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Commit | Line | Data |
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9e397995 | 1 | diff -urN --exclude-from=/usr/src/dontdiff linux-2.4.17_original/linux/include/linux/sched.h linux-2.4.17_SEMUNDO/linux/include/linux/sched.h |
2 | --- linux-2.4.17_original/linux/include/linux/sched.h Fri Dec 21 09:42:03 2001 | |
3 | +++ linux-2.4.17_SEMUNDO/linux/include/linux/sched.h Mon Jan 21 19:12:35 2002 | |
4 | @@ -381,7 +381,7 @@ | |
5 | struct tty_struct *tty; /* NULL if no tty */ | |
6 | unsigned int locks; /* How many file locks are being held */ | |
7 | /* ipc stuff */ | |
8 | - struct sem_undo *semundo; | |
9 | + struct sem_undohd *semundohd; | |
10 | struct sem_queue *semsleeping; | |
11 | /* CPU-specific state of this task */ | |
12 | struct thread_struct thread; | |
13 | diff -urN --exclude-from=/usr/src/dontdiff linux-2.4.17_original/linux/include/linux/sem.h linux-2.4.17_SEMUNDO/linux/include/linux/sem.h | |
14 | --- linux-2.4.17_original/linux/include/linux/sem.h Thu Nov 22 11:46:18 2001 | |
15 | +++ linux-2.4.17_SEMUNDO/linux/include/linux/sem.h Mon Jan 21 19:12:35 2002 | |
16 | @@ -121,6 +121,18 @@ | |
17 | short * semadj; /* array of adjustments, one per semaphore */ | |
18 | }; | |
19 | ||
20 | +/* Each PROCESS (i.e. collection of tasks that are running POSIX style threads) | |
21 | + * must share the same semundo list, in order to support POSIX SEMUNDO | |
22 | + * semantics for threads. The sem_undohd controls shared access to this | |
23 | + * list among all the tasks (threads) in that process. | |
24 | + */ | |
25 | +struct sem_undohd { | |
26 | + atomic_t refcnt; | |
27 | + spinlock_t lock; | |
28 | + volatile unsigned long add_count; | |
29 | + struct sem_undo *proc_list; | |
30 | +}; | |
31 | + | |
32 | asmlinkage long sys_semget (key_t key, int nsems, int semflg); | |
33 | asmlinkage long sys_semop (int semid, struct sembuf *sops, unsigned nsops); | |
34 | asmlinkage long sys_semctl (int semid, int semnum, int cmd, union semun arg); | |
35 | diff -urN --exclude-from=/usr/src/dontdiff linux-2.4.17_original/linux/ipc/sem.c linux-2.4.17_SEMUNDO/linux/ipc/sem.c | |
36 | --- linux-2.4.17_original/linux/ipc/sem.c Sun Sep 30 12:26:42 2001 | |
37 | +++ linux-2.4.17_SEMUNDO/linux/ipc/sem.c Mon Jan 21 19:08:05 2002 | |
38 | @@ -788,12 +788,75 @@ | |
39 | } | |
40 | } | |
41 | ||
42 | -static struct sem_undo* freeundos(struct sem_array *sma, struct sem_undo* un) | |
43 | +static inline void lock_semundo(void) | |
44 | +{ | |
45 | + struct sem_undohd *undohd; | |
46 | + | |
47 | + undohd = current->semundohd; | |
48 | + if ((undohd != NULL) && (atomic_read(&undohd->refcnt) != 1)) | |
49 | + spin_lock(&undohd->lock); | |
50 | +} | |
51 | + | |
52 | +/* This code has an interesting interaction with copy_semundo(): | |
53 | + * two tasks could have been sharing the semundohd at the time "first" one | |
54 | + * of those tasks acquires the lock acquired in lock_semundo. If the other | |
55 | + * tasks exits before * "the first one" releases the lock (by calling | |
56 | + * unlock_semundo), then the spin_unlock would NOT be called. This would | |
57 | + * leave the semundohd in a locked state. This would NOT be a problem unless | |
58 | + * the remaining task once again creates a new task that once again shares the | |
59 | + * semundohd. Cleanup up this last case is dealt with in copy_semundo by | |
