citp_fdinfo_p citp_fdtable_busy_wait(unsigned fd, int fdt_locked)
{
volatile citp_fdinfo_p* p_fdip = &citp_fdtable.table[fd].fdip;
citp_fdtable_waiter waiter;
int saved_errno = errno;
Log_V(ci_log("%s: fd=%u", __FUNCTION__, fd));
ci_assert(ci_is_multithreaded());
oo_rwlock_cond_init(&waiter.cond);
oo_rwlock_cond_lock(&waiter.cond);
again:
waiter.next = *p_fdip;
if( fdip_is_busy(waiter.next) ) {
/* we can replace one "busy" fdip by another without fdtable lock */
if( fdip_cas_succeed(p_fdip, waiter.next, waiter_to_fdip(&waiter)) )
oo_rwlock_cond_wait(&waiter.cond);
goto again;
}
oo_rwlock_cond_unlock(&waiter.cond);
oo_rwlock_cond_destroy(&waiter.cond);
errno = saved_errno;
return waiter.next;
}
static void citp_dump_config(void)
{
char buf[80];
confstr(_CS_GNU_LIBC_VERSION, buf, sizeof(buf));
log("GNU_LIBC_VERSION = %s", buf);
confstr(_CS_GNU_LIBPTHREAD_VERSION, buf, sizeof(buf));
log("GNU_LIBPTHREAD_VERSION = %s", buf);
log("ci_glibc_uses_nptl = %d", ci_glibc_uses_nptl());
log("ci_is_multithreaded = %d", ci_is_multithreaded());
}
citp_fdinfo *
citp_fdtable_lookup(unsigned fd)
{
/* Note that if we haven't yet initialised this module, then
** [inited_count] will be zero, and the following test will fail. So the
** test for initialisation is done further down...
**
** This is highly performance critial. DO NOT add any code between here
** and the first [return] statement.
*/
citp_fdinfo* fdi;
/* In some cases, we'll lock fdtable. Assert that it is possible: */
ci_assert(oo_per_thread_get()->sig.inside_lib);
if( fd < citp_fdtable.inited_count ) {
volatile citp_fdinfo_p* p_fdip = &citp_fdtable.table[fd].fdip;
citp_fdinfo_p fdip;
again:
/* Swap in the busy marker. */
fdip = *p_fdip;
if( fdip_is_normal(fdip) ) {
if( citp_fdtable_not_mt_safe() ) {
if( fdip_cas_succeed(p_fdip, fdip, fdip_busy) ) {
fdi = fdip_to_fdi(fdip);
ci_assert(fdi);
ci_assert_gt(oo_atomic_read(&fdi->ref_count), 0);
ci_assert(fdip_is_closing(fdip) || fdip_is_reserved(fdip) ||
fdi->fd == fd);
/* Bump the reference count. */
citp_fdinfo_ref(fdi);
if( ! citp_fdinfo_is_consistent(fdi) ) {
/* Something is wrong. Re-probe. */
fdi = citp_reprobe_moved(fdi, CI_FALSE, CI_TRUE);
}
else {
/* Swap the busy marker out again. */
citp_fdtable_busy_clear(fd, fdip, 0);
}
return fdi;
}
goto again;
}
else {
/* No need to use atomic ops when single-threaded. The definition
* of "fds_mt_safe" is that the app does not change the meaning of
* a file descriptor in one thread when it is being used in another
* thread. In that case I'm hoping this should be safe, but at
* time of writing I'm really not confident. (FIXME).
*/
fdi = fdip_to_fdi(fdip);
if( ci_is_multithreaded() )
citp_fdinfo_ref(fdi);
else
++fdi->ref_count.n;
if( ! citp_fdinfo_is_consistent(fdi) )
fdi = citp_reprobe_moved(fdi, CI_FALSE, CI_FALSE);
return fdi;
}
}
/* Not normal! */
if( fdip_is_passthru(fdip) ) return NULL;
if( fdip_is_busy(fdip) ) {
citp_fdtable_busy_wait(fd, 0);
goto again;
}
ci_assert(fdip_is_unknown(fdip));
goto probe;
}
if (citp.init_level < CITP_INIT_FDTABLE) {
if (_citp_do_init_inprogress == 0)
CI_TRY(citp_do_init(CITP_INIT_ALL));
else
CI_TRY(citp_do_init(CITP_INIT_FDTABLE)); /* get what we need */
}
if( fd >= citp_fdtable.size ) return NULL;
probe:
fdi = citp_fdtable_probe(fd);
return fdi;
}
int citp_ep_dup3(unsigned fromfd, unsigned tofd, int flags)
{
volatile citp_fdinfo_p* p_tofdip;
citp_fdinfo_p tofdip;
unsigned max;
Log_V(log("%s(%d, %d)", __FUNCTION__, fromfd, tofd));
/* Must be checked by callers. */
ci_assert(fromfd != tofd);
