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1da177e4 LT |
1 | /* |
2 | * linux/kernel/fork.c | |
3 | * | |
4 | * Copyright (C) 1991, 1992 Linus Torvalds | |
5 | */ | |
6 | ||
7 | /* | |
8 | * 'fork.c' contains the help-routines for the 'fork' system call | |
9 | * (see also entry.S and others). | |
10 | * Fork is rather simple, once you get the hang of it, but the memory | |
11 | * management can be a bitch. See 'mm/memory.c': 'copy_page_range()' | |
12 | */ | |
13 | ||
14 | #include <linux/config.h> | |
15 | #include <linux/slab.h> | |
16 | #include <linux/init.h> | |
17 | #include <linux/unistd.h> | |
18 | #include <linux/smp_lock.h> | |
19 | #include <linux/module.h> | |
20 | #include <linux/vmalloc.h> | |
21 | #include <linux/completion.h> | |
22 | #include <linux/namespace.h> | |
23 | #include <linux/personality.h> | |
24 | #include <linux/mempolicy.h> | |
25 | #include <linux/sem.h> | |
26 | #include <linux/file.h> | |
27 | #include <linux/key.h> | |
28 | #include <linux/binfmts.h> | |
29 | #include <linux/mman.h> | |
30 | #include <linux/fs.h> | |
31 | #include <linux/cpu.h> | |
32 | #include <linux/cpuset.h> | |
33 | #include <linux/security.h> | |
34 | #include <linux/swap.h> | |
35 | #include <linux/syscalls.h> | |
36 | #include <linux/jiffies.h> | |
37 | #include <linux/futex.h> | |
38 | #include <linux/ptrace.h> | |
39 | #include <linux/mount.h> | |
40 | #include <linux/audit.h> | |
41 | #include <linux/profile.h> | |
42 | #include <linux/rmap.h> | |
43 | #include <linux/acct.h> | |
44 | ||
45 | #include <asm/pgtable.h> | |
46 | #include <asm/pgalloc.h> | |
47 | #include <asm/uaccess.h> | |
48 | #include <asm/mmu_context.h> | |
49 | #include <asm/cacheflush.h> | |
50 | #include <asm/tlbflush.h> | |
51 | ||
52 | /* | |
53 | * Protected counters by write_lock_irq(&tasklist_lock) | |
54 | */ | |
55 | unsigned long total_forks; /* Handle normal Linux uptimes. */ | |
56 | int nr_threads; /* The idle threads do not count.. */ | |
57 | ||
58 | int max_threads; /* tunable limit on nr_threads */ | |
59 | ||
60 | DEFINE_PER_CPU(unsigned long, process_counts) = 0; | |
61 | ||
62 | __cacheline_aligned DEFINE_RWLOCK(tasklist_lock); /* outer */ | |
63 | ||
64 | EXPORT_SYMBOL(tasklist_lock); | |
65 | ||
66 | int nr_processes(void) | |
67 | { | |
68 | int cpu; | |
69 | int total = 0; | |
70 | ||
71 | for_each_online_cpu(cpu) | |
72 | total += per_cpu(process_counts, cpu); | |
73 | ||
74 | return total; | |
75 | } | |
76 | ||
77 | #ifndef __HAVE_ARCH_TASK_STRUCT_ALLOCATOR | |
78 | # define alloc_task_struct() kmem_cache_alloc(task_struct_cachep, GFP_KERNEL) | |
79 | # define free_task_struct(tsk) kmem_cache_free(task_struct_cachep, (tsk)) | |
80 | static kmem_cache_t *task_struct_cachep; | |
81 | #endif | |
82 | ||
83 | /* SLAB cache for signal_struct structures (tsk->signal) */ | |
84 | kmem_cache_t *signal_cachep; | |
85 | ||
86 | /* SLAB cache for sighand_struct structures (tsk->sighand) */ | |
87 | kmem_cache_t *sighand_cachep; | |
88 | ||
89 | /* SLAB cache for files_struct structures (tsk->files) */ | |
90 | kmem_cache_t *files_cachep; | |
91 | ||
92 | /* SLAB cache for fs_struct structures (tsk->fs) */ | |
93 | kmem_cache_t *fs_cachep; | |
94 | ||
95 | /* SLAB cache for vm_area_struct structures */ | |
96 | kmem_cache_t *vm_area_cachep; | |
97 | ||
98 | /* SLAB cache for mm_struct structures (tsk->mm) */ | |
99 | static kmem_cache_t *mm_cachep; | |
100 | ||
101 | void free_task(struct task_struct *tsk) | |
102 | { | |
103 | free_thread_info(tsk->thread_info); | |
104 | free_task_struct(tsk); | |
105 | } | |
106 | EXPORT_SYMBOL(free_task); | |
107 | ||
108 | void __put_task_struct(struct task_struct *tsk) | |
109 | { | |
110 | WARN_ON(!(tsk->exit_state & (EXIT_DEAD | EXIT_ZOMBIE))); | |
111 | WARN_ON(atomic_read(&tsk->usage)); | |
112 | WARN_ON(tsk == current); | |
113 | ||
114 | if (unlikely(tsk->audit_context)) | |
115 | audit_free(tsk); | |
116 | security_task_free(tsk); | |
117 | free_uid(tsk->user); | |
118 | put_group_info(tsk->group_info); | |
119 | ||
120 | if (!profile_handoff_task(tsk)) | |
121 | free_task(tsk); | |
122 | } | |
123 | ||
124 | void __init fork_init(unsigned long mempages) | |
125 | { | |
126 | #ifndef __HAVE_ARCH_TASK_STRUCT_ALLOCATOR | |
127 | #ifndef ARCH_MIN_TASKALIGN | |
128 | #define ARCH_MIN_TASKALIGN L1_CACHE_BYTES | |
129 | #endif | |
130 | /* create a slab on which task_structs can be allocated */ | |
131 | task_struct_cachep = | |
132 | kmem_cache_create("task_struct", sizeof(struct task_struct), | |
133 | ARCH_MIN_TASKALIGN, SLAB_PANIC, NULL, NULL); | |
134 | #endif | |
135 | ||
136 | /* | |
137 | * The default maximum number of threads is set to a safe | |
138 | * value: the thread structures can take up at most half | |
139 | * of memory. | |
140 | */ | |
141 | max_threads = mempages / (8 * THREAD_SIZE / PAGE_SIZE); | |
142 | ||
143 | /* | |
144 | * we need to allow at least 20 threads to boot a system | |
145 | */ | |
146 | if(max_threads < 20) | |
147 | max_threads = 20; | |
148 | ||
149 | init_task.signal->rlim[RLIMIT_NPROC].rlim_cur = max_threads/2; | |
150 | init_task.signal->rlim[RLIMIT_NPROC].rlim_max = max_threads/2; | |
151 | init_task.signal->rlim[RLIMIT_SIGPENDING] = | |
152 | init_task.signal->rlim[RLIMIT_NPROC]; | |
153 | } | |
154 | ||
155 | static struct task_struct *dup_task_struct(struct task_struct *orig) | |
156 | { | |
157 | struct task_struct *tsk; | |
158 | struct thread_info *ti; | |
159 | ||
160 | prepare_to_copy(orig); | |
161 | ||
