */
futex_wait_simple (&rwlock->__data.__readers_wakeup, waitval,
futex_shared);
/* Get the lock. */
lll_lock (rwlock->__data.__lock, rwlock->__data.__shared);
@ -103,8 +107,7 @@ __pthread_rwlock_rdlock_slow (pthread_rwlock_t *rwlock)
lll_unlock (rwlock->__data.__lock, rwlock->__data.__shared);
if (wake)
lll_futex_wake (&rwlock->__data.__readers_wakeup, INT_MAX,
rwlock->__data.__shared);
futex_wake (&rwlock->__data.__readers_wakeup, INT_MAX, futex_shared);
return result;
}
@ -117,6 +120,8 @@ __pthread_rwlock_rdlock (pthread_rwlock_t *rwlock)
{
int result = 0;
bool wake = false;
int futex_shared =
rwlock->__data.__shared == LLL_PRIVATE ? FUTEX_PRIVATE : FUTEX_SHARED;
LIBC_PROBE (rdlock_entry, 1, rwlock);
@ -164,8 +169,7 @@ __pthread_rwlock_rdlock (pthread_rwlock_t *rwlock)
lll_unlock (rwlock->__data.__lock, rwlock->__data.__shared);
if (wake)
lll_futex_wake (&rwlock->__data.__readers_wakeup, INT_MAX,
rwlock->__data.__shared);
futex_wake (&rwlock->__data.__readers_wakeup, INT_MAX, futex_shared);
return result;
}

57
nptl/pthread_rwlock_timedrdlock.c
View File

@ -19,10 +19,10 @@
#include <errno.h>
#include <sysdep.h>
#include <lowlevellock.h>
#include <futex-internal.h>
#include <pthread.h>
#include <pthreadP.h>
#include <sys/time.h>
#include <kernel-features.h>
#include <stdbool.h>
@ -34,6 +34,8 @@ pthread_rwlock_timedrdlock (rwlock, abstime)
{
int result = 0;
bool wake = false;
int futex_shared =
rwlock->__data.__shared == LLL_PRIVATE ? FUTEX_PRIVATE : FUTEX_SHARED;
/* Make sure we are alone. */
lll_lock(rwlock->__data.__lock, rwlock->__data.__shared);
@ -91,38 +93,6 @@ pthread_rwlock_timedrdlock (rwlock, abstime)
break;
}
/* Work around the fact that the kernel rejects negative timeout values
despite them being valid. */
if (__glibc_unlikely (abstime->tv_sec < 0))
{
result = ETIMEDOUT;
break;
}
#if (!defined __ASSUME_FUTEX_CLOCK_REALTIME \
|| !defined lll_futex_timed_wait_bitset)
/* Get the current time. So far we support only one clock. */
struct timeval tv;
(void) __gettimeofday (&tv, NULL);
/* Convert the absolute timeout value to a relative timeout. */
struct timespec rt;
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;
}
/* Did we already time out? */
if (rt.tv_sec < 0)
{
/* Yep, return with an appropriate error. */
result = ETIMEDOUT;
break;
}
#endif
/* Remember that we are a reader. */
if (++rwlock->__data.__nr_readers_queued == 0)
{
@ -137,17 +107,11 @@ pthread_rwlock_timedrdlock (rwlock, abstime)
/* Free the lock. */
lll_unlock (rwlock->__data.__lock, rwlock->__data.__shared);
/* Wait for the writer to finish. */
#if (!defined __ASSUME_FUTEX_CLOCK_REALTIME \
|| !defined lll_futex_timed_wait_bitset)
err = lll_futex_timed_wait (&rwlock->__data.__readers_wakeup,
waitval, &rt, rwlock->__data.__shared);
#else
err = lll_futex_timed_wait_bitset (&rwlock->__data.__readers_wakeup,
waitval, abstime,
FUTEX_CLOCK_REALTIME,
rwlock->__data.__shared);
#endif
/* Wait for the writer to finish. We handle ETIMEDOUT below; on other
return values, we decide how to continue based on the state of the
rwlock. */
err = futex_abstimed_wait (&rwlock->__data.__readers_wakeup, waitval,
abstime, futex_shared);
/* Get the lock. */
lll_lock (rwlock->__data.__lock, rwlock->__data.__shared);
@ -155,7 +119,7 @@ pthread_rwlock_timedrdlock (rwlock, abstime)
--rwlock->__data.__nr_readers_queued;
/* Did the futex call time out? */
if (err == -ETIMEDOUT)
if (err == ETIMEDOUT)
{
/* Yep, report it. */
result = ETIMEDOUT;
@ -167,8 +131,7 @@ pthread_rwlock_timedrdlock (rwlock, abstime)
lll_unlock (rwlock->__data.__lock, rwlock->__data.__shared);
if (wake)
lll_futex_wake (&rwlock->__data.__readers_wakeup, INT_MAX,
rwlock->__data.__shared);
futex_wake (&rwlock->__data.__readers_wakeup, INT_MAX, futex_shared);
return result;
}

56
nptl/pthread_rwlock_timedwrlock.c
View File

@ -19,10 +19,10 @@
#include <errno.h>
#include <sysdep.h>
#include <lowlevellock.h>
#include <futex-internal.h>
#include <pthread.h>
#include <pthreadP.h>
#include <sys/time.h>
#include <kernel-features.h>
#include <stdbool.h>
@ -34,6 +34,8 @@ pthread_rwlock_timedwrlock (rwlock, abstime)
{
int result = 0;
bool wake_readers = false;
int futex_shared =
rwlock->__data.__shared == LLL_PRIVATE ? FUTEX_PRIVATE : FUTEX_SHARED;
/* Make sure we are alone. */
lll_lock (rwlock->__data.__lock, rwlock->__data.__shared);
@ -71,37 +73,6 @@ pthread_rwlock_timedwrlock (rwlock, abstime)
break;
}
/* Work around the fact that the kernel rejects negative timeout values
despite them being valid. */
if (__glibc_unlikely (abstime->tv_sec < 0))
{
result = ETIMEDOUT;
break;
}
#if (!defined __ASSUME_FUTEX_CLOCK_REALTIME \
|| !defined lll_futex_timed_wait_bitset)
/* Get the current time. So far we support only one clock. */
struct timeval tv;
(void) __gettimeofday (&tv, NULL);
/* Convert the absolute timeout value to a relative timeout. */
struct timespec rt;
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;
}
/* Did we already time out? */
if (rt.tv_sec < 0)
{
result = ETIMEDOUT;
break;
}
#endif
/* Remember that we are a writer. */
if (++rwlock->__data.__nr_writers_queued == 0)
{
@ -116,17 +87,11 @@ pthread_rwlock_timedwrlock (rwlock, abstime)
/* Free the lock. */
lll_unlock (rwlock->__data.__lock, rwlock->__data.__shared);
/* Wait for the writer or reader(s) to finish. */
#if (!defined __ASSUME_FUTEX_CLOCK_REALTIME \
|| !defined lll_futex_timed_wait_bitset)
err = lll_futex_timed_wait (&rwlock->__data.__writer_wakeup,
waitval, &rt, rwlock->__data.__shared);
#else
err = lll_futex_timed_wait_bitset (&rwlock->__data.__writer_wakeup,
waitval, abstime,
FUTEX_CLOCK_REALTIME,
rwlock->__data.__shared);
#endif
/* Wait for the writer or reader(s) to finish. We handle ETIMEDOUT
below; on other return values, we decide how to continue based on
the state of the rwlock. */
err = futex_abstimed_wait (&rwlock->__data.__writer_wakeup, waitval,
abstime, futex_shared);
/* Get the lock. */
lll_lock (rwlock->__data.__lock, rwlock->__data.__shared);
@ -135,7 +100,7 @@ pthread_rwlock_timedwrlock (rwlock, abstime)
--rwlock->__data.__nr_writers_queued;
/* Did the futex call time out? */
if (err == -ETIMEDOUT)
if (err == ETIMEDOUT)
{
result = ETIMEDOUT;
/* If we prefer writers, it can have happened that readers blocked
@ -166,8 +131,7 @@ pthread_rwlock_timedwrlock (rwlock, abstime)
/* Might be required after timeouts. */
if (wake_readers)
lll_futex_wake (&rwlock->__data.__readers_wakeup, INT_MAX,
rwlock->__data.__shared);
futex_wake (&rwlock->__data.__readers_wakeup, INT_MAX, futex_shared);
return result;
}

