summaryrefslogtreecommitdiff
path: root/libpthread/linuxthreads/rwlock.c
diff options
context:
space:
mode:
Diffstat (limited to 'libpthread/linuxthreads/rwlock.c')
-rw-r--r--libpthread/linuxthreads/rwlock.c239
1 files changed, 34 insertions, 205 deletions
diff --git a/libpthread/linuxthreads/rwlock.c b/libpthread/linuxthreads/rwlock.c
index 4a0fb1bba..977fd88af 100644
--- a/libpthread/linuxthreads/rwlock.c
+++ b/libpthread/linuxthreads/rwlock.c
@@ -1,20 +1,20 @@
/* Read-write lock implementation.
- Copyright (C) 1998, 2000 Free Software Foundation, Inc.
+ Copyright (C) 1998 Free Software Foundation, Inc.
This file is part of the GNU C Library.
Contributed by Xavier Leroy <Xavier.Leroy@inria.fr>
and Ulrich Drepper <drepper@cygnus.com>, 1998.
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
+ modify it under the terms of the GNU Library General Public License as
+ published by the Free Software Foundation; either version 2 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.
+ Library General Public License for more details.
- You should have received a copy of the GNU Lesser General Public
+ You should have received a copy of the GNU Library General Public
License along with the GNU C Library; see the file COPYING.LIB. If not,
write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
Boston, MA 02111-1307, USA. */
@@ -27,33 +27,6 @@
#include "spinlock.h"
#include "restart.h"
-/* Function called by pthread_cancel to remove the thread from
- waiting inside pthread_rwlock_timedrdlock or pthread_rwlock_timedwrlock. */
-
-static int rwlock_rd_extricate_func(void *obj, pthread_descr th)
-{
- pthread_rwlock_t *rwlock = obj;
- int did_remove = 0;
-
- __pthread_lock(&rwlock->__rw_lock, NULL);
- did_remove = remove_from_queue(&rwlock->__rw_read_waiting, th);
- __pthread_unlock(&rwlock->__rw_lock);
-
- return did_remove;
-}
-
-static int rwlock_wr_extricate_func(void *obj, pthread_descr th)
-{
- pthread_rwlock_t *rwlock = obj;
- int did_remove = 0;
-
- __pthread_lock(&rwlock->__rw_lock, NULL);
- did_remove = remove_from_queue(&rwlock->__rw_write_waiting, th);
- __pthread_unlock(&rwlock->__rw_lock);
-
- return did_remove;
-}
-
/*
* Check whether the calling thread already owns one or more read locks on the
* specified lock. If so, return a pointer to the read lock info structure
@@ -65,8 +38,7 @@ rwlock_is_in_list(pthread_descr self, pthread_rwlock_t *rwlock)
{
pthread_readlock_info *info;
- for (info = THREAD_GETMEM (self, p_readlock_list); info != NULL;
- info = info->pr_next)
+ for (info = self->p_readlock_list; info != NULL; info = info->pr_next)
{
if (info->pr_lock == rwlock)
return info;
@@ -86,10 +58,10 @@ rwlock_is_in_list(pthread_descr self, pthread_rwlock_t *rwlock)
static pthread_readlock_info *
rwlock_add_to_list(pthread_descr self, pthread_rwlock_t *rwlock)
{
- pthread_readlock_info *info = THREAD_GETMEM (self, p_readlock_free);
+ pthread_readlock_info *info = self->p_readlock_free;
- if (info != NULL)
- THREAD_SETMEM (self, p_readlock_free, info->pr_next);
+ if (info != NULL)
+ self->p_readlock_free = info->pr_next;
else
info = malloc(sizeof *info);
@@ -98,8 +70,8 @@ rwlock_add_to_list(pthread_descr self, pthread_rwlock_t *rwlock)
info->pr_lock_count = 1;
info->pr_lock = rwlock;
- info->pr_next = THREAD_GETMEM (self, p_readlock_list);
- THREAD_SETMEM (self, p_readlock_list, info);
+ info->pr_next = self->p_readlock_list;
+ self->p_readlock_list = info;
return info;
}
@@ -128,7 +100,7 @@ rwlock_remove_from_list(pthread_descr self, pthread_rwlock_t *rwlock)
return info;
}
}
-
+
return NULL;
}
@@ -165,7 +137,7 @@ rwlock_can_rdlock(pthread_rwlock_t *rwlock, int have_lock_already)
* This function helps support brain-damaged recursive read locking
* semantics required by Unix 98, while maintaining write priority.