162 | tsk = alloc_task_struct(); | |
163 | if (!tsk) | |
164 | return NULL; | |
165 | ||
166 | ti = alloc_thread_info(tsk); | |
167 | if (!ti) { | |
168 | free_task_struct(tsk); | |
169 | return NULL; | |
170 | } | |
171 | ||
172 | *ti = *orig->thread_info; | |
173 | *tsk = *orig; | |
174 | tsk->thread_info = ti; | |
175 | ti->task = tsk; | |
176 | ||
177 | /* One for us, one for whoever does the "release_task()" (usually parent) */ | |
178 | atomic_set(&tsk->usage,2); | |
4b5d37ac | 179 | atomic_set(&tsk->fs_excl, 0); |
1da177e4 LT |
180 | return tsk; |
181 | } | |
182 | ||
183 | #ifdef CONFIG_MMU | |
184 | static inline int dup_mmap(struct mm_struct * mm, struct mm_struct * oldmm) | |
185 | { | |
186 | struct vm_area_struct * mpnt, *tmp, **pprev; | |
187 | struct rb_node **rb_link, *rb_parent; | |
188 | int retval; | |
189 | unsigned long charge; | |
190 | struct mempolicy *pol; | |
191 | ||
192 | down_write(&oldmm->mmap_sem); | |
193 | flush_cache_mm(current->mm); | |
194 | mm->locked_vm = 0; | |
195 | mm->mmap = NULL; | |
196 | mm->mmap_cache = NULL; | |
197 | mm->free_area_cache = oldmm->mmap_base; | |
1363c3cd | 198 | mm->cached_hole_size = ~0UL; |
1da177e4 LT |
199 | mm->map_count = 0; |
200 | set_mm_counter(mm, rss, 0); | |
201 | set_mm_counter(mm, anon_rss, 0); | |
202 | cpus_clear(mm->cpu_vm_mask); | |
203 | mm->mm_rb = RB_ROOT; | |
204 | rb_link = &mm->mm_rb.rb_node; | |
205 | rb_parent = NULL; | |
206 | pprev = &mm->mmap; | |
207 | ||
208 | for (mpnt = current->mm->mmap ; mpnt ; mpnt = mpnt->vm_next) { | |
209 | struct file *file; | |
210 | ||
211 | if (mpnt->vm_flags & VM_DONTCOPY) { | |
3b6bfcdb HD |
212 | long pages = vma_pages(mpnt); |
213 | mm->total_vm -= pages; | |
1da177e4 | 214 | __vm_stat_account(mm, mpnt->vm_flags, mpnt->vm_file, |
3b6bfcdb | 215 | -pages); |
1da177e4 LT |
216 | continue; |
217 | } | |
218 | charge = 0; | |
219 | if (mpnt->vm_flags & VM_ACCOUNT) { | |
220 | unsigned int len = (mpnt->vm_end - mpnt->vm_start) >> PAGE_SHIFT; | |
221 | if (security_vm_enough_memory(len)) | |
222 | goto fail_nomem; | |
223 | charge = len; | |
224 | } | |
225 | tmp = kmem_cache_alloc(vm_area_cachep, SLAB_KERNEL); | |
226 | if (!tmp) | |
227 | goto fail_nomem; | |
228 | *tmp = *mpnt; | |
229 | pol = mpol_copy(vma_policy(mpnt)); | |
230 | retval = PTR_ERR(pol); | |
231 | if (IS_ERR(pol)) | |
232 | goto fail_nomem_policy; | |
233 | vma_set_policy(tmp, pol); | |
234 | tmp->vm_flags &= ~VM_LOCKED; | |
235 | tmp->vm_mm = mm; | |
236 | tmp->vm_next = NULL; | |
237 | anon_vma_link(tmp); | |
238 | file = tmp->vm_file; | |
239 | if (file) { | |
240 | struct inode *inode = file->f_dentry->d_inode; | |
241 | get_file(file); | |
242 | if (tmp->vm_flags & VM_DENYWRITE) | |
243 | atomic_dec(&inode->i_writecount); | |
244 | ||
245 | /* insert tmp into the share list, just after mpnt */ | |
246 | spin_lock(&file->f_mapping->i_mmap_lock); | |
247 | tmp->vm_truncate_count = mpnt->vm_truncate_count; | |
248 | flush_dcache_mmap_lock(file->f_mapping); | |
249 | vma_prio_tree_add(tmp, mpnt); | |
250 | flush_dcache_mmap_unlock(file->f_mapping); | |
251 | spin_unlock(&file->f_mapping->i_mmap_lock); | |
252 | } | |
253 | ||
254 | /* | |
255 | * Link in the new vma and copy the page table entries: | |
45918e1a HD |
256 | * link in first so that swapoff can see swap entries. |
257 | * Note that, exceptionally, here the vma is inserted | |
258 | * without holding mm->mmap_sem. | |
1da177e4 LT |
259 | */ |
260 | spin_lock(&mm->page_table_lock); | |
261 | *pprev = tmp; | |
262 | pprev = &tmp->vm_next; | |
263 | ||
264 | __vma_link_rb(mm, tmp, rb_link, rb_parent); | |
265 | rb_link = &tmp->vm_rb.rb_right; | |
266 | rb_parent = &tmp->vm_rb; | |
267 | ||
268 | mm->map_count++; | |
269 | retval = copy_page_range(mm, current->mm, tmp); | |
270 | spin_unlock(&mm->page_table_lock); | |
271 | ||
272 | if (tmp->vm_ops && tmp->vm_ops->open) | |
273 | tmp->vm_ops->open(tmp); | |
274 | ||
275 | if (retval) | |
276 | goto out; | |
277 | } | |
278 | retval = 0; | |
279 | ||
280 | out: | |
281 | flush_tlb_mm(current->mm); | |
282 | up_write(&oldmm->mmap_sem); | |
283 | return retval; | |
284 | fail_nomem_policy: | |
285 | kmem_cache_free(vm_area_cachep, tmp); | |
286 | fail_nomem: | |
287 | retval = -ENOMEM; | |
288 | vm_unacct_memory(charge); | |
289 | goto out; | |
290 | } | |
291 | ||
292 | static inline int mm_alloc_pgd(struct mm_struct * mm) | |
293 | { | |
294 | mm->pgd = pgd_alloc(mm); | |
295 | if (unlikely(!mm->pgd)) | |
296 | return -ENOMEM; | |
297 | return 0; | |
298 | } | |
299 | ||
300 | static inline void mm_free_pgd(struct mm_struct * mm) | |
301 | { | |
302 | pgd_free(mm->pgd); | |
303 | } | |
304 | #else | |
305 | #define dup_mmap(mm, oldmm) (0) | |
306 | #define mm_alloc_pgd(mm) (0) | |
307 | #define mm_free_pgd(mm) | |
308 | #endif /* CONFIG_MMU */ | |
309 | ||
310 | __cacheline_aligned_in_smp DEFINE_SPINLOCK(mmlist_lock); | |
311 | ||
312 | #define allocate_mm() (kmem_cache_alloc(mm_cachep, SLAB_KERNEL)) | |
313 | #define free_mm(mm) (kmem_cache_free(mm_cachep, (mm))) | |
314 | ||
315 | #include <linux/init_task.h> | |
316 | ||
317 | static struct mm_struct * mm_init(struct mm_struct * mm) | |
318 | { | |
319 | atomic_set(&mm->mm_users, 1); | |
320 | atomic_set(&mm->mm_count, 1); | |
321 | init_rwsem(&mm->mmap_sem); | |
322 | INIT_LIST_HEAD(&mm->mmlist); | |
323 | mm->core_waiters = 0; | |
324 | mm->nr_ptes = 0; | |
325 | spin_lock_init(&mm->page_table_lock); | |
326 | rwlock_init(&mm->ioctx_list_lock); | |
327 | mm->ioctx_list = NULL; | |