6
nptl/pthread_rwlock_tryrdlock.c
View File

@ -19,6 +19,7 @@
#include <errno.h>
#include "pthreadP.h"
#include <lowlevellock.h>
#include <futex-internal.h>
#include <elide.h>
#include <stdbool.h>
@ -28,6 +29,8 @@ __pthread_rwlock_tryrdlock (pthread_rwlock_t *rwlock)
{
int result = EBUSY;
bool wake = false;
int futex_shared =
rwlock->__data.__shared == LLL_PRIVATE ? FUTEX_PRIVATE : FUTEX_SHARED;
if (ELIDE_TRYLOCK (rwlock->__data.__rwelision,
rwlock->__data.__lock == 0
@ -63,8 +66,7 @@ __pthread_rwlock_tryrdlock (pthread_rwlock_t *rwlock)
lll_unlock (rwlock->__data.__lock, rwlock->__data.__shared);
if (wake)
lll_futex_wake (&rwlock->__data.__readers_wakeup, INT_MAX,
rwlock->__data.__shared);
futex_wake (&rwlock->__data.__readers_wakeup, INT_MAX, futex_shared);
return result;
}

11
nptl/pthread_rwlock_unlock.c
View File

@ -19,6 +19,7 @@
#include <errno.h>
#include <sysdep.h>
#include <lowlevellock.h>
#include <futex-internal.h>
#include <pthread.h>
#include <pthreadP.h>
#include <stap-probe.h>
@ -29,6 +30,9 @@
int
__pthread_rwlock_unlock (pthread_rwlock_t *rwlock)
{
int futex_shared =
rwlock->__data.__shared == LLL_PRIVATE ? FUTEX_PRIVATE : FUTEX_SHARED;
LIBC_PROBE (rwlock_unlock, 1, rwlock);
if (ELIDE_UNLOCK (rwlock->__data.__writer == 0
@ -51,16 +55,15 @@ __pthread_rwlock_unlock (pthread_rwlock_t *rwlock)
{
++rwlock->__data.__writer_wakeup;
lll_unlock (rwlock->__data.__lock, rwlock->__data.__shared);
lll_futex_wake (&rwlock->__data.__writer_wakeup, 1,
rwlock->__data.__shared);
futex_wake (&rwlock->__data.__writer_wakeup, 1, futex_shared);
return 0;
}
else if (rwlock->__data.__nr_readers_queued)
{
++rwlock->__data.__readers_wakeup;
lll_unlock (rwlock->__data.__lock, rwlock->__data.__shared);
lll_futex_wake (&rwlock->__data.__readers_wakeup, INT_MAX,
rwlock->__data.__shared);
futex_wake (&rwlock->__data.__readers_wakeup, INT_MAX,
futex_shared);
return 0;
}
}

11
nptl/pthread_rwlock_wrlock.c
View File

@ -19,6 +19,7 @@
#include <errno.h>
#include <sysdep.h>
#include <lowlevellock.h>
#include <futex-internal.h>
#include <pthread.h>
#include <pthreadP.h>
#include <stap-probe.h>
@ -30,6 +31,8 @@ static int __attribute__((noinline))
__pthread_rwlock_wrlock_slow (pthread_rwlock_t *rwlock)
{
int result = 0;
int futex_shared =
rwlock->__data.__shared == LLL_PRIVATE ? FUTEX_PRIVATE : FUTEX_SHARED;
/* Caller has taken the lock. */
@ -58,9 +61,11 @@ __pthread_rwlock_wrlock_slow (pthread_rwlock_t *rwlock)
/* Free the lock. */
lll_unlock (rwlock->__data.__lock, rwlock->__data.__shared);
/* Wait for the writer or reader(s) to finish. */
lll_futex_wait (&rwlock->__data.__writer_wakeup, waitval,
rwlock->__data.__shared);
/* Wait for the writer or reader(s) to finish. We do not check the
return value because we decide how to continue based on the state of
the rwlock. */
futex_wait_simple (&rwlock->__data.__writer_wakeup, waitval,
futex_shared);
/* Get the lock. */
lll_lock (rwlock->__data.__lock, rwlock->__data.__shared);

7
nptl/pthread_rwlockattr_setpshared.c
View File

@ -18,6 +18,7 @@
#include <errno.h>
#include "pthreadP.h"
#include <futex-internal.h>
int
@ -27,9 +28,9 @@ pthread_rwlockattr_setpshared (attr, pshared)
{
struct pthread_rwlockattr *iattr;
if (pshared != PTHREAD_PROCESS_SHARED
&& __builtin_expect (pshared != PTHREAD_PROCESS_PRIVATE, 0))
return EINVAL;
int err = futex_supports_pshared (pshared);
if (err != 0)
return err;
iattr = (struct pthread_rwlockattr *) attr;

27
nptl/sem_init.c
View File

@ -21,22 +21,7 @@
#include <shlib-compat.h>
#include "semaphoreP.h"
#include <kernel-features.h>
/* Returns FUTEX_PRIVATE if pshared is zero and private futexes are supported;
returns FUTEX_SHARED otherwise.
TODO Remove when cleaning up the futex API throughout glibc. */
static __always_inline int
futex_private_if_supported (int pshared)
{
if (pshared != 0)
return LLL_SHARED;
#ifdef __ASSUME_PRIVATE_FUTEX
return LLL_PRIVATE;
#else
return THREAD_GETMEM (THREAD_SELF, header.private_futex)
^ FUTEX_PRIVATE_FLAG;
#endif
}
#include <futex-internal.h>
int
@ -48,6 +33,13 @@ __new_sem_init (sem_t *sem, int pshared, unsigned int value)
__set_errno (EINVAL);
return -1;
}
pshared = pshared != 0 ? PTHREAD_PROCESS_SHARED : PTHREAD_PROCESS_PRIVATE;
int err = futex_supports_pshared (pshared);
if (err != 0)
{
__set_errno (err);
return -1;
}
/* Map to the internal type. */
struct new_sem *isem = (struct new_sem *) sem;
@ -60,7 +52,8 @@ __new_sem_init (sem_t *sem, int pshared, unsigned int value)
isem->nwaiters = 0;
#endif
isem->private = futex_private_if_supported (pshared);
isem->private = (pshared == PTHREAD_PROCESS_PRIVATE
? FUTEX_PRIVATE : FUTEX_SHARED);
return 0;
}

11
nptl/sem_open.c
View File

@ -30,6 +30,7 @@
#include <sys/stat.h>
#include "semaphoreP.h"
#include <shm-directory.h>
#include <futex-internal.h>
/* Comparison function for search of existing mapping. */
@ -141,6 +142,14 @@ sem_open (const char *name, int oflag, ...)
int fd;
sem_t *result;
/* Check that shared futexes are supported. */
int err = futex_supports_pshared (PTHREAD_PROCESS_SHARED);
if (err != 0)
{
__set_errno (err);
return SEM_FAILED;
}
/* Create the name of the final file in local variable SHM_NAME. */
SHM_GET_NAME (EINVAL, SEM_FAILED, SEM_SHM_PREFIX);
@ -201,7 +210,7 @@ sem_open (const char *name, int oflag, ...)
sem.newsem.nwaiters = 0;
#endif
/* This always is a shared semaphore. */
sem.newsem.private = LLL_SHARED;
sem.newsem.private = FUTEX_SHARED;
/* Initialize the remaining bytes as well. */
memset ((char *) &sem.initsem + sizeof (struct new_sem), '\0',