60 | + * having it reinitialize the spin_lock when it once again creates a second | |
61 | + * task sharing the semundo. | |
62 | + */ | |
63 | +static inline void unlock_semundo(void) | |
64 | +{ | |
65 | + struct sem_undohd *undohd; | |
66 | + | |
67 | + undohd = current->semundohd; | |
68 | + if ((undohd != NULL) && (atomic_read(&undohd->refcnt) != 1)) | |
69 | + spin_unlock(&undohd->lock); | |
70 | +} | |
71 | + | |
72 | + | |
73 | +/* If the task doesn't already have a semundohd, then allocate one | |
74 | + * here. We guarantee there is only one thread using this undo list, | |
75 | + * and current is THE ONE | |
76 | + * | |
77 | + * If this allocation and assignment succeeds, but later | |
78 | + * portions of this code fail, there is no need to free the sem_undohd. | |
79 | + * Just let it stay associated with the task, and it'll be freed later | |
80 | + * at exit time. | |
81 | + * | |
82 | + * This can block, so callers must hold no locks. | |
83 | + */ | |
84 | +static inline int get_undohd(struct sem_undohd **undohdp) | |
85 | +{ | |
86 | + struct sem_undohd *undohd; | |
87 | + int size; | |
88 | + | |
89 | + undohd = current->semundohd; | |
90 | + if (!undohd) { | |
91 | + size = sizeof(struct sem_undohd); | |
92 | + undohd = (struct sem_undohd *) kmalloc(size, GFP_KERNEL); | |
93 | + if (undohd == NULL) | |
94 | + return -ENOMEM; | |
95 | + memset(undohd, 0, size); | |
96 | + /* don't initialize unodhd->lock here. It's done | |
97 | + * in copy_semundo() instead. | |
98 | + */ | |
99 | + atomic_set(&undohd->refcnt, 1); | |
100 | + current->semundohd = undohd; | |
101 | + } | |
102 | + *undohdp = undohd; | |
103 | + return 0; | |
104 | +} | |
105 | + | |
106 | +static struct sem_undo* freeundos(struct sem_undo* un) | |
107 | { | |
108 | struct sem_undo* u; | |
109 | struct sem_undo** up; | |
110 | ||
111 | - for(up = ¤t->semundo;(u=*up);up=&u->proc_next) { | |
112 | + for(up = ¤t->semundohd->proc_list;(u=*up);up=&u->proc_next) { | |
113 | if(un==u) { | |
114 | un=u->proc_next; | |
115 | *up=un; | |
116 | @@ -805,33 +868,87 @@ | |
117 | return un->proc_next; | |
118 | } | |
119 | ||
120 | -/* returns without sem_lock on error! */ | |
121 | +static inline struct sem_undo *find_undo(int semid) | |
122 | +{ | |
123 | + struct sem_undo *un; | |
124 | + | |
125 | + un = NULL; | |
126 | + if (current->semundohd != NULL) { | |
127 | + un = current->semundohd->proc_list; | |
128 | + } | |
129 | + while(un != NULL) { | |
130 | + if(un->semid==semid) | |
131 | + break; | |
132 | + if(un->semid==-1) | |
133 | + un=freeundos(un); | |
134 | + else | |
135 | + un=un->proc_next; | |
136 | + } | |
137 | + return un; | |
138 | +} | |
139 | + | |
140 | +/* returns without sem_lock and semundo list locks on error! */ | |
141 | static int alloc_undo(struct sem_array *sma, struct sem_undo** unp, int semid, int alter) | |
142 | { | |
143 | int size, nsems, error; | |
144 | - struct sem_undo *un; | |
145 | + struct sem_undo *un, *new_un; | |
146 | + struct sem_undohd *unhd; | |
147 | + unsigned long saved_add_count; | |
148 | + | |
149 | ||
150 | nsems = sma->sem_nsems; | |
151 | - size = sizeof(struct sem_undo) + sizeof(short)*nsems; | |
152 | + saved_add_count = 0; | |
153 | + if (current->semundohd != NULL) | |
154 | + saved_add_count = current->semundohd->add_count; | |
155 | sem_unlock(semid); | |
156 | + unlock_semundo(); | |
