[PATCH] uml: redo console locking

[deliverable/linux.git] / arch / um / drivers / line.c

/* 
 * Copyright (C) 2001, 2002 Jeff Dike (jdike@karaya.com)
 * Licensed under the GPL
 */

#include "linux/sched.h"
#include "linux/slab.h"
#include "linux/list.h"
#include "linux/kd.h"
#include "linux/interrupt.h"
#include "linux/devfs_fs_kernel.h"
#include "asm/uaccess.h"
#include "chan_kern.h"
#include "irq_user.h"
#include "line.h"
#include "kern.h"
#include "user_util.h"
#include "kern_util.h"
#include "os.h"
#include "irq_kern.h"

#define LINE_BUFSIZE 4096

static irqreturn_t line_interrupt(int irq, void *data, struct pt_regs *unused)
{
        struct tty_struct *tty = data;
        struct line *line = tty->driver_data;

        if (line)
                chan_interrupt(&line->chan_list, &line->task, tty, irq);
        return IRQ_HANDLED;
}

static void line_timer_cb(void *arg)
{
        struct tty_struct *tty = arg;
        struct line *line = tty->driver_data;

        line_interrupt(line->driver->read_irq, arg, NULL);
}

/* Returns the free space inside the ring buffer of this line.
 *
 * Should be called while holding line->lock (this does not modify datas).
 */
static int write_room(struct line *line)
{
        int n;

        if (line->buffer == NULL)
                return LINE_BUFSIZE - 1;

        /* This is for the case where the buffer is wrapped! */
        n = line->head - line->tail;

        if (n <= 0)
                n = LINE_BUFSIZE + n; /* The other case */
        return n - 1;
}

int line_write_room(struct tty_struct *tty)
{
        struct line *line = tty->driver_data;
        unsigned long flags;
        int room;

        if (tty->stopped)
                return 0;

        spin_lock_irqsave(&line->lock, flags);
        room = write_room(line);
        spin_unlock_irqrestore(&line->lock, flags);

        /*XXX: Warning to remove */
        if (0 == room)
                printk(KERN_DEBUG "%s: %s: no room left in buffer\n",
                       __FUNCTION__,tty->name);
        return room;
}

int line_chars_in_buffer(struct tty_struct *tty)
{
        struct line *line = tty->driver_data;
        unsigned long flags;
        int ret;

        spin_lock_irqsave(&line->lock, flags);

        /*write_room subtracts 1 for the needed NULL, so we readd it.*/
        ret = LINE_BUFSIZE - (write_room(line) + 1);
        spin_unlock_irqrestore(&line->lock, flags);

        return ret;
}

/*
 * This copies the content of buf into the circular buffer associated with
 * this line.
 * The return value is the number of characters actually copied, i.e. the ones
 * for which there was space: this function is not supposed to ever flush out
 * the circular buffer.
 *
 * Must be called while holding line->lock!
 */
static int buffer_data(struct line *line, const char *buf, int len)
{
        int end, room;

        if(line->buffer == NULL){
                line->buffer = kmalloc(LINE_BUFSIZE, GFP_ATOMIC);
                if (line->buffer == NULL) {
                        printk("buffer_data - atomic allocation failed\n");
                        return(0);
                }
                line->head = line->buffer;
                line->tail = line->buffer;
        }

        room = write_room(line);
        len = (len > room) ? room : len;

        end = line->buffer + LINE_BUFSIZE - line->tail;

        if (len < end){
                memcpy(line->tail, buf, len);
                line->tail += len;
        } else {
                /* The circular buffer is wrapping */
                memcpy(line->tail, buf, end);
                buf += end;
                memcpy(line->buffer, buf, len - end);
                line->tail = line->buffer + len - end;
        }

        return len;
}

/*
 * Flushes the ring buffer to the output channels. That is, write_chan is
 * called, passing it line->head as buffer, and an appropriate count.
 *
 * On exit, returns 1 when the buffer is empty,
 * 0 when the buffer is not empty on exit,
 * and -errno when an error occurred.
 *
 * Must be called while holding line->lock!*/
static int flush_buffer(struct line *line)
{
        int n, count;

        if ((line->buffer == NULL) || (line->head == line->tail))
                return 1;

        if (line->tail < line->head) {
                /* line->buffer + LINE_BUFSIZE is the end of the buffer! */
                count = line->buffer + LINE_BUFSIZE - line->head;

                n = write_chan(&line->chan_list, line->head, count,
                               line->driver->write_irq);
                if (n < 0)
                        return n;
                if (n == count) {
                        /* We have flushed from ->head to buffer end, now we
                         * must flush only from the beginning to ->tail.*/
                        line->head = line->buffer;
                } else {
                        line->head += n;
                        return 0;
                }
        }

        count = line->tail - line->head;
        n = write_chan(&line->chan_list, line->head, count, 
                       line->driver->write_irq);

        if(n < 0)
                return n;

        line->head += n;
        return line->head == line->tail;
}

void line_flush_buffer(struct tty_struct *tty)
{
        struct line *line = tty->driver_data;
        unsigned long flags;
        int err;

