kernel/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/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
  18 struct 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
  30 struct port_dev {
  31         struct port_list *port;
  32         int helper_pid;
  33         int telnetd_pid;
  34 };
  35
  36 struct 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
  45 static 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
  76 static 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, "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_SHARED, "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                 um_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);