[PATCH] uml: move sigio_user.c to os-Linux/sigio.c
[linux-2.6.git] / arch / um / os-Linux / sigio.c
1 /*
2  * Copyright (C) 2002 Jeff Dike (jdike@karaya.com)
3  * Licensed under the GPL
4  */
5
6 #include <unistd.h>
7 #include <stdlib.h>
8 #include <termios.h>
9 #include <pty.h>
10 #include <signal.h>
11 #include <errno.h>
12 #include <string.h>
13 #include <sched.h>
14 #include <sys/socket.h>
15 #include <sys/poll.h>
16 #include "init.h"
17 #include "user.h"
18 #include "kern_util.h"
19 #include "user_util.h"
20 #include "sigio.h"
21 #include "os.h"
22
23 /* Protected by sigio_lock(), also used by sigio_cleanup, which is an
24  * exitcall.
25  */
26 static int write_sigio_pid = -1;
27
28 /* These arrays are initialized before the sigio thread is started, and
29  * the descriptors closed after it is killed.  So, it can't see them change.
30  * On the UML side, they are changed under the sigio_lock.
31  */
32 static int write_sigio_fds[2] = { -1, -1 };
33 static int sigio_private[2] = { -1, -1 };
34
35 struct pollfds {
36         struct pollfd *poll;
37         int size;
38         int used;
39 };
40
41 /* Protected by sigio_lock().  Used by the sigio thread, but the UML thread
42  * synchronizes with it.
43  */
44 struct pollfds current_poll = {
45         .poll           = NULL,
46         .size           = 0,
47         .used           = 0
48 };
49
50 struct pollfds next_poll = {
51         .poll           = NULL,
52         .size           = 0,
53         .used           = 0
54 };
55
56 static int write_sigio_thread(void *unused)
57 {
58         struct pollfds *fds, tmp;
59         struct pollfd *p;
60         int i, n, respond_fd;
61         char c;
62
63         signal(SIGWINCH, SIG_IGN);
64         fds = &current_poll;
65         while(1){
66                 n = poll(fds->poll, fds->used, -1);
67                 if(n < 0){
68                         if(errno == EINTR) continue;
69                         printk("write_sigio_thread : poll returned %d, "
70                                "errno = %d\n", n, errno);
71                 }
72                 for(i = 0; i < fds->used; i++){
73                         p = &fds->poll[i];
74                         if(p->revents == 0) continue;
75                         if(p->fd == sigio_private[1]){
76                                 n = os_read_file(sigio_private[1], &c, sizeof(c));
77                                 if(n != sizeof(c))
78                                         printk("write_sigio_thread : "
79                                                "read failed, err = %d\n", -n);
80                                 tmp = current_poll;
81                                 current_poll = next_poll;
82                                 next_poll = tmp;
83                                 respond_fd = sigio_private[1];
84                         }
85                         else {
86                                 respond_fd = write_sigio_fds[1];
87                                 fds->used--;
88                                 memmove(&fds->poll[i], &fds->poll[i + 1],
89                                         (fds->used - i) * sizeof(*fds->poll));
90                         }
91
92                         n = os_write_file(respond_fd, &c, sizeof(c));
93                         if(n != sizeof(c))
94                                 printk("write_sigio_thread : write failed, "
95                                        "err = %d\n", -n);
96                 }
97         }
98
99         return 0;
100 }
101
102 static int need_poll(int n)
103 {
104         if(n <= next_poll.size){
105                 next_poll.used = n;
106                 return(0);
107         }
108         kfree(next_poll.poll);
109         next_poll.poll = um_kmalloc_atomic(n * sizeof(struct pollfd));
110         if(next_poll.poll == NULL){
111                 printk("need_poll : failed to allocate new pollfds\n");
112                 next_poll.size = 0;
113                 next_poll.used = 0;
114                 return(-1);
115         }
116         next_poll.size = n;
117         next_poll.used = n;
118         return(0);
119 }
120
121 /* Must be called with sigio_lock held, because it's needed by the marked
122  * critical section. */
123 static void update_thread(void)
124 {
125         unsigned long flags;
126         int n;
127         char c;
128
129         flags = set_signals(0);
130         n = os_write_file(sigio_private[0], &c, sizeof(c));
131         if(n != sizeof(c)){
132                 printk("update_thread : write failed, err = %d\n", -n);
133                 goto fail;
134         }
135
136         n = os_read_file(sigio_private[0], &c, sizeof(c));
137         if(n != sizeof(c)){
138                 printk("update_thread : read failed, err = %d\n", -n);
139                 goto fail;
140         }
141
142         set_signals(flags);
143         return;
144  fail:
145         /* Critical section start */
146         if(write_sigio_pid != -1)
147                 os_kill_process(write_sigio_pid, 1);
148         write_sigio_pid = -1;
149         close(sigio_private[0]);
150         close(sigio_private[1]);
151         close(write_sigio_fds[0]);
152         close(write_sigio_fds[1]);
153         /* Critical section end */
154         set_signals(flags);
155 }
156
