[PATCH] uml: move sigio_user.c to os-Linux/sigio.c

The serial UML OS-abstraction layer patch (um/kernel dir).

This moves sigio_user.c to os-Linux dir

Signed-off-by: Gennady Sharapov <Gennady.V.Sharapov@intel.com>
Signed-off-by: Jeff Dike <jdike@addtoit.com>
Cc: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 324 insertions, 0 deletions

diff --git a/arch/um/os-Linux/sigio.c b/arch/um/os-Linux/sigio.c
new file mode 100644
index 000000000000..7604c404c4c2
--- /dev/null
+++ b/arch/um/os-Linux/sigio.c
@@ -0,0 +1,324 @@
+/*
+ * 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.
+ */
+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;
+
+        signal(SIGWINCH, SIG_IGN);
+        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);
+                }
+        }
+
+        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 = &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 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_unlock;
+
+        write_sigio_pid = run_helper_thread(write_sigio_thread, NULL,
+                                            CLONE_FILES | CLONE_VM, &stack, 0);
+
+        if (write_sigio_pid < 0)
+                goto out_clear;
+
+        if (write_sigio_irq(l_write_sigio_fds[0]))
+                goto out_kill;
+
+        /* Success, finally. */
+        memcpy(write_sigio_fds, l_write_sigio_fds, sizeof(l_write_sigio_fds));
+        memcpy(sigio_private, l_sigio_private, sizeof(l_sigio_private));
+
+        current_poll = ((struct pollfds) { .poll        = p,
+                                           .used        = 1,
+                                           .size        = 1 });
+
+        sigio_unlock();
+        return;
+
+ out_kill:
+        l_write_sigio_pid = write_sigio_pid;
+        write_sigio_pid = -1;
+        sigio_unlock();
+        /* Going to call waitpid, avoid holding the lock. */
+        os_kill_process(l_write_sigio_pid, 1);
+        goto out_free;
+
+ out_clear:
+        write_sigio_pid = -1;
+ out_unlock:
+        sigio_unlock();
+ out_free:
+        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]);
+        return;
+}
+
+void sigio_cleanup(void)
+{
+        if(write_sigio_pid != -1){
+                os_kill_process(write_sigio_pid, 1);
+                write_sigio_pid = -1;
+        }
+}