* This basically determines whether this thread already holds a read lock
- * already. It returns 1 if so, otherwise it returns 0.
+ * already. It returns 1 if so, otherwise it returns 0.
*
* If the thread has any ``untracked read locks'' then it just assumes
* that this lock is among them, just to be safe, and returns 1.
@@ -189,12 +161,11 @@ rwlock_have_already(pthread_descr *pself, pthread_rwlock_t *rwlock,
if (rwlock->__rw_kind == PTHREAD_RWLOCK_PREFER_WRITER_NP)
{
if (!self)
- *pself = self = thread_self();
+ self = thread_self();
existing = rwlock_is_in_list(self, rwlock);
- if (existing != NULL
- || THREAD_GETMEM (self, p_untracked_readlock_count) > 0)
+ if (existing != NULL || self->p_untracked_readlock_count > 0)
have_lock_already = 1;
else
{
@@ -206,6 +177,7 @@ rwlock_have_already(pthread_descr *pself, pthread_rwlock_t *rwlock,
*pout_of_mem = out_of_mem;
*pexisting = existing;
+ *pself = self;
return have_lock_already;
}
@@ -235,7 +207,6 @@ pthread_rwlock_init (pthread_rwlock_t *rwlock,
}
-
int
pthread_rwlock_destroy (pthread_rwlock_t *rwlock)
{
@@ -253,7 +224,6 @@ pthread_rwlock_destroy (pthread_rwlock_t *rwlock)
return 0;
}
-
int
pthread_rwlock_rdlock (pthread_rwlock_t *rwlock)
{
@@ -262,65 +232,13 @@ pthread_rwlock_rdlock (pthread_rwlock_t *rwlock)
int out_of_mem, have_lock_already;
have_lock_already = rwlock_have_already(&self, rwlock,
- &existing, &out_of_mem);
-
- if (self == NULL)
- self = thread_self ();
+ &existing, &out_of_mem);
for (;;)
{
- __pthread_lock (&rwlock->__rw_lock, self);
-
- if (rwlock_can_rdlock(rwlock, have_lock_already))
- break;
-
- enqueue (&rwlock->__rw_read_waiting, self);
- __pthread_unlock (&rwlock->__rw_lock);
- suspend (self); /* This is not a cancellation point */
- }
-
- ++rwlock->__rw_readers;
- __pthread_unlock (&rwlock->__rw_lock);
-
- if (have_lock_already || out_of_mem)
- {
- if (existing != NULL)
- ++existing->pr_lock_count;
- else
- ++self->p_untracked_readlock_count;
- }
+ if (self == NULL)
+ self = thread_self ();
- return 0;
-}
-
-
-int
-pthread_rwlock_timedrdlock (pthread_rwlock_t *rwlock,
- const struct timespec *abstime)
-{
- pthread_descr self = NULL;
- pthread_readlock_info *existing;
- int out_of_mem, have_lock_already;
- pthread_extricate_if extr;
-
- if (abstime->tv_nsec < 0 || abstime->tv_nsec >= 1000000000)
- return EINVAL;
-
- have_lock_already = rwlock_have_already(&self, rwlock,
- &existing, &out_of_mem);
-
- if (self == NULL)
- self = thread_self ();
-
- /* Set up extrication interface */
- extr.pu_object = rwlock;
- extr.pu_extricate_func = rwlock_rd_extricate_func;
-
- /* Register extrication interface */
- __pthread_set_own_extricate_if (self, &extr);
-
- for (;;)
- {
