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fix deadlock in condition wait whenever there are multiple waiters

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it's amazing none of the conformance tests i've run even bothered to
check whether something so basic works...
This commit is contained in:
Rich Felker 2011-09-22 21:08:55 -04:00
parent 2eff02e4a0
commit 4b153ac424
4 changed files with 18 additions and 5 deletions
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1
src/internal/pthread_impl.h
View File

@ -66,6 +66,7 @@ struct __timer {
#define _m_count __u.__i[5]
#define _c_block __u.__i[0]
#define _c_clock __u.__i[1]
#define _c_waiters __u.__i[2]
#define _rw_lock __u.__i[0]
#define _rw_waiters __u.__i[1]
#define _b_inst __u.__p[0]

3
src/thread/pthread_cond_broadcast.c
View File

@ -2,7 +2,8 @@
int pthread_cond_broadcast(pthread_cond_t *c)
{
if (a_swap(&c->_c_block, 0))
int w = c->_c_waiters;
if (a_swap(&c->_c_block, 0) || w)
__wake(&c->_c_block, -1, 0);
return 0;
}

3
src/thread/pthread_cond_signal.c
View File

@ -2,7 +2,8 @@
int pthread_cond_signal(pthread_cond_t *c)
{
if (a_swap(&c->_c_block, 0));
int w = c->_c_waiters;
if (a_swap(&c->_c_block, 0) || w)
__wake(&c->_c_block, 1, 0);
return 0;
}

16
src/thread/pthread_cond_timedwait.c
View File

@ -1,12 +1,20 @@
#include "pthread_impl.h"
static void relock(void *m)
struct cm {
pthread_cond_t *c;
pthread_mutex_t *m;
};
static void cleanup(void *p)
{
pthread_mutex_lock(m);
struct cm *cm = p;
a_dec(&cm->c->_c_waiters);
pthread_mutex_lock(cm->m);
}
int pthread_cond_timedwait(pthread_cond_t *c, pthread_mutex_t *m, const struct timespec *ts)
{
struct cm cm = { .c=c, .m=m };
int r, e=0;
if (ts && ts->tv_nsec >= 1000000000UL)
@ -17,8 +25,10 @@ int pthread_cond_timedwait(pthread_cond_t *c, pthread_mutex_t *m, const struct t
c->_c_block = 1;
if ((r=pthread_mutex_unlock(m))) return r;
do e = __timedwait(&c->_c_block, 1, c->_c_clock, ts, relock, m, 0);
a_inc(&c->_c_waiters);
do e = __timedwait(&c->_c_block, 1, c->_c_clock, ts, cleanup, &cm, 0);
while (e == EINTR);
a_dec(&c->_c_waiters);
if ((r=pthread_mutex_lock(m))) return r;