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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/slab.h> | |
15 | #include <linux/init.h> | |
16 | #include <linux/unistd.h> | |
17 | #include <linux/module.h> | |
18 | #include <linux/vmalloc.h> | |
19 | #include <linux/completion.h> | |
20 | #include <linux/mnt_namespace.h> | |
21 | #include <linux/personality.h> | |
22 | #include <linux/mempolicy.h> | |
23 | #include <linux/sem.h> | |
24 | #include <linux/file.h> | |
25 | #include <linux/fdtable.h> | |
26 | #include <linux/iocontext.h> | |
27 | #include <linux/key.h> | |
28 | #include <linux/binfmts.h> | |
29 | #include <linux/mman.h> | |
30 | #include <linux/mmu_notifier.h> | |
31 | #include <linux/fs.h> | |
32 | #include <linux/nsproxy.h> | |
33 | #include <linux/capability.h> | |
34 | #include <linux/cpu.h> | |
35 | #include <linux/cgroup.h> | |
36 | #include <linux/security.h> | |
37 | #include <linux/hugetlb.h> | |
38 | #include <linux/swap.h> | |
39 | #include <linux/syscalls.h> | |
40 | #include <linux/jiffies.h> | |
41 | #include <linux/tracehook.h> | |
42 | #include <linux/futex.h> | |
43 | #include <linux/compat.h> | |
44 | #include <linux/task_io_accounting_ops.h> | |
45 | #include <linux/rcupdate.h> | |
46 | #include <linux/ptrace.h> | |
47 | #include <linux/mount.h> | |
48 | #include <linux/audit.h> | |
49 | #include <linux/memcontrol.h> | |
50 | #include <linux/ftrace.h> | |
51 | #include <linux/profile.h> | |
52 | #include <linux/rmap.h> | |
53 | #include <linux/acct.h> | |
54 | #include <linux/tsacct_kern.h> | |
55 | #include <linux/cn_proc.h> | |
56 | #include <linux/freezer.h> | |
57 | #include <linux/delayacct.h> | |
58 | #include <linux/taskstats_kern.h> | |
59 | #include <linux/random.h> | |
60 | #include <linux/tty.h> | |
61 | #include <linux/proc_fs.h> | |
62 | #include <linux/blkdev.h> | |
63 | #include <trace/sched.h> | |
64 | #include <linux/magic.h> | |
65 | ||
66 | #include <asm/pgtable.h> | |
67 | #include <asm/pgalloc.h> | |
68 | #include <asm/uaccess.h> | |
69 | #include <asm/mmu_context.h> | |
70 | #include <asm/cacheflush.h> | |
71 | #include <asm/tlbflush.h> | |
72 | ||
73 | /* | |
74 | * Protected counters by write_lock_irq(&tasklist_lock) | |
75 | */ | |
76 | unsigned long total_forks; /* Handle normal Linux uptimes. */ | |
77 | int nr_threads; /* The idle threads do not count.. */ | |
78 | ||
79 | int max_threads; /* tunable limit on nr_threads */ | |
80 | ||
81 | DEFINE_PER_CPU(unsigned long, process_counts) = 0; | |
82 | ||
83 | __cacheline_aligned DEFINE_RWLOCK(tasklist_lock); /* outer */ | |
84 | ||
85 | DEFINE_TRACE(sched_process_fork); | |
86 | ||
87 | int nr_processes(void) | |
88 | { | |
89 | int cpu; | |
90 | int total = 0; | |
91 | ||
92 | for_each_online_cpu(cpu) | |
93 | total += per_cpu(process_counts, cpu); | |
94 | ||
95 | return total; | |
96 | } | |
97 | ||
98 | #ifndef __HAVE_ARCH_TASK_STRUCT_ALLOCATOR | |
99 | # define alloc_task_struct() kmem_cache_alloc(task_struct_cachep, GFP_KERNEL) | |
100 | # define free_task_struct(tsk) kmem_cache_free(task_struct_cachep, (tsk)) | |
101 | static struct kmem_cache *task_struct_cachep; | |
102 | #endif | |
103 | ||
104 | #ifndef __HAVE_ARCH_THREAD_INFO_ALLOCATOR | |
105 | static inline struct thread_info *alloc_thread_info(struct task_struct *tsk) | |
106 | { | |
107 | #ifdef CONFIG_DEBUG_STACK_USAGE | |
108 | gfp_t mask = GFP_KERNEL | __GFP_ZERO; | |
109 | #else | |
110 | gfp_t mask = GFP_KERNEL; | |
111 | #endif | |
112 | return (struct thread_info *)__get_free_pages(mask, THREAD_SIZE_ORDER); | |
113 | } | |
114 | ||
115 | static inline void free_thread_info(struct thread_info *ti) | |
116 | { | |
117 | free_pages((unsigned long)ti, THREAD_SIZE_ORDER); | |
118 | } | |
119 | #endif | |
120 | ||
121 | /* SLAB cache for signal_struct structures (tsk->signal) */ | |
122 | static struct kmem_cache *signal_cachep; | |
123 | ||
124 | /* SLAB cache for sighand_struct structures (tsk->sighand) */ | |
125 | struct kmem_cache *sighand_cachep; | |
126 | ||
127 | /* SLAB cache for files_struct structures (tsk->files) */ | |
128 | struct kmem_cache *files_cachep; | |
129 | ||
130 | /* SLAB cache for fs_struct structures (tsk->fs) */ | |
131 | struct kmem_cache *fs_cachep; | |
132 | ||
133 | /* SLAB cache for vm_area_struct structures */ | |
134 | struct kmem_cache *vm_area_cachep; | |
135 | ||
136 | /* SLAB cache for mm_struct structures (tsk->mm) */ | |
137 | static struct kmem_cache *mm_cachep; | |
138 | ||
139 | void free_task(struct task_struct *tsk) | |
140 | { | |
141 | prop_local_destroy_single(&tsk->dirties); | |
142 | free_thread_info(tsk->stack); | |
143 | rt_mutex_debug_task_free(tsk); | |
144 | ftrace_graph_exit_task(tsk); | |
145 | free_task_struct(tsk); | |
146 | } | |
147 | EXPORT_SYMBOL(free_task); | |
148 | ||
149 | void __put_task_struct(struct task_struct *tsk) | |
150 | { | |
151 | WARN_ON(!tsk->exit_state); | |
152 | WARN_ON(atomic_read(&tsk->usage)); | |
153 | WARN_ON(tsk == current); | |
154 | ||
155 | put_cred(tsk->real_cred); | |
156 | put_cred(tsk->cred); | |
157 | delayacct_tsk_free(tsk); | |
158 | ||
159 | if (!profile_handoff_task(tsk)) | |
160 | free_task(tsk); | |
161 | } | |
162 | ||
163 | /* | |
164 | * macro override instead of weak attribute alias, to workaround | |
165 | * gcc 4.1.0 and 4.1.1 bugs with weak attribute and empty functions. | |
166 | */ | |
167 | #ifndef arch_task_cache_init | |
168 | #define arch_task_cache_init() | |
169 | #endif | |
170 | ||
171 | void __init fork_init(unsigned long mempages) | |
172 | { | |
173 | #ifndef __HAVE_ARCH_TASK_STRUCT_ALLOCATOR | |
174 | #ifndef ARCH_MIN_TASKALIGN | |
175 | #define ARCH_MIN_TASKALIGN L1_CACHE_BYTES | |
176 | #endif | |
177 | /* create a slab on which task_structs can be allocated */ | |
178 | task_struct_cachep = | |
179 | kmem_cache_create("task_struct", sizeof(struct task_struct), | |
180 | ARCH_MIN_TASKALIGN, SLAB_PANIC, NULL); | |
181 | #endif | |
182 | ||
183 | /* do the arch specific task caches init */ | |
184 | arch_task_cache_init(); | |
185 | ||
186 | /* | |
187 | * The default maximum number of threads is set to a safe | |
188 | * value: the thread structures can take up at most half | |
189 | * of memory. | |
190 | */ | |
191 | max_threads = mempages / (8 * THREAD_SIZE / PAGE_SIZE); | |
192 | ||
193 | /* | |
194 | * we need to allow at least 20 threads to boot a system | |
195 | */ | |
196 | if(max_threads < 20) | |
197 | max_threads = 20; | |
198 | ||
199 | init_task.signal->rlim[RLIMIT_NPROC].rlim_cur = max_threads/2; | |
200 | init_task.signal->rlim[RLIMIT_NPROC].rlim_max = max_threads/2; | |
201 | init_task.signal->rlim[RLIMIT_SIGPENDING] = | |
202 | init_task.signal->rlim[RLIMIT_NPROC]; | |
203 | } | |
204 | ||
205 | int __attribute__((weak)) arch_dup_task_struct(struct task_struct *dst, | |
206 | struct task_struct *src) | |
207 | { | |
208 | *dst = *src; | |
209 | return 0; | |
210 | } | |
211 | ||
212 | static struct task_struct *dup_task_struct(struct task_struct *orig) | |
213 | { | |
214 | struct task_struct *tsk; | |
215 | struct thread_info *ti; | |
216 | unsigned long *stackend; | |
217 | ||
218 | int err; | |
219 | ||
220 | prepare_to_copy(orig); | |
221 | ||
222 | tsk = alloc_task_struct(); | |
