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