328 | mm->default_kioctx = (struct kioctx)INIT_KIOCTX(mm->default_kioctx, *mm); | |
329 | mm->free_area_cache = TASK_UNMAPPED_BASE; | |
1363c3cd | 330 | mm->cached_hole_size = ~0UL; |
1da177e4 LT |
331 | |
332 | if (likely(!mm_alloc_pgd(mm))) { | |
333 | mm->def_flags = 0; | |
334 | return mm; | |
335 | } | |
336 | free_mm(mm); | |
337 | return NULL; | |
338 | } | |
339 | ||
340 | /* | |
341 | * Allocate and initialize an mm_struct. | |
342 | */ | |
343 | struct mm_struct * mm_alloc(void) | |
344 | { | |
345 | struct mm_struct * mm; | |
346 | ||
347 | mm = allocate_mm(); | |
348 | if (mm) { | |
349 | memset(mm, 0, sizeof(*mm)); | |
350 | mm = mm_init(mm); | |
351 | } | |
352 | return mm; | |
353 | } | |
354 | ||
355 | /* | |
356 | * Called when the last reference to the mm | |
357 | * is dropped: either by a lazy thread or by | |
358 | * mmput. Free the page directory and the mm. | |
359 | */ | |
360 | void fastcall __mmdrop(struct mm_struct *mm) | |
361 | { | |
362 | BUG_ON(mm == &init_mm); | |
363 | mm_free_pgd(mm); | |
364 | destroy_context(mm); | |
365 | free_mm(mm); | |
366 | } | |
367 | ||
368 | /* | |
369 | * Decrement the use count and release all resources for an mm. | |
370 | */ | |
371 | void mmput(struct mm_struct *mm) | |
372 | { | |
373 | if (atomic_dec_and_test(&mm->mm_users)) { | |
374 | exit_aio(mm); | |
375 | exit_mmap(mm); | |
376 | if (!list_empty(&mm->mmlist)) { | |
377 | spin_lock(&mmlist_lock); | |
378 | list_del(&mm->mmlist); | |
379 | spin_unlock(&mmlist_lock); | |
380 | } | |
381 | put_swap_token(mm); | |
382 | mmdrop(mm); | |
383 | } | |
384 | } | |
385 | EXPORT_SYMBOL_GPL(mmput); | |
386 | ||
387 | /** | |
388 | * get_task_mm - acquire a reference to the task's mm | |
389 | * | |
390 | * Returns %NULL if the task has no mm. Checks PF_BORROWED_MM (meaning | |
391 | * this kernel workthread has transiently adopted a user mm with use_mm, | |
392 | * to do its AIO) is not set and if so returns a reference to it, after | |
393 | * bumping up the use count. User must release the mm via mmput() | |
394 | * after use. Typically used by /proc and ptrace. | |
395 | */ | |
396 | struct mm_struct *get_task_mm(struct task_struct *task) | |
397 | { | |
398 | struct mm_struct *mm; | |
399 | ||
400 | task_lock(task); | |
401 | mm = task->mm; | |
402 | if (mm) { | |
403 | if (task->flags & PF_BORROWED_MM) | |
404 | mm = NULL; | |
405 | else | |
406 | atomic_inc(&mm->mm_users); | |
407 | } | |
408 | task_unlock(task); | |
409 | return mm; | |
410 | } | |
411 | EXPORT_SYMBOL_GPL(get_task_mm); | |
412 | ||
413 | /* Please note the differences between mmput and mm_release. | |
414 | * mmput is called whenever we stop holding onto a mm_struct, | |
415 | * error success whatever. | |
416 | * | |
417 | * mm_release is called after a mm_struct has been removed | |
418 | * from the current process. | |
419 | * | |
420 | * This difference is important for error handling, when we | |
421 | * only half set up a mm_struct for a new process and need to restore | |
422 | * the old one. Because we mmput the new mm_struct before | |
423 | * restoring the old one. . . | |
424 | * Eric Biederman 10 January 1998 | |
425 | */ | |
426 | void mm_release(struct task_struct *tsk, struct mm_struct *mm) | |
427 | { | |
428 | struct completion *vfork_done = tsk->vfork_done; | |
429 | ||
430 | /* Get rid of any cached register state */ | |
431 | deactivate_mm(tsk, mm); | |
432 | ||
433 | /* notify parent sleeping on vfork() */ | |
434 | if (vfork_done) { | |
435 | tsk->vfork_done = NULL; | |
436 | complete(vfork_done); | |
437 | } | |
438 | if (tsk->clear_child_tid && atomic_read(&mm->mm_users) > 1) { | |
439 | u32 __user * tidptr = tsk->clear_child_tid; | |
440 | tsk->clear_child_tid = NULL; | |
441 | ||
442 | /* | |
443 | * We don't check the error code - if userspace has | |
444 | * not set up a proper pointer then tough luck. | |
445 | */ | |
446 | put_user(0, tidptr); | |
447 | sys_futex(tidptr, FUTEX_WAKE, 1, NULL, NULL, 0); | |
448 | } | |
449 | } | |
450 | ||
451 | static int copy_mm(unsigned long clone_flags, struct task_struct * tsk) | |
452 | { | |
453 | struct mm_struct * mm, *oldmm; | |
454 | int retval; | |
455 | ||
456 | tsk->min_flt = tsk->maj_flt = 0; | |
457 | tsk->nvcsw = tsk->nivcsw = 0; | |
458 | ||
459 | tsk->mm = NULL; | |
460 | tsk->active_mm = NULL; | |
461 | ||
462 | /* | |
463 | * Are we cloning a kernel thread? | |
464 | * | |
465 | * We need to steal a active VM for that.. | |
466 | */ | |
467 | oldmm = current->mm; | |
468 | if (!oldmm) | |
469 | return 0; | |
470 | ||
471 | if (clone_flags & CLONE_VM) { | |
472 | atomic_inc(&oldmm->mm_users); | |
473 | mm = oldmm; | |
474 | /* | |
475 | * There are cases where the PTL is held to ensure no | |
476 | * new threads start up in user mode using an mm, which | |
477 | * allows optimizing out ipis; the tlb_gather_mmu code | |
478 | * is an example. | |
479 | */ | |
480 | spin_unlock_wait(&oldmm->page_table_lock); | |
481 | goto good_mm; | |
482 | } | |
483 | ||
484 | retval = -ENOMEM; | |
485 | mm = allocate_mm(); | |
486 | if (!mm) | |
487 | goto fail_nomem; | |
488 | ||
489 | /* Copy the current MM stuff.. */ | |
490 | memcpy(mm, oldmm, sizeof(*mm)); | |
491 | if (!mm_init(mm)) | |
492 | goto fail_nomem; | |
493 | ||
494 | if (init_new_context(tsk,mm)) | |
495 | goto fail_nocontext; | |
496 | ||
497 | retval = dup_mmap(mm, oldmm); | |
498 | if (retval) | |
499 | goto free_pt; | |
500 | ||
501 | mm->hiwater_rss = get_mm_counter(mm,rss); | |
502 | mm->hiwater_vm = mm->total_vm; | |