223 | if (!tsk) | |
224 | return NULL; | |
225 | ||
226 | ti = alloc_thread_info(tsk); | |
227 | if (!ti) { | |
228 | free_task_struct(tsk); | |
229 | return NULL; | |
230 | } | |
231 | ||
232 | err = arch_dup_task_struct(tsk, orig); | |
233 | if (err) | |
234 | goto out; | |
235 | ||
236 | tsk->stack = ti; | |
237 | ||
238 | err = prop_local_init_single(&tsk->dirties); | |
239 | if (err) | |
240 | goto out; | |
241 | ||
242 | setup_thread_stack(tsk, orig); | |
243 | stackend = end_of_stack(tsk); | |
244 | *stackend = STACK_END_MAGIC; /* for overflow detection */ | |
245 | ||
246 | #ifdef CONFIG_CC_STACKPROTECTOR | |
247 | tsk->stack_canary = get_random_int(); | |
248 | #endif | |
249 | ||
250 | /* One for us, one for whoever does the "release_task()" (usually parent) */ | |
251 | atomic_set(&tsk->usage,2); | |
252 | atomic_set(&tsk->fs_excl, 0); | |
253 | #ifdef CONFIG_BLK_DEV_IO_TRACE | |
254 | tsk->btrace_seq = 0; | |
255 | #endif | |
256 | tsk->splice_pipe = NULL; | |
257 | return tsk; | |
258 | ||
259 | out: | |
260 | free_thread_info(ti); | |
261 | free_task_struct(tsk); | |
262 | return NULL; | |
263 | } | |
264 | ||
265 | #ifdef CONFIG_MMU | |
266 | static int dup_mmap(struct mm_struct *mm, struct mm_struct *oldmm) | |
267 | { | |
268 | struct vm_area_struct *mpnt, *tmp, **pprev; | |
269 | struct rb_node **rb_link, *rb_parent; | |
270 | int retval; | |
271 | unsigned long charge; | |
272 | struct mempolicy *pol; | |
273 | ||
274 | down_write(&oldmm->mmap_sem); | |
275 | flush_cache_dup_mm(oldmm); | |
276 | /* | |
277 | * Not linked in yet - no deadlock potential: | |
278 | */ | |
279 | down_write_nested(&mm->mmap_sem, SINGLE_DEPTH_NESTING); | |
280 | ||
281 | mm->locked_vm = 0; | |
282 | mm->mmap = NULL; | |
283 | mm->mmap_cache = NULL; | |
284 | mm->free_area_cache = oldmm->mmap_base; | |
285 | mm->cached_hole_size = ~0UL; | |
286 | mm->map_count = 0; | |
287 | cpumask_clear(mm_cpumask(mm)); | |
288 | mm->mm_rb = RB_ROOT; | |
289 | rb_link = &mm->mm_rb.rb_node; | |
290 | rb_parent = NULL; | |
291 | pprev = &mm->mmap; | |
292 | ||
293 | for (mpnt = oldmm->mmap; mpnt; mpnt = mpnt->vm_next) { | |
294 | struct file *file; | |
295 | ||
296 | if (mpnt->vm_flags & VM_DONTCOPY) { | |
297 | long pages = vma_pages(mpnt); | |
298 | mm->total_vm -= pages; | |
299 | vm_stat_account(mm, mpnt->vm_flags, mpnt->vm_file, | |
300 | -pages); | |
301 | continue; | |
302 | } | |
303 | charge = 0; | |
304 | if (mpnt->vm_flags & VM_ACCOUNT) { | |
305 | unsigned int len = (mpnt->vm_end - mpnt->vm_start) >> PAGE_SHIFT; | |
306 | if (security_vm_enough_memory(len)) | |
307 | goto fail_nomem; | |
308 | charge = len; | |
309 | } | |
310 | tmp = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL); | |
311 | if (!tmp) | |
312 | goto fail_nomem; | |
313 | *tmp = *mpnt; | |
314 | pol = mpol_dup(vma_policy(mpnt)); | |
315 | retval = PTR_ERR(pol); | |
316 | if (IS_ERR(pol)) | |
317 | goto fail_nomem_policy; | |
318 | vma_set_policy(tmp, pol); | |
319 | tmp->vm_flags &= ~VM_LOCKED; | |
320 | tmp->vm_mm = mm; | |
321 | tmp->vm_next = NULL; | |
322 | anon_vma_link(tmp); | |
323 | file = tmp->vm_file; | |
324 | if (file) { | |
325 | struct inode *inode = file->f_path.dentry->d_inode; | |
326 | struct address_space *mapping = file->f_mapping; | |
327 | ||
328 | get_file(file); | |
329 | if (tmp->vm_flags & VM_DENYWRITE) | |
330 | atomic_dec(&inode->i_writecount); | |
331 | spin_lock(&mapping->i_mmap_lock); | |
332 | if (tmp->vm_flags & VM_SHARED) | |
333 | mapping->i_mmap_writable++; | |
334 | tmp->vm_truncate_count = mpnt->vm_truncate_count; | |
335 | flush_dcache_mmap_lock(mapping); | |
336 | /* insert tmp into the share list, just after mpnt */ | |
337 | vma_prio_tree_add(tmp, mpnt); | |
338 | flush_dcache_mmap_unlock(mapping); | |
339 | spin_unlock(&mapping->i_mmap_lock); | |
340 | } | |
341 | ||
342 | /* | |
343 | * Clear hugetlb-related page reserves for children. This only | |
344 | * affects MAP_PRIVATE mappings. Faults generated by the child | |
345 | * are not guaranteed to succeed, even if read-only | |
346 | */ | |
347 | if (is_vm_hugetlb_page(tmp)) | |
348 | reset_vma_resv_huge_pages(tmp); | |
349 | ||
350 | /* | |
351 | * Link in the new vma and copy the page table entries. | |
352 | */ | |
353 | *pprev = tmp; | |
354 | pprev = &tmp->vm_next; | |
355 | ||
356 | __vma_link_rb(mm, tmp, rb_link, rb_parent); | |
357 | rb_link = &tmp->vm_rb.rb_right; | |
358 | rb_parent = &tmp->vm_rb; | |
359 | ||
360 | mm->map_count++; | |
361 | retval = copy_page_range(mm, oldmm, mpnt); | |
362 | ||
363 | if (tmp->vm_ops && tmp->vm_ops->open) | |
364 | tmp->vm_ops->open(tmp); | |
365 | ||
366 | if (retval) | |
367 | goto out; | |
368 | } | |
369 | /* a new mm has just been created */ | |
370 | arch_dup_mmap(oldmm, mm); | |
371 | retval = 0; | |
372 | out: | |
373 | up_write(&mm->mmap_sem); | |
374 | flush_tlb_mm(oldmm); | |
375 | up_write(&oldmm->mmap_sem); | |
376 | return retval; | |
377 | fail_nomem_policy: | |
378 | kmem_cache_free(vm_area_cachep, tmp); | |
379 | fail_nomem: | |
380 | retval = -ENOMEM; | |
381 | vm_unacct_memory(charge); | |
382 | goto out; | |
383 | } | |
384 | ||
385 | static inline int mm_alloc_pgd(struct mm_struct * mm) | |
386 | { | |
387 | mm->pgd = pgd_alloc(mm); | |
388 | if (unlikely(!mm->pgd)) | |
389 | return -ENOMEM; | |
390 | return 0; | |
391 | } | |
392 | ||
393 | static inline void mm_free_pgd(struct mm_struct * mm) | |
394 | { | |
395 | pgd_free(mm, mm->pgd); | |
396 | } | |
397 | #else | |
398 | #define dup_mmap(mm, oldmm) (0) | |
399 | #define mm_alloc_pgd(mm) (0) | |
400 | #define mm_free_pgd(mm) | |
401 | #endif /* CONFIG_MMU */ | |
402 | ||
403 | __cacheline_aligned_in_smp DEFINE_SPINLOCK(mmlist_lock); | |
404 | ||
405 | #define allocate_mm() (kmem_cache_alloc(mm_cachep, GFP_KERNEL)) | |
406 | #define free_mm(mm) (kmem_cache_free(mm_cachep, (mm))) | |
407 | ||
408 | static unsigned long default_dump_filter = MMF_DUMP_FILTER_DEFAULT; | |
409 | ||
410 | static int __init coredump_filter_setup(char *s) | |
411 | { | |
412 | default_dump_filter = | |
413 | (simple_strtoul(s, NULL, 0) << MMF_DUMP_FILTER_SHIFT) & | |
414 | MMF_DUMP_FILTER_MASK; | |
415 | return 1; | |
416 | } | |
417 | ||
418 | __setup("coredump_filter=", coredump_filter_setup); | |
419 | ||
420 | #include <linux/init_task.h> | |
421 | ||
422 | static struct mm_struct * mm_init(struct mm_struct * mm, struct task_struct *p) | |
423 | { | |
424 | atomic_set(&mm->mm_users, 1); | |
425 | atomic_set(&mm->mm_count, 1); | |
426 | init_rwsem(&mm->mmap_sem); | |
427 | INIT_LIST_HEAD(&mm->mmlist); | |
428 | mm->flags = (current->mm) ? current->mm->flags : default_dump_filter; | |
429 | mm->core_state = NULL; | |
430 | mm->nr_ptes = 0; | |
431 | set_mm_counter(mm, file_rss, 0); | |
432 | set_mm_counter(mm, anon_rss, 0); | |
433 | spin_lock_init(&mm->page_table_lock); | |
434 | spin_lock_init(&mm->ioctx_lock); | |
435 | INIT_HLIST_HEAD(&mm->ioctx_list); | |
436 | mm->free_area_cache = TASK_UNMAPPED_BASE; | |
437 | mm->cached_hole_size = ~0UL; | |
438 | mm_init_owner(mm, p); | |
439 | ||
440 | if (likely(!mm_alloc_pgd(mm))) { | |
441 | mm->def_flags = 0; | |
442 | mmu_notifier_mm_init(mm); | |
443 | return mm; | |
444 | } | |