157 | ||
158 | + error = get_undohd(&unhd); | |
159 | + if (error) | |
160 | + return error; | |
161 | + | |
162 | + size = sizeof(struct sem_undo) + sizeof(short)*nsems; | |
163 | un = (struct sem_undo *) kmalloc(size, GFP_KERNEL); | |
164 | if (!un) | |
165 | return -ENOMEM; | |
166 | ||
167 | memset(un, 0, size); | |
168 | + lock_semundo(); | |
169 | error = sem_revalidate(semid, sma, nsems, alter ? S_IWUGO : S_IRUGO); | |
170 | if(error) { | |
171 | + unlock_semundo(); | |
172 | kfree(un); | |
173 | return error; | |
174 | } | |
175 | ||
176 | - un->semadj = (short *) &un[1]; | |
177 | - un->semid = semid; | |
178 | - un->proc_next = current->semundo; | |
179 | - current->semundo = un; | |
180 | - un->id_next = sma->undo; | |
181 | - sma->undo = un; | |
182 | + | |
183 | + /* alloc_undo has just | |
184 | + * released all locks and reacquired them. | |
185 | + * But, another thread may have | |
186 | + * added the semundo we were looking for | |
187 | + * during that time. | |
188 | + * So, we check for it again. | |
189 | + * only initialize and add the new one | |
190 | + * if we don't discover one. | |
191 | + */ | |
192 | + new_un = NULL; | |
193 | + if (current->semundohd->add_count != saved_add_count) | |
194 | + new_un = find_undo(semid); | |
195 | + | |
196 | + if (new_un != NULL) { | |
197 | + if (sma->undo != new_un) | |
198 | + BUG(); | |
199 | + kfree(un); | |
200 | + un = new_un; | |
201 | + } else { | |
202 | + current->semundohd->add_count++; | |
203 | + un->semadj = (short *) &un[1]; | |
204 | + un->semid = semid; | |
205 | + un->proc_next = unhd->proc_list; | |
206 | + unhd->proc_list = un; | |
207 | + un->id_next = sma->undo; | |
208 | + sma->undo = un; | |
209 | + } | |
210 | *unp = un; | |
211 | return 0; | |
212 | } | |
213 | @@ -846,6 +963,7 @@ | |
214 | int undos = 0, decrease = 0, alter = 0; | |
215 | struct sem_queue queue; | |
216 | ||
217 | + | |
218 | if (nsops < 1 || semid < 0) | |
219 | return -EINVAL; | |
220 | if (nsops > sc_semopm) | |
221 | @@ -859,17 +977,18 @@ | |
222 | error=-EFAULT; | |
223 | goto out_free; | |
224 | } | |
225 | + lock_semundo(); | |
226 | sma = sem_lock(semid); | |
227 | error=-EINVAL; | |
228 | if(sma==NULL) | |
229 | - goto out_free; | |
230 | + goto out_semundo_free; | |
231 | error = -EIDRM; | |
232 | if (sem_checkid(sma,semid)) | |
233 | - goto out_unlock_free; | |
234 | + goto out_unlock_semundo_free; | |
235 | error = -EFBIG; | |
236 | for (sop = sops; sop < sops + nsops; sop++) { | |
237 | if (sop->sem_num >= sma->sem_nsems) | |
238 | - goto out_unlock_free; | |
239 | + goto out_unlock_semundo_free; | |
240 | if (sop->sem_flg & SEM_UNDO) | |
241 | undos++; | |
242 | if (sop->sem_op < 0) | |
243 | @@ -881,24 +1000,18 @@ | |
244 | ||
245 | error = -EACCES; | |
246 | if (ipcperms(&sma->sem_perm, alter ? S_IWUGO : S_IRUGO)) | |
247 | - goto out_unlock_free; | |
248 | + goto out_unlock_semundo_free; | |
249 | if (undos) { | |
250 | /* Make sure we have an undo structure | |
251 | * for this process and this semaphore set. | |
252 | */ | |
253 | - un=current->semundo; | |
254 | - while(un != NULL) { | |
255 | - if(un->semid==semid) | |
256 | - break; | |
257 | - if(un->semid==-1) | |
258 | - un=freeundos(sma,un); | |
259 | - else | |
260 | - un=un->proc_next; | |
261 | - } | |
262 | + | |
263 | + un = find_undo(semid); | |
264 | if (!un) { | |
265 | error = alloc_undo(sma,&un,semid,alter); | |