503 | ||
504 | good_mm: | |
505 | tsk->mm = mm; | |
506 | tsk->active_mm = mm; | |
507 | return 0; | |
508 | ||
509 | free_pt: | |
510 | mmput(mm); | |
511 | fail_nomem: | |
512 | return retval; | |
513 | ||
514 | fail_nocontext: | |
515 | /* | |
516 | * If init_new_context() failed, we cannot use mmput() to free the mm | |
517 | * because it calls destroy_context() | |
518 | */ | |
519 | mm_free_pgd(mm); | |
520 | free_mm(mm); | |
521 | return retval; | |
522 | } | |
523 | ||
524 | static inline struct fs_struct *__copy_fs_struct(struct fs_struct *old) | |
525 | { | |
526 | struct fs_struct *fs = kmem_cache_alloc(fs_cachep, GFP_KERNEL); | |
527 | /* We don't need to lock fs - think why ;-) */ | |
528 | if (fs) { | |
529 | atomic_set(&fs->count, 1); | |
530 | rwlock_init(&fs->lock); | |
531 | fs->umask = old->umask; | |
532 | read_lock(&old->lock); | |
533 | fs->rootmnt = mntget(old->rootmnt); | |
534 | fs->root = dget(old->root); | |
535 | fs->pwdmnt = mntget(old->pwdmnt); | |
536 | fs->pwd = dget(old->pwd); | |
537 | if (old->altroot) { | |
538 | fs->altrootmnt = mntget(old->altrootmnt); | |
539 | fs->altroot = dget(old->altroot); | |
540 | } else { | |
541 | fs->altrootmnt = NULL; | |
542 | fs->altroot = NULL; | |
543 | } | |
544 | read_unlock(&old->lock); | |
545 | } | |
546 | return fs; | |
547 | } | |
548 | ||
549 | struct fs_struct *copy_fs_struct(struct fs_struct *old) | |
550 | { | |
551 | return __copy_fs_struct(old); | |
552 | } | |
553 | ||
554 | EXPORT_SYMBOL_GPL(copy_fs_struct); | |
555 | ||
556 | static inline int copy_fs(unsigned long clone_flags, struct task_struct * tsk) | |
557 | { | |
558 | if (clone_flags & CLONE_FS) { | |
559 | atomic_inc(¤t->fs->count); | |
560 | return 0; | |
561 | } | |
562 | tsk->fs = __copy_fs_struct(current->fs); | |
563 | if (!tsk->fs) | |
564 | return -ENOMEM; | |
565 | return 0; | |
566 | } | |
567 | ||
568 | static int count_open_files(struct files_struct *files, int size) | |
569 | { | |
570 | int i; | |
571 | ||
572 | /* Find the last open fd */ | |
573 | for (i = size/(8*sizeof(long)); i > 0; ) { | |
574 | if (files->open_fds->fds_bits[--i]) | |
575 | break; | |
576 | } | |
577 | i = (i+1) * 8 * sizeof(long); | |
578 | return i; | |
579 | } | |
580 | ||
581 | static int copy_files(unsigned long clone_flags, struct task_struct * tsk) | |
582 | { | |
583 | struct files_struct *oldf, *newf; | |
584 | struct file **old_fds, **new_fds; | |
585 | int open_files, size, i, error = 0, expand; | |
586 | ||
587 | /* | |
588 | * A background process may not have any files ... | |
589 | */ | |
590 | oldf = current->files; | |
591 | if (!oldf) | |
592 | goto out; | |
593 | ||
594 | if (clone_flags & CLONE_FILES) { | |
595 | atomic_inc(&oldf->count); | |
596 | goto out; | |
597 | } | |
598 | ||
599 | /* | |
600 | * Note: we may be using current for both targets (See exec.c) | |
601 | * This works because we cache current->files (old) as oldf. Don't | |
602 | * break this. | |
603 | */ | |
604 | tsk->files = NULL; | |
605 | error = -ENOMEM; | |
606 | newf = kmem_cache_alloc(files_cachep, SLAB_KERNEL); | |
607 | if (!newf) | |
608 | goto out; | |
609 | ||
610 | atomic_set(&newf->count, 1); | |
611 | ||
612 | spin_lock_init(&newf->file_lock); | |
613 | newf->next_fd = 0; | |
614 | newf->max_fds = NR_OPEN_DEFAULT; | |
615 | newf->max_fdset = __FD_SETSIZE; | |
616 | newf->close_on_exec = &newf->close_on_exec_init; | |
617 | newf->open_fds = &newf->open_fds_init; | |
618 | newf->fd = &newf->fd_array[0]; | |
619 | ||
620 | spin_lock(&oldf->file_lock); | |
621 | ||
622 | open_files = count_open_files(oldf, oldf->max_fdset); | |
623 | expand = 0; | |
624 | ||
625 | /* | |
626 | * Check whether we need to allocate a larger fd array or fd set. | |
627 | * Note: we're not a clone task, so the open count won't change. | |
628 | */ | |
629 | if (open_files > newf->max_fdset) { | |
630 | newf->max_fdset = 0; | |
631 | expand = 1; | |
632 | } | |
633 | if (open_files > newf->max_fds) { | |
634 | newf->max_fds = 0; | |
635 | expand = 1; | |
636 | } | |
637 | ||
638 | /* if the old fdset gets grown now, we'll only copy up to "size" fds */ | |
639 | if (expand) { | |
640 | spin_unlock(&oldf->file_lock); | |
641 | spin_lock(&newf->file_lock); | |
642 | error = expand_files(newf, open_files-1); | |
643 | spin_unlock(&newf->file_lock); | |
644 | if (error < 0) | |
645 | goto out_release; | |
646 | spin_lock(&oldf->file_lock); | |
647 | } | |
648 | ||
649 | old_fds = oldf->fd; | |
650 | new_fds = newf->fd; | |
651 | ||
652 | memcpy(newf->open_fds->fds_bits, oldf->open_fds->fds_bits, open_files/8); | |
653 | memcpy(newf->close_on_exec->fds_bits, oldf->close_on_exec->fds_bits, open_files/8); | |
654 | ||
655 | for (i = open_files; i != 0; i--) { | |
656 | struct file *f = *old_fds++; | |
657 | if (f) { | |
658 | get_file(f); | |
659 | } else { | |
660 | /* | |
661 | * The fd may be claimed in the fd bitmap but not yet | |
662 | * instantiated in the files array if a sibling thread | |
663 | * is partway through open(). So make sure that this | |
664 | * fd is available to the new process. | |
665 | */ | |
666 | FD_CLR(open_files - i, newf->open_fds); | |
667 | } | |
668 | *new_fds++ = f; | |
669 | } | |
670 | spin_unlock(&oldf->file_lock); | |
671 | ||
672 | /* compute the remainder to be cleared */ | |
673 | size = (newf->max_fds - open_files) * sizeof(struct file *); | |
674 | ||
675 | /* This is long word aligned thus could use a optimized version */ | |
676 | memset(new_fds, 0, size); | |
677 | ||
