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linux/arch/um/kernel/sigio_user.c

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/*
* Copyright (C) 2002 Jeff Dike (jdike@karaya.com)
* Licensed under the GPL
*/
#include <unistd.h>
#include <stdlib.h>
#include <termios.h>
#include <pty.h>
#include <signal.h>
#include <errno.h>
#include <string.h>
#include <sched.h>
#include <sys/socket.h>
#include <sys/poll.h>
#include "init.h"
#include "user.h"
#include "kern_util.h"
#include "user_util.h"
#include "sigio.h"
#include "helper.h"
#include "os.h"
/* Changed during early boot */
int pty_output_sigio = 0;
int pty_close_sigio = 0;
/* Used as a flag during SIGIO testing early in boot */
static volatile int got_sigio = 0;
void __init handler(int sig)
{
got_sigio = 1;
}
struct openpty_arg {
int master;
int slave;
int err;
};
static void openpty_cb(void *arg)
{
struct openpty_arg *info = arg;
info->err = 0;
if(openpty(&info->master, &info->slave, NULL, NULL, NULL))
info->err = -errno;
}
void __init check_one_sigio(void (*proc)(int, int))
{
struct sigaction old, new;
struct openpty_arg pty = { .master = -1, .slave = -1 };
int master, slave, err;
initial_thread_cb(openpty_cb, &pty);
if(pty.err){
printk("openpty failed, errno = %d\n", -pty.err);
return;
}
master = pty.master;
slave = pty.slave;
if((master == -1) || (slave == -1)){
printk("openpty failed to allocate a pty\n");
return;
}
/* Not now, but complain so we now where we failed. */
err = raw(master);
if (err < 0)
panic("check_sigio : __raw failed, errno = %d\n", -err);
err = os_sigio_async(master, slave);
if(err < 0)
panic("tty_fds : sigio_async failed, err = %d\n", -err);
if(sigaction(SIGIO, NULL, &old) < 0)
panic("check_sigio : sigaction 1 failed, errno = %d\n", errno);
new = old;
new.sa_handler = handler;
if(sigaction(SIGIO, &new, NULL) < 0)
panic("check_sigio : sigaction 2 failed, errno = %d\n", errno);
got_sigio = 0;
(*proc)(master, slave);
os_close_file(master);
os_close_file(slave);
if(sigaction(SIGIO, &old, NULL) < 0)
panic("check_sigio : sigaction 3 failed, errno = %d\n", errno);
}
static void tty_output(int master, int slave)
{
int n;
char buf[512];
printk("Checking that host ptys support output SIGIO...");
memset(buf, 0, sizeof(buf));
while(os_write_file(master, buf, sizeof(buf)) > 0) ;
if(errno != EAGAIN)
panic("check_sigio : write failed, errno = %d\n", errno);
while(((n = os_read_file(slave, buf, sizeof(buf))) > 0) && !got_sigio) ;
if (got_sigio) {
printk("Yes\n");
pty_output_sigio = 1;
} else if (n == -EAGAIN) {
printk("No, enabling workaround\n");
} else {
panic("check_sigio : read failed, err = %d\n", n);
}
}
static void tty_close(int master, int slave)
{
printk("Checking that host ptys support SIGIO on close...");
os_close_file(slave);
if(got_sigio){
printk("Yes\n");
pty_close_sigio = 1;
}
else printk("No, enabling workaround\n");
}
void __init check_sigio(void)
{
if((os_access("/dev/ptmx", OS_ACC_R_OK) < 0) &&
(os_access("/dev/ptyp0", OS_ACC_R_OK) < 0)){
printk("No pseudo-terminals available - skipping pty SIGIO "
"check\n");
return;
}
check_one_sigio(tty_output);
check_one_sigio(tty_close);
}
/* Protected by sigio_lock(), also used by sigio_cleanup, which is an
* exitcall.
*/
static int write_sigio_pid = -1;
/* These arrays are initialized before the sigio thread is started, and
* the descriptors closed after it is killed. So, it can't see them change.
* On the UML side, they are changed under the sigio_lock.
*/
static int write_sigio_fds[2] = { -1, -1 };
static int sigio_private[2] = { -1, -1 };
struct pollfds {
struct pollfd *poll;
int size;
int used;
};
/* Protected by sigio_lock(). Used by the sigio thread, but the UML thread
* synchronizes with it.