        /*XXX: copied from line_write, verify if it is correct!*/
        if(tty->stopped)
                return;
                //return 0;

        spin_lock_irqsave(&line->lock, flags);
        err = flush_buffer(line);
        /*if (err == 1)
                err = 0;*/
        spin_unlock_irqrestore(&line->lock, flags);
        //return err;
}

/* We map both ->flush_chars and ->put_char (which go in pair) onto ->flush_buffer
 * and ->write. Hope it's not that bad.*/
void line_flush_chars(struct tty_struct *tty)
{
        line_flush_buffer(tty);
}

void line_put_char(struct tty_struct *tty, unsigned char ch)
{
        line_write(tty, &ch, sizeof(ch));
}

int line_write(struct tty_struct *tty, const unsigned char *buf, int len)
{
        struct line *line = tty->driver_data;
        unsigned long flags;
        int n, err, ret = 0;

        if(tty->stopped)
                return 0;

        spin_lock_irqsave(&line->lock, flags);
        if (line->head != line->tail) {
                ret = buffer_data(line, buf, len);
                err = flush_buffer(line);
                if (err <= 0 && (err != -EAGAIN || !ret))
                        ret = err;
        } else {
                n = write_chan(&line->chan_list, buf, len, 
                               line->driver->write_irq);
                if (n < 0) {
                        ret = n;
                        goto out_up;
                }

                len -= n;
                ret += n;
                if (len > 0)
                        ret += buffer_data(line, buf + n, len);
        }
out_up:
        spin_unlock_irqrestore(&line->lock, flags);
        return ret;
}

void line_set_termios(struct tty_struct *tty, struct termios * old)
{
        /* nothing */
}

static struct {
        int  cmd;
        char *level;
        char *name;
} tty_ioctls[] = {
        /* don't print these, they flood the log ... */
        { TCGETS,      NULL,       "TCGETS"      },
        { TCSETS,      NULL,       "TCSETS"      },
        { TCSETSW,     NULL,       "TCSETSW"     },
        { TCFLSH,      NULL,       "TCFLSH"      },
        { TCSBRK,      NULL,       "TCSBRK"      },

        /* general tty stuff */
        { TCSETSF,     KERN_DEBUG, "TCSETSF"     },
        { TCGETA,      KERN_DEBUG, "TCGETA"      },
        { TIOCMGET,    KERN_DEBUG, "TIOCMGET"    },
        { TCSBRKP,     KERN_DEBUG, "TCSBRKP"     },
        { TIOCMSET,    KERN_DEBUG, "TIOCMSET"    },

        /* linux-specific ones */
        { TIOCLINUX,   KERN_INFO,  "TIOCLINUX"   },
        { KDGKBMODE,   KERN_INFO,  "KDGKBMODE"   },
        { KDGKBTYPE,   KERN_INFO,  "KDGKBTYPE"   },
        { KDSIGACCEPT, KERN_INFO,  "KDSIGACCEPT" },
};

int line_ioctl(struct tty_struct *tty, struct file * file,
               unsigned int cmd, unsigned long arg)
{
        int ret;
        int i;