678 | if (newf->max_fdset > open_files) { | |
679 | int left = (newf->max_fdset-open_files)/8; | |
680 | int start = open_files / (8 * sizeof(unsigned long)); | |
681 | ||
682 | memset(&newf->open_fds->fds_bits[start], 0, left); | |
683 | memset(&newf->close_on_exec->fds_bits[start], 0, left); | |
684 | } | |
685 | ||
686 | tsk->files = newf; | |
687 | error = 0; | |
688 | out: | |
689 | return error; | |
690 | ||
691 | out_release: | |
692 | free_fdset (newf->close_on_exec, newf->max_fdset); | |
693 | free_fdset (newf->open_fds, newf->max_fdset); | |
694 | free_fd_array(newf->fd, newf->max_fds); | |
695 | kmem_cache_free(files_cachep, newf); | |
696 | goto out; | |
697 | } | |
698 | ||
699 | /* | |
700 | * Helper to unshare the files of the current task. | |
701 | * We don't want to expose copy_files internals to | |
702 | * the exec layer of the kernel. | |
703 | */ | |
704 | ||
705 | int unshare_files(void) | |
706 | { | |
707 | struct files_struct *files = current->files; | |
708 | int rc; | |
709 | ||
710 | if(!files) | |
711 | BUG(); | |
712 | ||
713 | /* This can race but the race causes us to copy when we don't | |
714 | need to and drop the copy */ | |
715 | if(atomic_read(&files->count) == 1) | |
716 | { | |
717 | atomic_inc(&files->count); | |
718 | return 0; | |
719 | } | |
720 | rc = copy_files(0, current); | |
721 | if(rc) | |
722 | current->files = files; | |
723 | return rc; | |
724 | } | |
725 | ||
726 | EXPORT_SYMBOL(unshare_files); | |
727 | ||
728 | static inline int copy_sighand(unsigned long clone_flags, struct task_struct * tsk) | |
729 | { | |
730 | struct sighand_struct *sig; | |
731 | ||
732 | if (clone_flags & (CLONE_SIGHAND | CLONE_THREAD)) { | |
733 | atomic_inc(¤t->sighand->count); | |
734 | return 0; | |
735 | } | |
736 | sig = kmem_cache_alloc(sighand_cachep, GFP_KERNEL); | |
737 | tsk->sighand = sig; | |
738 | if (!sig) | |
739 | return -ENOMEM; | |
740 | spin_lock_init(&sig->siglock); | |
741 | atomic_set(&sig->count, 1); | |
742 | memcpy(sig->action, current->sighand->action, sizeof(sig->action)); | |
743 | return 0; | |
744 | } | |
745 | ||
746 | static inline int copy_signal(unsigned long clone_flags, struct task_struct * tsk) | |
747 | { | |
748 | struct signal_struct *sig; | |
749 | int ret; | |
750 | ||
751 | if (clone_flags & CLONE_THREAD) { | |
752 | atomic_inc(¤t->signal->count); | |
753 | atomic_inc(¤t->signal->live); | |
754 | return 0; | |
755 | } | |
756 | sig = kmem_cache_alloc(signal_cachep, GFP_KERNEL); | |
757 | tsk->signal = sig; | |
758 | if (!sig) | |
759 | return -ENOMEM; | |
760 | ||
761 | ret = copy_thread_group_keys(tsk); | |
762 | if (ret < 0) { | |
763 | kmem_cache_free(signal_cachep, sig); | |
764 | return ret; | |
765 | } | |
766 | ||
767 | atomic_set(&sig->count, 1); | |
768 | atomic_set(&sig->live, 1); | |
769 | init_waitqueue_head(&sig->wait_chldexit); | |
770 | sig->flags = 0; | |
771 | sig->group_exit_code = 0; | |
772 | sig->group_exit_task = NULL; | |
773 | sig->group_stop_count = 0; | |
774 | sig->curr_target = NULL; | |
775 | init_sigpending(&sig->shared_pending); | |
776 | INIT_LIST_HEAD(&sig->posix_timers); | |
777 | ||
778 | sig->it_real_value = sig->it_real_incr = 0; | |
779 | sig->real_timer.function = it_real_fn; | |
780 | sig->real_timer.data = (unsigned long) tsk; | |
781 | init_timer(&sig->real_timer); | |
782 | ||
783 | sig->it_virt_expires = cputime_zero; | |
784 | sig->it_virt_incr = cputime_zero; | |
785 | sig->it_prof_expires = cputime_zero; | |
786 | sig->it_prof_incr = cputime_zero; | |
787 | ||
788 | sig->tty = current->signal->tty; | |
789 | sig->pgrp = process_group(current); | |
790 | sig->session = current->signal->session; | |
791 | sig->leader = 0; /* session leadership doesn't inherit */ | |
792 | sig->tty_old_pgrp = 0; | |
793 | ||
794 | sig->utime = sig->stime = sig->cutime = sig->cstime = cputime_zero; | |
795 | sig->nvcsw = sig->nivcsw = sig->cnvcsw = sig->cnivcsw = 0; | |
796 | sig->min_flt = sig->maj_flt = sig->cmin_flt = sig->cmaj_flt = 0; | |
797 | sig->sched_time = 0; | |
798 | INIT_LIST_HEAD(&sig->cpu_timers[0]); | |
799 | INIT_LIST_HEAD(&sig->cpu_timers[1]); | |
800 | INIT_LIST_HEAD(&sig->cpu_timers[2]); | |
801 | ||
802 | task_lock(current->group_leader); | |
803 | memcpy(sig->rlim, current->signal->rlim, sizeof sig->rlim); | |
804 | task_unlock(current->group_leader); | |
805 | ||
806 | if (sig->rlim[RLIMIT_CPU].rlim_cur != RLIM_INFINITY) { | |
807 | /* | |
808 | * New sole thread in the process gets an expiry time | |
809 | * of the whole CPU time limit. | |
810 | */ | |
811 | tsk->it_prof_expires = | |
812 | secs_to_cputime(sig->rlim[RLIMIT_CPU].rlim_cur); | |
813 | } | |
814 | ||
815 | return 0; | |
816 | } | |
817 | ||
818 | static inline void copy_flags(unsigned long clone_flags, struct task_struct *p) | |
819 | { | |
820 | unsigned long new_flags = p->flags; | |
821 | ||
822 | new_flags &= ~PF_SUPERPRIV; | |
823 | new_flags |= PF_FORKNOEXEC; | |
824 | if (!(clone_flags & CLONE_PTRACE)) | |
825 | p->ptrace = 0; | |
826 | p->flags = new_flags; | |
827 | } | |
828 | ||
829 | asmlinkage long sys_set_tid_address(int __user *tidptr) | |
830 | { | |
831 | current->clear_child_tid = tidptr; | |
832 | ||
833 | return current->pid; | |
834 | } | |
835 | ||
836 | /* | |
837 | * This creates a new process as a copy of the old one, | |
838 | * but does not actually start it yet. | |
839 | * | |
840 | * It copies the registers, and all the appropriate | |
841 | * parts of the process environment (as per the clone | |
