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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/personality.h> |
21 | #include <linux/mempolicy.h> |
22 | #include <linux/sem.h> |
23 | #include <linux/file.h> |
24 | #include <linux/fdtable.h> |
25 | #include <linux/iocontext.h> |
26 | #include <linux/key.h> |
27 | #include <linux/binfmts.h> |
28 | #include <linux/mman.h> |
29 | #include <linux/mmu_notifier.h> |
30 | #include <linux/fs.h> |
31 | #include <linux/nsproxy.h> |
32 | #include <linux/capability.h> |
33 | #include <linux/cpu.h> |
34 | #include <linux/cgroup.h> |
35 | #include <linux/security.h> |
36 | #include <linux/hugetlb.h> |
37 | #include <linux/swap.h> |
38 | #include <linux/syscalls.h> |
39 | #include <linux/jiffies.h> |
40 | #include <linux/futex.h> |
41 | #include <linux/compat.h> |
42 | #include <linux/kthread.h> |
43 | #include <linux/task_io_accounting_ops.h> |
44 | #include <linux/rcupdate.h> |
45 | #include <linux/ptrace.h> |
46 | #include <linux/mount.h> |
47 | #include <linux/audit.h> |
48 | #include <linux/memcontrol.h> |
49 | #include <linux/ftrace.h> |
50 | #include <linux/proc_fs.h> |
51 | #include <linux/profile.h> |
52 | #include <linux/rmap.h> |
53 | #include <linux/ksm.h> |
54 | #include <linux/acct.h> |
55 | #include <linux/tsacct_kern.h> |
56 | #include <linux/cn_proc.h> |
57 | #include <linux/freezer.h> |
58 | #include <linux/delayacct.h> |
59 | #include <linux/taskstats_kern.h> |
60 | #include <linux/random.h> |
61 | #include <linux/tty.h> |
62 | #include <linux/blkdev.h> |
63 | #include <linux/fs_struct.h> |
64 | #include <linux/magic.h> |
65 | #include <linux/perf_event.h> |
66 | #include <linux/posix-timers.h> |
67 | #include <linux/user-return-notifier.h> |
68 | #include <linux/oom.h> |
69 | #include <linux/khugepaged.h> |
70 | #include <linux/signalfd.h> |
71 | |
72 | #include <asm/pgtable.h> |
73 | #include <asm/pgalloc.h> |
74 | #include <asm/uaccess.h> |
75 | #include <asm/mmu_context.h> |
76 | #include <asm/cacheflush.h> |
77 | #include <asm/tlbflush.h> |
78 | |
79 | #include <trace/events/sched.h> |
80 | |
81 | #define CREATE_TRACE_POINTS |
82 | #include <trace/events/task.h> |
83 | |
84 | /* |
85 | * Protected counters by write_lock_irq(&tasklist_lock) |
86 | */ |
87 | unsigned long total_forks; /* Handle normal Linux uptimes. */ |
88 | int nr_threads; /* The idle threads do not count.. */ |
89 | |
90 | int max_threads; /* tunable limit on nr_threads */ |
91 | |
92 | DEFINE_PER_CPU(unsigned long, process_counts) = 0; |
93 | |
94 | __cacheline_aligned DEFINE_RWLOCK(tasklist_lock); /* outer */ |
95 | |
96 | #ifdef CONFIG_PROVE_RCU |
97 | int lockdep_tasklist_lock_is_held(void) |
98 | { |
99 | return lockdep_is_held(&tasklist_lock); |
100 | } |
101 | EXPORT_SYMBOL_GPL(lockdep_tasklist_lock_is_held); |
102 | #endif /* #ifdef CONFIG_PROVE_RCU */ |
103 | |
104 | int nr_processes(void) |
105 | { |
106 | int cpu; |
107 | int total = 0; |
108 | |
109 | for_each_possible_cpu(cpu) |
110 | total += per_cpu(process_counts, cpu); |
111 | |
112 | return total; |
113 | } |
114 | |
115 | #ifndef __HAVE_ARCH_TASK_STRUCT_ALLOCATOR |
116 | # define alloc_task_struct_node(node) \ |
117 | kmem_cache_alloc_node(task_struct_cachep, GFP_KERNEL, node) |
118 | # define free_task_struct(tsk) \ |
119 | kmem_cache_free(task_struct_cachep, (tsk)) |
120 | static struct kmem_cache *task_struct_cachep; |
121 | #endif |
122 | |
123 | #ifndef __HAVE_ARCH_THREAD_INFO_ALLOCATOR |
124 | static struct thread_info *alloc_thread_info_node(struct task_struct *tsk, |
125 | int node) |
126 | { |
127 | #ifdef CONFIG_DEBUG_STACK_USAGE |
128 | gfp_t mask = GFP_KERNEL | __GFP_ZERO; |
129 | #else |
130 | gfp_t mask = GFP_KERNEL; |
131 | #endif |
132 | struct page *page = alloc_pages_node(node, mask, THREAD_SIZE_ORDER); |
133 | |
134 | return page ? page_address(page) : NULL; |
135 | } |
136 | |
137 | static inline void free_thread_info(struct thread_info *ti) |
138 | { |
139 | free_pages((unsigned long)ti, THREAD_SIZE_ORDER); |
140 | } |
141 | #endif |
142 | |
143 | /* SLAB cache for signal_struct structures (tsk->signal) */ |
144 | static struct kmem_cache *signal_cachep; |
145 | |
146 | /* SLAB cache for sighand_struct structures (tsk->sighand) */ |
147 | struct kmem_cache *sighand_cachep; |
148 | |
149 | /* SLAB cache for files_struct structures (tsk->files) */ |
150 | struct kmem_cache *files_cachep; |
151 | |
152 | /* SLAB cache for fs_struct structures (tsk->fs) */ |
153 | struct kmem_cache *fs_cachep; |
154 | |
155 | /* SLAB cache for vm_area_struct structures */ |
156 | struct kmem_cache *vm_area_cachep; |
157 | |
158 | /* SLAB cache for mm_struct structures (tsk->mm) */ |
159 | static struct kmem_cache *mm_cachep; |
160 | |
161 | static void account_kernel_stack(struct thread_info *ti, int account) |
162 | { |
163 | struct zone *zone = page_zone(virt_to_page(ti)); |
164 | |
165 | mod_zone_page_state(zone, NR_KERNEL_STACK, account); |
166 | } |
167 | |
168 | void free_task(struct task_struct *tsk) |
169 | { |
170 | account_kernel_stack(tsk->stack, -1); |
171 | free_thread_info(tsk->stack); |
172 | rt_mutex_debug_task_free(tsk); |
173 | ftrace_graph_exit_task(tsk); |
174 | free_task_struct(tsk); |
175 | } |
176 | EXPORT_SYMBOL(free_task); |
177 | |
178 | static inline void free_signal_struct(struct signal_struct *sig) |
179 | { |
180 | taskstats_tgid_free(sig); |
181 | sched_autogroup_exit(sig); |
182 | kmem_cache_free(signal_cachep, sig); |
183 | } |
184 | |
185 | static inline void put_signal_struct(struct signal_struct *sig) |
186 | { |
187 | if (atomic_dec_and_test(&sig->sigcnt)) |
188 | free_signal_struct(sig); |
189 | } |
190 | |
191 | void __put_task_struct(struct task_struct *tsk) |
192 | { |
193 | WARN_ON(!tsk->exit_state); |
194 | WARN_ON(atomic_read(&tsk->usage)); |
195 | WARN_ON(tsk == current); |
196 | |
197 | security_task_free(tsk); |
198 | exit_creds(tsk); |
199 | delayacct_tsk_free(tsk); |
200 | put_signal_struct(tsk->signal); |
201 | |
202 | if (!profile_handoff_task(tsk)) |
203 | free_task(tsk); |
204 | } |
205 | EXPORT_SYMBOL_GPL(__put_task_struct); |
206 | |
207 | /* |
208 | * macro override instead of weak attribute alias, to workaround |
209 | * gcc 4.1.0 and 4.1.1 bugs with weak attribute and empty functions. |
210 | */ |
211 | #ifndef arch_task_cache_init |
212 | #define arch_task_cache_init() |
213 | #endif |
214 | |
215 | void __init fork_init(unsigned long mempages) |
216 | { |
217 | #ifndef __HAVE_ARCH_TASK_STRUCT_ALLOCATOR |
218 | #ifndef ARCH_MIN_TASKALIGN |
219 | #define ARCH_MIN_TASKALIGN L1_CACHE_BYTES |
220 | #endif |
221 | /* create a slab on which task_structs can be allocated */ |
222 | task_struct_cachep = |
223 | kmem_cache_create("task_struct", sizeof(struct task_struct), |
224 | ARCH_MIN_TASKALIGN, SLAB_PANIC | SLAB_NOTRACK, NULL); |
225 | #endif |
226 | |
227 | /* do the arch specific task caches init */ |
228 | arch_task_cache_init(); |
229 | |
230 | /* |
231 | * The default maximum number of threads is set to a safe |
232 | * value: the thread structures can take up at most half |
233 | * of memory. |
234 | */ |
235 | max_threads = mempages / (8 * THREAD_SIZE / PAGE_SIZE); |