        ret = 0;
        switch(cmd) {
#ifdef TIOCGETP
        case TIOCGETP:
        case TIOCSETP:
        case TIOCSETN:
#endif
#ifdef TIOCGETC
        case TIOCGETC:
        case TIOCSETC:
#endif
#ifdef TIOCGLTC
        case TIOCGLTC:
        case TIOCSLTC:
#endif
        case TCGETS:
        case TCSETSF:
        case TCSETSW:
        case TCSETS:
        case TCGETA:
        case TCSETAF:
        case TCSETAW:
        case TCSETA:
        case TCXONC:
        case TCFLSH:
        case TIOCOUTQ:
        case TIOCINQ:
        case TIOCGLCKTRMIOS:
        case TIOCSLCKTRMIOS:
        case TIOCPKT:
        case TIOCGSOFTCAR:
        case TIOCSSOFTCAR:
                return -ENOIOCTLCMD;
#if 0
        case TCwhatever:
                /* do something */
                break;
#endif
        default:
                for (i = 0; i < ARRAY_SIZE(tty_ioctls); i++)
                        if (cmd == tty_ioctls[i].cmd)
                                break;
                if (i < ARRAY_SIZE(tty_ioctls)) {
                        if (NULL != tty_ioctls[i].level)
                                printk("%s%s: %s: ioctl %s called\n",
                                       tty_ioctls[i].level, __FUNCTION__,
                                       tty->name, tty_ioctls[i].name);
                } else {
                        printk(KERN_ERR "%s: %s: unknown ioctl: 0x%x\n",
                               __FUNCTION__, tty->name, cmd);
                }
                ret = -ENOIOCTLCMD;
                break;
        }
        return ret;
}

static irqreturn_t line_write_interrupt(int irq, void *data,
                                        struct pt_regs *unused)
{
        struct tty_struct *tty = data;
        struct line *line = tty->driver_data;
        int err;

        /* Interrupts are enabled here because we registered the interrupt with
         * SA_INTERRUPT (see line_setup_irq).*/

        spin_lock_irq(&line->lock);
        err = flush_buffer(line);
        if (err == 0) {
                return IRQ_NONE;
        } else if(err < 0) {
                line->head = line->buffer;
                line->tail = line->buffer;
        }
        spin_unlock_irq(&line->lock);

        if(tty == NULL)
                return IRQ_NONE;

        if (test_bit(TTY_DO_WRITE_WAKEUP, &tty->flags) &&
           (tty->ldisc.write_wakeup != NULL))
                (tty->ldisc.write_wakeup)(tty);
        
        /* BLOCKING mode
         * In blocking mode, everything sleeps on tty->write_wait.
         * Sleeping in the console driver would break non-blocking
         * writes.
         */

        if (waitqueue_active(&tty->write_wait))
                wake_up_interruptible(&tty->write_wait);
        return IRQ_HANDLED;
}

int line_setup_irq(int fd, int input, int output, struct tty_struct *tty)
{
        struct line *line = tty->driver_data;
        struct line_driver *driver = line->driver;
        int err = 0, flags = SA_INTERRUPT | SA_SHIRQ | SA_SAMPLE_RANDOM;

        if (input)
                err = um_request_irq(driver->read_irq, fd, IRQ_READ,
                                       line_interrupt, flags, 
                                       driver->read_irq_name, tty);
        if (err)
                return err;
        if (output)
                err = um_request_irq(driver->write_irq, fd, IRQ_WRITE,
                                        line_write_interrupt, flags, 
                                        driver->write_irq_name, tty);
        line->have_irq = 1;
        return err;
}

void line_disable(struct tty_struct *tty, int current_irq)
{
        struct line *line = tty->driver_data;

        if(!line->have_irq)
                return;

        if(line->driver->read_irq == current_irq)
                free_irq_later(line->driver->read_irq, tty);
        else {
                free_irq_by_irq_and_dev(line->driver->read_irq, tty);
                free_irq(line->driver->read_irq, tty);
        }

        if(line->driver->write_irq == current_irq)
                free_irq_later(line->driver->write_irq, tty);
        else {
                free_irq_by_irq_and_dev(line->driver->write_irq, tty);
                free_irq(line->driver->write_irq, tty);
        }

        line->have_irq = 0;
}

int line_open(struct line *lines, struct tty_struct *tty,
              struct chan_opts *opts)
{
        struct line *line;
        int err = 0;

        line = &lines[tty->index];
        tty->driver_data = line;

        /* The IRQ which takes this lock is not yet enabled and won't be run
         * before the end, so we don't need to use spin_lock_irq.*/
        spin_lock(&line->lock);
        if (tty->count == 1) {
                if (!line->valid) {
                        err = -ENODEV;
                        goto out;
                }
                if (list_empty(&line->chan_list)) {
                        err = parse_chan_pair(line->init_str, &line->chan_list,
                                              line->init_pri, tty->index, opts);
                        if(err) goto out;
                        err = open_chan(&line->chan_list);
                        if(err) goto out;
                }
                /* Here the interrupt is registered.*/
                enable_chan(&line->chan_list, tty);
                INIT_WORK(&line->task, line_timer_cb, tty);
        }

        if(!line->sigio){
                chan_enable_winch(&line->chan_list, tty);
                line->sigio = 1;
        }
        chan_window_size(&line->chan_list, &tty->winsize.ws_row,
                         &tty->winsize.ws_col);
        line->count++;

out:
        spin_unlock(&line->lock);
        return err;
}

void line_close(struct tty_struct *tty, struct file * filp)
{
        struct line *line = tty->driver_data;