28
nptl/sem_post.c
View File

@ -20,37 +20,13 @@
#include <atomic.h>
#include <errno.h>
#include <sysdep.h>
#include <lowlevellock.h>
#include <lowlevellock.h> /* lll_futex* used by the old code. */
#include <futex-internal.h>
#include <internaltypes.h>
#include <semaphore.h>
#include <shlib-compat.h>
/* Wrapper for lll_futex_wake, with error checking.
TODO Remove when cleaning up the futex API throughout glibc. */
static __always_inline void
futex_wake (unsigned int* futex, int processes_to_wake, int private)
{
int res = lll_futex_wake (futex, processes_to_wake, private);
/* No error. Ignore the number of woken processes. */
if (res >= 0)
return;
switch (res)
{
case -EFAULT: /* Could have happened due to memory reuse. */
case -EINVAL: /* Could be either due to incorrect alignment (a bug in
glibc or in the application) or due to memory being
reused for a PI futex. We cannot distinguish between the
two causes, and one of them is correct use, so we do not
act in this case. */
return;
case -ENOSYS: /* Must have been caused by a glibc bug. */
/* No other errors are documented at this time. */
default:
abort ();
}
}
/* See sem_wait for an explanation of the algorithm. */
int

1
nptl/sem_wait.c
View File

@ -17,6 +17,7 @@
License along with the GNU C Library; if not, see
<http://www.gnu.org/licenses/>. */
#include <lowlevellock.h> /* lll_futex* used by the old code. */
#include "sem_waitcommon.c"
int

115
nptl/sem_waitcommon.c
View File

@ -20,7 +20,7 @@
#include <kernel-features.h>
#include <errno.h>
#include <sysdep.h>
#include <lowlevellock.h>
#include <futex-internal.h>
#include <internaltypes.h>
#include <semaphore.h>
#include <sys/time.h>
@ -29,110 +29,6 @@
#include <shlib-compat.h>
#include <atomic.h>
/* Wrapper for lll_futex_wait with absolute timeout and error checking.
TODO Remove when cleaning up the futex API throughout glibc. */
static __always_inline int
futex_abstimed_wait (unsigned int* futex, unsigned int expected,
const struct timespec* abstime, int private, bool cancel)
{
int err, oldtype;
if (abstime == NULL)
{
if (cancel)
oldtype = __pthread_enable_asynccancel ();
err = lll_futex_wait (futex, expected, private);
if (cancel)
__pthread_disable_asynccancel (oldtype);
}
else
{
#if (defined __ASSUME_FUTEX_CLOCK_REALTIME \
&& defined lll_futex_timed_wait_bitset)
/* The Linux kernel returns EINVAL for this, but in userspace
such a value is valid. */
if (abstime->tv_sec < 0)
return ETIMEDOUT;
#else
struct timeval tv;
struct timespec rt;
int sec, nsec;
/* Get the current time. */
__gettimeofday (&tv, NULL);
/* Compute relative timeout. */
sec = abstime->tv_sec - tv.tv_sec;
nsec = abstime->tv_nsec - tv.tv_usec * 1000;
if (nsec < 0)
{
nsec += 1000000000;
--sec;
}
/* Already timed out? */
if (sec < 0)
return ETIMEDOUT;
/* Do wait. */
rt.tv_sec = sec;
rt.tv_nsec = nsec;
#endif
if (cancel)
oldtype = __pthread_enable_asynccancel ();
#if (defined __ASSUME_FUTEX_CLOCK_REALTIME \
&& defined lll_futex_timed_wait_bitset)
err = lll_futex_timed_wait_bitset (futex, expected, abstime,
FUTEX_CLOCK_REALTIME, private);
#else
err = lll_futex_timed_wait (futex, expected, &rt, private);
#endif
if (cancel)
__pthread_disable_asynccancel (oldtype);
}
switch (err)
{
case 0:
case -EAGAIN:
case -EINTR:
case -ETIMEDOUT:
return -err;
case -EFAULT: /* Must have been caused by a glibc or application bug. */
case -EINVAL: /* Either due to wrong alignment or due to the timeout not
being normalized. Must have been caused by a glibc or
application bug. */
case -ENOSYS: /* Must have been caused by a glibc bug. */
/* No other errors are documented at this time. */
default:
abort ();
}
}
/* Wrapper for lll_futex_wake, with error checking.
TODO Remove when cleaning up the futex API throughout glibc. */
static __always_inline void
futex_wake (unsigned int* futex, int processes_to_wake, int private)
{
int res = lll_futex_wake (futex, processes_to_wake, private);
/* No error. Ignore the number of woken processes. */
if (res >= 0)
return;
switch (res)
{
case -EFAULT: /* Could have happened due to memory reuse. */
case -EINVAL: /* Could be either due to incorrect alignment (a bug in
glibc or in the application) or due to memory being
reused for a PI futex. We cannot distinguish between the
two causes, and one of them is correct use, so we do not
act in this case. */
return;
case -ENOSYS: /* Must have been caused by a glibc bug. */
/* No other errors are documented at this time. */
default:
abort ();
}
}
/* The semaphore provides two main operations: sem_post adds a token to the
semaphore; sem_wait grabs a token from the semaphore, potentially waiting
@ -220,11 +116,12 @@ do_futex_wait (struct new_sem *sem, const struct timespec *abstime)
int err;
#if __HAVE_64B_ATOMICS
err = futex_abstimed_wait ((unsigned int *) &sem->data + SEM_VALUE_OFFSET, 0,
abstime, sem->private, true);
err = futex_abstimed_wait_cancelable (
(unsigned int *) &sem->data + SEM_VALUE_OFFSET, 0, abstime,
sem->private);
#else
err = futex_abstimed_wait (&sem->value, SEM_NWAITERS_MASK, abstime,
sem->private, true);
err = futex_abstimed_wait_cancelable (&sem->value, SEM_NWAITERS_MASK,
abstime, sem->private);
#endif
return err;

3
nptl/unregister-atfork.c
View File

@ -20,6 +20,7 @@
#include <stdlib.h>
#include <fork.h>
#include <atomic.h>
#include <futex-internal.h>
void
@ -114,7 +115,7 @@ __unregister_atfork (dso_handle)
atomic_decrement (&deleted->handler->refcntr);
unsigned int val;
while ((val = deleted->handler->refcntr) != 0)
lll_futex_wait (&deleted->handler->refcntr, val, LLL_PRIVATE);
futex_wait_simple (&deleted->handler->refcntr, val, FUTEX_PRIVATE);
deleted = deleted->next;
}

4
sysdeps/nacl/exit-thread.h
View File

@ -18,7 +18,7 @@
#include <assert.h>
#include <atomic.h>
#include <lowlevellock.h>
#include <futex-internal.h>
#include <nacl-interfaces.h>
#include <nptl/pthreadP.h>
@ -64,7 +64,7 @@ __exit_thread (void)
assert (NACL_EXITING_TID > 0);
atomic_store_relaxed (&pd->tid, NACL_EXITING_TID);
lll_futex_wake (&pd->tid, 1, LLL_PRIVATE);
futex_wake ((unsigned int *) &pd->tid, 1, FUTEX_PRIVATE);
}
/* This clears PD->tid some time after the thread stack can never