236 | |
237 | /* |
238 | * we need to allow at least 20 threads to boot a system |
239 | */ |
240 | if (max_threads < 20) |
241 | max_threads = 20; |
242 | |
243 | init_task.signal->rlim[RLIMIT_NPROC].rlim_cur = max_threads/2; |
244 | init_task.signal->rlim[RLIMIT_NPROC].rlim_max = max_threads/2; |
245 | init_task.signal->rlim[RLIMIT_SIGPENDING] = |
246 | init_task.signal->rlim[RLIMIT_NPROC]; |
247 | } |
248 | |
249 | int __attribute__((weak)) arch_dup_task_struct(struct task_struct *dst, |
250 | struct task_struct *src) |
251 | { |
252 | *dst = *src; |
253 | return 0; |
254 | } |
255 | |
256 | static struct task_struct *dup_task_struct(struct task_struct *orig) |
257 | { |
258 | struct task_struct *tsk; |
259 | struct thread_info *ti; |
260 | unsigned long *stackend; |
261 | int node = tsk_fork_get_node(orig); |
262 | int err; |
263 | |
264 | prepare_to_copy(orig); |
265 | |
266 | tsk = alloc_task_struct_node(node); |
267 | if (!tsk) |
268 | return NULL; |
269 | |
270 | ti = alloc_thread_info_node(tsk, node); |
271 | if (!ti) { |
272 | free_task_struct(tsk); |
273 | return NULL; |
274 | } |
275 | |
276 | err = arch_dup_task_struct(tsk, orig); |
277 | if (err) |
278 | goto out; |
279 | |
280 | tsk->stack = ti; |
281 | |
282 | setup_thread_stack(tsk, orig); |
283 | clear_user_return_notifier(tsk); |
284 | clear_tsk_need_resched(tsk); |
285 | stackend = end_of_stack(tsk); |
286 | *stackend = STACK_END_MAGIC; /* for overflow detection */ |
287 | |
288 | #ifdef CONFIG_CC_STACKPROTECTOR |
289 | tsk->stack_canary = get_random_int(); |
290 | #endif |
291 | |
292 | /* |
293 | * One for us, one for whoever does the "release_task()" (usually |
294 | * parent) |
295 | */ |
296 | atomic_set(&tsk->usage, 2); |
297 | #ifdef CONFIG_BLK_DEV_IO_TRACE |
298 | tsk->btrace_seq = 0; |
299 | #endif |
300 | tsk->splice_pipe = NULL; |
301 | |
302 | account_kernel_stack(ti, 1); |
303 | |
304 | return tsk; |
305 | |
306 | out: |
307 | free_thread_info(ti); |
308 | free_task_struct(tsk); |
309 | return NULL; |
310 | } |
311 | |
312 | #ifdef CONFIG_MMU |
313 | static int dup_mmap(struct mm_struct *mm, struct mm_struct *oldmm) |
314 | { |
315 | struct vm_area_struct *mpnt, *tmp, *prev, **pprev; |
316 | struct rb_node **rb_link, *rb_parent; |
317 | int retval; |
318 | unsigned long charge; |
319 | struct mempolicy *pol; |
320 | |
321 | down_write(&oldmm->mmap_sem); |
322 | flush_cache_dup_mm(oldmm); |
323 | /* |
324 | * Not linked in yet - no deadlock potential: |
325 | */ |
326 | down_write_nested(&mm->mmap_sem, SINGLE_DEPTH_NESTING); |
327 | |
328 | mm->locked_vm = 0; |
329 | mm->mmap = NULL; |
330 | mm->mmap_cache = NULL; |
331 | mm->free_area_cache = oldmm->mmap_base; |
332 | mm->cached_hole_size = ~0UL; |
333 | mm->map_count = 0; |
334 | cpumask_clear(mm_cpumask(mm)); |
335 | mm->mm_rb = RB_ROOT; |
336 | rb_link = &mm->mm_rb.rb_node; |
337 | rb_parent = NULL; |
338 | pprev = &mm->mmap; |
339 | retval = ksm_fork(mm, oldmm); |
340 | if (retval) |
341 | goto out; |
342 | retval = khugepaged_fork(mm, oldmm); |
343 | if (retval) |
344 | goto out; |
345 | |
346 | prev = NULL; |
347 | for (mpnt = oldmm->mmap; mpnt; mpnt = mpnt->vm_next) { |
348 | struct file *file; |
349 | |
350 | if (mpnt->vm_flags & VM_DONTCOPY) { |
351 | long pages = vma_pages(mpnt); |
352 | mm->total_vm -= pages; |
353 | vm_stat_account(mm, mpnt->vm_flags, mpnt->vm_file, |
354 | -pages); |
355 | continue; |
356 | } |
357 | charge = 0; |
358 | if (mpnt->vm_flags & VM_ACCOUNT) { |
359 | unsigned int len = (mpnt->vm_end - mpnt->vm_start) >> PAGE_SHIFT; |
360 | if (security_vm_enough_memory_mm(oldmm, len)) /* sic */ |
361 | goto fail_nomem; |
362 | charge = len; |
363 | } |
364 | tmp = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL); |
365 | if (!tmp) |
366 | goto fail_nomem; |
367 | *tmp = *mpnt; |
368 | INIT_LIST_HEAD(&tmp->anon_vma_chain); |
369 | pol = mpol_dup(vma_policy(mpnt)); |
370 | retval = PTR_ERR(pol); |
371 | if (IS_ERR(pol)) |
372 | goto fail_nomem_policy; |
373 | vma_set_policy(tmp, pol); |
374 | tmp->vm_mm = mm; |
375 | if (anon_vma_fork(tmp, mpnt)) |
376 | goto fail_nomem_anon_vma_fork; |
377 | tmp->vm_flags &= ~VM_LOCKED; |
378 | tmp->vm_next = tmp->vm_prev = NULL; |
379 | file = tmp->vm_file; |
380 | if (file) { |
381 | struct inode *inode = file->f_path.dentry->d_inode; |
382 | struct address_space *mapping = file->f_mapping; |
383 | |
384 | get_file(file); |
385 | if (tmp->vm_flags & VM_DENYWRITE) |
386 | atomic_dec(&inode->i_writecount); |
387 | mutex_lock(&mapping->i_mmap_mutex); |
388 | if (tmp->vm_flags & VM_SHARED) |
389 | mapping->i_mmap_writable++; |
390 | flush_dcache_mmap_lock(mapping); |
391 | /* insert tmp into the share list, just after mpnt */ |
392 | vma_prio_tree_add(tmp, mpnt); |
393 | flush_dcache_mmap_unlock(mapping); |
394 | mutex_unlock(&mapping->i_mmap_mutex); |
395 | } |
396 | |
397 | /* |
398 | * Clear hugetlb-related page reserves for children. This only |
399 | * affects MAP_PRIVATE mappings. Faults generated by the child |
400 | * are not guaranteed to succeed, even if read-only |
401 | */ |
402 | if (is_vm_hugetlb_page(tmp)) |
403 | reset_vma_resv_huge_pages(tmp); |
404 | |
405 | /* |
406 | * Link in the new vma and copy the page table entries. |
407 | */ |
408 | *pprev = tmp; |
409 | pprev = &tmp->vm_next; |
410 | tmp->vm_prev = prev; |
411 | prev = tmp; |
412 | |
413 | __vma_link_rb(mm, tmp, rb_link, rb_parent); |
414 | rb_link = &tmp->vm_rb.rb_right; |
415 | rb_parent = &tmp->vm_rb; |
416 | |
417 | mm->map_count++; |
418 | retval = copy_page_range(mm, oldmm, mpnt); |
419 | |
420 | if (tmp->vm_ops && tmp->vm_ops->open) |
421 | tmp->vm_ops->open(tmp); |
422 | |
423 | if (retval) |
424 | goto out; |
425 | } |
426 | /* a new mm has just been created */ |
427 | arch_dup_mmap(oldmm, mm); |
428 | retval = 0; |
429 | out: |
430 | up_write(&mm->mmap_sem); |
431 | flush_tlb_mm(oldmm); |
432 | up_write(&oldmm->mmap_sem); |
433 | return retval; |
434 | fail_nomem_anon_vma_fork: |
435 | mpol_put(pol); |
436 | fail_nomem_policy: |
437 | kmem_cache_free(vm_area_cachep, tmp); |
438 | fail_nomem: |
439 | retval = -ENOMEM; |
440 | vm_unacct_memory(charge); |
441 | goto out; |
442 | } |
443 | |
444 | static inline int mm_alloc_pgd(struct mm_struct *mm) |
445 | { |
446 | mm->pgd = pgd_alloc(mm); |
447 | if (unlikely(!mm->pgd)) |
448 | return -ENOMEM; |
449 | return 0; |
450 | } |
451 | |
452 | static inline void mm_free_pgd(struct mm_struct *mm) |
453 | { |
454 | pgd_free(mm, mm->pgd); |
455 | } |
456 | #else |
457 | #define dup_mmap(mm, oldmm) (0) |
458 | #define mm_alloc_pgd(mm) (0) |
459 | #define mm_free_pgd(mm) |
460 | #endif /* CONFIG_MMU */ |
461 | |
462 | __cacheline_aligned_in_smp DEFINE_SPINLOCK(mmlist_lock); |
463 | |
464 | #define allocate_mm() (kmem_cache_alloc(mm_cachep, GFP_KERNEL)) |
465 | #define free_mm(mm) (kmem_cache_free(mm_cachep, (mm))) |
466 | |
467 | static unsigned long default_dump_filter = MMF_DUMP_FILTER_DEFAULT; |
468 | |
469 | static int __init coredump_filter_setup(char *s) |
470 | { |
471 | default_dump_filter = |
472 | (simple_strtoul(s, NULL, 0) << MMF_DUMP_FILTER_SHIFT) & |
473 | MMF_DUMP_FILTER_MASK; |
474 | return 1; |