445 | ||
446 | free_mm(mm); | |
447 | return NULL; | |
448 | } | |
449 | ||
450 | /* | |
451 | * Allocate and initialize an mm_struct. | |
452 | */ | |
453 | struct mm_struct * mm_alloc(void) | |
454 | { | |
455 | struct mm_struct * mm; | |
456 | ||
457 | mm = allocate_mm(); | |
458 | if (mm) { | |
459 | memset(mm, 0, sizeof(*mm)); | |
460 | mm = mm_init(mm, current); | |
461 | } | |
462 | return mm; | |
463 | } | |
464 | ||
465 | /* | |
466 | * Called when the last reference to the mm | |
467 | * is dropped: either by a lazy thread or by | |
468 | * mmput. Free the page directory and the mm. | |
469 | */ | |
470 | void __mmdrop(struct mm_struct *mm) | |
471 | { | |
472 | BUG_ON(mm == &init_mm); | |
473 | mm_free_pgd(mm); | |
474 | destroy_context(mm); | |
475 | mmu_notifier_mm_destroy(mm); | |
476 | free_mm(mm); | |
477 | } | |
478 | EXPORT_SYMBOL_GPL(__mmdrop); | |
479 | ||
480 | /* | |
481 | * Decrement the use count and release all resources for an mm. | |
482 | */ | |
483 | void mmput(struct mm_struct *mm) | |
484 | { | |
485 | might_sleep(); | |
486 | ||
487 | if (atomic_dec_and_test(&mm->mm_users)) { | |
488 | exit_aio(mm); | |
489 | exit_mmap(mm); | |
490 | set_mm_exe_file(mm, NULL); | |
491 | if (!list_empty(&mm->mmlist)) { | |
492 | spin_lock(&mmlist_lock); | |
493 | list_del(&mm->mmlist); | |
494 | spin_unlock(&mmlist_lock); | |
495 | } | |
496 | put_swap_token(mm); | |
497 | mmdrop(mm); | |
498 | } | |
499 | } | |
500 | EXPORT_SYMBOL_GPL(mmput); | |
501 | ||
502 | /** | |
503 | * get_task_mm - acquire a reference to the task's mm | |
504 | * | |
505 | * Returns %NULL if the task has no mm. Checks PF_KTHREAD (meaning | |
506 | * this kernel workthread has transiently adopted a user mm with use_mm, | |
507 | * to do its AIO) is not set and if so returns a reference to it, after | |
508 | * bumping up the use count. User must release the mm via mmput() | |
509 | * after use. Typically used by /proc and ptrace. | |
510 | */ | |
511 | struct mm_struct *get_task_mm(struct task_struct *task) | |
512 | { | |
513 | struct mm_struct *mm; | |
514 | ||
515 | task_lock(task); | |
516 | mm = task->mm; | |
517 | if (mm) { | |
518 | if (task->flags & PF_KTHREAD) | |
519 | mm = NULL; | |
520 | else | |
521 | atomic_inc(&mm->mm_users); | |
522 | } | |
523 | task_unlock(task); | |
524 | return mm; | |
525 | } | |
526 | EXPORT_SYMBOL_GPL(get_task_mm); | |
527 | ||
528 | /* Please note the differences between mmput and mm_release. | |
529 | * mmput is called whenever we stop holding onto a mm_struct, | |
530 | * error success whatever. | |
531 | * | |
532 | * mm_release is called after a mm_struct has been removed | |
533 | * from the current process. | |
534 | * | |
535 | * This difference is important for error handling, when we | |
536 | * only half set up a mm_struct for a new process and need to restore | |
537 | * the old one. Because we mmput the new mm_struct before | |
538 | * restoring the old one. . . | |
539 | * Eric Biederman 10 January 1998 | |
540 | */ | |
541 | void mm_release(struct task_struct *tsk, struct mm_struct *mm) | |
542 | { | |
543 | struct completion *vfork_done = tsk->vfork_done; | |
544 | ||
545 | /* Get rid of any futexes when releasing the mm */ | |
546 | #ifdef CONFIG_FUTEX | |
547 | if (unlikely(tsk->robust_list)) | |
548 | exit_robust_list(tsk); | |
549 | #ifdef CONFIG_COMPAT | |
550 | if (unlikely(tsk->compat_robust_list)) | |
551 | compat_exit_robust_list(tsk); | |
552 | #endif | |
553 | #endif | |
554 | ||
555 | /* Get rid of any cached register state */ | |
556 | deactivate_mm(tsk, mm); | |
557 | ||
558 | /* notify parent sleeping on vfork() */ | |
559 | if (vfork_done) { | |
560 | tsk->vfork_done = NULL; | |
561 | complete(vfork_done); | |
562 | } | |
563 | ||
564 | /* | |
565 | * If we're exiting normally, clear a user-space tid field if | |
566 | * requested. We leave this alone when dying by signal, to leave | |
567 | * the value intact in a core dump, and to save the unnecessary | |
568 | * trouble otherwise. Userland only wants this done for a sys_exit. | |
569 | */ | |
570 | if (tsk->clear_child_tid | |
571 | && !(tsk->flags & PF_SIGNALED) | |
572 | && atomic_read(&mm->mm_users) > 1) { | |
573 | u32 __user * tidptr = tsk->clear_child_tid; | |
574 | tsk->clear_child_tid = NULL; | |
575 | ||
576 | /* | |
577 | * We don't check the error code - if userspace has | |
578 | * not set up a proper pointer then tough luck. | |
579 | */ | |
580 | put_user(0, tidptr); | |
581 | sys_futex(tidptr, FUTEX_WAKE, 1, NULL, NULL, 0); | |
582 | } | |
583 | } | |
584 | ||
585 | /* | |
586 | * Allocate a new mm structure and copy contents from the | |
587 | * mm structure of the passed in task structure. | |
588 | */ | |
589 | struct mm_struct *dup_mm(struct task_struct *tsk) | |
590 | { | |
591 | struct mm_struct *mm, *oldmm = current->mm; | |
592 | int err; | |
593 | ||
594 | if (!oldmm) | |
595 | return NULL; | |
596 | ||
597 | mm = allocate_mm(); | |
598 | if (!mm) | |
599 | goto fail_nomem; | |
600 | ||
601 | memcpy(mm, oldmm, sizeof(*mm)); | |
602 | ||
603 | /* Initializing for Swap token stuff */ | |
604 | mm->token_priority = 0; | |
605 | mm->last_interval = 0; | |
606 | ||
607 | if (!mm_init(mm, tsk)) | |
608 | goto fail_nomem; | |
609 | ||
610 | if (init_new_context(tsk, mm)) | |
611 | goto fail_nocontext; | |
612 | ||
613 | dup_mm_exe_file(oldmm, mm); | |
614 | ||
615 | err = dup_mmap(mm, oldmm); | |
616 | if (err) | |
617 | goto free_pt; | |
618 | ||
619 | mm->hiwater_rss = get_mm_rss(mm); | |
620 | mm->hiwater_vm = mm->total_vm; | |
621 | ||
622 | return mm; | |
623 | ||
624 | free_pt: | |
625 | mmput(mm); | |
626 | ||
627 | fail_nomem: | |
628 | return NULL; | |
629 | ||
630 | fail_nocontext: | |
631 | /* | |
632 | * If init_new_context() failed, we cannot use mmput() to free the mm | |
633 | * because it calls destroy_context() | |
634 | */ | |
635 | mm_free_pgd(mm); | |
636 | free_mm(mm); | |
637 | return NULL; | |
638 | } | |
639 | ||
640 | static int copy_mm(unsigned long clone_flags, struct task_struct * tsk) | |
641 | { | |
642 | struct mm_struct * mm, *oldmm; | |
643 | int retval; | |
644 | ||
645 | tsk->min_flt = tsk->maj_flt = 0; | |
646 | tsk->nvcsw = tsk->nivcsw = 0; | |
647 | ||
648 | tsk->mm = NULL; | |
649 | tsk->active_mm = NULL; | |
650 | ||
651 | /* | |
652 | * Are we cloning a kernel thread? | |
653 | * | |
654 | * We need to steal a active VM for that.. | |
655 | */ | |
656 | oldmm = current->mm; | |
657 | if (!oldmm) | |
658 | return 0; | |
659 | ||
660 | if (clone_flags & CLONE_VM) { | |
661 | atomic_inc(&oldmm->mm_users); | |
662 | mm = oldmm; | |
663 | goto good_mm; | |
664 | } | |
665 | ||
666 | retval = -ENOMEM; | |
667 | mm = dup_mm(tsk); | |
668 | if (!mm) | |
669 | goto fail_nomem; | |
670 | ||
671 | good_mm: | |
672 | /* Initializing for Swap token stuff */ | |
673 | mm->token_priority = 0; | |
674 | mm->last_interval = 0; | |
675 | ||
676 | tsk->mm = mm; | |
677 | tsk->active_mm = mm; | |
678 | return 0; | |
679 | ||
680 | fail_nomem: | |
681 | return retval; | |
682 | } | |
683 | ||
684 | static struct fs_struct *__copy_fs_struct(struct fs_struct *old) | |
685 | { | |
686 | struct fs_struct *fs = kmem_cache_alloc(fs_cachep, GFP_KERNEL); | |