248
sysdeps/nacl/futex-internal.h Normal file
View File

@ -0,0 +1,248 @@
/* futex operations for glibc-internal use. NaCl version.
Copyright (C) 2014-2015 Free Software Foundation, Inc.
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 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/>. */
#ifndef FUTEX_INTERNAL_H
#define FUTEX_INTERNAL_H
#include <sysdeps/nptl/futex-internal.h>
#include <errno.h>
#include <lowlevellock-futex.h>
#include <nacl-interfaces.h>
#include <nptl/pthreadP.h>
/* See sysdeps/nptl/futex-internal.h for documentation; this file only
contains NaCl-specific comments.
There is no support yet for shared futexes nor for exact relative
timeouts. */
/* See sysdeps/nptl/futex-internal.h for constraints on the value of the
FUTEX_PRIVATE and FUTEX_SHARED constants.
Shared futexes are not yet supported, and we never allow clients to
actually request shared futexes. Therefore, we do not need a different
value. */
#undef FUTEX_SHARED
#define FUTEX_SHARED FUTEX_PRIVATE
/* FUTEX_SHARED is not yet supported. */
static __always_inline int
futex_supports_pshared (int pshared)
{
if (__glibc_likely (pshared == PTHREAD_PROCESS_PRIVATE))
return 0;
else if (pshared == PTHREAD_PROCESS_SHARED)
return ENOTSUP;
else
return EINVAL;
}
/* Relative timeouts are only emulated via absolute timeouts using the
system clock. */
static __always_inline bool
futex_supports_exact_relative_timeouts (void)
{
return false;
}
/* See sysdeps/nptl/futex-internal.h for details. */
static __always_inline int
futex_wait (unsigned int *futex_word, unsigned int expected, int private)
{
int err = lll_futex_timed_wait (futex_word, expected, NULL, private);
switch (err)
{
case 0:
case -EAGAIN:
case -EINTR:
return -err;
case -ETIMEDOUT: /* Cannot have happened as we provided no timeout. */
case -EFAULT: /* Must have been caused by a glibc or application bug. */
case -EINVAL: /* Either due to wrong alignment or due to the timeout not
being normalized. Must have been caused by a glibc or
application bug. */
case -ENOSYS: /* Must have been caused by a glibc bug. */
/* No other errors are documented at this time. */
default:
futex_fatal_error ();
}
}
/* See sysdeps/nptl/futex-internal.h for details. */
static __always_inline int
futex_wait_cancelable (unsigned int *futex_word, unsigned int expected,
int private)
{
int oldtype;
oldtype = __pthread_enable_asynccancel ();
int err = lll_futex_timed_wait (futex_word, expected, NULL, private);
__pthread_disable_asynccancel (oldtype);
switch (err)
{
case 0:
case -EAGAIN:
case -EINTR:
return -err;
case -ETIMEDOUT: /* Cannot have happened as we provided no timeout. */
case -EFAULT: /* Must have been caused by a glibc or application bug. */
case -EINVAL: /* Either due to wrong alignment or due to the timeout not
being normalized. Must have been caused by a glibc or
application bug. */
case -ENOSYS: /* Must have been caused by a glibc bug. */
/* No other errors are documented at this time. */
default:
futex_fatal_error ();
}
}
/* See sysdeps/nptl/futex-internal.h for details. */
static __always_inline int
futex_reltimed_wait (unsigned int *futex_word, unsigned int expected,
const struct timespec *reltime, int private)
{
int err = lll_futex_timed_wait (futex_word, expected, reltime, private);
switch (err)
{
case 0:
case -EAGAIN:
case -EINTR:
case -ETIMEDOUT:
return -err;
case -EFAULT: /* Must have been caused by a glibc or application bug. */
case -EINVAL: /* Either due to wrong alignment or due to the timeout not
being normalized. Must have been caused by a glibc or
application bug. */
case -ENOSYS: /* Must have been caused by a glibc bug. */
/* No other errors are documented at this time. */
default:
futex_fatal_error ();
}
}
/* See sysdeps/nptl/futex-internal.h for details. */
static __always_inline int
futex_reltimed_wait_cancelable (unsigned int *futex_word,
unsigned int expected,
const struct timespec *reltime, int private)
{
int oldtype;
oldtype = __pthread_enable_asynccancel ();
int err = lll_futex_timed_wait (futex_word, expected, reltime, private);
__pthread_disable_asynccancel (oldtype);
switch (err)
{
case 0:
case -EAGAIN:
case -EINTR:
case -ETIMEDOUT:
return -err;
case -EFAULT: /* Must have been caused by a glibc or application bug. */
case -EINVAL: /* Either due to wrong alignment or due to the timeout not
being normalized. Must have been caused by a glibc or
application bug. */
case -ENOSYS: /* Must have been caused by a glibc bug. */
/* No other errors are documented at this time. */
default:
futex_fatal_error ();
}
}
/* See sysdeps/nptl/futex-internal.h for details. */
static __always_inline int
futex_abstimed_wait (unsigned int *futex_word, unsigned int expected,
const struct timespec *abstime, int private)
{
int err = __nacl_irt_futex.futex_wait_abs ((volatile int *) futex_word,
expected, abstime);
switch (err)
{
case 0:
case EAGAIN:
case EINTR:
case ETIMEDOUT:
return err;
case EFAULT: /* Must have been caused by a glibc or application bug. */
case EINVAL: /* Either due to wrong alignment or due to the timeout not
being normalized. Must have been caused by a glibc or
application bug. */
case ENOSYS: /* Must have been caused by a glibc bug. */
/* No other errors are documented at this time. */
default:
futex_fatal_error ();
}
}
/* See sysdeps/nptl/futex-internal.h for details. */
static __always_inline int
futex_abstimed_wait_cancelable (unsigned int *futex_word,
unsigned int expected,
const struct timespec *abstime, int private)
{
int oldtype;
oldtype = __pthread_enable_asynccancel ();
int err = __nacl_irt_futex.futex_wait_abs ((volatile int *) futex_word,
expected, abstime);
__pthread_disable_asynccancel (oldtype);
switch (err)
{
case 0:
case EAGAIN:
case EINTR:
case ETIMEDOUT:
return err;
case EFAULT: /* Must have been caused by a glibc or application bug. */
case EINVAL: /* Either due to wrong alignment or due to the timeout not
being normalized. Must have been caused by a glibc or
application bug. */
case ENOSYS: /* Must have been caused by a glibc bug. */
/* No other errors are documented at this time. */
default:
futex_fatal_error ();
}
}
/* See sysdeps/nptl/futex-internal.h for details. */
static __always_inline void
futex_wake (unsigned int *futex_word, int processes_to_wake, int private)
{
int res = lll_futex_wake (futex_word, processes_to_wake, private);
/* No error. Ignore the number of woken processes. */
if (res >= 0)
return;
switch (res)
{
case -EFAULT: /* Could have happened due to memory reuse. */
case -EINVAL: /* Could be either due to incorrect alignment (a bug in
glibc or in the application) or due to memory being
reused for a PI futex. We cannot distinguish between the
two causes, and one of them is correct use, so we do not
act in this case. */
return;
case -ENOSYS: /* Must have been caused by a glibc bug. */
/* No other errors are documented at this time. */
default:
futex_fatal_error ();
}
}
#endif /* futex-internal.h */

