uml: port mutex conversion
[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 "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);