687 | /* We don't need to lock fs - think why ;-) */ | |
688 | if (fs) { | |
689 | atomic_set(&fs->count, 1); | |
690 | rwlock_init(&fs->lock); | |
691 | fs->umask = old->umask; | |
692 | read_lock(&old->lock); | |
693 | fs->root = old->root; | |
694 | path_get(&old->root); | |
695 | fs->pwd = old->pwd; | |
696 | path_get(&old->pwd); | |
697 | read_unlock(&old->lock); | |
698 | } | |
699 | return fs; | |
700 | } | |
701 | ||
702 | struct fs_struct *copy_fs_struct(struct fs_struct *old) | |
703 | { | |
704 | return __copy_fs_struct(old); | |
705 | } | |
706 | ||
707 | EXPORT_SYMBOL_GPL(copy_fs_struct); | |
708 | ||
709 | static int copy_fs(unsigned long clone_flags, struct task_struct *tsk) | |
710 | { | |
711 | if (clone_flags & CLONE_FS) { | |
712 | atomic_inc(¤t->fs->count); | |
713 | return 0; | |
714 | } | |
715 | tsk->fs = __copy_fs_struct(current->fs); | |
716 | if (!tsk->fs) | |
717 | return -ENOMEM; | |
718 | return 0; | |
719 | } | |
720 | ||
721 | static int copy_files(unsigned long clone_flags, struct task_struct * tsk) | |
722 | { | |
723 | struct files_struct *oldf, *newf; | |
724 | int error = 0; | |
725 | ||
726 | /* | |
727 | * A background process may not have any files ... | |
728 | */ | |
729 | oldf = current->files; | |
730 | if (!oldf) | |
731 | goto out; | |
732 | ||
733 | if (clone_flags & CLONE_FILES) { | |
734 | atomic_inc(&oldf->count); | |
735 | goto out; | |
736 | } | |
737 | ||
738 | newf = dup_fd(oldf, &error); | |
739 | if (!newf) | |
740 | goto out; | |
741 | ||
742 | tsk->files = newf; | |
743 | error = 0; | |
744 | out: | |
745 | return error; | |
746 | } | |
747 | ||
748 | static int copy_io(unsigned long clone_flags, struct task_struct *tsk) | |
749 | { | |
750 | #ifdef CONFIG_BLOCK | |
751 | struct io_context *ioc = current->io_context; | |
752 | ||
753 | if (!ioc) | |
754 | return 0; | |
755 | /* | |
756 | * Share io context with parent, if CLONE_IO is set | |
757 | */ | |
758 | if (clone_flags & CLONE_IO) { | |
759 | tsk->io_context = ioc_task_link(ioc); | |
760 | if (unlikely(!tsk->io_context)) | |
761 | return -ENOMEM; | |
762 | } else if (ioprio_valid(ioc->ioprio)) { | |
763 | tsk->io_context = alloc_io_context(GFP_KERNEL, -1); | |
764 | if (unlikely(!tsk->io_context)) | |
765 | return -ENOMEM; | |
766 | ||
767 | tsk->io_context->ioprio = ioc->ioprio; | |
768 | } | |
769 | #endif | |
770 | return 0; | |
771 | } | |
772 | ||
773 | static int copy_sighand(unsigned long clone_flags, struct task_struct *tsk) | |
774 | { | |
775 | struct sighand_struct *sig; | |
776 | ||
777 | if (clone_flags & CLONE_SIGHAND) { | |
778 | atomic_inc(¤t->sighand->count); | |
779 | return 0; | |
780 | } | |
781 | sig = kmem_cache_alloc(sighand_cachep, GFP_KERNEL); | |
782 | rcu_assign_pointer(tsk->sighand, sig); | |
783 | if (!sig) | |
784 | return -ENOMEM; | |
785 | atomic_set(&sig->count, 1); | |
786 | memcpy(sig->action, current->sighand->action, sizeof(sig->action)); | |
787 | return 0; | |
788 | } | |
789 | ||
790 | void __cleanup_sighand(struct sighand_struct *sighand) | |
791 | { | |
792 | if (atomic_dec_and_test(&sighand->count)) | |
793 | kmem_cache_free(sighand_cachep, sighand); | |
794 | } | |
795 | ||
796 | ||
797 | /* | |
798 | * Initialize POSIX timer handling for a thread group. | |
799 | */ | |
800 | static void posix_cpu_timers_init_group(struct signal_struct *sig) | |
801 | { | |
802 | /* Thread group counters. */ | |
803 | thread_group_cputime_init(sig); | |
804 | ||
805 | /* Expiration times and increments. */ | |
806 | sig->it_virt_expires = cputime_zero; | |
807 | sig->it_virt_incr = cputime_zero; | |
808 | sig->it_prof_expires = cputime_zero; | |
809 | sig->it_prof_incr = cputime_zero; | |
810 | ||
811 | /* Cached expiration times. */ | |
812 | sig->cputime_expires.prof_exp = cputime_zero; | |
813 | sig->cputime_expires.virt_exp = cputime_zero; | |
814 | sig->cputime_expires.sched_exp = 0; | |
815 | ||
816 | /* The timer lists. */ | |
817 | INIT_LIST_HEAD(&sig->cpu_timers[0]); | |
818 | INIT_LIST_HEAD(&sig->cpu_timers[1]); | |
819 | INIT_LIST_HEAD(&sig->cpu_timers[2]); | |
820 | } | |
821 | ||
822 | static int copy_signal(unsigned long clone_flags, struct task_struct *tsk) | |
823 | { | |
824 | struct signal_struct *sig; | |
825 | ||
826 | if (clone_flags & CLONE_THREAD) { | |
827 | atomic_inc(¤t->signal->count); | |
828 | atomic_inc(¤t->signal->live); | |
829 | return 0; | |
830 | } | |
831 | sig = kmem_cache_alloc(signal_cachep, GFP_KERNEL); | |
832 | ||
833 | if (sig) | |
834 | posix_cpu_timers_init_group(sig); | |
835 | ||
836 | tsk->signal = sig; | |
837 | if (!sig) | |
838 | return -ENOMEM; | |
839 | ||
840 | atomic_set(&sig->count, 1); | |
841 | atomic_set(&sig->live, 1); | |
842 | init_waitqueue_head(&sig->wait_chldexit); | |
843 | sig->flags = 0; | |
844 | sig->group_exit_code = 0; | |
845 | sig->group_exit_task = NULL; | |
846 | sig->group_stop_count = 0; | |
847 | sig->curr_target = tsk; | |
848 | init_sigpending(&sig->shared_pending); | |
849 | INIT_LIST_HEAD(&sig->posix_timers); | |
850 | ||
851 | hrtimer_init(&sig->real_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL); | |
852 | sig->it_real_incr.tv64 = 0; | |
853 | sig->real_timer.function = it_real_fn; | |
854 | ||
855 | sig->leader = 0; /* session leadership doesn't inherit */ | |
856 | sig->tty_old_pgrp = NULL; | |
857 | sig->tty = NULL; | |
858 | ||
859 | sig->utime = sig->stime = sig->cutime = sig->cstime = cputime_zero; | |
860 | sig->gtime = cputime_zero; | |
861 | sig->cgtime = cputime_zero; | |
862 | sig->nvcsw = sig->nivcsw = sig->cnvcsw = sig->cnivcsw = 0; | |
863 | sig->min_flt = sig->maj_flt = sig->cmin_flt = sig->cmaj_flt = 0; | |
864 | sig->inblock = sig->oublock = sig->cinblock = sig->coublock = 0; | |
865 | task_io_accounting_init(&sig->ioac); | |
866 | sig->sum_sched_runtime = 0; | |
867 | taskstats_tgid_init(sig); | |
868 | ||
869 | task_lock(current->group_leader); | |
870 | memcpy(sig->rlim, current->signal->rlim, sizeof sig->rlim); | |
871 | task_unlock(current->group_leader); | |
872 | ||
873 | acct_init_pacct(&sig->pacct); | |
874 | ||
875 | tty_audit_fork(sig); | |
876 | ||
877 | return 0; | |
878 | } | |
879 | ||
880 | void __cleanup_signal(struct signal_struct *sig) | |
881 | { | |
882 | thread_group_cputime_free(sig); | |
883 | tty_kref_put(sig->tty); | |
884 | kmem_cache_free(signal_cachep, sig); | |
885 | } | |
886 | ||
887 | static void cleanup_signal(struct task_struct *tsk) | |
888 | { | |
889 | struct signal_struct *sig = tsk->signal; | |
890 | ||
891 | atomic_dec(&sig->live); | |
892 | ||
893 | if (atomic_dec_and_test(&sig->count)) | |
894 | __cleanup_signal(sig); | |
895 | } | |
896 | ||
897 | static void copy_flags(unsigned long clone_flags, struct task_struct *p) | |
898 | { | |
899 | unsigned long new_flags = p->flags; | |
900 | ||
901 | new_flags &= ~PF_SUPERPRIV; | |
902 | new_flags |= PF_FORKNOEXEC; | |
903 | new_flags |= PF_STARTING; | |
904 | p->flags = new_flags; | |
905 | clear_freeze_flag(p); | |
906 | } | |
907 | ||
908 | SYSCALL_DEFINE1(set_tid_address, int __user *, tidptr) | |
909 | { | |
910 | current->clear_child_tid = tidptr; | |
911 | ||
912 | return task_pid_vnr(current); | |
913 | } | |
914 | ||
915 | static void rt_mutex_init_task(struct task_struct *p) | |