16
sysdeps/nptl/aio_misc.h
View File

@ -22,14 +22,14 @@
#include <assert.h>
#include <nptl/pthreadP.h>
#include <lowlevellock.h>
#include <futex-internal.h>
#define DONT_NEED_AIO_MISC_COND 1
#define AIO_MISC_NOTIFY(waitlist) \
do { \
if (*waitlist->counterp > 0 && --*waitlist->counterp == 0) \
lll_futex_wake (waitlist->counterp, 1, LLL_PRIVATE); \
futex_wake ((unsigned int *) waitlist->counterp, 1, FUTEX_PRIVATE); \
} while (0)
#define AIO_MISC_WAIT(result, futex, timeout, cancel) \
@ -48,9 +48,9 @@
int status; \
do \
{ \
status = lll_futex_timed_wait (futexaddr, oldval, timeout, \
LLL_PRIVATE); \
if (status != -EWOULDBLOCK) \
status = futex_reltimed_wait ((unsigned int *) futexaddr, oldval, \
timeout, FUTEX_PRIVATE); \
if (status != EAGAIN) \
break; \
\
oldval = *futexaddr; \
@ -60,12 +60,12 @@
if (cancel) \
LIBC_CANCEL_RESET (oldtype); \
\
if (status == -EINTR) \
if (status == EINTR) \
result = EINTR; \
else if (status == -ETIMEDOUT) \
else if (status == ETIMEDOUT) \
result = EAGAIN; \
else \
assert (status == 0 || status == -EWOULDBLOCK); \
assert (status == 0 || status == EAGAIN); \
\
pthread_mutex_lock (&__aio_requests_mutex); \
} \

3
sysdeps/nptl/fork.c
View File

@ -30,6 +30,7 @@
#include <nptl/pthreadP.h>
#include <fork.h>
#include <arch-fork.h>
#include <futex-internal.h>
static void
@ -219,7 +220,7 @@ __libc_fork (void)
if (atomic_decrement_and_test (&allp->handler->refcntr)
&& allp->handler->need_signal)
lll_futex_wake (&allp->handler->refcntr, 1, LLL_PRIVATE);
futex_wake (&allp->handler->refcntr, 1, FUTEX_PRIVATE);
allp = allp->next;
}

203
sysdeps/nptl/futex-internal.h Normal file
View File

@ -0,0 +1,203 @@
/* futex operations for glibc-internal use. Stub version; do not include
this file directly.
Copyright (C) 2014-2015 Free Software Foundation, Inc.
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 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/>. */
#ifndef STUB_FUTEX_INTERNAL_H
#define STUB_FUTEX_INTERNAL_H
#include <sys/time.h>
#include <stdio.h>
#include <stdbool.h>
#include <libc-internal.h>
/* This file defines futex operations used internally in glibc. A futex
consists of the so-called futex word in userspace, which is of type
unsigned int and represents an application-specific condition, and kernel
state associated with this particular futex word (e.g., wait queues). The
futex operations we provide are wrappers for the futex syscalls and add
glibc-specific error checking of the syscall return value. We abort on
error codes that are caused by bugs in glibc or in the calling application,
or when an error code is not known. We return error codes that can arise
in correct executions to the caller. Each operation calls out exactly the
return values that callers need to handle.
The private flag must be either FUTEX_PRIVATE or FUTEX_SHARED.
FUTEX_PRIVATE is always supported, and the implementation can internally
use FUTEX_SHARED when FUTEX_PRIVATE is requested. FUTEX_SHARED is not
necessarily supported (use futex_supports_pshared to detect this).
We expect callers to only use these operations if futexes and the
specific futex operations being used are supported (e.g., FUTEX_SHARED).
Given that waking other threads waiting on a futex involves concurrent
accesses to the futex word, you must use atomic operations to access the
futex word.
Both absolute and relative timeouts can be used. An absolute timeout
expires when the given specific point in time on the CLOCK_REALTIME clock
passes, or when it already has passed. A relative timeout expires when
the given duration of time on the CLOCK_MONOTONIC clock passes. Relative
timeouts may be imprecise (see futex_supports_exact_relative_timeouts).
Due to POSIX requirements on when synchronization data structures such
as mutexes or semaphores can be destroyed and due to the futex design
having separate fast/slow paths for wake-ups, we need to consider that
futex_wake calls might effectively target a data structure that has been
destroyed and reused for another object, or unmapped; thus, some
errors or spurious wake-ups can happen in correct executions that would
not be possible in a program using just a single futex whose lifetime
does not end before the program terminates. For background, see:
https://sourceware.org/ml/libc-alpha/2014-04/msg00075.html
https://lkml.org/lkml/2014/11/27/472 */
/* Defined this way for interoperability with lowlevellock.
FUTEX_PRIVATE must be zero because the initializers for pthread_mutex_t,
pthread_rwlock_t, and pthread_cond_t initialize the respective field of
those structures to zero, and we want FUTEX_PRIVATE to be the default. */
#define FUTEX_PRIVATE LLL_PRIVATE
#define FUTEX_SHARED LLL_SHARED
#if FUTEX_PRIVATE != 0
# error FUTEX_PRIVATE must be equal to 0
#endif
/* Returns EINVAL if PSHARED is neither PTHREAD_PROCESS_PRIVATE nor
PTHREAD_PROCESS_SHARED; otherwise, returns 0 if PSHARED is supported, and
ENOTSUP if not. */
static __always_inline int
futex_supports_pshared (int pshared);
/* Returns true if relative timeouts are robust to concurrent changes to the
system clock. If this returns false, relative timeouts can still be used
but might be effectively longer or shorter than requested. */
static __always_inline bool
futex_supports_exact_relative_timeouts (void);
/* Atomically wrt other futex operations on the same futex, this blocks iff
the value *FUTEX_WORD matches the expected value. This is
semantically equivalent to:
l = <get lock associated with futex> (FUTEX_WORD);
wait_flag = <get wait_flag associated with futex> (FUTEX_WORD);
lock (l);
val = atomic_load_relaxed (FUTEX_WORD);
if (val != expected) { unlock (l); return EAGAIN; }
atomic_store_relaxed (wait_flag, true);
unlock (l);
// Now block; can time out in futex_time_wait (see below)
while (atomic_load_relaxed(wait_flag) && !<spurious wake-up>);
Note that no guarantee of a happens-before relation between a woken
futex_wait and a futex_wake is documented; however, this does not matter
in practice because we have to consider spurious wake-ups (see below),
and thus would not be able to reliably reason about which futex_wake woke
us.
Returns 0 if woken by a futex operation or spuriously. (Note that due to
the POSIX requirements mentioned above, we need to conservatively assume
that unrelated futex_wake operations could wake this futex; it is easiest
to just be prepared for spurious wake-ups.)
Returns EAGAIN if the futex word did not match the expected value.
Returns EINTR if waiting was interrupted by a signal.
Note that some previous code in glibc assumed the underlying futex
operation (e.g., syscall) to start with or include the equivalent of a
seq_cst fence; this allows one to avoid an explicit seq_cst fence before
a futex_wait call when synchronizing similar to Dekker synchronization.
However, we make no such guarantee here. */
static __always_inline int
futex_wait (unsigned int *futex_word, unsigned int expected, int private);
/* Like futex_wait but does not provide any indication why we stopped waiting.
Thus, when this function returns, you have to always check FUTEX_WORD to
determine whether you need to continue waiting, and you cannot detect
whether the waiting was interrupted by a signal. Example use:
while (atomic_load_relaxed (&futex_word) == 23)
futex_wait_simple (&futex_word, 23, FUTEX_PRIVATE);
This is common enough to make providing this wrapper worthwhile. */
static __always_inline void
futex_wait_simple (unsigned int *futex_word, unsigned int expected,
int private)
{
ignore_value (futex_wait (futex_word, expected, private));
}
/* Like futex_wait but is a POSIX cancellation point. */
static __always_inline int
futex_wait_cancelable (unsigned int *futex_word, unsigned int expected,
int private);
/* Like futex_wait, but will eventually time out (i.e., stop being
blocked) after the duration of time provided (i.e., RELTIME) has
passed. The caller must provide a normalized RELTIME. RELTIME can also
equal NULL, in which case this function behaves equivalent to futex_wait.
Returns the same values as futex_wait under those same conditions;
additionally, returns ETIMEDOUT if the timeout expired.
*/
static __always_inline int
futex_reltimed_wait (unsigned int* futex_word, unsigned int expected,
const struct timespec* reltime, int private);
/* Like futex_reltimed_wait but is a POSIX cancellation point. */
static __always_inline int
futex_reltimed_wait_cancelable (unsigned int* futex_word,
unsigned int expected,
const struct timespec* reltime, int private);
/* Like futex_reltimed_wait, but the provided timeout (ABSTIME) is an
absolute point in time; a call will time out after this point in time. */
static __always_inline int
futex_abstimed_wait (unsigned int* futex_word, unsigned int expected,
const struct timespec* abstime, int private);
/* Like futex_reltimed_wait but is a POSIX cancellation point. */
static __always_inline int
futex_abstimed_wait_cancelable (unsigned int* futex_word,
unsigned int expected,
const struct timespec* abstime, int private);
/* Atomically wrt other futex operations on the same futex, this unblocks the
specified number of processes, or all processes blocked on this futex if
there are fewer than the specified number. Semantically, this is
equivalent to:
l = <get lock associated with futex> (FUTEX_WORD);
lock (l);
for (res = 0; PROCESSES_TO_WAKE > 0; PROCESSES_TO_WAKE--, res++) {
if (<no process blocked on futex>) break;
wf = <get wait_flag of a process blocked on futex> (FUTEX_WORD);
// No happens-before guarantee with woken futex_wait (see above)
atomic_store_relaxed (wf, 0);
}
return res;
Note that we need to support futex_wake calls to past futexes whose memory
has potentially been reused due to POSIX' requirements on synchronization
object destruction (see above); therefore, we must not report or abort
on most errors. */
static __always_inline void
futex_wake (unsigned int* futex_word, int processes_to_wake, int private);
/* Calls __libc_fatal with an error message. Convenience function for
concrete implementations of the futex interface. */
static __always_inline __attribute__ ((__noreturn__)) void
futex_fatal_error (void)
{
__libc_fatal ("The futex facility returned an unexpected error code.");
}
#endif /* futex-internal.h */

