arch/um/drivers/port_kern.c

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