        /* XXX: I assume this should be called in process context, not with interrupt
         * disabled!*/
        spin_lock_irq(&line->lock);

        /* We ignore the error anyway! */
        flush_buffer(line);

        line->count--;
        if (tty->count == 1) {
                line_disable(tty, -1);
                tty->driver_data = NULL;
        }
        spin_unlock_irq(&line->lock);
}

void close_lines(struct line *lines, int nlines)
{
        int i;

        for(i = 0; i < nlines; i++)
                close_chan(&lines[i].chan_list);
}

/* Common setup code for both startup command line and mconsole initialization.
 * @lines contains the the array (of size @num) to modify;
 * @init is the setup string;
 * @all_allowed is a boolean saying if we can setup the whole @lines
 * at once. For instance, it will be usually true for startup init. (where we
 * can use con=xterm) and false for mconsole.*/

int line_setup(struct line *lines, unsigned int num, char *init, int all_allowed)
{
        int i, n;
        char *end;

        if(*init == '=') {
                /* We said con=/ssl= instead of con#=, so we are configuring all
                 * consoles at once.*/
                n = -1;
        } else {
                n = simple_strtoul(init, &end, 0);
                if(*end != '='){
                        printk(KERN_ERR "line_setup failed to parse \"%s\"\n", 
                               init);
                        return 0;
                }
                init = end;
        }
        init++;

        if (n >= (signed int) num) {
                printk("line_setup - %d out of range ((0 ... %d) allowed)\n",
                       n, num - 1);
                return 0;
        } else if (n >= 0){
                if (lines[n].count > 0) {
                        printk("line_setup - device %d is open\n", n);
                        return 0;
                }
                if (lines[n].init_pri <= INIT_ONE){
                        lines[n].init_pri = INIT_ONE;
                        if (!strcmp(init, "none"))
                                lines[n].valid = 0;
                        else {
                                lines[n].init_str = init;
                                lines[n].valid = 1;
                        }       
                }
        } else if(!all_allowed){
                printk("line_setup - can't configure all devices from "
                       "mconsole\n");
                return 0;
        } else {
                for(i = 0; i < num; i++){
                        if(lines[i].init_pri <= INIT_ALL){
                                lines[i].init_pri = INIT_ALL;
                                if(!strcmp(init, "none")) lines[i].valid = 0;
                                else {
                                        lines[i].init_str = init;
                                        lines[i].valid = 1;
                                }
                        }
                }
        }
        return 1;
}

int line_config(struct line *lines, unsigned int num, char *str)
{
        char *new = uml_strdup(str);

        if(new == NULL){
                printk("line_config - uml_strdup failed\n");
                return -ENOMEM;
        }
        return !line_setup(lines, num, new, 0);
}

int line_get_config(char *name, struct line *lines, unsigned int num, char *str,
                    int size, char **error_out)
{
        struct line *line;
        char *end;
        int dev, n = 0;

        dev = simple_strtoul(name, &end, 0);
        if((*end != '\0') || (end == name)){
                *error_out = "line_get_config failed to parse device number";
                return 0;
        }

        if((dev < 0) || (dev >= num)){
                *error_out = "device number out of range";
                return 0;
        }

        line = &lines[dev];

        spin_lock(&line->lock);
        if(!line->valid)
                CONFIG_CHUNK(str, size, n, "none", 1);
        else if(line->count == 0)
                CONFIG_CHUNK(str, size, n, line->init_str, 1);
        else n = chan_config_string(&line->chan_list, str, size, error_out);
        spin_unlock(&line->lock);

        return n;
}

int line_remove(struct line *lines, unsigned int num, char *str)
{
        char config[sizeof("conxxxx=none\0")];

        sprintf(config, "%s=none", str);
        return !line_setup(lines, num, config, 0);
}

struct tty_driver *line_register_devfs(struct lines *set,
                         struct line_driver *line_driver, 
                         struct tty_operations *ops, struct line *lines,
                         int nlines)
{
        int i;
        struct tty_driver *driver = alloc_tty_driver(nlines);

        if (!driver)
                return NULL;