16
sysdeps/nptl/gai_misc.h
View File

@ -23,14 +23,14 @@
#include <assert.h>
#include <signal.h>
#include <nptl/pthreadP.h>
#include <lowlevellock.h>
#include <futex-internal.h>
#define DONT_NEED_GAI_MISC_COND 1
#define GAI_MISC_NOTIFY(waitlist) \
do { \
if (*waitlist->counterp > 0 && --*waitlist->counterp == 0) \
lll_futex_wake (waitlist->counterp, 1, LLL_PRIVATE); \
futex_wake ((unsigned int *) waitlist->counterp, 1, FUTEX_PRIVATE); \
} while (0)
#define GAI_MISC_WAIT(result, futex, timeout, cancel) \
@ -49,9 +49,9 @@
int status; \
do \
{ \
status = lll_futex_timed_wait (futexaddr, oldval, timeout, \
LLL_PRIVATE); \
if (status != -EWOULDBLOCK) \
status = futex_reltimed_wait ((unsigned int *) futexaddr, oldval, \
timeout, FUTEX_PRIVATE); \
if (status != EAGAIN) \
break; \
\
oldval = *futexaddr; \
@ -61,12 +61,12 @@
if (cancel) \
LIBC_CANCEL_RESET (oldtype); \
\
if (status == -EINTR) \
if (status == EINTR) \
result = EINTR; \
else if (status == -ETIMEDOUT) \
else if (status == ETIMEDOUT) \
result = EAGAIN; \
else \
assert (status == 0 || status == -EWOULDBLOCK); \
assert (status == 0 || status == EAGAIN); \
\
pthread_mutex_lock (&__gai_requests_mutex); \
} \

7
sysdeps/sparc/nptl/pthread_barrier_init.c
View File

@ -35,10 +35,9 @@ __pthread_barrier_init (barrier, attr, count)
struct pthread_barrierattr *iattr = (struct pthread_barrierattr *) attr;
if (iattr != NULL)
{
if (iattr->pshared != PTHREAD_PROCESS_PRIVATE
&& __builtin_expect (iattr->pshared != PTHREAD_PROCESS_SHARED, 0))
/* Invalid attribute. */
return EINVAL;
int err = futex_supports_pshared (iattr->pshared);
if (err != 0)
return err;
}
ibarrier = (union sparc_pthread_barrier *) barrier;

6
sysdeps/sparc/nptl/pthread_barrier_wait.c
View File

@ -21,6 +21,7 @@
#include <lowlevellock.h>
#include <pthreadP.h>
#include <sparc-nptl.h>
#include <futex-internal.h>
/* Wait on barrier. */
int
@ -31,6 +32,7 @@ __pthread_barrier_wait (barrier)
= (union sparc_pthread_barrier *) barrier;
int result = 0;
int private = ibarrier->s.pshared ? LLL_SHARED : LLL_PRIVATE;
int futex_private = ibarrier->s.pshared ? FUTEX_SHARED : FUTEX_PRIVATE;
/* Make sure we are alone. */
lll_lock (ibarrier->b.lock, private);
@ -46,7 +48,7 @@ __pthread_barrier_wait (barrier)
++ibarrier->b.curr_event;
/* Wake up everybody. */
lll_futex_wake (&ibarrier->b.curr_event, INT_MAX, private);
futex_wake (&ibarrier->b.curr_event, INT_MAX, futex_private);
/* This is the thread which finished the serialization. */
result = PTHREAD_BARRIER_SERIAL_THREAD;
@ -62,7 +64,7 @@ __pthread_barrier_wait (barrier)
/* Wait for the event counter of the barrier to change. */
do
lll_futex_wait (&ibarrier->b.curr_event, event, private);
futex_wait_simple (&ibarrier->b.curr_event, event, futex_private);
while (event == ibarrier->b.curr_event);
}

6
sysdeps/sparc/sparc32/pthread_barrier_wait.c
View File

@ -21,6 +21,7 @@
#include <lowlevellock.h>
#include <pthreadP.h>
#include <sparc-nptl.h>
#include <futex-internal.h>
/* Wait on barrier. */
int
@ -31,6 +32,7 @@ __pthread_barrier_wait (barrier)
= (union sparc_pthread_barrier *) barrier;
int result = 0;
int private = ibarrier->s.pshared ? LLL_SHARED : LLL_PRIVATE;
int futex_private = ibarrier->s.pshared ? FUTEX_SHARED : FUTEX_PRIVATE;
/* Make sure we are alone. */
lll_lock (ibarrier->b.lock, private);
@ -46,7 +48,7 @@ __pthread_barrier_wait (barrier)
++ibarrier->b.curr_event;
/* Wake up everybody. */
lll_futex_wake (&ibarrier->b.curr_event, INT_MAX, private);
futex_wake (&ibarrier->b.curr_event, INT_MAX, futex_private);
/* This is the thread which finished the serialization. */
result = PTHREAD_BARRIER_SERIAL_THREAD;
@ -62,7 +64,7 @@ __pthread_barrier_wait (barrier)
/* Wait for the event counter of the barrier to change. */
do
lll_futex_wait (&ibarrier->b.curr_event, event, private);
futex_wait_simple (&ibarrier->b.curr_event, event, futex_private);
while (event == ibarrier->b.curr_event);
}