475 | } |
476 | |
477 | __setup("coredump_filter=", coredump_filter_setup); |
478 | |
479 | #include <linux/init_task.h> |
480 | |
481 | static void mm_init_aio(struct mm_struct *mm) |
482 | { |
483 | #ifdef CONFIG_AIO |
484 | spin_lock_init(&mm->ioctx_lock); |
485 | INIT_HLIST_HEAD(&mm->ioctx_list); |
486 | #endif |
487 | } |
488 | |
489 | static struct mm_struct *mm_init(struct mm_struct *mm, struct task_struct *p) |
490 | { |
491 | atomic_set(&mm->mm_users, 1); |
492 | atomic_set(&mm->mm_count, 1); |
493 | init_rwsem(&mm->mmap_sem); |
494 | INIT_LIST_HEAD(&mm->mmlist); |
495 | mm->flags = (current->mm) ? |
496 | (current->mm->flags & MMF_INIT_MASK) : default_dump_filter; |
497 | mm->core_state = NULL; |
498 | mm->nr_ptes = 0; |
499 | memset(&mm->rss_stat, 0, sizeof(mm->rss_stat)); |
500 | spin_lock_init(&mm->page_table_lock); |
501 | mm->free_area_cache = TASK_UNMAPPED_BASE; |
502 | mm->cached_hole_size = ~0UL; |
503 | mm_init_aio(mm); |
504 | mm_init_owner(mm, p); |
505 | |
506 | if (likely(!mm_alloc_pgd(mm))) { |
507 | mm->def_flags = 0; |
508 | mmu_notifier_mm_init(mm); |
509 | return mm; |
510 | } |
511 | |
512 | free_mm(mm); |
513 | return NULL; |
514 | } |
515 | |
516 | static void check_mm(struct mm_struct *mm) |
517 | { |
518 | int i; |
519 | |
520 | for (i = 0; i < NR_MM_COUNTERS; i++) { |
521 | long x = atomic_long_read(&mm->rss_stat.count[i]); |
522 | |
523 | if (unlikely(x)) |
524 | printk(KERN_ALERT "BUG: Bad rss-counter state " |
525 | "mm:%p idx:%d val:%ld\n", mm, i, x); |
526 | } |
527 | |
528 | #ifdef CONFIG_TRANSPARENT_HUGEPAGE |
529 | VM_BUG_ON(mm->pmd_huge_pte); |
530 | #endif |
531 | } |
532 | |
533 | /* |
534 | * Allocate and initialize an mm_struct. |
535 | */ |
536 | struct mm_struct *mm_alloc(void) |
537 | { |
538 | struct mm_struct *mm; |
539 | |
540 | mm = allocate_mm(); |
541 | if (!mm) |
542 | return NULL; |
543 | |
544 | memset(mm, 0, sizeof(*mm)); |
545 | mm_init_cpumask(mm); |
546 | return mm_init(mm, current); |
547 | } |
548 | |
549 | /* |
550 | * Called when the last reference to the mm |
551 | * is dropped: either by a lazy thread or by |
552 | * mmput. Free the page directory and the mm. |
553 | */ |
554 | void __mmdrop(struct mm_struct *mm) |
555 | { |
556 | BUG_ON(mm == &init_mm); |
557 | mm_free_pgd(mm); |
558 | destroy_context(mm); |
559 | mmu_notifier_mm_destroy(mm); |
560 | check_mm(mm); |
561 | free_mm(mm); |
562 | } |
563 | EXPORT_SYMBOL_GPL(__mmdrop); |
564 | |
565 | /* |
566 | * Decrement the use count and release all resources for an mm. |
567 | */ |
568 | void mmput(struct mm_struct *mm) |
569 | { |
570 | might_sleep(); |
571 | |
572 | if (atomic_dec_and_test(&mm->mm_users)) { |
573 | exit_aio(mm); |
574 | ksm_exit(mm); |
575 | khugepaged_exit(mm); /* must run before exit_mmap */ |
576 | exit_mmap(mm); |
577 | set_mm_exe_file(mm, NULL); |
578 | if (!list_empty(&mm->mmlist)) { |
579 | spin_lock(&mmlist_lock); |
580 | list_del(&mm->mmlist); |
581 | spin_unlock(&mmlist_lock); |
582 | } |
583 | put_swap_token(mm); |
584 | if (mm->binfmt) |
585 | module_put(mm->binfmt->module); |
586 | mmdrop(mm); |
587 | } |
588 | } |
589 | EXPORT_SYMBOL_GPL(mmput); |
590 | |
591 | /* |
592 | * We added or removed a vma mapping the executable. The vmas are only mapped |
593 | * during exec and are not mapped with the mmap system call. |
594 | * Callers must hold down_write() on the mm's mmap_sem for these |
595 | */ |
596 | void added_exe_file_vma(struct mm_struct *mm) |
597 | { |
598 | mm->num_exe_file_vmas++; |
599 | } |
600 | |
601 | void removed_exe_file_vma(struct mm_struct *mm) |
602 | { |
603 | mm->num_exe_file_vmas--; |
604 | if ((mm->num_exe_file_vmas == 0) && mm->exe_file) { |
605 | fput(mm->exe_file); |
606 | mm->exe_file = NULL; |
607 | } |
608 | |
609 | } |
610 | |
611 | void set_mm_exe_file(struct mm_struct *mm, struct file *new_exe_file) |
612 | { |
613 | if (new_exe_file) |
614 | get_file(new_exe_file); |
615 | if (mm->exe_file) |
616 | fput(mm->exe_file); |
617 | mm->exe_file = new_exe_file; |
618 | mm->num_exe_file_vmas = 0; |
619 | } |
620 | |
621 | struct file *get_mm_exe_file(struct mm_struct *mm) |
622 | { |
623 | struct file *exe_file; |
624 | |
625 | /* We need mmap_sem to protect against races with removal of |
626 | * VM_EXECUTABLE vmas */ |
627 | down_read(&mm->mmap_sem); |
628 | exe_file = mm->exe_file; |
629 | if (exe_file) |
630 | get_file(exe_file); |
631 | up_read(&mm->mmap_sem); |
632 | return exe_file; |
633 | } |
634 | |
635 | static void dup_mm_exe_file(struct mm_struct *oldmm, struct mm_struct *newmm) |
636 | { |
637 | /* It's safe to write the exe_file pointer without exe_file_lock because |
638 | * this is called during fork when the task is not yet in /proc */ |
639 | newmm->exe_file = get_mm_exe_file(oldmm); |
640 | } |
641 | |
642 | /** |
643 | * get_task_mm - acquire a reference to the task's mm |
644 | * |
645 | * Returns %NULL if the task has no mm. Checks PF_KTHREAD (meaning |
646 | * this kernel workthread has transiently adopted a user mm with use_mm, |
647 | * to do its AIO) is not set and if so returns a reference to it, after |
648 | * bumping up the use count. User must release the mm via mmput() |
649 | * after use. Typically used by /proc and ptrace. |
650 | */ |
651 | struct mm_struct *get_task_mm(struct task_struct *task) |
652 | { |
653 | struct mm_struct *mm; |
654 | |
655 | task_lock(task); |
656 | mm = task->mm; |
657 | if (mm) { |
658 | if (task->flags & PF_KTHREAD) |
659 | mm = NULL; |
660 | else |
661 | atomic_inc(&mm->mm_users); |
662 | } |
663 | task_unlock(task); |
664 | return mm; |
665 | } |
666 | EXPORT_SYMBOL_GPL(get_task_mm); |
667 | |
668 | struct mm_struct *mm_access(struct task_struct *task, unsigned int mode) |
669 | { |
670 | struct mm_struct *mm; |
671 | int err; |
672 | |
673 | err = mutex_lock_killable(&task->signal->cred_guard_mutex); |
674 | if (err) |
675 | return ERR_PTR(err); |
676 | |
677 | mm = get_task_mm(task); |
678 | if (mm && mm != current->mm && |
679 | !ptrace_may_access(task, mode)) { |
680 | mmput(mm); |
681 | mm = ERR_PTR(-EACCES); |
682 | } |
683 | mutex_unlock(&task->signal->cred_guard_mutex); |
684 | |
685 | return mm; |
686 | } |
687 | |
688 | static void complete_vfork_done(struct task_struct *tsk) |
689 | { |
690 | struct completion *vfork; |
691 | |
692 | task_lock(tsk); |
693 | vfork = tsk->vfork_done; |
694 | if (likely(vfork)) { |
695 | tsk->vfork_done = NULL; |
696 | complete(vfork); |
697 | } |
698 | task_unlock(tsk); |
699 | } |
700 | |
701 | static int wait_for_vfork_done(struct task_struct *child, |
702 | struct completion *vfork) |
703 | { |
704 | int killed; |
705 | |
706 | freezer_do_not_count(); |
707 | killed = wait_for_completion_killable(vfork); |
708 | freezer_count(); |
709 | |
710 | if (killed) { |
711 | task_lock(child); |
712 | child->vfork_done = NULL; |
713 | task_unlock(child); |
714 | } |
715 | |
716 | put_task_struct(child); |
717 | return killed; |
718 | } |
719 | |
720 | /* Please note the differences between mmput and mm_release. |
721 | * mmput is called whenever we stop holding onto a mm_struct, |
722 | * error success whatever. |
723 | * |