842 | * flags). The actual kick-off is left to the caller. | |
843 | */ | |
844 | static task_t *copy_process(unsigned long clone_flags, | |
845 | unsigned long stack_start, | |
846 | struct pt_regs *regs, | |
847 | unsigned long stack_size, | |
848 | int __user *parent_tidptr, | |
849 | int __user *child_tidptr, | |
850 | int pid) | |
851 | { | |
852 | int retval; | |
853 | struct task_struct *p = NULL; | |
854 | ||
855 | if ((clone_flags & (CLONE_NEWNS|CLONE_FS)) == (CLONE_NEWNS|CLONE_FS)) | |
856 | return ERR_PTR(-EINVAL); | |
857 | ||
858 | /* | |
859 | * Thread groups must share signals as well, and detached threads | |
860 | * can only be started up within the thread group. | |
861 | */ | |
862 | if ((clone_flags & CLONE_THREAD) && !(clone_flags & CLONE_SIGHAND)) | |
863 | return ERR_PTR(-EINVAL); | |
864 | ||
865 | /* | |
866 | * Shared signal handlers imply shared VM. By way of the above, | |
867 | * thread groups also imply shared VM. Blocking this case allows | |
868 | * for various simplifications in other code. | |
869 | */ | |
870 | if ((clone_flags & CLONE_SIGHAND) && !(clone_flags & CLONE_VM)) | |
871 | return ERR_PTR(-EINVAL); | |
872 | ||
873 | retval = security_task_create(clone_flags); | |
874 | if (retval) | |
875 | goto fork_out; | |
876 | ||
877 | retval = -ENOMEM; | |
878 | p = dup_task_struct(current); | |
879 | if (!p) | |
880 | goto fork_out; | |
881 | ||
882 | retval = -EAGAIN; | |
883 | if (atomic_read(&p->user->processes) >= | |
884 | p->signal->rlim[RLIMIT_NPROC].rlim_cur) { | |
885 | if (!capable(CAP_SYS_ADMIN) && !capable(CAP_SYS_RESOURCE) && | |
886 | p->user != &root_user) | |
887 | goto bad_fork_free; | |
888 | } | |
889 | ||
890 | atomic_inc(&p->user->__count); | |
891 | atomic_inc(&p->user->processes); | |
892 | get_group_info(p->group_info); | |
893 | ||
894 | /* | |
895 | * If multiple threads are within copy_process(), then this check | |
896 | * triggers too late. This doesn't hurt, the check is only there | |
897 | * to stop root fork bombs. | |
898 | */ | |
899 | if (nr_threads >= max_threads) | |
900 | goto bad_fork_cleanup_count; | |
901 | ||
902 | if (!try_module_get(p->thread_info->exec_domain->module)) | |
903 | goto bad_fork_cleanup_count; | |
904 | ||
905 | if (p->binfmt && !try_module_get(p->binfmt->module)) | |
906 | goto bad_fork_cleanup_put_domain; | |
907 | ||
908 | p->did_exec = 0; | |
909 | copy_flags(clone_flags, p); | |
910 | p->pid = pid; | |
911 | retval = -EFAULT; | |
912 | if (clone_flags & CLONE_PARENT_SETTID) | |
913 | if (put_user(p->pid, parent_tidptr)) | |
914 | goto bad_fork_cleanup; | |
915 | ||
916 | p->proc_dentry = NULL; | |
917 | ||
918 | INIT_LIST_HEAD(&p->children); | |
919 | INIT_LIST_HEAD(&p->sibling); | |
920 | p->vfork_done = NULL; | |
921 | spin_lock_init(&p->alloc_lock); | |
922 | spin_lock_init(&p->proc_lock); | |
923 | ||
924 | clear_tsk_thread_flag(p, TIF_SIGPENDING); | |
925 | init_sigpending(&p->pending); | |
926 | ||
927 | p->utime = cputime_zero; | |
928 | p->stime = cputime_zero; | |
929 | p->sched_time = 0; | |
930 | p->rchar = 0; /* I/O counter: bytes read */ | |
931 | p->wchar = 0; /* I/O counter: bytes written */ | |
932 | p->syscr = 0; /* I/O counter: read syscalls */ | |
933 | p->syscw = 0; /* I/O counter: write syscalls */ | |
934 | acct_clear_integrals(p); | |
935 | ||
936 | p->it_virt_expires = cputime_zero; | |
937 | p->it_prof_expires = cputime_zero; | |
938 | p->it_sched_expires = 0; | |
939 | INIT_LIST_HEAD(&p->cpu_timers[0]); | |
940 | INIT_LIST_HEAD(&p->cpu_timers[1]); | |
941 | INIT_LIST_HEAD(&p->cpu_timers[2]); | |
942 | ||
943 | p->lock_depth = -1; /* -1 = no lock */ | |
944 | do_posix_clock_monotonic_gettime(&p->start_time); | |
945 | p->security = NULL; | |
946 | p->io_context = NULL; | |
947 | p->io_wait = NULL; | |
948 | p->audit_context = NULL; | |
949 | #ifdef CONFIG_NUMA | |
950 | p->mempolicy = mpol_copy(p->mempolicy); | |
951 | if (IS_ERR(p->mempolicy)) { | |
952 | retval = PTR_ERR(p->mempolicy); | |
953 | p->mempolicy = NULL; | |
954 | goto bad_fork_cleanup; | |
955 | } | |
956 | #endif | |
957 | ||
958 | p->tgid = p->pid; | |
959 | if (clone_flags & CLONE_THREAD) | |
960 | p->tgid = current->tgid; | |
961 | ||
962 | if ((retval = security_task_alloc(p))) | |
963 | goto bad_fork_cleanup_policy; | |
964 | if ((retval = audit_alloc(p))) | |
965 | goto bad_fork_cleanup_security; | |
966 | /* copy all the process information */ | |
967 | if ((retval = copy_semundo(clone_flags, p))) | |
968 | goto bad_fork_cleanup_audit; | |
969 | if ((retval = copy_files(clone_flags, p))) | |
970 | goto bad_fork_cleanup_semundo; | |
971 | if ((retval = copy_fs(clone_flags, p))) | |
972 | goto bad_fork_cleanup_files; | |
973 | if ((retval = copy_sighand(clone_flags, p))) | |
974 | goto bad_fork_cleanup_fs; | |
975 | if ((retval = copy_signal(clone_flags, p))) | |
976 | goto bad_fork_cleanup_sighand; | |
977 | if ((retval = copy_mm(clone_flags, p))) | |
978 | goto bad_fork_cleanup_signal; | |
979 | if ((retval = copy_keys(clone_flags, p))) | |
980 | goto bad_fork_cleanup_mm; | |
981 | if ((retval = copy_namespace(clone_flags, p))) | |
982 | goto bad_fork_cleanup_keys; | |
983 | retval = copy_thread(0, clone_flags, stack_start, stack_size, p, regs); | |
984 | if (retval) | |
985 | goto bad_fork_cleanup_namespace; | |
986 | ||
987 | p->set_child_tid = (clone_flags & CLONE_CHILD_SETTID) ? child_tidptr : NULL; | |
988 | /* | |
989 | * Clear TID on mm_release()? | |
990 | */ | |
991 | p->clear_child_tid = (clone_flags & CLONE_CHILD_CLEARTID) ? child_tidptr: NULL; | |