*/
struct pollfds current_poll = {
.poll = NULL,
.size = 0,
.used = 0
};
struct pollfds next_poll = {
.poll = NULL,
.size = 0,
.used = 0
};
static int write_sigio_thread(void *unused)
{
struct pollfds *fds, tmp;
struct pollfd *p;
int i, n, respond_fd;
char c;
fds = &current_poll;
while(1){
n = poll(fds->poll, fds->used, -1);
if(n < 0){
if(errno == EINTR) continue;
printk("write_sigio_thread : poll returned %d, "
"errno = %d\n", n, errno);
}
for(i = 0; i < fds->used; i++){
p = &fds->poll[i];
if(p->revents == 0) continue;
if(p->fd == sigio_private[1]){
n = os_read_file(sigio_private[1], &c, sizeof(c));
if(n != sizeof(c))
printk("write_sigio_thread : "
"read failed, err = %d\n", -n);
tmp = current_poll;
current_poll = next_poll;
next_poll = tmp;
respond_fd = sigio_private[1];
}
else {
respond_fd = write_sigio_fds[1];
fds->used--;
memmove(&fds->poll[i], &fds->poll[i + 1],
(fds->used - i) * sizeof(*fds->poll));
}
n = os_write_file(respond_fd, &c, sizeof(c));
if(n != sizeof(c))
printk("write_sigio_thread : write failed, "
"err = %d\n", -n);
}
}
}
static int need_poll(int n)
{
if(n <= next_poll.size){
next_poll.used = n;
return(0);
}
if(next_poll.poll != NULL) kfree(next_poll.poll);
next_poll.poll = um_kmalloc_atomic(n * sizeof(struct pollfd));
if(next_poll.poll == NULL){
printk("need_poll : failed to allocate new pollfds\n");
next_poll.size = 0;
next_poll.used = 0;
return(-1);
}
next_poll.size = n;
next_poll.used = n;
return(0);
}
/* Must be called with sigio_lock held, because it's needed by the marked
* critical section. */
static void update_thread(void)
{
unsigned long flags;
int n;
char c;
flags = set_signals(0);
n = os_write_file(sigio_private[0], &c, sizeof(c));
if(n != sizeof(c)){
printk("update_thread : write failed, err = %d\n", -n);
goto fail;
}
n = os_read_file(sigio_private[0], &c, sizeof(c));
if(n != sizeof(c)){
printk("update_thread : read failed, err = %d\n", -n);
goto fail;
}
set_signals(flags);
return;
fail:
/* Critical section start */
if(write_sigio_pid != -1)
os_kill_process(write_sigio_pid, 1);
write_sigio_pid = -1;
os_close_file(sigio_private[0]);
os_close_file(sigio_private[1]);
os_close_file(write_sigio_fds[0]);
os_close_file(write_sigio_fds[1]);
/* Critical section end */
set_signals(flags);
}
int add_sigio_fd(int fd, int read)
{
int err = 0, i, n, events;
sigio_lock();
for(i = 0; i < current_poll.used; i++){
if(current_poll.poll[i].fd == fd)
goto out;
}
n = current_poll.used + 1;
err = need_poll(n);
if(err)
goto out;
for(i = 0; i < current_poll.used; i++)
next_poll.poll[i] = current_poll.poll[i];
if(read) events = POLLIN;
else events = POLLOUT;
next_poll.poll[n - 1] = ((struct pollfd) { .fd = fd,
.events = events,
.revents = 0 });
update_thread();
out:
sigio_unlock();
return(err);
}
int ignore_sigio_fd(int fd)
{
struct pollfd *p;
int err = 0, i, n = 0;
sigio_lock();
for(i = 0; i < current_poll.used; i++){
if(current_poll.poll[i].fd == fd) break;
}
if(i == current_poll.used)
goto out;
err = need_poll(current_poll.used - 1);
if(err)
goto out;
for(i = 0; i < current_poll.used; i++){
p = &current_poll.poll[i];
if(p->fd != fd) next_poll.poll[n++] = current_poll.poll[i];
}
if(n == i){
printk("ignore_sigio_fd : fd %d not found\n", fd);
err = -1;
goto out;
}
update_thread();
out:
sigio_unlock();
return(err);
}
static int setup_initial_poll(int fd)
{
struct pollfd *p;
p = um_kmalloc(sizeof(struct pollfd));
if(p == NULL){
printk("setup_initial_poll : failed to allocate poll\n");
return(-1);
}
*p = ((struct pollfd) { .fd = fd,
.events = POLLIN,
.revents = 0 });
current_poll = ((struct pollfds) { .poll = p,
.used = 1,
.size = 1 });
return(0);
}
void write_sigio_workaround(void)
{
unsigned long stack;
int err;
sigio_lock();
if(write_sigio_pid != -1)
goto out;
err = os_pipe(write_sigio_fds, 1, 1);
if(err < 0){
printk("write_sigio_workaround - os_pipe 1 failed, "
"err = %d\n", -err);
goto out;
}
err = os_pipe(sigio_private, 1, 1);
if(err < 0){
printk("write_sigio_workaround - os_pipe 2 failed, "
"err = %d\n", -err);
goto out_close1;
}
if(setup_initial_poll(sigio_private[1]))
goto out_close2;
write_sigio_pid = run_helper_thread(write_sigio_thread, NULL,
CLONE_FILES | CLONE_VM, &stack, 0);
if(write_sigio_pid < 0) goto out_close2;
if(write_sigio_irq(write_sigio_fds[0]))
goto out_kill;
out:
sigio_unlock();
return;
out_kill:
os_kill_process(write_sigio_pid, 1);
write_sigio_pid = -1;
out_close2:
os_close_file(sigio_private[0]);
os_close_file(sigio_private[1]);
out_close1:
os_close_file(write_sigio_fds[0]);
os_close_file(write_sigio_fds[1]);
sigio_unlock();
}
int read_sigio_fd(int fd)
{
int n;
char c;
n = os_read_file(fd, &c, sizeof(c));
if(n != sizeof(c)){
if(n < 0) {
printk("read_sigio_fd - read failed, err = %d\n", -n);
return(n);
}
else {
printk("read_sigio_fd - short read, bytes = %d\n", n);
return(-EIO);
}
}
return(n);
}
static void sigio_cleanup(void)
{
if (write_sigio_pid != -1) {
os_kill_process(write_sigio_pid, 1);
write_sigio_pid = -1;
}
}
__uml_exitcall(sigio_cleanup);