linux/arch/um/drivers/port_kern.c
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   1/*
   2 * Copyright (C) 2001 - 2007 Jeff Dike (jdike@{linux.intel,addtoit}.com)
   3 * Licensed under the GPL
   4 */
   5
   6#include "linux/completion.h"
   7#include "linux/interrupt.h"
   8#include "linux/list.h"
   9#include "linux/mutex.h"
  10#include "linux/slab.h"
  11#include "linux/workqueue.h"
  12#include "asm/atomic.h"
  13#include "init.h"
  14#include "irq_kern.h"
  15#include "os.h"
  16#include "port.h"
  17
  18struct port_list {
  19        struct list_head list;
  20        atomic_t wait_count;
  21        int has_connection;
  22        struct completion done;
  23        int port;
  24        int fd;
  25        spinlock_t lock;
  26        struct list_head pending;
  27        struct list_head connections;
  28};
  29
  30struct port_dev {
  31        struct port_list *port;
  32        int helper_pid;
  33        int telnetd_pid;
  34};
  35
  36struct connection {
  37        struct list_head list;
  38        int fd;
  39        int helper_pid;
  40        int socket[2];
  41        int telnetd_pid;
  42        struct port_list *port;
  43};
  44
  45static irqreturn_t pipe_interrupt(int irq, void *data)
  46{
  47        struct connection *conn = data;
  48        int fd;
  49
  50        fd = os_rcv_fd(conn->socket[0], &conn->helper_pid);
  51        if (fd < 0) {
  52                if (fd == -EAGAIN)
  53                        return IRQ_NONE;
  54
  55                printk(KERN_ERR "pipe_interrupt : os_rcv_fd returned %d\n",
  56                       -fd);
  57                os_close_file(conn->fd);
  58        }
  59
  60        list_del(&conn->list);
  61
  62        conn->fd = fd;
  63        list_add(&conn->list, &conn->port->connections);
  64
  65        complete(&conn->port->done);
  66        return IRQ_HANDLED;
  67}
  68
  69#define NO_WAITER_MSG \
  70    "****\n" \
  71    "There are currently no UML consoles waiting for port connections.\n" \
  72    "Either disconnect from one to make it available or activate some more\n" \
  73    "by enabling more consoles in the UML /etc/inittab.\n" \
  74    "****\n"
  75
  76static int port_accept(struct port_list *port)
  77{
  78        struct connection *conn;
  79        int fd, socket[2], pid;
  80
  81        fd = port_connection(port->fd, socket, &pid);
  82        if (fd < 0) {
  83                if (fd != -EAGAIN)
  84                        printk(KERN_ERR "port_accept : port_connection "
  85                               "returned %d\n", -fd);
  86                goto out;
  87        }
  88
  89        conn = kmalloc(sizeof(*conn), GFP_ATOMIC);
  90        if (conn == NULL) {
  91                printk(KERN_ERR "port_accept : failed to allocate "
  92                       "connection\n");
  93                goto out_close;
  94        }
  95        *conn = ((struct connection)
  96                { .list         = LIST_HEAD_INIT(conn->list),
  97                  .fd           = fd,
  98                  .socket       = { socket[0], socket[1] },
  99                  .telnetd_pid  = pid,
 100                  .port         = port });
 101
 102        if (um_request_irq(TELNETD_IRQ, socket[0], IRQ_READ, pipe_interrupt,
 103                          IRQF_SHARED | IRQF_SAMPLE_RANDOM,
 104                          "telnetd", conn)) {
 105                printk(KERN_ERR "port_accept : failed to get IRQ for "
 106                       "telnetd\n");
 107                goto out_free;
 108        }
 109
 110        if (atomic_read(&port->wait_count) == 0) {
 111                os_write_file(fd, NO_WAITER_MSG, sizeof(NO_WAITER_MSG));
 112                printk(KERN_ERR "No one waiting for port\n");
 113        }
 114        list_add(&conn->list, &port->pending);
 115        return 1;
 116
 117 out_free:
 118        kfree(conn);
 119 out_close:
 120        os_close_file(fd);
 121        os_kill_process(pid, 1);
 122 out:
 123        return 0;
 124}
 125
 126static DEFINE_MUTEX(ports_mutex);
 127static LIST_HEAD(ports);
 128
 129static void port_work_proc(struct work_struct *unused)
 130{
 131        struct port_list *port;
 132        struct list_head *ele;
 133        unsigned long flags;
 134
 135        local_irq_save(flags);
 136        list_for_each(ele, &ports) {
 137                port = list_entry(ele, struct port_list, list);
 138                if (!port->has_connection)
 139                        continue;
 140
 141                reactivate_fd(port->fd, ACCEPT_IRQ);
 142                while (port_accept(port))
 143                        ;
 144                port->has_connection = 0;
 145        }
 146        local_irq_restore(flags);
 147}
 148
 149DECLARE_WORK(port_work, port_work_proc);
 150
 151static irqreturn_t port_interrupt(int irq, void *data)
 152{
 153        struct port_list *port = data;
 154
 155        port->has_connection = 1;
 156        schedule_work(&port_work);
 157        return IRQ_HANDLED;
 158}
 159
 160void *port_data(int port_num)
 161{
 162        struct list_head *ele;