992 | ||
993 | /* | |
994 | * Syscall tracing should be turned off in the child regardless | |
995 | * of CLONE_PTRACE. | |
996 | */ | |
997 | clear_tsk_thread_flag(p, TIF_SYSCALL_TRACE); | |
ed75e8d5 LV |
998 | #ifdef TIF_SYSCALL_EMU |
999 | clear_tsk_thread_flag(p, TIF_SYSCALL_EMU); | |
1000 | #endif | |
1da177e4 LT |
1001 | |
1002 | /* Our parent execution domain becomes current domain | |
1003 | These must match for thread signalling to apply */ | |
1004 | ||
1005 | p->parent_exec_id = p->self_exec_id; | |
1006 | ||
1007 | /* ok, now we should be set up.. */ | |
1008 | p->exit_signal = (clone_flags & CLONE_THREAD) ? -1 : (clone_flags & CSIGNAL); | |
1009 | p->pdeath_signal = 0; | |
1010 | p->exit_state = 0; | |
1011 | ||
1da177e4 LT |
1012 | /* |
1013 | * Ok, make it visible to the rest of the system. | |
1014 | * We dont wake it up yet. | |
1015 | */ | |
1016 | p->group_leader = p; | |
1017 | INIT_LIST_HEAD(&p->ptrace_children); | |
1018 | INIT_LIST_HEAD(&p->ptrace_list); | |
1019 | ||
476d139c NP |
1020 | /* Perform scheduler related setup. Assign this task to a CPU. */ |
1021 | sched_fork(p, clone_flags); | |
1022 | ||
1da177e4 LT |
1023 | /* Need tasklist lock for parent etc handling! */ |
1024 | write_lock_irq(&tasklist_lock); | |
1025 | ||
1026 | /* | |
476d139c NP |
1027 | * The task hasn't been attached yet, so its cpus_allowed mask will |
1028 | * not be changed, nor will its assigned CPU. | |
1029 | * | |
1030 | * The cpus_allowed mask of the parent may have changed after it was | |
1031 | * copied first time - so re-copy it here, then check the child's CPU | |
1032 | * to ensure it is on a valid CPU (and if not, just force it back to | |
1033 | * parent's CPU). This avoids alot of nasty races. | |
1da177e4 LT |
1034 | */ |
1035 | p->cpus_allowed = current->cpus_allowed; | |
476d139c NP |
1036 | if (unlikely(!cpu_isset(task_cpu(p), p->cpus_allowed))) |
1037 | set_task_cpu(p, smp_processor_id()); | |
1da177e4 LT |
1038 | |
1039 | /* | |
1040 | * Check for pending SIGKILL! The new thread should not be allowed | |
1041 | * to slip out of an OOM kill. (or normal SIGKILL.) | |
1042 | */ | |
1043 | if (sigismember(¤t->pending.signal, SIGKILL)) { | |
1044 | write_unlock_irq(&tasklist_lock); | |
1045 | retval = -EINTR; | |
1046 | goto bad_fork_cleanup_namespace; | |
1047 | } | |
1048 | ||
1049 | /* CLONE_PARENT re-uses the old parent */ | |
1050 | if (clone_flags & (CLONE_PARENT|CLONE_THREAD)) | |
1051 | p->real_parent = current->real_parent; | |
1052 | else | |
1053 | p->real_parent = current; | |
1054 | p->parent = p->real_parent; | |
1055 | ||
1056 | if (clone_flags & CLONE_THREAD) { | |
1057 | spin_lock(¤t->sighand->siglock); | |
1058 | /* | |
1059 | * Important: if an exit-all has been started then | |
1060 | * do not create this new thread - the whole thread | |
1061 | * group is supposed to exit anyway. | |
1062 | */ | |
1063 | if (current->signal->flags & SIGNAL_GROUP_EXIT) { | |
1064 | spin_unlock(¤t->sighand->siglock); | |
1065 | write_unlock_irq(&tasklist_lock); | |
1066 | retval = -EAGAIN; | |
1067 | goto bad_fork_cleanup_namespace; | |
1068 | } | |
1069 | p->group_leader = current->group_leader; | |
1070 | ||
1071 | if (current->signal->group_stop_count > 0) { | |
1072 | /* | |
1073 | * There is an all-stop in progress for the group. | |
1074 | * We ourselves will stop as soon as we check signals. | |
1075 | * Make the new thread part of that group stop too. | |
1076 | */ | |
1077 | current->signal->group_stop_count++; | |
1078 | set_tsk_thread_flag(p, TIF_SIGPENDING); | |
1079 | } | |
1080 | ||
1081 | if (!cputime_eq(current->signal->it_virt_expires, | |
1082 | cputime_zero) || | |
1083 | !cputime_eq(current->signal->it_prof_expires, | |
1084 | cputime_zero) || | |
1085 | current->signal->rlim[RLIMIT_CPU].rlim_cur != RLIM_INFINITY || | |
1086 | !list_empty(¤t->signal->cpu_timers[0]) || | |
1087 | !list_empty(¤t->signal->cpu_timers[1]) || | |
1088 | !list_empty(¤t->signal->cpu_timers[2])) { | |
1089 | /* | |
1090 | * Have child wake up on its first tick to check | |
1091 | * for process CPU timers. | |
1092 | */ | |
1093 | p->it_prof_expires = jiffies_to_cputime(1); | |
1094 | } | |
1095 | ||
1096 | spin_unlock(¤t->sighand->siglock); | |
1097 | } | |
1098 | ||
22e2c507 JA |
1099 | /* |
1100 | * inherit ioprio | |
1101 | */ | |
1102 | p->ioprio = current->ioprio; | |
1103 | ||
1da177e4 LT |
1104 | SET_LINKS(p); |
1105 | if (unlikely(p->ptrace & PT_PTRACED)) | |
1106 | __ptrace_link(p, current->parent); | |
1107 | ||
1108 | cpuset_fork(p); | |
1109 | ||
1110 | attach_pid(p, PIDTYPE_PID, p->pid); | |
1111 | attach_pid(p, PIDTYPE_TGID, p->tgid); | |
1112 | if (thread_group_leader(p)) { | |
1113 | attach_pid(p, PIDTYPE_PGID, process_group(p)); | |
1114 | attach_pid(p, PIDTYPE_SID, p->signal->session); | |
1115 | if (p->pid) | |
1116 | __get_cpu_var(process_counts)++; | |
1117 | } | |
1118 | ||
b0d62e6d JB |
1119 | if (!current->signal->tty && p->signal->tty) |
1120 | p->signal->tty = NULL; | |
1121 | ||
1da177e4 LT |
1122 | nr_threads++; |
1123 | total_forks++; | |
1124 | write_unlock_irq(&tasklist_lock); | |
1125 | retval = 0; | |
1126 | ||
1127 | fork_out: | |
1128 | if (retval) | |
1129 | return ERR_PTR(retval); | |
1130 | return p; | |
1131 | ||
1132 | bad_fork_cleanup_namespace: | |
1133 | exit_namespace(p); | |
1134 | bad_fork_cleanup_keys: | |
1135 | exit_keys(p); | |
1136 | bad_fork_cleanup_mm: | |
1137 | if (p->mm) | |
1138 | mmput(p->mm); | |
1139 | bad_fork_cleanup_signal: | |