724 | * mm_release is called after a mm_struct has been removed |
725 | * from the current process. |
726 | * |
727 | * This difference is important for error handling, when we |
728 | * only half set up a mm_struct for a new process and need to restore |
729 | * the old one. Because we mmput the new mm_struct before |
730 | * restoring the old one. . . |
731 | * Eric Biederman 10 January 1998 |
732 | */ |
733 | void mm_release(struct task_struct *tsk, struct mm_struct *mm) |
734 | { |
735 | /* Get rid of any futexes when releasing the mm */ |
736 | #ifdef CONFIG_FUTEX |
737 | if (unlikely(tsk->robust_list)) { |
738 | exit_robust_list(tsk); |
739 | tsk->robust_list = NULL; |
740 | } |
741 | #ifdef CONFIG_COMPAT |
742 | if (unlikely(tsk->compat_robust_list)) { |
743 | compat_exit_robust_list(tsk); |
744 | tsk->compat_robust_list = NULL; |
745 | } |
746 | #endif |
747 | if (unlikely(!list_empty(&tsk->pi_state_list))) |
748 | exit_pi_state_list(tsk); |
749 | #endif |
750 | |
751 | /* Get rid of any cached register state */ |
752 | deactivate_mm(tsk, mm); |
753 | |
754 | if (tsk->vfork_done) |
755 | complete_vfork_done(tsk); |
756 | |
757 | /* |
758 | * If we're exiting normally, clear a user-space tid field if |
759 | * requested. We leave this alone when dying by signal, to leave |
760 | * the value intact in a core dump, and to save the unnecessary |
761 | * trouble, say, a killed vfork parent shouldn't touch this mm. |
762 | * Userland only wants this done for a sys_exit. |
763 | */ |
764 | if (tsk->clear_child_tid) { |
765 | if (!(tsk->flags & PF_SIGNALED) && |
766 | atomic_read(&mm->mm_users) > 1) { |
767 | /* |
768 | * We don't check the error code - if userspace has |
769 | * not set up a proper pointer then tough luck. |
770 | */ |
771 | put_user(0, tsk->clear_child_tid); |
772 | sys_futex(tsk->clear_child_tid, FUTEX_WAKE, |
773 | 1, NULL, NULL, 0); |
774 | } |
775 | tsk->clear_child_tid = NULL; |
776 | } |
777 | } |
778 | |
779 | /* |
780 | * Allocate a new mm structure and copy contents from the |
781 | * mm structure of the passed in task structure. |
782 | */ |
783 | struct mm_struct *dup_mm(struct task_struct *tsk) |
784 | { |
785 | struct mm_struct *mm, *oldmm = current->mm; |
786 | int err; |
787 | |
788 | if (!oldmm) |
789 | return NULL; |
790 | |
791 | mm = allocate_mm(); |
792 | if (!mm) |
793 | goto fail_nomem; |
794 | |
795 | memcpy(mm, oldmm, sizeof(*mm)); |
796 | mm_init_cpumask(mm); |
797 | |
798 | /* Initializing for Swap token stuff */ |
799 | mm->token_priority = 0; |
800 | mm->last_interval = 0; |
801 | |
802 | #ifdef CONFIG_TRANSPARENT_HUGEPAGE |
803 | mm->pmd_huge_pte = NULL; |
804 | #endif |
805 | |
806 | if (!mm_init(mm, tsk)) |
807 | goto fail_nomem; |
808 | |
809 | if (init_new_context(tsk, mm)) |
810 | goto fail_nocontext; |
811 | |
812 | dup_mm_exe_file(oldmm, mm); |
813 | |
814 | err = dup_mmap(mm, oldmm); |
815 | if (err) |
816 | goto free_pt; |
817 | |
818 | mm->hiwater_rss = get_mm_rss(mm); |
819 | mm->hiwater_vm = mm->total_vm; |
820 | |
821 | if (mm->binfmt && !try_module_get(mm->binfmt->module)) |
822 | goto free_pt; |
823 | |
824 | return mm; |
825 | |
826 | free_pt: |
827 | /* don't put binfmt in mmput, we haven't got module yet */ |
828 | mm->binfmt = NULL; |
829 | mmput(mm); |
830 | |
831 | fail_nomem: |
832 | return NULL; |
833 | |
834 | fail_nocontext: |
835 | /* |
836 | * If init_new_context() failed, we cannot use mmput() to free the mm |
837 | * because it calls destroy_context() |
838 | */ |
839 | mm_free_pgd(mm); |
840 | free_mm(mm); |
841 | return NULL; |
842 | } |
843 | |
844 | static int copy_mm(unsigned long clone_flags, struct task_struct *tsk) |
845 | { |
846 | struct mm_struct *mm, *oldmm; |
847 | int retval; |
848 | |
849 | tsk->min_flt = tsk->maj_flt = 0; |
850 | tsk->nvcsw = tsk->nivcsw = 0; |
851 | #ifdef CONFIG_DETECT_HUNG_TASK |
852 | tsk->last_switch_count = tsk->nvcsw + tsk->nivcsw; |
853 | #endif |
854 | |
855 | tsk->mm = NULL; |
856 | tsk->active_mm = NULL; |
857 | |
858 | /* |
859 | * Are we cloning a kernel thread? |
860 | * |
861 | * We need to steal a active VM for that.. |
862 | */ |
863 | oldmm = current->mm; |
864 | if (!oldmm) |
865 | return 0; |
866 | |
867 | if (clone_flags & CLONE_VM) { |
868 | atomic_inc(&oldmm->mm_users); |
869 | mm = oldmm; |
870 | goto good_mm; |
871 | } |
872 | |
873 | retval = -ENOMEM; |
874 | mm = dup_mm(tsk); |
875 | if (!mm) |
876 | goto fail_nomem; |
877 | |
878 | good_mm: |
879 | /* Initializing for Swap token stuff */ |
880 | mm->token_priority = 0; |
881 | mm->last_interval = 0; |
882 | |
883 | tsk->mm = mm; |
884 | tsk->active_mm = mm; |
885 | return 0; |
886 | |
887 | fail_nomem: |
888 | return retval; |
889 | } |
890 | |
891 | static int copy_fs(unsigned long clone_flags, struct task_struct *tsk) |
892 | { |
893 | struct fs_struct *fs = current->fs; |
894 | if (clone_flags & CLONE_FS) { |
895 | /* tsk->fs is already what we want */ |
896 | spin_lock(&fs->lock); |
897 | if (fs->in_exec) { |
898 | spin_unlock(&fs->lock); |
899 | return -EAGAIN; |
900 | } |
901 | fs->users++; |
902 | spin_unlock(&fs->lock); |
903 | return 0; |
904 | } |
905 | tsk->fs = copy_fs_struct(fs); |
906 | if (!tsk->fs) |
907 | return -ENOMEM; |
908 | return 0; |
909 | } |
910 | |
911 | static int copy_files(unsigned long clone_flags, struct task_struct *tsk) |
912 | { |
913 | struct files_struct *oldf, *newf; |
914 | int error = 0; |
915 | |
916 | /* |
917 | * A background process may not have any files ... |
918 | */ |
919 | oldf = current->files; |
920 | if (!oldf) |
921 | goto out; |
922 | |
923 | if (clone_flags & CLONE_FILES) { |
924 | atomic_inc(&oldf->count); |
925 | goto out; |
926 | } |
927 | |
928 | newf = dup_fd(oldf, &error); |
929 | if (!newf) |
930 | goto out; |
931 | |
932 | tsk->files = newf; |
933 | error = 0; |
934 | out: |
935 | return error; |
936 | } |
937 | |
938 | static int copy_io(unsigned long clone_flags, struct task_struct *tsk) |
939 | { |
940 | #ifdef CONFIG_BLOCK |
941 | struct io_context *ioc = current->io_context; |
942 | struct io_context *new_ioc; |
943 | |
944 | if (!ioc) |
945 | return 0; |
946 | /* |
947 | * Share io context with parent, if CLONE_IO is set |
948 | */ |
949 | if (clone_flags & CLONE_IO) { |
950 | tsk->io_context = ioc_task_link(ioc); |
951 | if (unlikely(!tsk->io_context)) |
952 | return -ENOMEM; |
953 | } else if (ioprio_valid(ioc->ioprio)) { |
954 | new_ioc = get_task_io_context(tsk, GFP_KERNEL, NUMA_NO_NODE); |
955 | if (unlikely(!new_ioc)) |
956 | return -ENOMEM; |
957 | |
958 | new_ioc->ioprio = ioc->ioprio; |
959 | put_io_context(new_ioc); |
960 | } |
961 | #endif |
962 | return 0; |
963 | } |
964 | |
965 | static int copy_sighand(unsigned long clone_flags, struct task_struct *tsk) |
966 | { |
967 | struct sighand_struct *sig; |
968 | |
969 | if (clone_flags & CLONE_SIGHAND) { |
970 | atomic_inc(¤t->sighand->count); |
971 | return 0; |
972 | } |
973 | sig = kmem_cache_alloc(sighand_cachep, GFP_KERNEL); |
974 | rcu_assign_pointer(tsk->sighand, sig); |
975 | if (!sig) |
976 | return -ENOMEM; |
977 | atomic_set(&sig->count, 1); |
978 | memcpy(sig->action, current->sighand->action, sizeof(sig->action)); |
