arch/um/drivers/port_kern.c

   1 /*
   2  * Copyright (C) 2001, 2002 Jeff Dike (jdike@karaya.com)
   3  * Licensed under the GPL
   4  */
   5
   6 #include "linux/list.h"
   7 #include "linux/sched.h"
   8 #include "linux/slab.h"
   9 #include "linux/interrupt.h"
  10 #include "linux/irq.h"
  11 #include "linux/spinlock.h"
  12 #include "linux/errno.h"
  13 #include "asm/atomic.h"
  14 #include "asm/semaphore.h"
  15 #include "asm/errno.h"
  16 #include "kern_util.h"
  17 #include "kern.h"
  18 #include "irq_user.h"
  19 #include "irq_kern.h"
  20 #include "port.h"
  21 #include "init.h"
  22 #include "os.h"
  23
  24 struct port_list {
  25         struct list_head list;
  26         atomic_t wait_count;
  27         int has_connection;
  28         struct completion done;
  29         int port;
  30         int fd;
  31         spinlock_t lock;
  32         struct list_head pending;
  33         struct list_head connections;
  34 };
  35
  36 struct port_dev {
  37         struct port_list *port;
  38         int helper_pid;
  39         int telnetd_pid;
  40 };
  41
  42 struct connection {
  43         struct list_head list;
  44         int fd;
  45         int helper_pid;
  46         int socket[2];
  47         int telnetd_pid;
  48         struct port_list *port;
  49 };
  50
  51 static irqreturn_t pipe_interrupt(int irq, void *data, struct pt_regs *regs)
  52 {
  53         struct connection *conn = data;
  54         int fd;
  55
  56         fd = os_rcv_fd(conn->socket[0], &conn->helper_pid);
  57         if(fd < 0){
  58                 if(fd == -EAGAIN)
  59                         return(IRQ_NONE);
  60
  61                 printk(KERN_ERR "pipe_interrupt : os_rcv_fd returned %d\n",
  62                        -fd);
  63                 os_close_file(conn->fd);
  64         }
  65
  66         list_del(&conn->list);
  67
  68         conn->fd = fd;
  69         list_add(&conn->list, &conn->port->connections);
  70
  71         complete(&conn->port->done);
  72         return(IRQ_HANDLED);
  73 }
  74
  75 #define NO_WAITER_MSG \
  76     "****\n" \
  77     "There are currently no UML consoles waiting for port connections.\n" \
  78     "Either disconnect from one to make it available or activate some more\n" \
  79     "by enabling more consoles in the UML /etc/inittab.\n" \
  80     "****\n"
  81
  82 static int port_accept(struct port_list *port)
  83 {
  84         struct connection *conn;
  85         int fd, socket[2], pid, ret = 0;
  86
  87         fd = port_connection(port->fd, socket, &pid);
  88         if(fd < 0){
  89                 if(fd != -EAGAIN)
  90                         printk(KERN_ERR "port_accept : port_connection "
  91                                "returned %d\n", -fd);
  92                 goto out;
  93         }
  94
  95         conn = kmalloc(sizeof(*conn), GFP_ATOMIC);
  96         if(conn == NULL){
  97                 printk(KERN_ERR "port_accept : failed to allocate "
  98                        "connection\n");
  99                 goto out_close;
 100         }
 101         *conn = ((struct connection)
 102                 { .list         = LIST_HEAD_INIT(conn->list),
 103                   .fd           = fd,
 104                   .socket       = { socket[0], socket[1] },
 105                   .telnetd_pid  = pid,
 106                   .port         = port });
 107
 108         if(um_request_irq(TELNETD_IRQ, socket[0], IRQ_READ, pipe_interrupt,
 109                           SA_INTERRUPT | SA_SHIRQ | SA_SAMPLE_RANDOM,
 110                           "telnetd", conn)){
 111                 printk(KERN_ERR "port_accept : failed to get IRQ for "
 112                        "telnetd\n");
 113                 goto out_free;
 114         }
 115
 116         if(atomic_read(&port->wait_count) == 0){
 117                 os_write_file(fd, NO_WAITER_MSG, sizeof(NO_WAITER_MSG));
 118                 printk("No one waiting for port\n");
 119         }
 120         list_add(&conn->list, &port->pending);
 121         return(1);
 122
 123  out_free:
 124         kfree(conn);
 125  out_close:
 126         os_close_file(fd);
 127         if(pid != -1)
 128                 os_kill_process(pid, 1);
 129  out:
 130         return(ret);
 131 }
 132
 133 DECLARE_MUTEX(ports_sem);
 134 struct list_head ports = LIST_HEAD_INIT(ports);
 135
 136 void port_work_proc(void *unused)
 137 {
 138         struct port_list *port;
 139         struct list_head *ele;
 140         unsigned long flags;
 141
 142         local_irq_save(flags);
 143         list_for_each(ele, &ports){
 144                 port = list_entry(ele, struct port_list, list);
 145                 if(!port->has_connection)
 146                         continue;
 147                 reactivate_fd(port->fd, ACCEPT_IRQ);
 148                 while(port_accept(port)) ;
 149                 port->has_connection = 0;
 150         }
 151         local_irq_restore(flags);
 152 }
 153
 154 DECLARE_WORK(port_work, port_work_proc, NULL);
 155
 156 static irqreturn_t port_interrupt(int irq, void *data, struct pt_regs *regs)
 157 {
 158         struct port_list *port = data;
 159
 160         port->has_connection = 1;
 161         schedule_work(&port_work);
