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