979 | return 0; |
980 | } |
981 | |
982 | void __cleanup_sighand(struct sighand_struct *sighand) |
983 | { |
984 | if (atomic_dec_and_test(&sighand->count)) { |
985 | signalfd_cleanup(sighand); |
986 | kmem_cache_free(sighand_cachep, sighand); |
987 | } |
988 | } |
989 | |
990 | |
991 | /* |
992 | * Initialize POSIX timer handling for a thread group. |
993 | */ |
994 | static void posix_cpu_timers_init_group(struct signal_struct *sig) |
995 | { |
996 | unsigned long cpu_limit; |
997 | |
998 | /* Thread group counters. */ |
999 | thread_group_cputime_init(sig); |
1000 | |
1001 | cpu_limit = ACCESS_ONCE(sig->rlim[RLIMIT_CPU].rlim_cur); |
1002 | if (cpu_limit != RLIM_INFINITY) { |
1003 | sig->cputime_expires.prof_exp = secs_to_cputime(cpu_limit); |
1004 | sig->cputimer.running = 1; |
1005 | } |
1006 | |
1007 | /* The timer lists. */ |
1008 | INIT_LIST_HEAD(&sig->cpu_timers[0]); |
1009 | INIT_LIST_HEAD(&sig->cpu_timers[1]); |
1010 | INIT_LIST_HEAD(&sig->cpu_timers[2]); |
1011 | } |
1012 | |
1013 | static int copy_signal(unsigned long clone_flags, struct task_struct *tsk) |
1014 | { |
1015 | struct signal_struct *sig; |
1016 | |
1017 | if (clone_flags & CLONE_THREAD) |
1018 | return 0; |
1019 | |
1020 | sig = kmem_cache_zalloc(signal_cachep, GFP_KERNEL); |
1021 | tsk->signal = sig; |
1022 | if (!sig) |
1023 | return -ENOMEM; |
1024 | |
1025 | sig->nr_threads = 1; |
1026 | atomic_set(&sig->live, 1); |
1027 | atomic_set(&sig->sigcnt, 1); |
1028 | init_waitqueue_head(&sig->wait_chldexit); |
1029 | if (clone_flags & CLONE_NEWPID) |
1030 | sig->flags |= SIGNAL_UNKILLABLE; |
1031 | sig->curr_target = tsk; |
1032 | init_sigpending(&sig->shared_pending); |
1033 | INIT_LIST_HEAD(&sig->posix_timers); |
1034 | |
1035 | hrtimer_init(&sig->real_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL); |
1036 | sig->real_timer.function = it_real_fn; |
1037 | |
1038 | task_lock(current->group_leader); |
1039 | memcpy(sig->rlim, current->signal->rlim, sizeof sig->rlim); |
1040 | task_unlock(current->group_leader); |
1041 | |
1042 | posix_cpu_timers_init_group(sig); |
1043 | |
1044 | tty_audit_fork(sig); |
1045 | sched_autogroup_fork(sig); |
1046 | |
1047 | #ifdef CONFIG_CGROUPS |
1048 | init_rwsem(&sig->group_rwsem); |
1049 | #endif |
1050 | |
1051 | sig->oom_adj = current->signal->oom_adj; |
1052 | sig->oom_score_adj = current->signal->oom_score_adj; |
1053 | sig->oom_score_adj_min = current->signal->oom_score_adj_min; |
1054 | |
1055 | sig->has_child_subreaper = current->signal->has_child_subreaper || |
1056 | current->signal->is_child_subreaper; |
1057 | |
1058 | mutex_init(&sig->cred_guard_mutex); |
1059 | |
1060 | return 0; |
1061 | } |
1062 | |
1063 | static void copy_flags(unsigned long clone_flags, struct task_struct *p) |
1064 | { |
1065 | unsigned long new_flags = p->flags; |
1066 | |
1067 | new_flags &= ~(PF_SUPERPRIV | PF_WQ_WORKER); |
1068 | new_flags |= PF_FORKNOEXEC; |
1069 | p->flags = new_flags; |
1070 | } |
1071 | |
1072 | SYSCALL_DEFINE1(set_tid_address, int __user *, tidptr) |
1073 | { |
1074 | current->clear_child_tid = tidptr; |
1075 | |
1076 | return task_pid_vnr(current); |
1077 | } |
1078 | |
1079 | static void rt_mutex_init_task(struct task_struct *p) |
1080 | { |
1081 | raw_spin_lock_init(&p->pi_lock); |
1082 | #ifdef CONFIG_RT_MUTEXES |
1083 | plist_head_init(&p->pi_waiters); |
1084 | p->pi_blocked_on = NULL; |
1085 | #endif |
1086 | } |
1087 | |
1088 | #ifdef CONFIG_MM_OWNER |
1089 | void mm_init_owner(struct mm_struct *mm, struct task_struct *p) |
1090 | { |
1091 | mm->owner = p; |
1092 | } |
1093 | #endif /* CONFIG_MM_OWNER */ |
1094 | |
1095 | /* |
1096 | * Initialize POSIX timer handling for a single task. |
1097 | */ |
1098 | static void posix_cpu_timers_init(struct task_struct *tsk) |
1099 | { |
1100 | tsk->cputime_expires.prof_exp = 0; |
1101 | tsk->cputime_expires.virt_exp = 0; |
1102 | tsk->cputime_expires.sched_exp = 0; |
1103 | INIT_LIST_HEAD(&tsk->cpu_timers[0]); |
1104 | INIT_LIST_HEAD(&tsk->cpu_timers[1]); |
1105 | INIT_LIST_HEAD(&tsk->cpu_timers[2]); |
1106 | } |
1107 | |
1108 | /* |
1109 | * This creates a new process as a copy of the old one, |
1110 | * but does not actually start it yet. |
1111 | * |
1112 | * It copies the registers, and all the appropriate |
1113 | * parts of the process environment (as per the clone |
1114 | * flags). The actual kick-off is left to the caller. |
1115 | */ |
1116 | static struct task_struct *copy_process(unsigned long clone_flags, |
1117 | unsigned long stack_start, |
1118 | struct pt_regs *regs, |
1119 | unsigned long stack_size, |
1120 | int __user *child_tidptr, |
1121 | struct pid *pid, |
1122 | int trace) |
1123 | { |
1124 | int retval; |
1125 | struct task_struct *p; |
1126 | int cgroup_callbacks_done = 0; |
1127 | |
1128 | if ((clone_flags & (CLONE_NEWNS|CLONE_FS)) == (CLONE_NEWNS|CLONE_FS)) |
1129 | return ERR_PTR(-EINVAL); |
1130 | |
1131 | /* |
1132 | * Thread groups must share signals as well, and detached threads |
1133 | * can only be started up within the thread group. |
1134 | */ |
1135 | if ((clone_flags & CLONE_THREAD) && !(clone_flags & CLONE_SIGHAND)) |
1136 | return ERR_PTR(-EINVAL); |
1137 | |
1138 | /* |
1139 | * Shared signal handlers imply shared VM. By way of the above, |
1140 | * thread groups also imply shared VM. Blocking this case allows |
1141 | * for various simplifications in other code. |
1142 | */ |
1143 | if ((clone_flags & CLONE_SIGHAND) && !(clone_flags & CLONE_VM)) |
1144 | return ERR_PTR(-EINVAL); |
1145 | |
1146 | /* |
1147 | * Siblings of global init remain as zombies on exit since they are |
1148 | * not reaped by their parent (swapper). To solve this and to avoid |
1149 | * multi-rooted process trees, prevent global and container-inits |
1150 | * from creating siblings. |
1151 | */ |
1152 | if ((clone_flags & CLONE_PARENT) && |
1153 | current->signal->flags & SIGNAL_UNKILLABLE) |
1154 | return ERR_PTR(-EINVAL); |
1155 | |
1156 | retval = security_task_create(clone_flags); |
1157 | if (retval) |
1158 | goto fork_out; |
1159 | |
1160 | retval = -ENOMEM; |
1161 | p = dup_task_struct(current); |
1162 | if (!p) |
1163 | goto fork_out; |
1164 | |
1165 | ftrace_graph_init_task(p); |
1166 | |
1167 | rt_mutex_init_task(p); |
1168 | |
1169 | #ifdef CONFIG_PROVE_LOCKING |
1170 | DEBUG_LOCKS_WARN_ON(!p->hardirqs_enabled); |
1171 | DEBUG_LOCKS_WARN_ON(!p->softirqs_enabled); |
1172 | #endif |
1173 | retval = -EAGAIN; |
1174 | if (atomic_read(&p->real_cred->user->processes) >= |
1175 | task_rlimit(p, RLIMIT_NPROC)) { |
1176 | if (!capable(CAP_SYS_ADMIN) && !capable(CAP_SYS_RESOURCE) && |
1177 | p->real_cred->user != INIT_USER) |
1178 | goto bad_fork_free; |
1179 | } |
1180 | current->flags &= ~PF_NPROC_EXCEEDED; |
1181 | |
1182 | retval = copy_creds(p, clone_flags); |
1183 | if (retval < 0) |
1184 | goto bad_fork_free; |
1185 | |
1186 | /* |
1187 | * If multiple threads are within copy_process(), then this check |
1188 | * triggers too late. This doesn't hurt, the check is only there |
1189 | * to stop root fork bombs. |
1190 | */ |
1191 | retval = -EAGAIN; |
1192 | if (nr_threads >= max_threads) |
1193 | goto bad_fork_cleanup_count; |
1194 | |