1140 | exit_signal(p); | |
1141 | bad_fork_cleanup_sighand: | |
1142 | exit_sighand(p); | |
1143 | bad_fork_cleanup_fs: | |
1144 | exit_fs(p); /* blocking */ | |
1145 | bad_fork_cleanup_files: | |
1146 | exit_files(p); /* blocking */ | |
1147 | bad_fork_cleanup_semundo: | |
1148 | exit_sem(p); | |
1149 | bad_fork_cleanup_audit: | |
1150 | audit_free(p); | |
1151 | bad_fork_cleanup_security: | |
1152 | security_task_free(p); | |
1153 | bad_fork_cleanup_policy: | |
1154 | #ifdef CONFIG_NUMA | |
1155 | mpol_free(p->mempolicy); | |
1156 | #endif | |
1157 | bad_fork_cleanup: | |
1158 | if (p->binfmt) | |
1159 | module_put(p->binfmt->module); | |
1160 | bad_fork_cleanup_put_domain: | |
1161 | module_put(p->thread_info->exec_domain->module); | |
1162 | bad_fork_cleanup_count: | |
1163 | put_group_info(p->group_info); | |
1164 | atomic_dec(&p->user->processes); | |
1165 | free_uid(p->user); | |
1166 | bad_fork_free: | |
1167 | free_task(p); | |
1168 | goto fork_out; | |
1169 | } | |
1170 | ||
1171 | struct pt_regs * __devinit __attribute__((weak)) idle_regs(struct pt_regs *regs) | |
1172 | { | |
1173 | memset(regs, 0, sizeof(struct pt_regs)); | |
1174 | return regs; | |
1175 | } | |
1176 | ||
1177 | task_t * __devinit fork_idle(int cpu) | |
1178 | { | |
1179 | task_t *task; | |
1180 | struct pt_regs regs; | |
1181 | ||
1182 | task = copy_process(CLONE_VM, 0, idle_regs(®s), 0, NULL, NULL, 0); | |
1183 | if (!task) | |
1184 | return ERR_PTR(-ENOMEM); | |
1185 | init_idle(task, cpu); | |
1186 | unhash_process(task); | |
1187 | return task; | |
1188 | } | |
1189 | ||
1190 | static inline int fork_traceflag (unsigned clone_flags) | |
1191 | { | |
1192 | if (clone_flags & CLONE_UNTRACED) | |
1193 | return 0; | |
1194 | else if (clone_flags & CLONE_VFORK) { | |
1195 | if (current->ptrace & PT_TRACE_VFORK) | |
1196 | return PTRACE_EVENT_VFORK; | |
1197 | } else if ((clone_flags & CSIGNAL) != SIGCHLD) { | |
1198 | if (current->ptrace & PT_TRACE_CLONE) | |
1199 | return PTRACE_EVENT_CLONE; | |
1200 | } else if (current->ptrace & PT_TRACE_FORK) | |
1201 | return PTRACE_EVENT_FORK; | |
1202 | ||
1203 | return 0; | |
1204 | } | |
1205 | ||
1206 | /* | |
1207 | * Ok, this is the main fork-routine. | |
1208 | * | |
1209 | * It copies the process, and if successful kick-starts | |
1210 | * it and waits for it to finish using the VM if required. | |
1211 | */ | |
1212 | long do_fork(unsigned long clone_flags, | |
1213 | unsigned long stack_start, | |
1214 | struct pt_regs *regs, | |
1215 | unsigned long stack_size, | |
1216 | int __user *parent_tidptr, | |
1217 | int __user *child_tidptr) | |
1218 | { | |
1219 | struct task_struct *p; | |
1220 | int trace = 0; | |
1221 | long pid = alloc_pidmap(); | |
1222 | ||
1223 | if (pid < 0) | |
1224 | return -EAGAIN; | |
1225 | if (unlikely(current->ptrace)) { | |
1226 | trace = fork_traceflag (clone_flags); | |
1227 | if (trace) | |
1228 | clone_flags |= CLONE_PTRACE; | |
1229 | } | |
1230 | ||
1231 | p = copy_process(clone_flags, stack_start, regs, stack_size, parent_tidptr, child_tidptr, pid); | |
1232 | /* | |
1233 | * Do this prior waking up the new thread - the thread pointer | |
1234 | * might get invalid after that point, if the thread exits quickly. | |
1235 | */ | |
1236 | if (!IS_ERR(p)) { | |
1237 | struct completion vfork; | |
1238 | ||
1239 | if (clone_flags & CLONE_VFORK) { | |
1240 | p->vfork_done = &vfork; | |
1241 | init_completion(&vfork); | |
1242 | } | |
1243 | ||
1244 | if ((p->ptrace & PT_PTRACED) || (clone_flags & CLONE_STOPPED)) { | |
1245 | /* | |
1246 | * We'll start up with an immediate SIGSTOP. | |
1247 | */ | |
1248 | sigaddset(&p->pending.signal, SIGSTOP); | |
1249 | set_tsk_thread_flag(p, TIF_SIGPENDING); | |
1250 | } | |
1251 | ||
1252 | if (!(clone_flags & CLONE_STOPPED)) | |
1253 | wake_up_new_task(p, clone_flags); | |
1254 | else | |
1255 | p->state = TASK_STOPPED; | |
1256 | ||
1257 | if (unlikely (trace)) { | |
1258 | current->ptrace_message = pid; | |
1259 | ptrace_notify ((trace << 8) | SIGTRAP); | |
1260 | } | |
1261 | ||
1262 | if (clone_flags & CLONE_VFORK) { | |
1263 | wait_for_completion(&vfork); | |
1264 | if (unlikely (current->ptrace & PT_TRACE_VFORK_DONE)) | |
1265 | ptrace_notify ((PTRACE_EVENT_VFORK_DONE << 8) | SIGTRAP); | |
1266 | } | |
1267 | } else { | |
1268 | free_pidmap(pid); | |
1269 | pid = PTR_ERR(p); | |
1270 | } | |
1271 | return pid; | |
1272 | } | |
1273 | ||
1274 | void __init proc_caches_init(void) | |
1275 | { | |
1276 | sighand_cachep = kmem_cache_create("sighand_cache", | |
1277 | sizeof(struct sighand_struct), 0, | |
1278 | SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL, NULL); | |
1279 | signal_cachep = kmem_cache_create("signal_cache", | |
1280 | sizeof(struct signal_struct), 0, | |
1281 | SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL, NULL); | |
1282 | files_cachep = kmem_cache_create("files_cache", | |
1283 | sizeof(struct files_struct), 0, | |
1284 | SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL, NULL); | |
1285 | fs_cachep = kmem_cache_create("fs_cache", | |
1286 | sizeof(struct fs_struct), 0, | |
1287 | SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL, NULL); | |
1288 | vm_area_cachep = kmem_cache_create("vm_area_struct", | |
1289 | sizeof(struct vm_area_struct), 0, | |
1290 | SLAB_PANIC, NULL, NULL); | |
1291 | mm_cachep = kmem_cache_create("mm_struct", | |
1292 | sizeof(struct mm_struct), 0, | |
1293 | SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL, NULL); | |
1294 | } |