916 | { | |
917 | spin_lock_init(&p->pi_lock); | |
918 | #ifdef CONFIG_RT_MUTEXES | |
919 | plist_head_init(&p->pi_waiters, &p->pi_lock); | |
920 | p->pi_blocked_on = NULL; | |
921 | #endif | |
922 | } | |
923 | ||
924 | #ifdef CONFIG_MM_OWNER | |
925 | void mm_init_owner(struct mm_struct *mm, struct task_struct *p) | |
926 | { | |
927 | mm->owner = p; | |
928 | } | |
929 | #endif /* CONFIG_MM_OWNER */ | |
930 | ||
931 | /* | |
932 | * Initialize POSIX timer handling for a single task. | |
933 | */ | |
934 | static void posix_cpu_timers_init(struct task_struct *tsk) | |
935 | { | |
936 | tsk->cputime_expires.prof_exp = cputime_zero; | |
937 | tsk->cputime_expires.virt_exp = cputime_zero; | |
938 | tsk->cputime_expires.sched_exp = 0; | |
939 | INIT_LIST_HEAD(&tsk->cpu_timers[0]); | |
940 | INIT_LIST_HEAD(&tsk->cpu_timers[1]); | |
941 | INIT_LIST_HEAD(&tsk->cpu_timers[2]); | |
942 | } | |
943 | ||
944 | /* | |
945 | * This creates a new process as a copy of the old one, | |
946 | * but does not actually start it yet. | |
947 | * | |
948 | * It copies the registers, and all the appropriate | |
949 | * parts of the process environment (as per the clone | |
950 | * flags). The actual kick-off is left to the caller. | |
951 | */ | |
952 | static struct task_struct *copy_process(unsigned long clone_flags, | |
953 | unsigned long stack_start, | |
954 | struct pt_regs *regs, | |
955 | unsigned long stack_size, | |
956 | int __user *child_tidptr, | |
957 | struct pid *pid, | |
958 | int trace) | |
959 | { | |
960 | int retval; | |
961 | struct task_struct *p; | |
962 | int cgroup_callbacks_done = 0; | |
963 | ||
964 | if ((clone_flags & (CLONE_NEWNS|CLONE_FS)) == (CLONE_NEWNS|CLONE_FS)) | |
965 | return ERR_PTR(-EINVAL); | |
966 | ||
967 | /* | |
968 | * Thread groups must share signals as well, and detached threads | |
969 | * can only be started up within the thread group. | |
970 | */ | |
971 | if ((clone_flags & CLONE_THREAD) && !(clone_flags & CLONE_SIGHAND)) | |
972 | return ERR_PTR(-EINVAL); | |
973 | ||
974 | /* | |
975 | * Shared signal handlers imply shared VM. By way of the above, | |
976 | * thread groups also imply shared VM. Blocking this case allows | |
977 | * for various simplifications in other code. | |
978 | */ | |
979 | if ((clone_flags & CLONE_SIGHAND) && !(clone_flags & CLONE_VM)) | |
980 | return ERR_PTR(-EINVAL); | |
981 | ||
982 | retval = security_task_create(clone_flags); | |
983 | if (retval) | |
984 | goto fork_out; | |
985 | ||
986 | retval = -ENOMEM; | |
987 | p = dup_task_struct(current); | |
988 | if (!p) | |
989 | goto fork_out; | |
990 | ||
991 | rt_mutex_init_task(p); | |
992 | ||
993 | #ifdef CONFIG_PROVE_LOCKING | |
994 | DEBUG_LOCKS_WARN_ON(!p->hardirqs_enabled); | |
995 | DEBUG_LOCKS_WARN_ON(!p->softirqs_enabled); | |
996 | #endif | |
997 | retval = -EAGAIN; | |
998 | if (atomic_read(&p->real_cred->user->processes) >= | |
999 | p->signal->rlim[RLIMIT_NPROC].rlim_cur) { | |
1000 | if (!capable(CAP_SYS_ADMIN) && !capable(CAP_SYS_RESOURCE) && | |
1001 | p->real_cred->user != INIT_USER) | |
1002 | goto bad_fork_free; | |
1003 | } | |
1004 | ||
1005 | retval = copy_creds(p, clone_flags); | |
1006 | if (retval < 0) | |
1007 | goto bad_fork_free; | |
1008 | ||
1009 | /* | |
1010 | * If multiple threads are within copy_process(), then this check | |
1011 | * triggers too late. This doesn't hurt, the check is only there | |
1012 | * to stop root fork bombs. | |
1013 | */ | |
1014 | retval = -EAGAIN; | |
1015 | if (nr_threads >= max_threads) | |
1016 | goto bad_fork_cleanup_count; | |
1017 | ||
1018 | if (!try_module_get(task_thread_info(p)->exec_domain->module)) | |
1019 | goto bad_fork_cleanup_count; | |
1020 | ||
1021 | if (p->binfmt && !try_module_get(p->binfmt->module)) | |
1022 | goto bad_fork_cleanup_put_domain; | |
1023 | ||
1024 | p->did_exec = 0; | |
1025 | delayacct_tsk_init(p); /* Must remain after dup_task_struct() */ | |
1026 | copy_flags(clone_flags, p); | |
1027 | INIT_LIST_HEAD(&p->children); | |
1028 | INIT_LIST_HEAD(&p->sibling); | |
1029 | #ifdef CONFIG_PREEMPT_RCU | |
1030 | p->rcu_read_lock_nesting = 0; | |
1031 | p->rcu_flipctr_idx = 0; | |
1032 | #endif /* #ifdef CONFIG_PREEMPT_RCU */ | |
1033 | p->vfork_done = NULL; | |
1034 | spin_lock_init(&p->alloc_lock); | |
1035 | ||
1036 | clear_tsk_thread_flag(p, TIF_SIGPENDING); | |
1037 | init_sigpending(&p->pending); | |
1038 | ||
1039 | p->utime = cputime_zero; | |
1040 | p->stime = cputime_zero; | |
1041 | p->gtime = cputime_zero; | |
1042 | p->utimescaled = cputime_zero; | |
1043 | p->stimescaled = cputime_zero; | |
1044 | p->prev_utime = cputime_zero; | |
1045 | p->prev_stime = cputime_zero; | |
1046 | ||
1047 | p->default_timer_slack_ns = current->timer_slack_ns; | |
1048 | ||
1049 | #ifdef CONFIG_DETECT_SOFTLOCKUP | |
1050 | p->last_switch_count = 0; | |
1051 | p->last_switch_timestamp = 0; | |
1052 | #endif | |
1053 | ||
1054 | task_io_accounting_init(&p->ioac); | |
1055 | acct_clear_integrals(p); | |
1056 | ||
1057 | posix_cpu_timers_init(p); | |
1058 | ||
1059 | p->lock_depth = -1; /* -1 = no lock */ | |
1060 | do_posix_clock_monotonic_gettime(&p->start_time); | |
1061 | p->real_start_time = p->start_time; | |
1062 | monotonic_to_bootbased(&p->real_start_time); | |
1063 | p->io_context = NULL; | |
1064 | p->audit_context = NULL; | |
1065 | cgroup_fork(p); | |
1066 | #ifdef CONFIG_NUMA | |
1067 | p->mempolicy = mpol_dup(p->mempolicy); | |
1068 | if (IS_ERR(p->mempolicy)) { | |
1069 | retval = PTR_ERR(p->mempolicy); | |
1070 | p->mempolicy = NULL; | |
1071 | goto bad_fork_cleanup_cgroup; | |
1072 | } | |
1073 | mpol_fix_fork_child_flag(p); | |
1074 | #endif | |
1075 | #ifdef CONFIG_TRACE_IRQFLAGS | |
1076 | p->irq_events = 0; | |
1077 | #ifdef __ARCH_WANT_INTERRUPTS_ON_CTXSW | |
1078 | p->hardirqs_enabled = 1; | |
1079 | #else | |
1080 | p->hardirqs_enabled = 0; | |
1081 | #endif | |
1082 | p->hardirq_enable_ip = 0; | |
1083 | p->hardirq_enable_event = 0; | |
1084 | p->hardirq_disable_ip = _THIS_IP_; | |
1085 | p->hardirq_disable_event = 0; | |
1086 | p->softirqs_enabled = 1; | |
1087 | p->softirq_enable_ip = _THIS_IP_; | |
1088 | p->softirq_enable_event = 0; | |
1089 | p->softirq_disable_ip = 0; | |
1090 | p->softirq_disable_event = 0; | |
1091 | p->hardirq_context = 0; | |
1092 | p->softirq_context = 0; | |
1093 | #endif | |
1094 | #ifdef CONFIG_LOCKDEP | |
1095 | p->lockdep_depth = 0; /* no locks held yet */ | |
1096 | p->curr_chain_key = 0; | |
1097 | p->lockdep_recursion = 0; | |
1098 | #endif | |
1099 | ||
1100 | #ifdef CONFIG_DEBUG_MUTEXES | |
1101 | p->blocked_on = NULL; /* not blocked yet */ | |
1102 | #endif | |
1103 | if (unlikely(current->ptrace)) | |
1104 | ptrace_fork(p, clone_flags); | |
1105 | ||
1106 | /* Perform scheduler related setup. Assign this task to a CPU. */ | |
1107 | sched_fork(p, clone_flags); | |
1108 | ||
1109 | if ((retval = audit_alloc(p))) | |
1110 | goto bad_fork_cleanup_policy; | |
1111 | /* copy all the process information */ | |
1112 | if ((retval = copy_semundo(clone_flags, p))) | |
1113 | goto bad_fork_cleanup_audit; | |
1114 | if ((retval = copy_files(clone_flags, p))) | |
1115 | goto bad_fork_cleanup_semundo; | |