        driver->driver_name = line_driver->name;
        driver->name = line_driver->device_name;
        driver->devfs_name = line_driver->devfs_name;
        driver->major = line_driver->major;
        driver->minor_start = line_driver->minor_start;
        driver->type = line_driver->type;
        driver->subtype = line_driver->subtype;
        driver->flags = TTY_DRIVER_REAL_RAW;
        driver->init_termios = tty_std_termios;
        tty_set_operations(driver, ops);

        if (tty_register_driver(driver)) {
                printk("%s: can't register %s driver\n",
                       __FUNCTION__,line_driver->name);
                put_tty_driver(driver);
                return NULL;
        }

        for(i = 0; i < nlines; i++){
                if(!lines[i].valid) 
                        tty_unregister_device(driver, i);
        }

        mconsole_register_dev(&line_driver->mc);
        return driver;
}

void lines_init(struct line *lines, int nlines)
{
        struct line *line;
        int i;

        for(i = 0; i < nlines; i++){
                line = &lines[i];
                INIT_LIST_HEAD(&line->chan_list);
                spin_lock_init(&line->lock);
                if(line->init_str != NULL){
                        line->init_str = uml_strdup(line->init_str);
                        if(line->init_str == NULL)
                                printk("lines_init - uml_strdup returned "
                                       "NULL\n");
                }
        }
}

struct winch {
        struct list_head list;
        int fd;
        int tty_fd;
        int pid;
        struct tty_struct *tty;
};

irqreturn_t winch_interrupt(int irq, void *data, struct pt_regs *unused)
{
        struct winch *winch = data;
        struct tty_struct *tty;
        struct line *line;
        int err;
        char c;

        if(winch->fd != -1){
                err = generic_read(winch->fd, &c, NULL);
                if(err < 0){
                        if(err != -EAGAIN){
                                printk("winch_interrupt : read failed, "
                                       "errno = %d\n", -err);
                                printk("fd %d is losing SIGWINCH support\n",
                                       winch->tty_fd);
                                return IRQ_HANDLED;
                        }
                        goto out;
                }
        }
        tty  = winch->tty;
        if (tty != NULL) {
                line = tty->driver_data;
                chan_window_size(&line->chan_list,
                                 &tty->winsize.ws_row, 
                                 &tty->winsize.ws_col);
                kill_pg(tty->pgrp, SIGWINCH, 1);
        }
 out:
        if(winch->fd != -1)
                reactivate_fd(winch->fd, WINCH_IRQ);
        return IRQ_HANDLED;
}

DECLARE_MUTEX(winch_handler_sem);
LIST_HEAD(winch_handlers);

void register_winch_irq(int fd, int tty_fd, int pid, struct tty_struct *tty)
{
        struct winch *winch;

        down(&winch_handler_sem);
        winch = kmalloc(sizeof(*winch), GFP_KERNEL);
        if (winch == NULL) {
                printk("register_winch_irq - kmalloc failed\n");
                goto out;
        }
        *winch = ((struct winch) { .list        = LIST_HEAD_INIT(winch->list),
                                   .fd          = fd,
                                   .tty_fd      = tty_fd,
                                   .pid         = pid,
                                   .tty         = tty });
        list_add(&winch->list, &winch_handlers);
        if(um_request_irq(WINCH_IRQ, fd, IRQ_READ, winch_interrupt,
                          SA_INTERRUPT | SA_SHIRQ | SA_SAMPLE_RANDOM, 
                          "winch", winch) < 0)
                printk("register_winch_irq - failed to register IRQ\n");
 out:
        up(&winch_handler_sem);
}

static void winch_cleanup(void)
{
        struct list_head *ele;
        struct winch *winch;

        list_for_each(ele, &winch_handlers){
                winch = list_entry(ele, struct winch, list);
                if(winch->fd != -1){
                        deactivate_fd(winch->fd, WINCH_IRQ);
                        os_close_file(winch->fd);
                }
                if(winch->pid != -1) 
                        os_kill_process(winch->pid, 1);
        }
}
__uml_exitcall(winch_cleanup);

char *add_xterm_umid(char *base)
{
        char *umid, *title;
        int len;

        umid = get_umid(1);
        if(umid == NULL)
                return base;
        
        len = strlen(base) + strlen(" ()") + strlen(umid) + 1;
        title = kmalloc(len, GFP_KERNEL);
        if(title == NULL){
                printk("Failed to allocate buffer for xterm title\n");
                return base;
        }

        snprintf(title, len, "%s (%s)", base, umid);
        return title;
}