266 | - if(error) | |
267 | + if (error) | |
268 | goto out_free; | |
269 | + | |
270 | } | |
271 | } else | |
272 | un = NULL; | |
273 | @@ -930,16 +1043,18 @@ | |
274 | queue.sleeper = current; | |
275 | current->state = TASK_INTERRUPTIBLE; | |
276 | sem_unlock(semid); | |
277 | + unlock_semundo(); | |
278 | ||
279 | schedule(); | |
280 | ||
281 | + lock_semundo(); | |
282 | tmp = sem_lock(semid); | |
283 | if(tmp==NULL) { | |
284 | if(queue.prev != NULL) | |
285 | BUG(); | |
286 | current->semsleeping = NULL; | |
287 | error = -EIDRM; | |
288 | - goto out_free; | |
289 | + goto out_semundo_free; | |
290 | } | |
291 | /* | |
292 | * If queue.status == 1 we where woken up and | |
293 | @@ -960,7 +1075,7 @@ | |
294 | break; | |
295 | /* Everything done by update_queue */ | |
296 | current->semsleeping = NULL; | |
297 | - goto out_unlock_free; | |
298 | + goto out_unlock_semundo_free; | |
299 | } | |
300 | } | |
301 | current->semsleeping = NULL; | |
302 | @@ -968,14 +1083,61 @@ | |
303 | update: | |
304 | if (alter) | |
305 | update_queue (sma); | |
306 | -out_unlock_free: | |
307 | +out_unlock_semundo_free: | |
308 | sem_unlock(semid); | |
309 | +out_semundo_free: | |
310 | + unlock_semundo(); | |
311 | out_free: | |
312 | if(sops != fast_sops) | |
313 | kfree(sops); | |
314 | return error; | |
315 | } | |
316 | ||
317 | +/* For now, assume that if ALL clone flags are set, then | |
318 | + * we must be creating a POSIX thread, and we want undo lists | |
319 | + * to be shared among all the threads in that thread group. | |
320 | + * | |
321 | + * See the notes above unlock_semundo() regarding the spin_lock_init() | |
322 | + * in this code. Initialize the undohd->lock here instead of get_undohd() | |
323 | + * because of the reasoning in the note referenced here. | |
324 | + */ | |
325 | +#define CLONE_SEMUNDO (CLONE_VM|CLONE_FS|CLONE_FILES|CLONE_SIGHAND) | |
326 | + | |
327 | +int copy_semundo(unsigned long clone_flags, struct task_struct *tsk) | |
328 | +{ | |
329 | + struct sem_undohd *undohd; | |
330 | + int error; | |
331 | + | |
332 | + if (((clone_flags & CLONE_SEMUNDO) == CLONE_SEMUNDO) || | |
333 | + (clone_flags & CLONE_THREAD)) { | |
334 | + error = get_undohd(&undohd); | |
335 | + if (error) | |
336 | + return error; | |
337 | + if (atomic_read(&undohd->refcnt) == 1) | |
338 | + spin_lock_init(&undohd->lock); | |
339 | + atomic_inc(&undohd->refcnt); | |
340 | + tsk->semundohd = undohd; | |
341 | + } else | |
342 | + tsk->semundohd = NULL; | |
343 | + | |
344 | + return 0; | |
345 | +} | |
346 | + | |
347 | +static inline void __exit_semundo(struct task_struct *tsk) | |
348 | +{ | |
349 | + struct sem_undohd *unhd; | |
350 | + | |
351 | + unhd = tsk->semundohd; | |
352 | + if (!atomic_dec_and_test(&unhd->refcnt)) | |
353 | + kfree(unhd); | |
354 | +} | |
355 | + | |
356 | +void exit_semundo(struct task_struct *tsk) | |
357 | +{ | |
358 | + if (tsk->semundohd != NULL) | |
359 | + __exit_semundo(tsk); | |
360 | +} | |
361 | + | |
362 | /* | |
363 | * add semadj values to semaphores, free undo structures. | |
364 | * undo structures are not freed when semaphore arrays are destroyed | |
365 | @@ -993,6 +1155,7 @@ | |
366 | struct sem_queue *q; | |
367 | struct sem_undo *u, *un = NULL, **up, **unp; | |
368 | struct sem_array *sma; | |
369 | + struct sem_undohd *undohd; | |
370 | int nsems, i; | |
371 | ||