1116 | if ((retval = copy_fs(clone_flags, p))) | |
1117 | goto bad_fork_cleanup_files; | |
1118 | if ((retval = copy_sighand(clone_flags, p))) | |
1119 | goto bad_fork_cleanup_fs; | |
1120 | if ((retval = copy_signal(clone_flags, p))) | |
1121 | goto bad_fork_cleanup_sighand; | |
1122 | if ((retval = copy_mm(clone_flags, p))) | |
1123 | goto bad_fork_cleanup_signal; | |
1124 | if ((retval = copy_namespaces(clone_flags, p))) | |
1125 | goto bad_fork_cleanup_mm; | |
1126 | if ((retval = copy_io(clone_flags, p))) | |
1127 | goto bad_fork_cleanup_namespaces; | |
1128 | retval = copy_thread(clone_flags, stack_start, stack_size, p, regs); | |
1129 | if (retval) | |
1130 | goto bad_fork_cleanup_io; | |
1131 | ||
1132 | if (pid != &init_struct_pid) { | |
1133 | retval = -ENOMEM; | |
1134 | pid = alloc_pid(p->nsproxy->pid_ns); | |
1135 | if (!pid) | |
1136 | goto bad_fork_cleanup_io; | |
1137 | ||
1138 | if (clone_flags & CLONE_NEWPID) { | |
1139 | retval = pid_ns_prepare_proc(p->nsproxy->pid_ns); | |
1140 | if (retval < 0) | |
1141 | goto bad_fork_free_pid; | |
1142 | } | |
1143 | } | |
1144 | ||
1145 | ftrace_graph_init_task(p); | |
1146 | ||
1147 | p->pid = pid_nr(pid); | |
1148 | p->tgid = p->pid; | |
1149 | if (clone_flags & CLONE_THREAD) | |
1150 | p->tgid = current->tgid; | |
1151 | ||
1152 | if (current->nsproxy != p->nsproxy) { | |
1153 | retval = ns_cgroup_clone(p, pid); | |
1154 | if (retval) | |
1155 | goto bad_fork_free_graph; | |
1156 | } | |
1157 | ||
1158 | p->set_child_tid = (clone_flags & CLONE_CHILD_SETTID) ? child_tidptr : NULL; | |
1159 | /* | |
1160 | * Clear TID on mm_release()? | |
1161 | */ | |
1162 | p->clear_child_tid = (clone_flags & CLONE_CHILD_CLEARTID) ? child_tidptr: NULL; | |
1163 | #ifdef CONFIG_FUTEX | |
1164 | p->robust_list = NULL; | |
1165 | #ifdef CONFIG_COMPAT | |
1166 | p->compat_robust_list = NULL; | |
1167 | #endif | |
1168 | INIT_LIST_HEAD(&p->pi_state_list); | |
1169 | p->pi_state_cache = NULL; | |
1170 | #endif | |
1171 | /* | |
1172 | * sigaltstack should be cleared when sharing the same VM | |
1173 | */ | |
1174 | if ((clone_flags & (CLONE_VM|CLONE_VFORK)) == CLONE_VM) | |
1175 | p->sas_ss_sp = p->sas_ss_size = 0; | |
1176 | ||
1177 | /* | |
1178 | * Syscall tracing should be turned off in the child regardless | |
1179 | * of CLONE_PTRACE. | |
1180 | */ | |
1181 | clear_tsk_thread_flag(p, TIF_SYSCALL_TRACE); | |
1182 | #ifdef TIF_SYSCALL_EMU | |
1183 | clear_tsk_thread_flag(p, TIF_SYSCALL_EMU); | |
1184 | #endif | |
1185 | clear_all_latency_tracing(p); | |
1186 | ||
1187 | /* ok, now we should be set up.. */ | |
1188 | p->exit_signal = (clone_flags & CLONE_THREAD) ? -1 : (clone_flags & CSIGNAL); | |
1189 | p->pdeath_signal = 0; | |
1190 | p->exit_state = 0; | |
1191 | ||
1192 | /* | |
1193 | * Ok, make it visible to the rest of the system. | |
1194 | * We dont wake it up yet. | |
1195 | */ | |
1196 | p->group_leader = p; | |
1197 | INIT_LIST_HEAD(&p->thread_group); | |
1198 | ||
1199 | /* Now that the task is set up, run cgroup callbacks if | |
1200 | * necessary. We need to run them before the task is visible | |
1201 | * on the tasklist. */ | |
1202 | cgroup_fork_callbacks(p); | |
1203 | cgroup_callbacks_done = 1; | |
1204 | ||
1205 | /* Need tasklist lock for parent etc handling! */ | |
1206 | write_lock_irq(&tasklist_lock); | |
1207 | ||
1208 | /* | |
1209 | * The task hasn't been attached yet, so its cpus_allowed mask will | |
1210 | * not be changed, nor will its assigned CPU. | |
1211 | * | |
1212 | * The cpus_allowed mask of the parent may have changed after it was | |
1213 | * copied first time - so re-copy it here, then check the child's CPU | |
1214 | * to ensure it is on a valid CPU (and if not, just force it back to | |
1215 | * parent's CPU). This avoids alot of nasty races. | |
1216 | */ | |
1217 | p->cpus_allowed = current->cpus_allowed; | |
1218 | p->rt.nr_cpus_allowed = current->rt.nr_cpus_allowed; | |
1219 | if (unlikely(!cpu_isset(task_cpu(p), p->cpus_allowed) || | |
1220 | !cpu_online(task_cpu(p)))) | |
1221 | set_task_cpu(p, smp_processor_id()); | |
1222 | ||
1223 | /* CLONE_PARENT re-uses the old parent */ | |
1224 | if (clone_flags & (CLONE_PARENT|CLONE_THREAD)) { | |
1225 | p->real_parent = current->real_parent; | |
1226 | p->parent_exec_id = current->parent_exec_id; | |
1227 | } else { | |
1228 | p->real_parent = current; | |
1229 | p->parent_exec_id = current->self_exec_id; | |
1230 | } | |
1231 | ||
1232 | spin_lock(¤t->sighand->siglock); | |
1233 | ||
1234 | /* | |
1235 | * Process group and session signals need to be delivered to just the | |
1236 | * parent before the fork or both the parent and the child after the | |
1237 | * fork. Restart if a signal comes in before we add the new process to | |
1238 | * it's process group. | |
1239 | * A fatal signal pending means that current will exit, so the new | |
1240 | * thread can't slip out of an OOM kill (or normal SIGKILL). | |
1241 | */ | |
1242 | recalc_sigpending(); | |
1243 | if (signal_pending(current)) { | |
1244 | spin_unlock(¤t->sighand->siglock); | |
1245 | write_unlock_irq(&tasklist_lock); | |
1246 | retval = -ERESTARTNOINTR; | |
1247 | goto bad_fork_free_graph; | |
1248 | } | |
1249 | ||
1250 | if (clone_flags & CLONE_THREAD) { | |
1251 | p->group_leader = current->group_leader; | |
1252 | list_add_tail_rcu(&p->thread_group, &p->group_leader->thread_group); | |
1253 | } | |
1254 | ||
1255 | if (likely(p->pid)) { | |
1256 | list_add_tail(&p->sibling, &p->real_parent->children); | |
1257 | tracehook_finish_clone(p, clone_flags, trace); | |
1258 | ||
1259 | if (thread_group_leader(p)) { | |
1260 | if (clone_flags & CLONE_NEWPID) | |
1261 | p->nsproxy->pid_ns->child_reaper = p; | |
1262 | ||
1263 | p->signal->leader_pid = pid; | |
1264 | tty_kref_put(p->signal->tty); | |
1265 | p->signal->tty = tty_kref_get(current->signal->tty); | |
1266 | set_task_pgrp(p, task_pgrp_nr(current)); | |
1267 | set_task_session(p, task_session_nr(current)); | |
1268 | attach_pid(p, PIDTYPE_PGID, task_pgrp(current)); | |
1269 | attach_pid(p, PIDTYPE_SID, task_session(current)); | |
1270 | list_add_tail_rcu(&p->tasks, &init_task.tasks); | |
1271 | __get_cpu_var(process_counts)++; | |
1272 | } | |
1273 | attach_pid(p, PIDTYPE_PID, pid); | |
1274 | nr_threads++; | |
1275 | } | |
1276 | ||
1277 | total_forks++; | |
1278 | spin_unlock(¤t->sighand->siglock); | |
1279 | write_unlock_irq(&tasklist_lock); | |
1280 | proc_fork_connector(p); | |
1281 | cgroup_post_fork(p); | |
1282 | return p; | |
1283 | ||
1284 | bad_fork_free_graph: | |
1285 | ftrace_graph_exit_task(p); | |
1286 | bad_fork_free_pid: | |
1287 | if (pid != &init_struct_pid) | |
1288 | free_pid(pid); | |
1289 | bad_fork_cleanup_io: | |
1290 | put_io_context(p->io_context); | |
1291 | bad_fork_cleanup_namespaces: | |
1292 | exit_task_namespaces(p); | |
1293 | bad_fork_cleanup_mm: | |
1294 | if (p->mm) | |
1295 | mmput(p->mm); | |
1296 | bad_fork_cleanup_signal: | |
1297 | cleanup_signal(p); | |
1298 | bad_fork_cleanup_sighand: | |
1299 | __cleanup_sighand(p->sighand); | |
1300 | bad_fork_cleanup_fs: | |
1301 | exit_fs(p); /* blocking */ | |
1302 | bad_fork_cleanup_files: | |
1303 | exit_files(p); /* blocking */ | |
1304 | bad_fork_cleanup_semundo: | |
1305 | exit_sem(p); | |