1195 | if (!try_module_get(task_thread_info(p)->exec_domain->module)) |
1196 | goto bad_fork_cleanup_count; |
1197 | |
1198 | p->did_exec = 0; |
1199 | delayacct_tsk_init(p); /* Must remain after dup_task_struct() */ |
1200 | copy_flags(clone_flags, p); |
1201 | INIT_LIST_HEAD(&p->children); |
1202 | INIT_LIST_HEAD(&p->sibling); |
1203 | rcu_copy_process(p); |
1204 | p->vfork_done = NULL; |
1205 | spin_lock_init(&p->alloc_lock); |
1206 | |
1207 | init_sigpending(&p->pending); |
1208 | |
1209 | p->utime = p->stime = p->gtime = 0; |
1210 | p->utimescaled = p->stimescaled = 0; |
1211 | #ifndef CONFIG_VIRT_CPU_ACCOUNTING |
1212 | p->prev_utime = p->prev_stime = 0; |
1213 | #endif |
1214 | #if defined(SPLIT_RSS_COUNTING) |
1215 | memset(&p->rss_stat, 0, sizeof(p->rss_stat)); |
1216 | #endif |
1217 | |
1218 | p->default_timer_slack_ns = current->timer_slack_ns; |
1219 | |
1220 | task_io_accounting_init(&p->ioac); |
1221 | acct_clear_integrals(p); |
1222 | |
1223 | posix_cpu_timers_init(p); |
1224 | |
1225 | do_posix_clock_monotonic_gettime(&p->start_time); |
1226 | p->real_start_time = p->start_time; |
1227 | monotonic_to_bootbased(&p->real_start_time); |
1228 | p->io_context = NULL; |
1229 | p->audit_context = NULL; |
1230 | if (clone_flags & CLONE_THREAD) |
1231 | threadgroup_change_begin(current); |
1232 | cgroup_fork(p); |
1233 | #ifdef CONFIG_NUMA |
1234 | p->mempolicy = mpol_dup(p->mempolicy); |
1235 | if (IS_ERR(p->mempolicy)) { |
1236 | retval = PTR_ERR(p->mempolicy); |
1237 | p->mempolicy = NULL; |
1238 | goto bad_fork_cleanup_cgroup; |
1239 | } |
1240 | mpol_fix_fork_child_flag(p); |
1241 | #endif |
1242 | #ifdef CONFIG_CPUSETS |
1243 | p->cpuset_mem_spread_rotor = NUMA_NO_NODE; |
1244 | p->cpuset_slab_spread_rotor = NUMA_NO_NODE; |
1245 | seqcount_init(&p->mems_allowed_seq); |
1246 | #endif |
1247 | #ifdef CONFIG_TRACE_IRQFLAGS |
1248 | p->irq_events = 0; |
1249 | #ifdef __ARCH_WANT_INTERRUPTS_ON_CTXSW |
1250 | p->hardirqs_enabled = 1; |
1251 | #else |
1252 | p->hardirqs_enabled = 0; |
1253 | #endif |
1254 | p->hardirq_enable_ip = 0; |
1255 | p->hardirq_enable_event = 0; |
1256 | p->hardirq_disable_ip = _THIS_IP_; |
1257 | p->hardirq_disable_event = 0; |
1258 | p->softirqs_enabled = 1; |
1259 | p->softirq_enable_ip = _THIS_IP_; |
1260 | p->softirq_enable_event = 0; |
1261 | p->softirq_disable_ip = 0; |
1262 | p->softirq_disable_event = 0; |
1263 | p->hardirq_context = 0; |
1264 | p->softirq_context = 0; |
1265 | #endif |
1266 | #ifdef CONFIG_LOCKDEP |
1267 | p->lockdep_depth = 0; /* no locks held yet */ |
1268 | p->curr_chain_key = 0; |
1269 | p->lockdep_recursion = 0; |
1270 | #endif |
1271 | |
1272 | #ifdef CONFIG_DEBUG_MUTEXES |
1273 | p->blocked_on = NULL; /* not blocked yet */ |
1274 | #endif |
1275 | #ifdef CONFIG_CGROUP_MEM_RES_CTLR |
1276 | p->memcg_batch.do_batch = 0; |
1277 | p->memcg_batch.memcg = NULL; |
1278 | #endif |
1279 | |
1280 | /* Perform scheduler related setup. Assign this task to a CPU. */ |
1281 | sched_fork(p); |
1282 | |
1283 | retval = perf_event_init_task(p); |
1284 | if (retval) |
1285 | goto bad_fork_cleanup_policy; |
1286 | retval = audit_alloc(p); |
1287 | if (retval) |
1288 | goto bad_fork_cleanup_policy; |
1289 | /* copy all the process information */ |
1290 | retval = copy_semundo(clone_flags, p); |
1291 | if (retval) |
1292 | goto bad_fork_cleanup_audit; |
1293 | retval = copy_files(clone_flags, p); |
1294 | if (retval) |
1295 | goto bad_fork_cleanup_semundo; |
1296 | retval = copy_fs(clone_flags, p); |
1297 | if (retval) |
1298 | goto bad_fork_cleanup_files; |
1299 | retval = copy_sighand(clone_flags, p); |
1300 | if (retval) |
1301 | goto bad_fork_cleanup_fs; |
1302 | retval = copy_signal(clone_flags, p); |
1303 | if (retval) |
1304 | goto bad_fork_cleanup_sighand; |
1305 | retval = copy_mm(clone_flags, p); |
1306 | if (retval) |
1307 | goto bad_fork_cleanup_signal; |
1308 | retval = copy_namespaces(clone_flags, p); |
1309 | if (retval) |
1310 | goto bad_fork_cleanup_mm; |
1311 | retval = copy_io(clone_flags, p); |
1312 | if (retval) |
1313 | goto bad_fork_cleanup_namespaces; |
1314 | retval = copy_thread(clone_flags, stack_start, stack_size, p, regs); |
1315 | if (retval) |
1316 | goto bad_fork_cleanup_io; |
1317 | |
1318 | if (pid != &init_struct_pid) { |
1319 | retval = -ENOMEM; |
1320 | pid = alloc_pid(p->nsproxy->pid_ns); |
1321 | if (!pid) |
1322 | goto bad_fork_cleanup_io; |
1323 | } |
1324 | |
1325 | p->pid = pid_nr(pid); |
1326 | p->tgid = p->pid; |
1327 | if (clone_flags & CLONE_THREAD) |
1328 | p->tgid = current->tgid; |
1329 | |
1330 | p->set_child_tid = (clone_flags & CLONE_CHILD_SETTID) ? child_tidptr : NULL; |
1331 | /* |
1332 | * Clear TID on mm_release()? |
1333 | */ |
1334 | p->clear_child_tid = (clone_flags & CLONE_CHILD_CLEARTID) ? child_tidptr : NULL; |
1335 | #ifdef CONFIG_BLOCK |
1336 | p->plug = NULL; |
1337 | #endif |
1338 | #ifdef CONFIG_FUTEX |
1339 | p->robust_list = NULL; |
1340 | #ifdef CONFIG_COMPAT |
1341 | p->compat_robust_list = NULL; |
1342 | #endif |
1343 | INIT_LIST_HEAD(&p->pi_state_list); |
1344 | p->pi_state_cache = NULL; |
1345 | #endif |
1346 | /* |
1347 | * sigaltstack should be cleared when sharing the same VM |
1348 | */ |
1349 | if ((clone_flags & (CLONE_VM|CLONE_VFORK)) == CLONE_VM) |
1350 | p->sas_ss_sp = p->sas_ss_size = 0; |
1351 | |
1352 | /* |
1353 | * Syscall tracing and stepping should be turned off in the |
1354 | * child regardless of CLONE_PTRACE. |
1355 | */ |
1356 | user_disable_single_step(p); |
1357 | clear_tsk_thread_flag(p, TIF_SYSCALL_TRACE); |
1358 | #ifdef TIF_SYSCALL_EMU |
1359 | clear_tsk_thread_flag(p, TIF_SYSCALL_EMU); |
1360 | #endif |
1361 | clear_all_latency_tracing(p); |
1362 | |
1363 | /* ok, now we should be set up.. */ |
1364 | if (clone_flags & CLONE_THREAD) |
1365 | p->exit_signal = -1; |
1366 | else if (clone_flags & CLONE_PARENT) |
1367 | p->exit_signal = current->group_leader->exit_signal; |
1368 | else |
1369 | p->exit_signal = (clone_flags & CSIGNAL); |
1370 | |
1371 | p->pdeath_signal = 0; |
1372 | p->exit_state = 0; |
1373 | |
1374 | p->nr_dirtied = 0; |
1375 | p->nr_dirtied_pause = 128 >> (PAGE_SHIFT - 10); |
1376 | p->dirty_paused_when = 0; |
1377 | |
1378 | /* |
1379 | * Ok, make it visible to the rest of the system. |
1380 | * We dont wake it up yet. |
1381 | */ |
1382 | p->group_leader = p; |
1383 | INIT_LIST_HEAD(&p->thread_group); |
1384 | |
1385 | /* Now that the task is set up, run cgroup callbacks if |
1386 | * necessary. We need to run them before the task is visible |
1387 | * on the tasklist. */ |
1388 | cgroup_fork_callbacks(p); |
1389 | cgroup_callbacks_done = 1; |
1390 | |
1391 | /* Need tasklist lock for parent etc handling! */ |
1392 | write_lock_irq(&tasklist_lock); |
1393 | |
1394 | /* CLONE_PARENT re-uses the old parent */ |
1395 | if (clone_flags & (CLONE_PARENT|CLONE_THREAD)) { |
1396 | p->real_parent = current->real_parent; |
1397 | p->parent_exec_id = current->parent_exec_id; |
1398 | } else { |
1399 | p->real_parent = current; |
1400 | p->parent_exec_id = current->self_exec_id; |
1401 | } |
1402 | |
1403 | spin_lock(¤t->sighand->siglock); |
1404 | |
1405 | /* |