__pthread_lock (&rwlock->__rw_lock, self);
if (rwlock_can_rdlock(rwlock, have_lock_already))
@@ -328,43 +246,23 @@ pthread_rwlock_timedrdlock (pthread_rwlock_t *rwlock,
enqueue (&rwlock->__rw_read_waiting, self);
__pthread_unlock (&rwlock->__rw_lock);
- /* This is not a cancellation point */
- if (timedsuspend (self, abstime) == 0)
- {
- int was_on_queue;
-
- __pthread_lock (&rwlock->__rw_lock, self);
- was_on_queue = remove_from_queue (&rwlock->__rw_read_waiting, self);
- __pthread_unlock (&rwlock->__rw_lock);
-
- if (was_on_queue)
- {
- __pthread_set_own_extricate_if (self, 0);
- return ETIMEDOUT;
- }
-
- /* Eat the outstanding restart() from the signaller */
- suspend (self);
- }
+ suspend (self); /* This is not a cancellation point */
}
- __pthread_set_own_extricate_if (self, 0);
-
++rwlock->__rw_readers;
__pthread_unlock (&rwlock->__rw_lock);
if (have_lock_already || out_of_mem)
{
if (existing != NULL)
- ++existing->pr_lock_count;
+ existing->pr_lock_count++;
else
- ++self->p_untracked_readlock_count;
+ self->p_untracked_readlock_count++;
}
-
+
return 0;
}
-
int
pthread_rwlock_tryrdlock (pthread_rwlock_t *rwlock)
{
@@ -379,7 +277,7 @@ pthread_rwlock_tryrdlock (pthread_rwlock_t *rwlock)
__pthread_lock (&rwlock->__rw_lock, self);
/* 0 is passed to here instead of have_lock_already.
- This is to meet Single Unix Spec requirements:
+ This is to meet Single Unix Spec requirements:
if writers are waiting, pthread_rwlock_tryrdlock
does not acquire a read lock, even if the caller has
one or more read locks already. */
@@ -397,17 +295,16 @@ pthread_rwlock_tryrdlock (pthread_rwlock_t *rwlock)
if (have_lock_already || out_of_mem)
{
if (existing != NULL)
- ++existing->pr_lock_count;
+ existing->pr_lock_count++;
else
- ++self->p_untracked_readlock_count;
+ self->p_untracked_readlock_count++;
}
}
-
+
return retval;
}
-
int
pthread_rwlock_wrlock (pthread_rwlock_t *rwlock)
{
@@ -431,64 +328,6 @@ pthread_rwlock_wrlock (pthread_rwlock_t *rwlock)
}
-
-int
-pthread_rwlock_timedwrlock (pthread_rwlock_t *rwlock,
- const struct timespec *abstime)
-{
- pthread_descr self;
- pthread_extricate_if extr;
-
- if (abstime->tv_nsec < 0 || abstime->tv_nsec >= 1000000000)
- return EINVAL;
-
- self = thread_self ();
-
- /* Set up extrication interface */
- extr.pu_object = rwlock;
- extr.pu_extricate_func = rwlock_wr_extricate_func;
-
- /* Register extrication interface */
- __pthread_set_own_extricate_if (self, &extr);
-
- while(1)
- {
- __pthread_lock (&rwlock->__rw_lock, self);
-
- if (rwlock->__rw_readers == 0 && rwlock->__rw_writer == NULL)
- {
- rwlock->__rw_writer = self;
- __pthread_set_own_extricate_if (self, 0);
- __pthread_unlock (&rwlock->__rw_lock);
- return 0;
- }
-
- /* Suspend ourselves, then try again */
- enqueue (&rwlock->__rw_write_waiting, self);