1306 | bad_fork_cleanup_audit: | |
1307 | audit_free(p); | |
1308 | bad_fork_cleanup_policy: | |
1309 | #ifdef CONFIG_NUMA | |
1310 | mpol_put(p->mempolicy); | |
1311 | bad_fork_cleanup_cgroup: | |
1312 | #endif | |
1313 | cgroup_exit(p, cgroup_callbacks_done); | |
1314 | delayacct_tsk_free(p); | |
1315 | if (p->binfmt) | |
1316 | module_put(p->binfmt->module); | |
1317 | bad_fork_cleanup_put_domain: | |
1318 | module_put(task_thread_info(p)->exec_domain->module); | |
1319 | bad_fork_cleanup_count: | |
1320 | atomic_dec(&p->cred->user->processes); | |
1321 | put_cred(p->real_cred); | |
1322 | put_cred(p->cred); | |
1323 | bad_fork_free: | |
1324 | free_task(p); | |
1325 | fork_out: | |
1326 | return ERR_PTR(retval); | |
1327 | } | |
1328 | ||
1329 | noinline struct pt_regs * __cpuinit __attribute__((weak)) idle_regs(struct pt_regs *regs) | |
1330 | { | |
1331 | memset(regs, 0, sizeof(struct pt_regs)); | |
1332 | return regs; | |
1333 | } | |
1334 | ||
1335 | struct task_struct * __cpuinit fork_idle(int cpu) | |
1336 | { | |
1337 | struct task_struct *task; | |
1338 | struct pt_regs regs; | |
1339 | ||
1340 | task = copy_process(CLONE_VM, 0, idle_regs(®s), 0, NULL, | |
1341 | &init_struct_pid, 0); | |
1342 | if (!IS_ERR(task)) | |
1343 | init_idle(task, cpu); | |
1344 | ||
1345 | return task; | |
1346 | } | |
1347 | ||
1348 | /* | |
1349 | * Ok, this is the main fork-routine. | |
1350 | * | |
1351 | * It copies the process, and if successful kick-starts | |
1352 | * it and waits for it to finish using the VM if required. | |
1353 | */ | |
1354 | long do_fork(unsigned long clone_flags, | |
1355 | unsigned long stack_start, | |
1356 | struct pt_regs *regs, | |
1357 | unsigned long stack_size, | |
1358 | int __user *parent_tidptr, | |
1359 | int __user *child_tidptr) | |
1360 | { | |
1361 | struct task_struct *p; | |
1362 | int trace = 0; | |
1363 | long nr; | |
1364 | ||
1365 | /* | |
1366 | * Do some preliminary argument and permissions checking before we | |
1367 | * actually start allocating stuff | |
1368 | */ | |
1369 | if (clone_flags & CLONE_NEWUSER) { | |
1370 | if (clone_flags & CLONE_THREAD) | |
1371 | return -EINVAL; | |
1372 | /* hopefully this check will go away when userns support is | |
1373 | * complete | |
1374 | */ | |
1375 | if (!capable(CAP_SYS_ADMIN) || !capable(CAP_SETUID) || | |
1376 | !capable(CAP_SETGID)) | |
1377 | return -EPERM; | |
1378 | } | |
1379 | ||
1380 | /* | |
1381 | * We hope to recycle these flags after 2.6.26 | |
1382 | */ | |
1383 | if (unlikely(clone_flags & CLONE_STOPPED)) { | |
1384 | static int __read_mostly count = 100; | |
1385 | ||
1386 | if (count > 0 && printk_ratelimit()) { | |
1387 | char comm[TASK_COMM_LEN]; | |
1388 | ||
1389 | count--; | |
1390 | printk(KERN_INFO "fork(): process `%s' used deprecated " | |
1391 | "clone flags 0x%lx\n", | |
1392 | get_task_comm(comm, current), | |
1393 | clone_flags & CLONE_STOPPED); | |
1394 | } | |
1395 | } | |
1396 | ||
1397 | /* | |
1398 | * When called from kernel_thread, don't do user tracing stuff. | |
1399 | */ | |
1400 | if (likely(user_mode(regs))) | |
1401 | trace = tracehook_prepare_clone(clone_flags); | |
1402 | ||
1403 | p = copy_process(clone_flags, stack_start, regs, stack_size, | |
1404 | child_tidptr, NULL, trace); | |
1405 | /* | |
1406 | * Do this prior waking up the new thread - the thread pointer | |
1407 | * might get invalid after that point, if the thread exits quickly. | |
1408 | */ | |
1409 | if (!IS_ERR(p)) { | |
1410 | struct completion vfork; | |
1411 | ||
1412 | trace_sched_process_fork(current, p); | |
1413 | ||
1414 | nr = task_pid_vnr(p); | |
1415 | ||
1416 | if (clone_flags & CLONE_PARENT_SETTID) | |
1417 | put_user(nr, parent_tidptr); | |
1418 | ||
1419 | if (clone_flags & CLONE_VFORK) { | |
1420 | p->vfork_done = &vfork; | |
1421 | init_completion(&vfork); | |
1422 | } | |
1423 | ||
1424 | audit_finish_fork(p); | |
1425 | tracehook_report_clone(trace, regs, clone_flags, nr, p); | |
1426 | ||
1427 | /* | |
1428 | * We set PF_STARTING at creation in case tracing wants to | |
1429 | * use this to distinguish a fully live task from one that | |
1430 | * hasn't gotten to tracehook_report_clone() yet. Now we | |
1431 | * clear it and set the child going. | |
1432 | */ | |
1433 | p->flags &= ~PF_STARTING; | |
1434 | ||
1435 | if (unlikely(clone_flags & CLONE_STOPPED)) { | |
1436 | /* | |
1437 | * We'll start up with an immediate SIGSTOP. | |
1438 | */ | |
1439 | sigaddset(&p->pending.signal, SIGSTOP); | |
1440 | set_tsk_thread_flag(p, TIF_SIGPENDING); | |
1441 | __set_task_state(p, TASK_STOPPED); | |
1442 | } else { | |
1443 | wake_up_new_task(p, clone_flags); | |
1444 | } | |
1445 | ||
1446 | tracehook_report_clone_complete(trace, regs, | |
1447 | clone_flags, nr, p); | |
1448 | ||
1449 | if (clone_flags & CLONE_VFORK) { | |
1450 | freezer_do_not_count(); | |
1451 | wait_for_completion(&vfork); | |
1452 | freezer_count(); | |
1453 | tracehook_report_vfork_done(p, nr); | |
1454 | } | |
1455 | } else { | |
1456 | nr = PTR_ERR(p); | |
1457 | } | |
1458 | return nr; | |
1459 | } | |
1460 | ||
1461 | #ifndef ARCH_MIN_MMSTRUCT_ALIGN | |
1462 | #define ARCH_MIN_MMSTRUCT_ALIGN 0 | |
1463 | #endif | |
1464 | ||
1465 | static void sighand_ctor(void *data) | |
1466 | { | |
1467 | struct sighand_struct *sighand = data; | |
1468 | ||
1469 | spin_lock_init(&sighand->siglock); | |
1470 | init_waitqueue_head(&sighand->signalfd_wqh); | |
1471 | } | |
1472 | ||
1473 | void __init proc_caches_init(void) | |
1474 | { | |
1475 | sighand_cachep = kmem_cache_create("sighand_cache", | |
1476 | sizeof(struct sighand_struct), 0, | |
1477 | SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_DESTROY_BY_RCU, | |
1478 | sighand_ctor); | |
1479 | signal_cachep = kmem_cache_create("signal_cache", | |
1480 | sizeof(struct signal_struct), 0, | |
1481 | SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL); | |
1482 | files_cachep = kmem_cache_create("files_cache", | |
1483 | sizeof(struct files_struct), 0, | |
1484 | SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL); | |
1485 | fs_cachep = kmem_cache_create("fs_cache", | |
1486 | sizeof(struct fs_struct), 0, | |
1487 | SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL); | |
1488 | mm_cachep = kmem_cache_create("mm_struct", | |
1489 | sizeof(struct mm_struct), ARCH_MIN_MMSTRUCT_ALIGN, | |
1490 | SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL); | |
1491 | vm_area_cachep = KMEM_CACHE(vm_area_struct, SLAB_PANIC); | |
1492 | mmap_init(); | |
1493 | } | |
1494 | ||
1495 | /* | |
1496 | * Check constraints on flags passed to the unshare system call and | |
1497 | * force unsharing of additional process context as appropriate. | |
1498 | */ | |
1499 | static void check_unshare_flags(unsigned long *flags_ptr) | |
1500 | { | |
1501 | /* | |
1502 | * If unsharing a thread from a thread group, must also | |
1503 | * unshare vm. | |
1504 | */ | |
1505 | if (*flags_ptr & CLONE_THREAD) | |
1506 | *flags_ptr |= CLONE_VM; | |
1507 | ||
1508 | /* | |
1509 | * If unsharing vm, must also unshare signal handlers. | |
1510 | */ | |
1511 | if (*flags_ptr & CLONE_VM) | |
1512 | *flags_ptr |= CLONE_SIGHAND; | |
1513 | ||
1514 | /* | |
