--- /dev/null
+/*
+ * 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 "os.h"
+
+/* 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.
+ */
+#define SIGIO_FDS_INIT {-1, -1}
+
+static int write_sigio_fds[2] = SIGIO_FDS_INIT;
+static int sigio_private[2] = SIGIO_FDS_INIT;
+
+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;
+
+ signal(SIGWINCH, SIG_IGN);
+ fds = ¤t_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);
+ }
+ }
+
+ return 0;
+}
+
+static int need_poll(int n)
+{
+ if(n <= next_poll.size){
+ next_poll.used = n;
+ return(0);
+ }
+ 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;
+ close(sigio_private[0]);
+ close(sigio_private[1]);
+ close(write_sigio_fds[0]);
+ close(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 = ¤t_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 struct pollfd *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 NULL;
+ }
+ *p = ((struct pollfd) { .fd = fd,
+ .events = POLLIN,
+ .revents = 0 });
+ return p;
+}
+
+void write_sigio_workaround(void)
+{
+ unsigned long stack;
+ struct pollfd *p;
+ int err;
+ int l_write_sigio_fds[2];
+ int l_sigio_private[2];
+ int l_write_sigio_pid;
+
+ /* We call this *tons* of times - and most ones we must just fail. */
+ sigio_lock();
+ l_write_sigio_pid = write_sigio_pid;
+ sigio_unlock();
+
+ if (l_write_sigio_pid != -1)
+ return;
+
+ err = os_pipe(l_write_sigio_fds, 1, 1);
+ if(err < 0){
+ printk("write_sigio_workaround - os_pipe 1 failed, "
+ "err = %d\n", -err);
+ return;
+ }
+ err = os_pipe(l_sigio_private, 1, 1);
+ if(err < 0){
+ printk("write_sigio_workaround - os_pipe 2 failed, "
+ "err = %d\n", -err);
+ goto out_close1;
+ }
+
+ p = setup_initial_poll(l_sigio_private[1]);
+ if(!p)
+ goto out_close2;
+
+ sigio_lock();
+
+ /* Did we race? Don't try to optimize this, please, it's not so likely
+ * to happen, and no more than once at the boot. */
+ if(write_sigio_pid != -1)
+ goto out_free;
+
+ current_poll = ((struct pollfds) { .poll = p,
+ .used = 1,
+ .size = 1 });
+
+ if (write_sigio_irq(l_write_sigio_fds[0]))
+ goto out_clear_poll;
+
+ memcpy(write_sigio_fds, l_write_sigio_fds, sizeof(l_write_sigio_fds));
+ memcpy(sigio_private, l_sigio_private, sizeof(l_sigio_private));
+
+ write_sigio_pid = run_helper_thread(write_sigio_thread, NULL,
+ CLONE_FILES | CLONE_VM, &stack, 0);
+
+ if (write_sigio_pid < 0)
+ goto out_clear;
+
+ sigio_unlock();
+ return;
+
+out_clear:
+ write_sigio_pid = -1;
+ write_sigio_fds[0] = -1;
+ write_sigio_fds[1] = -1;
+ sigio_private[0] = -1;
+ sigio_private[1] = -1;
+out_clear_poll:
+ current_poll = ((struct pollfds) { .poll = NULL,
+ .size = 0,
+ .used = 0 });
+out_free:
+ sigio_unlock();
+ kfree(p);
+out_close2:
+ close(l_sigio_private[0]);
+ close(l_sigio_private[1]);
+out_close1:
+ close(l_write_sigio_fds[0]);
+ close(l_write_sigio_fds[1]);
+}
+
+void sigio_cleanup(void)
+{
+ if(write_sigio_pid != -1){
+ os_kill_process(write_sigio_pid, 1);
+ write_sigio_pid = -1;
+ }
+}
git://git.onelab.eu / linux-2.6.git / blobdiff