- __pthread_unlock (&rwlock->__rw_lock);
- /* This is not a cancellation point */
- if (timedsuspend (self, abstime) == 0)
- {
- int was_on_queue;
-
- __pthread_lock (&rwlock->__rw_lock, self);
- was_on_queue = remove_from_queue (&rwlock->__rw_write_waiting, self);
- __pthread_unlock (&rwlock->__rw_lock);
-
- if (was_on_queue)
- {
- __pthread_set_own_extricate_if (self, 0);
- return ETIMEDOUT;
- }
-
- /* Eat the outstanding restart() from the signaller */
- suspend (self);
- }
- }
-}
-
-
-
int
pthread_rwlock_trywrlock (pthread_rwlock_t *rwlock)
{
@@ -506,7 +345,6 @@ pthread_rwlock_trywrlock (pthread_rwlock_t *rwlock)
}
-
int
pthread_rwlock_unlock (pthread_rwlock_t *rwlock)
{
@@ -524,9 +362,8 @@ pthread_rwlock_unlock (pthread_rwlock_t *rwlock)
}
rwlock->__rw_writer = NULL;
- if ((rwlock->__rw_kind == PTHREAD_RWLOCK_PREFER_READER_NP
- && !queue_is_empty(&rwlock->__rw_read_waiting))
- || (th = dequeue(&rwlock->__rw_write_waiting)) == NULL)
+ if (rwlock->__rw_kind == PTHREAD_RWLOCK_PREFER_READER_NP
+ || (th = dequeue (&rwlock->__rw_write_waiting)) == NULL)
{
/* Restart all waiting readers. */
torestart = rwlock->__rw_read_waiting;
@@ -573,15 +410,14 @@ pthread_rwlock_unlock (pthread_rwlock_t *rwlock)
{
if (victim->pr_lock_count == 0)
{
- victim->pr_next = THREAD_GETMEM (self, p_readlock_free);
- THREAD_SETMEM (self, p_readlock_free, victim);
+ victim->pr_next = self->p_readlock_free;
+ self->p_readlock_free = victim;
}
}
else
{
- int val = THREAD_GETMEM (self, p_untracked_readlock_count);
- if (val > 0)
- THREAD_SETMEM (self, p_untracked_readlock_count, val - 1);
+ if (self->p_untracked_readlock_count > 0)
+ self->p_untracked_readlock_count--;
}
}
}
@@ -591,12 +427,11 @@ pthread_rwlock_unlock (pthread_rwlock_t *rwlock)
-
int
pthread_rwlockattr_init (pthread_rwlockattr_t *attr)
{
attr->__lockkind = 0;
- attr->__pshared = PTHREAD_PROCESS_PRIVATE;
+ attr->__pshared = 0;
return 0;
}
@@ -609,7 +444,6 @@ pthread_rwlockattr_destroy (pthread_rwlockattr_t *attr)
}
-
int
pthread_rwlockattr_getpshared (const pthread_rwlockattr_t *attr, int *pshared)
{
@@ -624,10 +458,6 @@ pthread_rwlockattr_setpshared (pthread_rwlockattr_t *attr, int pshared)
if (pshared != PTHREAD_PROCESS_PRIVATE && pshared != PTHREAD_PROCESS_SHARED)
return EINVAL;
- /* For now it is not possible to shared a conditional variable. */
- if (pshared != PTHREAD_PROCESS_PRIVATE)
- return ENOSYS;
-
attr->__pshared = pshared;
return 0;
@@ -647,7 +477,6 @@ pthread_rwlockattr_setkind_np (pthread_rwlockattr_t *attr, int pref)
{
if (pref != PTHREAD_RWLOCK_PREFER_READER_NP
&& pref != PTHREAD_RWLOCK_PREFER_WRITER_NP
- && pref != PTHREAD_RWLOCK_PREFER_WRITER_NONRECURSIVE_NP
&& pref != PTHREAD_RWLOCK_DEFAULT_NP)
return EINVAL;