157 int add_sigio_fd(int fd, int read)
158 {
159         int err = 0, i, n, events;
160
161         sigio_lock();
162         for(i = 0; i < current_poll.used; i++){
163                 if(current_poll.poll[i].fd == fd)
164                         goto out;
165         }
166
167         n = current_poll.used + 1;
168         err = need_poll(n);
169         if(err)
170                 goto out;
171
172         for(i = 0; i < current_poll.used; i++)
173                 next_poll.poll[i] = current_poll.poll[i];
174
175         if(read) events = POLLIN;
176         else events = POLLOUT;
177
178         next_poll.poll[n - 1] = ((struct pollfd) { .fd          = fd,
179                                                    .events      = events,
180                                                    .revents     = 0 });
181         update_thread();
182  out:
183         sigio_unlock();
184         return(err);
185 }
186
187 int ignore_sigio_fd(int fd)
188 {
189         struct pollfd *p;
190         int err = 0, i, n = 0;
191
192         sigio_lock();
193         for(i = 0; i < current_poll.used; i++){
194                 if(current_poll.poll[i].fd == fd) break;
195         }
196         if(i == current_poll.used)
197                 goto out;
198
199         err = need_poll(current_poll.used - 1);
200         if(err)
201                 goto out;
202
203         for(i = 0; i < current_poll.used; i++){
204                 p = &current_poll.poll[i];
205                 if(p->fd != fd) next_poll.poll[n++] = current_poll.poll[i];
206         }
207         if(n == i){
208                 printk("ignore_sigio_fd : fd %d not found\n", fd);
209                 err = -1;
210                 goto out;
211         }
212
213         update_thread();
214  out:
215         sigio_unlock();
216         return(err);
217 }
218
219 static struct pollfd *setup_initial_poll(int fd)
220 {
221         struct pollfd *p;
222
223         p = um_kmalloc(sizeof(struct pollfd));
224         if (p == NULL) {
225                 printk("setup_initial_poll : failed to allocate poll\n");
226                 return NULL;
227         }
228         *p = ((struct pollfd) { .fd     = fd,
229                                 .events         = POLLIN,
230                                 .revents        = 0 });
231         return p;
232 }
233
234 void write_sigio_workaround(void)
235 {
236         unsigned long stack;
237         struct pollfd *p;
238         int err;
239         int l_write_sigio_fds[2];
240         int l_sigio_private[2];
241         int l_write_sigio_pid;
242
243         /* We call this *tons* of times - and most ones we must just fail. */
244         sigio_lock();
245         l_write_sigio_pid = write_sigio_pid;
246         sigio_unlock();
247
248         if (l_write_sigio_pid != -1)
249                 return;
250
251         err = os_pipe(l_write_sigio_fds, 1, 1);
252         if(err < 0){
253                 printk("write_sigio_workaround - os_pipe 1 failed, "
254                        "err = %d\n", -err);
255                 return;
256         }
257         err = os_pipe(l_sigio_private, 1, 1);
258         if(err < 0){
259                 printk("write_sigio_workaround - os_pipe 2 failed, "
260                        "err = %d\n", -err);
261                 goto out_close1;
262         }
263
264         p = setup_initial_poll(l_sigio_private[1]);
265         if(!p)
266                 goto out_close2;
267
268         sigio_lock();
269
270         /* Did we race? Don't try to optimize this, please, it's not so likely
271          * to happen, and no more than once at the boot. */
272         if(write_sigio_pid != -1)
273                 goto out_unlock;
274
275         write_sigio_pid = run_helper_thread(write_sigio_thread, NULL,
276                                             CLONE_FILES | CLONE_VM, &stack, 0);
277
278         if (write_sigio_pid < 0)
279                 goto out_clear;
280
281         if (write_sigio_irq(l_write_sigio_fds[0]))
282                 goto out_kill;
283
284         /* Success, finally. */
285         memcpy(write_sigio_fds, l_write_sigio_fds, sizeof(l_write_sigio_fds));
286         memcpy(sigio_private, l_sigio_private, sizeof(l_sigio_private));
287
288         current_poll = ((struct pollfds) { .poll        = p,
289                                            .used        = 1,
290                                            .size        = 1 });
291
292         sigio_unlock();
293         return;
294
295  out_kill:
296         l_write_sigio_pid = write_sigio_pid;
297         write_sigio_pid = -1;
298         sigio_unlock();
299         /* Going to call waitpid, avoid holding the lock. */
300         os_kill_process(l_write_sigio_pid, 1);
301         goto out_free;
302
303  out_clear:
304         write_sigio_pid = -1;
305  out_unlock:
306         sigio_unlock();
307  out_free:
308         kfree(p);
309  out_close2:
310         close(l_sigio_private[0]);
311         close(l_sigio_private[1]);
312  out_close1:
313         close(l_write_sigio_fds[0]);
314         close(l_write_sigio_fds[1]);
315         return;
316 }
317
318 void sigio_cleanup(void)
319 {
320         if(write_sigio_pid != -1){
321                 os_kill_process(write_sigio_pid, 1);
322                 write_sigio_pid = -1;
323         }
324 }