29
sysdeps/sparc/sparc32/sem_init.c
View File

@ -20,23 +20,7 @@
#include <semaphore.h>
#include <shlib-compat.h>
#include "semaphoreP.h"
#include <kernel-features.h>
/* Returns FUTEX_PRIVATE if pshared is zero and private futexes are supported;
returns FUTEX_SHARED otherwise.
TODO Remove when cleaning up the futex API throughout glibc. */
static __always_inline int
futex_private_if_supported (int pshared)
{
if (pshared != 0)
return LLL_SHARED;
#ifdef __ASSUME_PRIVATE_FUTEX
return LLL_PRIVATE;
#else
return THREAD_GETMEM (THREAD_SELF, header.private_futex)
^ FUTEX_PRIVATE_FLAG;
#endif
}
#include <futex-internal.h>
int
@ -49,6 +33,14 @@ __new_sem_init (sem_t *sem, int pshared, unsigned int value)
return -1;
}
pshared = pshared != 0 ? PTHREAD_PROCESS_SHARED : PTHREAD_PROCESS_PRIVATE;
int err = futex_supports_pshared (pshared);
if (err != 0)
{
__set_errno (err);
return -1;
}
/* Map to the internal type. */
struct new_sem *isem = (struct new_sem *) sem;
@ -57,7 +49,8 @@ __new_sem_init (sem_t *sem, int pshared, unsigned int value)
isem->pad = 0;
isem->nwaiters = 0;
isem->private = futex_private_if_supported (pshared);
isem->private = (pshared == PTHREAD_PROCESS_PRIVATE
? FUTEX_PRIVATE : FUTEX_SHARED);
return 0;
}

2
sysdeps/sparc/sparc32/sem_open.c
View File

@ -199,7 +199,7 @@ sem_open (const char *name, int oflag, ...)
sem.newsem.nwaiters = 0;
/* This always is a shared semaphore. */
sem.newsem.private = LLL_SHARED;
sem.newsem.private = FUTEX_SHARED;
/* Initialize the remaining bytes as well. */
memset ((char *) &sem.initsem + sizeof (struct new_sem), '\0',

26
sysdeps/sparc/sparc32/sem_post.c
View File

@ -23,34 +23,10 @@
#include <lowlevellock.h>
#include <internaltypes.h>
#include <semaphore.h>
#include <futex-internal.h>
#include <shlib-compat.h>
/* Wrapper for lll_futex_wake, with error checking.
TODO Remove when cleaning up the futex API throughout glibc. */
static __always_inline void
futex_wake (unsigned int* futex, int processes_to_wake, int private)
{
int res = lll_futex_wake (futex, processes_to_wake, private);
/* No error. Ignore the number of woken processes. */
if (res >= 0)
return;
switch (res)
{
case -EFAULT: /* Could have happened due to memory reuse. */
case -EINVAL: /* Could be either due to incorrect alignment (a bug in
glibc or in the application) or due to memory being
reused for a PI futex. We cannot distinguish between the
two causes, and one of them is correct use, so we do not
act in this case. */
return;
case -ENOSYS: /* Must have been caused by a glibc bug. */
/* No other errors are documented at this time. */
default:
abort ();
}
}
/* See sem_wait for an explanation of the algorithm. */
int

1
sysdeps/sparc/sparc32/sem_wait.c
View File

@ -17,6 +17,7 @@
License along with the GNU C Library; if not, see
<http://www.gnu.org/licenses/>. */
#include <lowlevellock.h> /* lll_futex* used by the old code. */
#include "sem_waitcommon.c"
int

107
sysdeps/sparc/sparc32/sem_waitcommon.c
View File

@ -19,7 +19,7 @@
#include <errno.h>
#include <sysdep.h>
#include <lowlevellock.h>
#include <futex-internal.h>
#include <internaltypes.h>
#include <semaphore.h>
#include <sys/time.h>
@ -28,104 +28,6 @@
#include <shlib-compat.h>
#include <atomic.h>
/* Wrapper for lll_futex_wait with absolute timeout and error checking.
TODO Remove when cleaning up the futex API throughout glibc. */
static __always_inline int
futex_abstimed_wait (unsigned int* futex, unsigned int expected,
const struct timespec* abstime, int private, bool cancel)
{
int err, oldtype;
if (abstime == NULL)
{
if (cancel)
oldtype = __pthread_enable_asynccancel ();
err = lll_futex_wait (futex, expected, private);
if (cancel)
__pthread_disable_asynccancel (oldtype);
}
else
{
struct timeval tv;
struct timespec rt;
int sec, nsec;
/* Get the current time. */
__gettimeofday (&tv, NULL);
/* Compute relative timeout. */
sec = abstime->tv_sec - tv.tv_sec;
nsec = abstime->tv_nsec - tv.tv_usec * 1000;
if (nsec < 0)
{
nsec += 1000000000;
--sec;
}
/* Already timed out? */
if (sec < 0)
return ETIMEDOUT;
/* Do wait. */
rt.tv_sec = sec;
rt.tv_nsec = nsec;
if (cancel)
oldtype = __pthread_enable_asynccancel ();
err = lll_futex_timed_wait (futex, expected, &rt, private);
if (cancel)
__pthread_disable_asynccancel (oldtype);
}
switch (err)
{
case 0:
case -EAGAIN:
case -EINTR:
case -ETIMEDOUT:
return -err;
case -EFAULT: /* Must have been caused by a glibc or application bug. */
case -EINVAL: /* Either due to wrong alignment or due to the timeout not
being normalized. Must have been caused by a glibc or
application bug. */
case -ENOSYS: /* Must have been caused by a glibc bug. */
/* No other errors are documented at this time. */
default:
abort ();
}
}
/* Wrapper for lll_futex_wake, with error checking.
TODO Remove when cleaning up the futex API throughout glibc. */
static __always_inline void
futex_wake (unsigned int* futex, int processes_to_wake, int private)
{
int res = lll_futex_wake (futex, processes_to_wake, private);
/* No error. Ignore the number of woken processes. */
if (res >= 0)
return;
switch (res)
{
case -EFAULT: /* Could have happened due to memory reuse. */
case -EINVAL: /* Could be either due to incorrect alignment (a bug in
glibc or in the application) or due to memory being
reused for a PI futex. We cannot distinguish between the
two causes, and one of them is correct use, so we do not
act in this case. */
return;
case -ENOSYS: /* Must have been caused by a glibc bug. */
/* No other errors are documented at this time. */
default:
abort ();
}
}
/* Set this to true if you assume that, in contrast to current Linux futex
documentation, lll_futex_wake can return -EINTR only if interrupted by a
signal, not spuriously due to some other reason.
TODO Discuss EINTR conditions with the Linux kernel community. For
now, we set this to true to not change behavior of semaphores compared
to previous glibc builds. */
static const int sem_assume_only_signals_cause_futex_EINTR = 1;
static void
__sem_wait_32_finish (struct new_sem *sem);
@ -149,8 +51,8 @@ do_futex_wait (struct new_sem *sem, const struct timespec *abstime)
{
int err;
err = futex_abstimed_wait (&sem->value, SEM_NWAITERS_MASK, abstime,
sem->private, true);
err = futex_abstimed_wait_cancelable (&sem->value, SEM_NWAITERS_MASK,
abstime, sem->private);
return err;
}
@ -202,8 +104,7 @@ __new_sem_wait_slow (struct new_sem *sem, const struct timespec *abstime)
__sparc32_atomic_do_unlock24(&sem->pad);
err = do_futex_wait(sem, abstime);
if (err == ETIMEDOUT ||
(err == EINTR && sem_assume_only_signals_cause_futex_EINTR))
if (err == ETIMEDOUT || err == EINTR)
{
__set_errno (err);
err = -1;