 163        struct port_list *port;
 164        struct port_dev *dev = NULL;
 165        int fd;
 166
 167        mutex_lock(&ports_mutex);
 168        list_for_each(ele, &ports) {
 169                port = list_entry(ele, struct port_list, list);
 170                if (port->port == port_num)
 171                        goto found;
 172        }
 173        port = kmalloc(sizeof(struct port_list), GFP_KERNEL);
 174        if (port == NULL) {
 175                printk(KERN_ERR "Allocation of port list failed\n");
 176                goto out;
 177        }
 178
 179        fd = port_listen_fd(port_num);
 180        if (fd < 0) {
 181                printk(KERN_ERR "binding to port %d failed, errno = %d\n",
 182                       port_num, -fd);
 183                goto out_free;
 184        }
 185
 186        if (um_request_irq(ACCEPT_IRQ, fd, IRQ_READ, port_interrupt,
 187                          IRQF_SHARED | IRQF_SAMPLE_RANDOM,
 188                          "port", port)) {
 189                printk(KERN_ERR "Failed to get IRQ for port %d\n", port_num);
 190                goto out_close;
 191        }
 192
 193        *port = ((struct port_list)
 194                { .list                 = LIST_HEAD_INIT(port->list),
 195                  .wait_count           = ATOMIC_INIT(0),
 196                  .has_connection       = 0,
 197                  .port                 = port_num,
 198                  .fd                   = fd,
 199                  .pending              = LIST_HEAD_INIT(port->pending),
 200                  .connections          = LIST_HEAD_INIT(port->connections) });
 201        spin_lock_init(&port->lock);
 202        init_completion(&port->done);
 203        list_add(&port->list, &ports);
 204
 205 found:
 206        dev = kmalloc(sizeof(struct port_dev), GFP_KERNEL);
 207        if (dev == NULL) {
 208                printk(KERN_ERR "Allocation of port device entry failed\n");
 209                goto out;
 210        }
 211
 212        *dev = ((struct port_dev) { .port               = port,
 213                                    .helper_pid         = -1,
 214                                    .telnetd_pid        = -1 });
 215        goto out;
 216
 217 out_close:
 218        os_close_file(fd);
 219 out_free:
 220        kfree(port);
 221 out:
 222        mutex_unlock(&ports_mutex);
 223        return dev;
 224}
 225
 226int port_wait(void *data)
 227{
 228        struct port_dev *dev = data;
 229        struct connection *conn;
 230        struct port_list *port = dev->port;
 231        int fd;
 232
 233        atomic_inc(&port->wait_count);
 234        while (1) {
 235                fd = -ERESTARTSYS;
 236                if (wait_for_completion_interruptible(&port->done))
 237                        goto out;
 238
 239                spin_lock(&port->lock);
 240
 241                conn = list_entry(port->connections.next, struct connection,
 242                                  list);
 243                list_del(&conn->list);
 244                spin_unlock(&port->lock);
 245
 246                os_shutdown_socket(conn->socket[0], 1, 1);
 247                os_close_file(conn->socket[0]);
 248                os_shutdown_socket(conn->socket[1], 1, 1);
 249                os_close_file(conn->socket[1]);
 250
 251                /* This is done here because freeing an IRQ can't be done
 252                 * within the IRQ handler.  So, pipe_interrupt always ups
 253                 * the semaphore regardless of whether it got a successful
 254                 * connection.  Then we loop here throwing out failed
 255                 * connections until a good one is found.
 256                 */
 257                free_irq(TELNETD_IRQ, conn);
 258
 259                if (conn->fd >= 0)
 260                        break;
 261                os_close_file(conn->fd);
 262                kfree(conn);
 263        }
 264
 265        fd = conn->fd;
 266        dev->helper_pid = conn->helper_pid;
 267        dev->telnetd_pid = conn->telnetd_pid;
 268        kfree(conn);
 269 out:
 270        atomic_dec(&port->wait_count);
 271        return fd;
 272}
 273
 274void port_remove_dev(void *d)
 275{
 276        struct port_dev *dev = d;
 277
 278        if (dev->helper_pid != -1)
 279                os_kill_process(dev->helper_pid, 0);
 280        if (dev->telnetd_pid != -1)
 281                os_kill_process(dev->telnetd_pid, 1);
 282        dev->helper_pid = -1;
 283        dev->telnetd_pid = -1;
 284}
 285
 286void port_kern_free(void *d)
 287{
 288        struct port_dev *dev = d;
 289
 290        port_remove_dev(dev);
 291        kfree(dev);
 292}
 293
 294static void free_port(void)
 295{
 296        struct list_head *ele;
 297        struct port_list *port;
 298
 299        list_for_each(ele, &ports) {
 300                port = list_entry(ele, struct port_list, list);
 301                free_irq_by_fd(port->fd);
 302                os_close_file(port->fd);
 303        }
 304}
 305
 306__uml_exitcall(free_port);
 307
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