 162         return(IRQ_HANDLED);
 163 }
 164
 165 void *port_data(int port_num)
 166 {
 167         struct list_head *ele;
 168         struct port_list *port;
 169         struct port_dev *dev = NULL;
 170         int fd;
 171
 172         down(&ports_sem);
 173         list_for_each(ele, &ports){
 174                 port = list_entry(ele, struct port_list, list);
 175                 if(port->port == port_num) goto found;
 176         }
 177         port = kmalloc(sizeof(struct port_list), GFP_KERNEL);
 178         if(port == NULL){
 179                 printk(KERN_ERR "Allocation of port list failed\n");
 180                 goto out;
 181         }
 182
 183         fd = port_listen_fd(port_num);
 184         if(fd < 0){
 185                 printk(KERN_ERR "binding to port %d failed, errno = %d\n",
 186                        port_num, -fd);
 187                 goto out_free;
 188         }
 189         if(um_request_irq(ACCEPT_IRQ, fd, IRQ_READ, port_interrupt,
 190                           SA_INTERRUPT | SA_SHIRQ | SA_SAMPLE_RANDOM, "port",
 191                           port)){
 192                 printk(KERN_ERR "Failed to get IRQ for port %d\n", port_num);
 193                 goto out_close;
 194         }
 195
 196         *port = ((struct port_list)
 197                 { .list                 = LIST_HEAD_INIT(port->list),
 198                   .wait_count           = ATOMIC_INIT(0),
 199                   .has_connection       = 0,
 200                   .port                 = port_num,
 201                   .fd                   = fd,
 202                   .pending              = LIST_HEAD_INIT(port->pending),
 203                   .connections          = LIST_HEAD_INIT(port->connections) });
 204         spin_lock_init(&port->lock);
 205         init_completion(&port->done);
 206         list_add(&port->list, &ports);
 207
 208  found:
 209         dev = kmalloc(sizeof(struct port_dev), GFP_KERNEL);
 210         if(dev == NULL){
 211                 printk(KERN_ERR "Allocation of port device entry failed\n");
 212                 goto out;
 213         }
 214
 215         *dev = ((struct port_dev) { .port               = port,
 216                                     .helper_pid         = -1,
 217                                     .telnetd_pid        = -1 });
 218         goto out;
 219
 220  out_free:
 221         kfree(port);
 222  out_close:
 223         os_close_file(fd);
 224  out:
 225         up(&ports_sem);
 226         return(dev);
 227 }
 228
 229 int port_wait(void *data)
 230 {
 231         struct port_dev *dev = data;
 232         struct connection *conn;
 233         struct port_list *port = dev->port;
 234         int fd;
 235
 236         atomic_inc(&port->wait_count);
 237         while(1){
 238                 fd = -ERESTARTSYS;
 239                 if(wait_for_completion_interruptible(&port->done))
 240                         goto out;
 241
 242                 spin_lock(&port->lock);
 243
 244                 conn = list_entry(port->connections.next, struct connection,
 245                                   list);
 246                 list_del(&conn->list);
 247                 spin_unlock(&port->lock);
 248
 249                 os_shutdown_socket(conn->socket[0], 1, 1);
 250                 os_close_file(conn->socket[0]);
 251                 os_shutdown_socket(conn->socket[1], 1, 1);
 252                 os_close_file(conn->socket[1]);
 253
 254                 /* This is done here because freeing an IRQ can't be done
 255                  * within the IRQ handler.  So, pipe_interrupt always ups
 256                  * the semaphore regardless of whether it got a successful
 257                  * connection.  Then we loop here throwing out failed
 258                  * connections until a good one is found.
 259                  */
 260                 free_irq_by_irq_and_dev(TELNETD_IRQ, conn);
 261                 free_irq(TELNETD_IRQ, conn);
 262
 263                 if(conn->fd >= 0) break;
 264                 os_close_file(conn->fd);
 265                 kfree(conn);
 266         }
 267
 268         fd = conn->fd;
 269         dev->helper_pid = conn->helper_pid;
 270         dev->telnetd_pid = conn->telnetd_pid;
 271         kfree(conn);
 272  out:
 273         atomic_dec(&port->wait_count);
 274         return fd;
 275 }
 276
 277 void port_remove_dev(void *d)
 278 {
 279         struct port_dev *dev = d;
 280
 281         if(dev->helper_pid != -1)
 282                 os_kill_process(dev->helper_pid, 0);
 283         if(dev->telnetd_pid != -1)
 284                 os_kill_process(dev->telnetd_pid, 1);
 285         dev->helper_pid = -1;
 286         dev->telnetd_pid = -1;
 287 }
 288
 289 void port_kern_free(void *d)
 290 {
 291         struct port_dev *dev = d;
 292
 293         port_remove_dev(dev);
 294         kfree(dev);
 295 }
 296
 297 static void free_port(void)
 298 {
 299         struct list_head *ele;
 300         struct port_list *port;
 301
 302         list_for_each(ele, &ports){
 303                 port = list_entry(ele, struct port_list, list);
 304                 free_irq_by_fd(port->fd);
 305                 os_close_file(port->fd);
 306         }
 307 }
 308
 309 __uml_exitcall(free_port);