251
sysdeps/unix/sysv/linux/futex-internal.h Normal file
View File

@ -0,0 +1,251 @@
/* futex operations for glibc-internal use. Linux version.
Copyright (C) 2014-2015 Free Software Foundation, Inc.
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 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/>. */
#ifndef FUTEX_INTERNAL_H
#define FUTEX_INTERNAL_H
#include <sysdeps/nptl/futex-internal.h>
#include <errno.h>
#include <lowlevellock-futex.h>
#include <nptl/pthreadP.h>
/* See sysdeps/nptl/futex-internal.h for documentation; this file only
contains Linux-specific comments.
The Linux kernel treats provides absolute timeouts based on the
CLOCK_REALTIME clock and relative timeouts measured against the
CLOCK_MONOTONIC clock.
We expect a Linux kernel version of 2.6.22 or more recent (since this
version, EINTR is not returned on spurious wake-ups anymore). */
/* FUTEX_SHARED is always supported by the Linux kernel. */
static __always_inline int
futex_supports_pshared (int pshared)
{
if (__glibc_likely (pshared == PTHREAD_PROCESS_PRIVATE))
return 0;
else if (pshared == PTHREAD_PROCESS_SHARED)
return 0;
else
return EINVAL;
}
/* The Linux kernel supports relative timeouts measured against the
CLOCK_MONOTONIC clock. */
static __always_inline bool
futex_supports_exact_relative_timeouts (void)
{
return true;
}
/* See sysdeps/nptl/futex-internal.h for details. */
static __always_inline int
futex_wait (unsigned int *futex_word, unsigned int expected, int private)
{
int err = lll_futex_timed_wait (futex_word, expected, NULL, private);
switch (err)
{
case 0:
case -EAGAIN:
case -EINTR:
return -err;
case -ETIMEDOUT: /* Cannot have happened as we provided no timeout. */
case -EFAULT: /* Must have been caused by a glibc or application bug. */
case -EINVAL: /* Either due to wrong alignment or due to the timeout not
being normalized. Must have been caused by a glibc or
application bug. */
case -ENOSYS: /* Must have been caused by a glibc bug. */
/* No other errors are documented at this time. */
default:
futex_fatal_error ();
}
}
/* See sysdeps/nptl/futex-internal.h for details. */
static __always_inline int
futex_wait_cancelable (unsigned int *futex_word, unsigned int expected,
int private)
{
int oldtype;
oldtype = __pthread_enable_asynccancel ();
int err = lll_futex_timed_wait (futex_word, expected, NULL, private);
__pthread_disable_asynccancel (oldtype);
switch (err)
{
case 0:
case -EAGAIN:
case -EINTR:
return -err;
case -ETIMEDOUT: /* Cannot have happened as we provided no timeout. */
case -EFAULT: /* Must have been caused by a glibc or application bug. */
case -EINVAL: /* Either due to wrong alignment or due to the timeout not
being normalized. Must have been caused by a glibc or
application bug. */
case -ENOSYS: /* Must have been caused by a glibc bug. */
/* No other errors are documented at this time. */
default:
futex_fatal_error ();
}
}
/* See sysdeps/nptl/futex-internal.h for details. */
static __always_inline int
futex_reltimed_wait (unsigned int *futex_word, unsigned int expected,
const struct timespec *reltime, int private)
{
int err = lll_futex_timed_wait (futex_word, expected, reltime, private);
switch (err)
{
case 0:
case -EAGAIN:
case -EINTR:
case -ETIMEDOUT:
return -err;
case -EFAULT: /* Must have been caused by a glibc or application bug. */
case -EINVAL: /* Either due to wrong alignment or due to the timeout not
being normalized. Must have been caused by a glibc or
application bug. */
case -ENOSYS: /* Must have been caused by a glibc bug. */
/* No other errors are documented at this time. */
default:
futex_fatal_error ();
}
}
/* See sysdeps/nptl/futex-internal.h for details. */
static __always_inline int
futex_reltimed_wait_cancelable (unsigned int *futex_word,
unsigned int expected,
const struct timespec *reltime, int private)
{
int oldtype;
oldtype = __pthread_enable_asynccancel ();
int err = lll_futex_timed_wait (futex_word, expected, reltime, private);
__pthread_disable_asynccancel (oldtype);
switch (err)
{
case 0:
case -EAGAIN:
case -EINTR:
case -ETIMEDOUT:
return -err;
case -EFAULT: /* Must have been caused by a glibc or application bug. */
case -EINVAL: /* Either due to wrong alignment or due to the timeout not
being normalized. Must have been caused by a glibc or
application bug. */
case -ENOSYS: /* Must have been caused by a glibc bug. */
/* No other errors are documented at this time. */
default:
futex_fatal_error ();
}
}
/* See sysdeps/nptl/futex-internal.h for details. */
static __always_inline int
futex_abstimed_wait (unsigned int *futex_word, unsigned int expected,
const struct timespec *abstime, int private)
{
/* Work around the fact that the kernel rejects negative timeout values
despite them being valid. */
if (__glibc_unlikely ((abstime != NULL) && (abstime->tv_sec < 0)))
return ETIMEDOUT;
int err = lll_futex_timed_wait_bitset (futex_word, expected, abstime,
FUTEX_CLOCK_REALTIME, private);
switch (err)
{
case 0:
case -EAGAIN:
case -EINTR:
case -ETIMEDOUT:
return -err;
case -EFAULT: /* Must have been caused by a glibc or application bug. */
case -EINVAL: /* Either due to wrong alignment or due to the timeout not
being normalized. Must have been caused by a glibc or
application bug. */
case -ENOSYS: /* Must have been caused by a glibc bug. */
/* No other errors are documented at this time. */
default:
futex_fatal_error ();
}
}
/* See sysdeps/nptl/futex-internal.h for details. */
static __always_inline int
futex_abstimed_wait_cancelable (unsigned int *futex_word,
unsigned int expected,
const struct timespec *abstime, int private)
{
/* Work around the fact that the kernel rejects negative timeout values
despite them being valid. */
if (__glibc_unlikely ((abstime != NULL) && (abstime->tv_sec < 0)))
return ETIMEDOUT;
int oldtype;
oldtype = __pthread_enable_asynccancel ();
int err = lll_futex_timed_wait_bitset (futex_word, expected, abstime,
FUTEX_CLOCK_REALTIME, private);
__pthread_disable_asynccancel (oldtype);
switch (err)
{
case 0:
case -EAGAIN:
case -EINTR:
case -ETIMEDOUT:
return -err;
case -EFAULT: /* Must have been caused by a glibc or application bug. */
case -EINVAL: /* Either due to wrong alignment or due to the timeout not
being normalized. Must have been caused by a glibc or
application bug. */
case -ENOSYS: /* Must have been caused by a glibc bug. */
/* No other errors are documented at this time. */
default:
futex_fatal_error ();
}
}
/* See sysdeps/nptl/futex-internal.h for details. */
static __always_inline void
futex_wake (unsigned int *futex_word, int processes_to_wake, int private)
{
int res = lll_futex_wake (futex_word, processes_to_wake, private);
/* No error. Ignore the number of woken processes. */
if (res >= 0)
return;
switch (res)
{
case -EFAULT: /* Could have happened due to memory reuse. */
case -EINVAL: /* Could be either due to incorrect alignment (a bug in
glibc or in the application) or due to memory being
reused for a PI futex. We cannot distinguish between the
two causes, and one of them is correct use, so we do not
act in this case. */
return;
case -ENOSYS: /* Must have been caused by a glibc bug. */
/* No other errors are documented at this time. */
default:
futex_fatal_error ();
}
}
#endif /* futex-internal.h */