330543b3129b5a7ac613e3566456eaf3ef50040c
[linux-2.6.git] / 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);