/* Hack: if [tofd] is the fd we're using for logging, we'd better choose
** a different one!
*/
if( tofd == citp.log_fd ) citp_log_change_fd();
ci_assert(citp.init_level >= CITP_INIT_FDTABLE);
max = CI_MAX(fromfd, tofd);
if( max >= citp_fdtable.inited_count ) {
ci_assert(max < citp_fdtable.size);
CITP_FDTABLE_LOCK();
__citp_fdtable_extend(max);
CITP_FDTABLE_UNLOCK();
}
/* Bug1151: Concurrent threads doing dup2(x,y) and dup2(y,x) can deadlock
** against one another. So we take out a fat lock to prevent concurrent
** dup2()s.
*/
/* Lock tofd. We need to interlock against select and poll etc, so we
** also grab the exclusive lock. Also grab the bug1151 lock.
*/
pthread_mutex_lock(&citp_dup_lock);
CITP_FDTABLE_LOCK();
p_tofdip = &citp_fdtable.table[tofd].fdip;
lock_tofdip_again:
tofdip = *p_tofdip;
if( fdip_is_busy(tofdip) )
tofdip = citp_fdtable_busy_wait(tofd, 1);
if( fdip_is_closing(tofdip) )
tofdip = citp_fdtable_closing_wait(tofd, 1);
if( fdip_is_reserved(tofdip) ) {
/* ?? FIXME: we can't cope with this at the moment */
CITP_FDTABLE_UNLOCK();
Log_U(log("%s(%d, %d): target is reserved", __FUNCTION__, fromfd, tofd));
errno = EBUSY;
tofd = -1;
goto out;
}
if( fdip_cas_fail(p_tofdip, tofdip, fdip_busy) )
goto lock_tofdip_again;
CITP_FDTABLE_UNLOCK();
ci_assert(fdip_is_normal(tofdip) | fdip_is_passthru(tofdip) |
fdip_is_unknown(tofdip));
if( fdip_is_normal(tofdip) ) {
/* We're duping onto a user-level socket. */
citp_fdinfo* tofdi = fdip_to_fdi(tofdip);
if( tofdi->epoll_fd >= 0 ) {
citp_fdinfo* epoll_fdi = citp_epoll_fdi_from_member(tofdi, 0);
if( epoll_fdi ) {
if( epoll_fdi->protocol->type == CITP_EPOLL_FD )
citp_epoll_on_close(epoll_fdi, tofdi, 0);
citp_fdinfo_release_ref(epoll_fdi, 0);
}
}
ci_assert_equal(tofdi->on_ref_count_zero, FDI_ON_RCZ_NONE);
tofdi->on_ref_count_zero = FDI_ON_RCZ_DUP2;
tofdi->on_rcz.dup3_args.fd = fromfd;
tofdi->on_rcz.dup3_args.flags = flags;
citp_fdinfo_release_ref(tofdi, 0);
{
int i = 0;
/* We need to free this fdi. If someone is using it right now,
* we are in trouble. So, we spin for a while and interrupt the
* user. See bug 28123. */
while( tofdi->on_ref_count_zero != FDI_ON_RCZ_DONE ) {
if( ci_is_multithreaded() && i % 10000 == 9999 ) {
pthread_t pth = tofdi->thread_id;
if( pth != pthread_self() && pth != PTHREAD_NULL ) {
pthread_kill(pth, SIGONLOAD);
sleep(1);
}
}
ci_spinloop_pause();
i++;
}
ci_rmb();
}
if( tofdi->on_rcz.dup2_result < 0 ) {
errno = -tofdi->on_rcz.dup2_result;
/* Need to re-insert [tofdi] into the table. */
ci_assert_equal(oo_atomic_read(&tofdi->ref_count), 0);
oo_atomic_set(&tofdi->ref_count, 1);
CI_DEBUG(tofdi->on_ref_count_zero = FDI_ON_RCZ_NONE);
citp_fdtable_busy_clear(tofd, tofdip, 0);
tofd = -1;
}
else {
ci_assert(tofdi->on_rcz.dup2_result == tofd);
citp_fdinfo_get_ops(tofdi)->dtor(tofdi, 0);
citp_fdinfo_free(tofdi);
}
goto out;
}
ci_assert(fdip_is_passthru(tofdip) | fdip_is_unknown(tofdip));
{ /* We're dupping onto an O/S descriptor, or it may be closed. Create a
** dummy [citp_fdinfo], just so we can share code with the case above.
*/
citp_fdinfo fdi;
fdi.fd = tofd;
fdi.on_rcz.dup3_args.fd = fromfd;
fdi.on_rcz.dup3_args.flags = flags;
dup2_complete(&fdi, tofdip, 0);
if( fdi.on_rcz.dup2_result < 0 ) {
errno = -fdi.on_rcz.dup2_result;
citp_fdtable_busy_clear(tofd, tofdip, 0);
tofd = -1;
}
else
ci_assert(fdi.on_rcz.dup2_result == tofd);
}
out:
pthread_mutex_unlock(&citp_dup_lock);
return tofd;
}
