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Code Issues Releases Activity

Revert revision 214007, I realized that MySQL wants to resolve

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a silly rwlock deadlock problem, the deadlock is caused by writer
waiters, if a thread has already locked a reader lock, and wants to
acquire another reader lock, it will be blocked by writer waiters,
but we had already fixed it years ago.
This commit is contained in:
David Xu 2010-10-20 02:34:02 +00:00
parent cfca8a1862
commit de1e74c6a5
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=214093
6 changed files with 2 additions and 56 deletions
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2
lib/libc/include/namespace.h
View File

@ -177,10 +177,8 @@
#define pthread_rwlock_unlock _pthread_rwlock_unlock
#define pthread_rwlock_wrlock _pthread_rwlock_wrlock
#define pthread_rwlockattr_destroy _pthread_rwlockattr_destroy
#define pthread_rwlockattr_getkind_np _pthread_rwlockattr_getkind_np
#define pthread_rwlockattr_getpshared _pthread_rwlockattr_getpshared
#define pthread_rwlockattr_init _pthread_rwlockattr_init
#define pthread_rwlockattr_setkind_np _pthread_rwlockattr_setkind_np
#define pthread_rwlockattr_setpshared _pthread_rwlockattr_setpshared
#define pthread_self _pthread_self
#define pthread_set_name_np _pthread_set_name_np

2
lib/libc/include/un-namespace.h
View File

@ -158,10 +158,8 @@
#undef pthread_rwlock_unlock
#undef pthread_rwlock_wrlock
#undef pthread_rwlockattr_destroy
#undef pthread_rwlockattr_getkind_np
#undef pthread_rwlockattr_getpshared
#undef pthread_rwlockattr_init
#undef pthread_rwlockattr_setkind_np
#undef pthread_rwlockattr_setpshared
#undef pthread_self
#undef pthread_set_name_np

4
lib/libthr/pthread.map
View File

@ -318,9 +318,7 @@ FBSDprivate_1.0 {
_pthread_rwlock_wrlock;
_pthread_rwlockattr_destroy;
_pthread_rwlockattr_getpshared;
_pthread_rwlockattr_getkind_np;
_pthread_rwlockattr_init;
_pthread_rwlockattr_setkind_np;
_pthread_rwlockattr_setpshared;
_pthread_self;
_pthread_set_name_np;
@ -403,8 +401,6 @@ FBSD_1.1 {
FBSD_1.2 {
openat;
pthread_rwlockattr_getkind_np;
pthread_rwlockattr_setkind_np;
setcontext;
swapcontext;
};

3
lib/libthr/thread/thr_private.h
View File

@ -285,14 +285,11 @@ struct pthread_prio {
struct pthread_rwlockattr {
int pshared;
int kind;
};
struct pthread_rwlock {
struct urwlock lock;
struct pthread *owner;
int recurse;
int kind;
};
/*

25
lib/libthr/thread/thr_rwlock.c
View File

@ -63,19 +63,13 @@ __weak_reference(_pthread_rwlock_timedwrlock, pthread_rwlock_timedwrlock);
*/
static int
rwlock_init(pthread_rwlock_t *rwlock, const pthread_rwlockattr_t *attr)
rwlock_init(pthread_rwlock_t *rwlock, const pthread_rwlockattr_t *attr __unused)
{
pthread_rwlock_t prwlock;
prwlock = (pthread_rwlock_t)calloc(1, sizeof(struct pthread_rwlock));
if (prwlock == NULL)
return (ENOMEM);
if (attr != NULL)
prwlock->kind = (*attr)->kind;
else
prwlock->kind = PTHREAD_RWLOCK_DEFAULT_NP;
if (prwlock->kind == PTHREAD_RWLOCK_PREFER_READER_NP)
prwlock->lock.rw_flags |= URWLOCK_PREFER_READER;
*rwlock = prwlock;
return (0);
}
@ -118,7 +112,7 @@ init_static(struct pthread *thread, pthread_rwlock_t *rwlock)
}
int
_pthread_rwlock_init(pthread_rwlock_t *rwlock, const pthread_rwlockattr_t *attr)
_pthread_rwlock_init (pthread_rwlock_t *rwlock, const pthread_rwlockattr_t *attr)
{
*rwlock = NULL;
return (rwlock_init(rwlock, attr));
@ -266,14 +260,6 @@ rwlock_wrlock_common (pthread_rwlock_t *rwlock, const struct timespec *abstime)
CHECK_AND_INIT_RWLOCK
if (__predict_false(prwlock->owner == curthread)) {
if (__predict_false(
prwlock->kind == PTHREAD_RWLOCK_PREFER_WRITER_NP)) {
prwlock->recurse++;
return (0);
}
}
/*
* POSIX said the validity of the abstimeout parameter need
* not be checked if the lock can be immediately acquired.
@ -349,13 +335,6 @@ _pthread_rwlock_unlock (pthread_rwlock_t *rwlock)
if (state & URWLOCK_WRITE_OWNER) {
if (__predict_false(prwlock->owner != curthread))
return (EPERM);
if (__predict_false(
prwlock->kind == PTHREAD_RWLOCK_PREFER_WRITER_NP)) {
if (prwlock->recurse > 0) {
prwlock->recurse--;
return (0);
}
}
prwlock->owner = NULL;
}

22
lib/libthr/thread/thr_rwlockattr.c
View File

@ -36,10 +36,8 @@
__weak_reference(_pthread_rwlockattr_destroy, pthread_rwlockattr_destroy);
__weak_reference(_pthread_rwlockattr_getpshared, pthread_rwlockattr_getpshared);
__weak_reference(_pthread_rwlockattr_getkind_np, pthread_rwlockattr_getkind_np);
__weak_reference(_pthread_rwlockattr_init, pthread_rwlockattr_init);
__weak_reference(_pthread_rwlockattr_setpshared, pthread_rwlockattr_setpshared);
__weak_reference(_pthread_rwlockattr_setkind_np, pthread_rwlockattr_setkind_np);
int
_pthread_rwlockattr_destroy(pthread_rwlockattr_t *rwlockattr)
@ -83,7 +81,6 @@ _pthread_rwlockattr_init(pthread_rwlockattr_t *rwlockattr)
return(ENOMEM);
prwlockattr->pshared = PTHREAD_PROCESS_PRIVATE;
prwlockattr->kind = PTHREAD_RWLOCK_PREFER_WRITER_NONRECURSIVE_NP;
*rwlockattr = prwlockattr;
return(0);
@ -100,22 +97,3 @@ _pthread_rwlockattr_setpshared(pthread_rwlockattr_t *rwlockattr, int pshared)
return(0);
}
int
_pthread_rwlockattr_setkind_np(pthread_rwlockattr_t *attr, int kind)
{
if (kind != PTHREAD_RWLOCK_PREFER_READER_NP &&
kind != PTHREAD_RWLOCK_PREFER_WRITER_NONRECURSIVE_NP &&
kind != PTHREAD_RWLOCK_PREFER_WRITER_NP) {
return (EINVAL);
}
(*attr)->kind = kind;
return (0);
}
int
_pthread_rwlockattr_getkind_np(const pthread_rwlockattr_t *attr, int *kind)
{
*kind = (*attr)->kind;
return (0);
}