1515 | * If unsharing signal handlers and the task was created | |
1516 | * using CLONE_THREAD, then must unshare the thread | |
1517 | */ | |
1518 | if ((*flags_ptr & CLONE_SIGHAND) && | |
1519 | (atomic_read(¤t->signal->count) > 1)) | |
1520 | *flags_ptr |= CLONE_THREAD; | |
1521 | ||
1522 | /* | |
1523 | * If unsharing namespace, must also unshare filesystem information. | |
1524 | */ | |
1525 | if (*flags_ptr & CLONE_NEWNS) | |
1526 | *flags_ptr |= CLONE_FS; | |
1527 | } | |
1528 | ||
1529 | /* | |
1530 | * Unsharing of tasks created with CLONE_THREAD is not supported yet | |
1531 | */ | |
1532 | static int unshare_thread(unsigned long unshare_flags) | |
1533 | { | |
1534 | if (unshare_flags & CLONE_THREAD) | |
1535 | return -EINVAL; | |
1536 | ||
1537 | return 0; | |
1538 | } | |
1539 | ||
1540 | /* | |
1541 | * Unshare the filesystem structure if it is being shared | |
1542 | */ | |
1543 | static int unshare_fs(unsigned long unshare_flags, struct fs_struct **new_fsp) | |
1544 | { | |
1545 | struct fs_struct *fs = current->fs; | |
1546 | ||
1547 | if ((unshare_flags & CLONE_FS) && | |
1548 | (fs && atomic_read(&fs->count) > 1)) { | |
1549 | *new_fsp = __copy_fs_struct(current->fs); | |
1550 | if (!*new_fsp) | |
1551 | return -ENOMEM; | |
1552 | } | |
1553 | ||
1554 | return 0; | |
1555 | } | |
1556 | ||
1557 | /* | |
1558 | * Unsharing of sighand is not supported yet | |
1559 | */ | |
1560 | static int unshare_sighand(unsigned long unshare_flags, struct sighand_struct **new_sighp) | |
1561 | { | |
1562 | struct sighand_struct *sigh = current->sighand; | |
1563 | ||
1564 | if ((unshare_flags & CLONE_SIGHAND) && atomic_read(&sigh->count) > 1) | |
1565 | return -EINVAL; | |
1566 | else | |
1567 | return 0; | |
1568 | } | |
1569 | ||
1570 | /* | |
1571 | * Unshare vm if it is being shared | |
1572 | */ | |
1573 | static int unshare_vm(unsigned long unshare_flags, struct mm_struct **new_mmp) | |
1574 | { | |
1575 | struct mm_struct *mm = current->mm; | |
1576 | ||
1577 | if ((unshare_flags & CLONE_VM) && | |
1578 | (mm && atomic_read(&mm->mm_users) > 1)) { | |
1579 | return -EINVAL; | |
1580 | } | |
1581 | ||
1582 | return 0; | |
1583 | } | |
1584 | ||
1585 | /* | |
1586 | * Unshare file descriptor table if it is being shared | |
1587 | */ | |
1588 | static int unshare_fd(unsigned long unshare_flags, struct files_struct **new_fdp) | |
1589 | { | |
1590 | struct files_struct *fd = current->files; | |
1591 | int error = 0; | |
1592 | ||
1593 | if ((unshare_flags & CLONE_FILES) && | |
1594 | (fd && atomic_read(&fd->count) > 1)) { | |
1595 | *new_fdp = dup_fd(fd, &error); | |
1596 | if (!*new_fdp) | |
1597 | return error; | |
1598 | } | |
1599 | ||
1600 | return 0; | |
1601 | } | |
1602 | ||
1603 | /* | |
1604 | * unshare allows a process to 'unshare' part of the process | |
1605 | * context which was originally shared using clone. copy_* | |
1606 | * functions used by do_fork() cannot be used here directly | |
1607 | * because they modify an inactive task_struct that is being | |
1608 | * constructed. Here we are modifying the current, active, | |
1609 | * task_struct. | |
1610 | */ | |
1611 | SYSCALL_DEFINE1(unshare, unsigned long, unshare_flags) | |
1612 | { | |
1613 | int err = 0; | |
1614 | struct fs_struct *fs, *new_fs = NULL; | |
1615 | struct sighand_struct *new_sigh = NULL; | |
1616 | struct mm_struct *mm, *new_mm = NULL, *active_mm = NULL; | |
1617 | struct files_struct *fd, *new_fd = NULL; | |
1618 | struct nsproxy *new_nsproxy = NULL; | |
1619 | int do_sysvsem = 0; | |
1620 | ||
1621 | check_unshare_flags(&unshare_flags); | |
1622 | ||
1623 | /* Return -EINVAL for all unsupported flags */ | |
1624 | err = -EINVAL; | |
1625 | if (unshare_flags & ~(CLONE_THREAD|CLONE_FS|CLONE_NEWNS|CLONE_SIGHAND| | |
1626 | CLONE_VM|CLONE_FILES|CLONE_SYSVSEM| | |
1627 | CLONE_NEWUTS|CLONE_NEWIPC|CLONE_NEWNET)) | |
1628 | goto bad_unshare_out; | |
1629 | ||
1630 | /* | |
1631 | * CLONE_NEWIPC must also detach from the undolist: after switching | |
1632 | * to a new ipc namespace, the semaphore arrays from the old | |
1633 | * namespace are unreachable. | |
1634 | */ | |
1635 | if (unshare_flags & (CLONE_NEWIPC|CLONE_SYSVSEM)) | |
1636 | do_sysvsem = 1; | |
1637 | if ((err = unshare_thread(unshare_flags))) | |
1638 | goto bad_unshare_out; | |
1639 | if ((err = unshare_fs(unshare_flags, &new_fs))) | |
1640 | goto bad_unshare_cleanup_thread; | |
1641 | if ((err = unshare_sighand(unshare_flags, &new_sigh))) | |
1642 | goto bad_unshare_cleanup_fs; | |
1643 | if ((err = unshare_vm(unshare_flags, &new_mm))) | |
1644 | goto bad_unshare_cleanup_sigh; | |
1645 | if ((err = unshare_fd(unshare_flags, &new_fd))) | |
1646 | goto bad_unshare_cleanup_vm; | |
1647 | if ((err = unshare_nsproxy_namespaces(unshare_flags, &new_nsproxy, | |
1648 | new_fs))) | |
1649 | goto bad_unshare_cleanup_fd; | |
1650 | ||
1651 | if (new_fs || new_mm || new_fd || do_sysvsem || new_nsproxy) { | |
1652 | if (do_sysvsem) { | |
1653 | /* | |
1654 | * CLONE_SYSVSEM is equivalent to sys_exit(). | |
1655 | */ | |
1656 | exit_sem(current); | |
1657 | } | |
1658 | ||
1659 | if (new_nsproxy) { | |
1660 | switch_task_namespaces(current, new_nsproxy); | |
1661 | new_nsproxy = NULL; | |
1662 | } | |
1663 | ||
1664 | task_lock(current); | |
1665 | ||
1666 | if (new_fs) { | |
1667 | fs = current->fs; | |
1668 | current->fs = new_fs; | |
1669 | new_fs = fs; | |
1670 | } | |
1671 | ||
1672 | if (new_mm) { | |
1673 | mm = current->mm; | |
1674 | active_mm = current->active_mm; | |
1675 | current->mm = new_mm; | |
1676 | current->active_mm = new_mm; | |
1677 | activate_mm(active_mm, new_mm); | |
1678 | new_mm = mm; | |
1679 | } | |
1680 | ||
1681 | if (new_fd) { | |
1682 | fd = current->files; | |
1683 | current->files = new_fd; | |
1684 | new_fd = fd; | |
1685 | } | |
1686 | ||
1687 | task_unlock(current); | |
1688 | } | |
1689 | ||
1690 | if (new_nsproxy) | |
1691 | put_nsproxy(new_nsproxy); | |
1692 | ||
1693 | bad_unshare_cleanup_fd: | |
1694 | if (new_fd) | |
1695 | put_files_struct(new_fd); | |
1696 | ||
1697 | bad_unshare_cleanup_vm: | |
1698 | if (new_mm) | |
1699 | mmput(new_mm); | |
1700 | ||
1701 | bad_unshare_cleanup_sigh: | |
1702 | if (new_sigh) | |
1703 | if (atomic_dec_and_test(&new_sigh->count)) | |
1704 | kmem_cache_free(sighand_cachep, new_sigh); | |
1705 | ||
1706 | bad_unshare_cleanup_fs: | |
1707 | if (new_fs) | |
1708 | put_fs_struct(new_fs); | |
1709 | ||
1710 | bad_unshare_cleanup_thread: | |
1711 | bad_unshare_out: | |
1712 | return err; | |
1713 | } | |
1714 | ||
1715 | /* | |
1716 | * Helper to unshare the files of the current task. | |
1717 | * We don't want to expose copy_files internals to | |
1718 | * the exec layer of the kernel. | |
1719 | */ | |
1720 | ||
1721 | int unshare_files(struct files_struct **displaced) | |
1722 | { | |
1723 | struct task_struct *task = current; | |
1724 | struct files_struct *copy = NULL; | |
1725 | int error; | |
1726 | ||
1727 | error = unshare_fd(CLONE_FILES, ©); | |
1728 | if (error || !copy) { | |
1729 | *displaced = NULL; | |
1730 | return error; | |
1731 | } | |
1732 | *displaced = task->files; | |
1733 | task_lock(task); | |
1734 | task->files = copy; | |
1735 | task_unlock(task); | |
1736 | return 0; | |
1737 | } |