372 | /* If the current process was sleeping for a semaphore, | |
373 | @@ -1012,7 +1175,14 @@ | |
374 | sem_unlock(semid); | |
375 | } | |
376 | ||
377 | - for (up = ¤t->semundo; (u = *up); *up = u->proc_next, kfree(u)) { | |
378 | + undohd = current->semundohd; | |
379 | + if ((undohd == NULL) || (atomic_read(&undohd->refcnt) != 1)) | |
380 | + return; | |
381 | + | |
382 | + /* There's no need to hold the semundo list lock, as current | |
383 | + * is the last task exiting for this undo list. | |
384 | + */ | |
385 | + for (up = &undohd->proc_list; (u = *up); *up = u->proc_next, kfree(u)) { | |
386 | int semid = u->semid; | |
387 | if(semid == -1) | |
388 | continue; | |
389 | @@ -1050,7 +1220,7 @@ | |
390 | next_entry: | |
391 | sem_unlock(semid); | |
392 | } | |
393 | - current->semundo = NULL; | |
394 | + __exit_semundo(current); | |
395 | } | |
396 | ||
397 | #ifdef CONFIG_PROC_FS | |
398 | diff -urN --exclude-from=/usr/src/dontdiff linux-2.4.17_original/linux/ipc/util.c linux-2.4.17_SEMUNDO/linux/ipc/util.c | |
399 | --- linux-2.4.17_original/linux/ipc/util.c Sun Aug 12 17:37:53 2001 | |
400 | +++ linux-2.4.17_SEMUNDO/linux/ipc/util.c Mon Jan 21 19:08:05 2002 | |
401 | @@ -340,6 +340,17 @@ | |
402 | * Dummy functions when SYSV IPC isn't configured | |
403 | */ | |
404 | ||
405 | +int copy_semundo(unsigned long clone_flags, struct task_struct *tsk) | |
406 | +{ | |
407 | + return 0; | |
408 | +} | |
409 | + | |
410 | +void exit_semundo(struct task_struct *tsk) | |
411 | +{ | |
412 | + return; | |
413 | +} | |
414 | + | |
415 | + | |
416 | void sem_exit (void) | |
417 | { | |
418 | return; | |
419 | diff -urN --exclude-from=/usr/src/dontdiff linux-2.4.17_original/linux/kernel/fork.c linux-2.4.17_SEMUNDO/linux/kernel/fork.c | |
420 | --- linux-2.4.17_original/linux/kernel/fork.c Wed Nov 21 10:18:42 2001 | |
421 | +++ linux-2.4.17_SEMUNDO/linux/kernel/fork.c Mon Jan 21 19:08:05 2002 | |
422 | @@ -26,6 +26,9 @@ | |
423 | #include <asm/uaccess.h> | |
424 | #include <asm/mmu_context.h> | |
425 | ||
426 | +extern int copy_semundo(unsigned long clone_flags, struct task_struct *tsk); | |
427 | +extern void exit_semundo(struct task_struct *tsk); | |
428 | + | |
429 | /* The idle threads do not count.. */ | |
430 | int nr_threads; | |
431 | int nr_running; | |
432 | @@ -653,8 +656,10 @@ | |
433 | ||
434 | retval = -ENOMEM; | |
435 | /* copy all the process information */ | |
436 | - if (copy_files(clone_flags, p)) | |
437 | + if (copy_semundo(clone_flags, p)) | |
438 | goto bad_fork_cleanup; | |
439 | + if (copy_files(clone_flags, p)) | |
440 | + goto bad_fork_cleanup_semundo; | |
441 | if (copy_fs(clone_flags, p)) | |
442 | goto bad_fork_cleanup_files; | |
443 | if (copy_sighand(clone_flags, p)) | |
444 | @@ -664,7 +669,6 @@ | |
445 | retval = copy_thread(0, clone_flags, stack_start, stack_size, p, regs); | |
446 | if (retval) | |
447 | goto bad_fork_cleanup_mm; | |
448 | - p->semundo = NULL; | |
449 | ||
450 | /* Our parent execution domain becomes current domain | |
451 | These must match for thread signalling to apply */ | |
452 | @@ -738,6 +742,8 @@ | |
453 | exit_fs(p); /* blocking */ | |
454 | bad_fork_cleanup_files: | |
455 | exit_files(p); /* blocking */ | |
456 | +bad_fork_cleanup_semundo: | |
457 | + exit_semundo(p); | |
458 | bad_fork_cleanup: | |
459 | put_exec_domain(p->exec_domain); | |
460 | if (p->binfmt && p->binfmt->module) |