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