1406 | * Process group and session signals need to be delivered to just the |
1407 | * parent before the fork or both the parent and the child after the |
1408 | * fork. Restart if a signal comes in before we add the new process to |
1409 | * it's process group. |
1410 | * A fatal signal pending means that current will exit, so the new |
1411 | * thread can't slip out of an OOM kill (or normal SIGKILL). |
1412 | */ |
1413 | recalc_sigpending(); |
1414 | if (signal_pending(current)) { |
1415 | spin_unlock(¤t->sighand->siglock); |
1416 | write_unlock_irq(&tasklist_lock); |
1417 | retval = -ERESTARTNOINTR; |
1418 | goto bad_fork_free_pid; |
1419 | } |
1420 | |
1421 | if (clone_flags & CLONE_THREAD) { |
1422 | current->signal->nr_threads++; |
1423 | atomic_inc(¤t->signal->live); |
1424 | atomic_inc(¤t->signal->sigcnt); |
1425 | p->group_leader = current->group_leader; |
1426 | list_add_tail_rcu(&p->thread_group, &p->group_leader->thread_group); |
1427 | } |
1428 | |
1429 | if (likely(p->pid)) { |
1430 | ptrace_init_task(p, (clone_flags & CLONE_PTRACE) || trace); |
1431 | |
1432 | if (thread_group_leader(p)) { |
1433 | if (is_child_reaper(pid)) |
1434 | p->nsproxy->pid_ns->child_reaper = p; |
1435 | |
1436 | p->signal->leader_pid = pid; |
1437 | p->signal->tty = tty_kref_get(current->signal->tty); |
1438 | attach_pid(p, PIDTYPE_PGID, task_pgrp(current)); |
1439 | attach_pid(p, PIDTYPE_SID, task_session(current)); |
1440 | list_add_tail(&p->sibling, &p->real_parent->children); |
1441 | list_add_tail_rcu(&p->tasks, &init_task.tasks); |
1442 | __this_cpu_inc(process_counts); |
1443 | } |
1444 | attach_pid(p, PIDTYPE_PID, pid); |
1445 | nr_threads++; |
1446 | } |
1447 | |
1448 | total_forks++; |
1449 | spin_unlock(¤t->sighand->siglock); |
1450 | write_unlock_irq(&tasklist_lock); |
1451 | proc_fork_connector(p); |
1452 | cgroup_post_fork(p); |
1453 | if (clone_flags & CLONE_THREAD) |
1454 | threadgroup_change_end(current); |
1455 | perf_event_fork(p); |
1456 | |
1457 | trace_task_newtask(p, clone_flags); |
1458 | |
1459 | return p; |
1460 | |
1461 | bad_fork_free_pid: |
1462 | if (pid != &init_struct_pid) |
1463 | free_pid(pid); |
1464 | bad_fork_cleanup_io: |
1465 | if (p->io_context) |
1466 | exit_io_context(p); |
1467 | bad_fork_cleanup_namespaces: |
1468 | if (unlikely(clone_flags & CLONE_NEWPID)) |
1469 | pid_ns_release_proc(p->nsproxy->pid_ns); |
1470 | exit_task_namespaces(p); |
1471 | bad_fork_cleanup_mm: |
1472 | if (p->mm) |
1473 | mmput(p->mm); |
1474 | bad_fork_cleanup_signal: |
1475 | if (!(clone_flags & CLONE_THREAD)) |
1476 | free_signal_struct(p->signal); |
1477 | bad_fork_cleanup_sighand: |
1478 | __cleanup_sighand(p->sighand); |
1479 | bad_fork_cleanup_fs: |
1480 | exit_fs(p); /* blocking */ |
1481 | bad_fork_cleanup_files: |
1482 | exit_files(p); /* blocking */ |
1483 | bad_fork_cleanup_semundo: |
1484 | exit_sem(p); |
1485 | bad_fork_cleanup_audit: |
1486 | audit_free(p); |
1487 | bad_fork_cleanup_policy: |
1488 | perf_event_free_task(p); |
1489 | #ifdef CONFIG_NUMA |
1490 | mpol_put(p->mempolicy); |
1491 | bad_fork_cleanup_cgroup: |
1492 | #endif |
1493 | if (clone_flags & CLONE_THREAD) |
1494 | threadgroup_change_end(current); |
1495 | cgroup_exit(p, cgroup_callbacks_done); |
1496 | delayacct_tsk_free(p); |
1497 | module_put(task_thread_info(p)->exec_domain->module); |
1498 | bad_fork_cleanup_count: |
1499 | atomic_dec(&p->cred->user->processes); |
1500 | exit_creds(p); |
1501 | bad_fork_free: |
1502 | free_task(p); |
1503 | fork_out: |
1504 | return ERR_PTR(retval); |
1505 | } |
1506 | |
1507 | noinline struct pt_regs * __cpuinit __attribute__((weak)) idle_regs(struct pt_regs *regs) |
1508 | { |
1509 | memset(regs, 0, sizeof(struct pt_regs)); |
1510 | return regs; |
1511 | } |
1512 | |
1513 | static inline void init_idle_pids(struct pid_link *links) |
1514 | { |
1515 | enum pid_type type; |
1516 | |
1517 | for (type = PIDTYPE_PID; type < PIDTYPE_MAX; ++type) { |
1518 | INIT_HLIST_NODE(&links[type].node); /* not really needed */ |
1519 | links[type].pid = &init_struct_pid; |
1520 | } |
1521 | } |
1522 | |
1523 | struct task_struct * __cpuinit fork_idle(int cpu) |
1524 | { |
1525 | struct task_struct *task; |
1526 | struct pt_regs regs; |
1527 | |
1528 | task = copy_process(CLONE_VM, 0, idle_regs(®s), 0, NULL, |
1529 | &init_struct_pid, 0); |
1530 | if (!IS_ERR(task)) { |
1531 | init_idle_pids(task->pids); |
1532 | init_idle(task, cpu); |
1533 | } |
1534 | |
1535 | return task; |
1536 | } |
1537 | |
1538 | /* |
1539 | * Ok, this is the main fork-routine. |
1540 | * |
1541 | * It copies the process, and if successful kick-starts |
1542 | * it and waits for it to finish using the VM if required. |
1543 | */ |
1544 | long do_fork(unsigned long clone_flags, |
1545 | unsigned long stack_start, |
1546 | struct pt_regs *regs, |
1547 | unsigned long stack_size, |
1548 | int __user *parent_tidptr, |
1549 | int __user *child_tidptr) |
1550 | { |
1551 | struct task_struct *p; |
1552 | int trace = 0; |
1553 | long nr; |
1554 | |
1555 | /* |
1556 | * Do some preliminary argument and permissions checking before we |
1557 | * actually start allocating stuff |
1558 | */ |
1559 | if (clone_flags & CLONE_NEWUSER) { |
1560 | if (clone_flags & CLONE_THREAD) |
1561 | return -EINVAL; |
1562 | /* hopefully this check will go away when userns support is |
1563 | * complete |
1564 | */ |
1565 | if (!capable(CAP_SYS_ADMIN) || !capable(CAP_SETUID) || |
1566 | !capable(CAP_SETGID)) |
1567 | return -EPERM; |
1568 | } |
1569 | |
1570 | /* |
1571 | * Determine whether and which event to report to ptracer. When |
1572 | * called from kernel_thread or CLONE_UNTRACED is explicitly |
1573 | * requested, no event is reported; otherwise, report if the event |
1574 | * for the type of forking is enabled. |
1575 | */ |
1576 | if (likely(user_mode(regs)) && !(clone_flags & CLONE_UNTRACED)) { |
1577 | if (clone_flags & CLONE_VFORK) |
1578 | trace = PTRACE_EVENT_VFORK; |
1579 | else if ((clone_flags & CSIGNAL) != SIGCHLD) |
1580 | trace = PTRACE_EVENT_CLONE; |
1581 | else |
1582 | trace = PTRACE_EVENT_FORK; |
1583 | |
1584 | if (likely(!ptrace_event_enabled(current, trace))) |
1585 | trace = 0; |
1586 | } |
1587 | |
1588 | p = copy_process(clone_flags, stack_start, regs, stack_size, |
1589 | child_tidptr, NULL, trace); |
1590 | /* |
1591 | * Do this prior waking up the new thread - the thread pointer |
1592 | * might get invalid after that point, if the thread exits quickly. |
1593 | */ |
1594 | if (!IS_ERR(p)) { |
1595 | struct completion vfork; |
1596 | |
1597 | trace_sched_process_fork(current, p); |
1598 | |
1599 | nr = task_pid_vnr(p); |
1600 | |
1601 | if (clone_flags & CLONE_PARENT_SETTID) |
1602 | put_user(nr, parent_tidptr); |
1603 | |
1604 | if (clone_flags & CLONE_VFORK) { |
1605 | p->vfork_done = &vfork; |
1606 | init_completion(&vfork); |
1607 | get_task_struct(p); |
1608 | } |
1609 | |
1610 | wake_up_new_task(p); |
1611 | |
1612 | /* forking complete and child started to run, tell ptracer */ |
1613 | if (unlikely(trace)) |
1614 | ptrace_event(trace, nr); |
1615 | |
1616 | if (clone_flags & CLONE_VFORK) { |
1617 | if (!wait_for_vfork_done(p, &vfork)) |
1618 | ptrace_event(PTRACE_EVENT_VFORK_DONE, nr); |
1619 | } |
1620 | } else { |
1621 | nr = PTR_ERR(p); |
1622 | } |
1623 | return nr; |
1624 | } |
1625 | |
1626 | #ifndef ARCH_MIN_MMSTRUCT_ALIGN |
1627 | #define ARCH_MIN_MMSTRUCT_ALIGN 0 |
1628 | #endif |
1629 | |
1630 | static void sighand_ctor(void *data) |
1631 | { |
1632 | struct sighand_struct *sighand = data; |
1633 | |
1634 | spin_lock_init(&sighand->siglock); |
1635 | init_waitqueue_head(&sighand->signalfd_wqh); |
1636 | } |
1637 | |
1638 | void __init proc_caches_init(void) |
1639 | { |
1640 | sighand_cachep = kmem_cache_create("sighand_cache", |
1641 | sizeof(struct sighand_struct), 0, |
1642 | SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_DESTROY_BY_RCU| |
1643 | SLAB_NOTRACK, sighand_ctor); |
1644 | signal_cachep = kmem_cache_create("signal_cache", |
1645 | sizeof(struct signal_struct), 0, |
1646 | SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_NOTRACK, NULL); |
1647 | files_cachep = kmem_cache_create("files_cache", |
1648 | sizeof(struct files_struct), 0, |
1649 | SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_NOTRACK, NULL); |
1650 | fs_cachep = kmem_cache_create("fs_cache", |
1651 | sizeof(struct fs_struct), 0, |
1652 | SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_NOTRACK, NULL); |
1653 | /* |
1654 | * FIXME! The "sizeof(struct mm_struct)" currently includes the |
1655 | * whole struct cpumask for the OFFSTACK case. We could change |
1656 | * this to *only* allocate as much of it as required by the |
1657 | * maximum number of CPU's we can ever have. The cpumask_allocation |
1658 | * is at the end of the structure, exactly for that reason. |
1659 | */ |
1660 | mm_cachep = kmem_cache_create("mm_struct", |
1661 | sizeof(struct mm_struct), ARCH_MIN_MMSTRUCT_ALIGN, |
1662 | SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_NOTRACK, NULL); |
1663 | vm_area_cachep = KMEM_CACHE(vm_area_struct, SLAB_PANIC); |
1664 | mmap_init(); |
1665 | nsproxy_cache_init(); |
1666 | } |
1667 | |
1668 | /* |
1669 | * Check constraints on flags passed to the unshare system call. |
1670 | */ |
1671 | static int check_unshare_flags(unsigned long unshare_flags) |
1672 | { |
1673 | if (unshare_flags & ~(CLONE_THREAD|CLONE_FS|CLONE_NEWNS|CLONE_SIGHAND| |
1674 | CLONE_VM|CLONE_FILES|CLONE_SYSVSEM| |
1675 | CLONE_NEWUTS|CLONE_NEWIPC|CLONE_NEWNET)) |
1676 | return -EINVAL; |
1677 | /* |
1678 | * Not implemented, but pretend it works if there is nothing to |
1679 | * unshare. Note that unsharing CLONE_THREAD or CLONE_SIGHAND |
1680 | * needs to unshare vm. |
1681 | */ |
1682 | if (unshare_flags & (CLONE_THREAD | CLONE_SIGHAND | CLONE_VM)) { |
1683 | /* FIXME: get_task_mm() increments ->mm_users */ |
1684 | if (atomic_read(¤t->mm->mm_users) > 1) |
1685 | return -EINVAL; |
1686 | } |
1687 | |
1688 | return 0; |
1689 | } |
1690 | |
1691 | /* |
1692 | * Unshare the filesystem structure if it is being shared |
1693 | */ |
1694 | static int unshare_fs(unsigned long unshare_flags, struct fs_struct **new_fsp) |
1695 | { |
1696 | struct fs_struct *fs = current->fs; |
1697 | |
1698 | if (!(unshare_flags & CLONE_FS) || !fs) |
1699 | return 0; |
1700 | |
1701 | /* don't need lock here; in the worst case we'll do useless copy */ |
1702 | if (fs->users == 1) |
1703 | return 0; |
1704 | |
1705 | *new_fsp = copy_fs_struct(fs); |
1706 | if (!*new_fsp) |
1707 | return -ENOMEM; |
1708 | |
1709 | return 0; |
1710 | } |
1711 | |
1712 | /* |
1713 | * Unshare file descriptor table if it is being shared |
1714 | */ |
1715 | static int unshare_fd(unsigned long unshare_flags, struct files_struct **new_fdp) |
1716 | { |
1717 | struct files_struct *fd = current->files; |
1718 | int error = 0; |
1719 | |
1720 | if ((unshare_flags & CLONE_FILES) && |
1721 | (fd && atomic_read(&fd->count) > 1)) { |
1722 | *new_fdp = dup_fd(fd, &error); |
1723 | if (!*new_fdp) |
1724 | return error; |
1725 | } |
1726 | |
1727 | return 0; |
1728 | } |
1729 | |
1730 | /* |
1731 | * unshare allows a process to 'unshare' part of the process |
1732 | * context which was originally shared using clone. copy_* |
1733 | * functions used by do_fork() cannot be used here directly |
1734 | * because they modify an inactive task_struct that is being |
1735 | * constructed. Here we are modifying the current, active, |
1736 | * task_struct. |
1737 | */ |
1738 | SYSCALL_DEFINE1(unshare, unsigned long, unshare_flags) |
1739 | { |
1740 | struct fs_struct *fs, *new_fs = NULL; |
1741 | struct files_struct *fd, *new_fd = NULL; |
1742 | struct nsproxy *new_nsproxy = NULL; |
1743 | int do_sysvsem = 0; |
1744 | int err; |
1745 | |
1746 | err = check_unshare_flags(unshare_flags); |
1747 | if (err) |
1748 | goto bad_unshare_out; |
1749 | |
1750 | /* |
1751 | * If unsharing namespace, must also unshare filesystem information. |
1752 | */ |
1753 | if (unshare_flags & CLONE_NEWNS) |
1754 | unshare_flags |= CLONE_FS; |
1755 | /* |
1756 | * CLONE_NEWIPC must also detach from the undolist: after switching |
1757 | * to a new ipc namespace, the semaphore arrays from the old |
1758 | * namespace are unreachable. |
1759 | */ |
1760 | if (unshare_flags & (CLONE_NEWIPC|CLONE_SYSVSEM)) |
1761 | do_sysvsem = 1; |
1762 | err = unshare_fs(unshare_flags, &new_fs); |
1763 | if (err) |
1764 | goto bad_unshare_out; |
1765 | err = unshare_fd(unshare_flags, &new_fd); |
1766 | if (err) |
1767 | goto bad_unshare_cleanup_fs; |
1768 | err = unshare_nsproxy_namespaces(unshare_flags, &new_nsproxy, new_fs); |
1769 | if (err) |
1770 | goto bad_unshare_cleanup_fd; |
1771 | |
1772 | if (new_fs || new_fd || do_sysvsem || new_nsproxy) { |
1773 | if (do_sysvsem) { |
1774 | /* |
1775 | * CLONE_SYSVSEM is equivalent to sys_exit(). |
1776 | */ |
1777 | exit_sem(current); |
1778 | } |
1779 | |
1780 | if (new_nsproxy) { |
1781 | switch_task_namespaces(current, new_nsproxy); |
1782 | new_nsproxy = NULL; |
1783 | } |
1784 | |
1785 | task_lock(current); |
1786 | |
1787 | if (new_fs) { |
1788 | fs = current->fs; |
1789 | spin_lock(&fs->lock); |
1790 | current->fs = new_fs; |
1791 | if (--fs->users) |
1792 | new_fs = NULL; |
1793 | else |
1794 | new_fs = fs; |
1795 | spin_unlock(&fs->lock); |
1796 | } |
1797 | |
1798 | if (new_fd) { |
1799 | fd = current->files; |
1800 | current->files = new_fd; |
1801 | new_fd = fd; |
1802 | } |
1803 | |
1804 | task_unlock(current); |
1805 | } |
1806 | |
1807 | if (new_nsproxy) |
1808 | put_nsproxy(new_nsproxy); |
1809 | |
1810 | bad_unshare_cleanup_fd: |
1811 | if (new_fd) |
1812 | put_files_struct(new_fd); |
1813 | |
1814 | bad_unshare_cleanup_fs: |
1815 | if (new_fs) |
1816 | free_fs_struct(new_fs); |
1817 | |
1818 | bad_unshare_out: |
1819 | return err; |
1820 | } |
1821 | |
1822 | /* |
1823 | * Helper to unshare the files of the current task. |
1824 | * We don't want to expose copy_files internals to |
1825 | * the exec layer of the kernel. |
1826 | */ |
1827 | |
1828 | int unshare_files(struct files_struct **displaced) |
1829 | { |
1830 | struct task_struct *task = current; |
1831 | struct files_struct *copy = NULL; |
1832 | int error; |
1833 | |
1834 | error = unshare_fd(CLONE_FILES, ©); |
1835 | if (error || !copy) { |
1836 | *displaced = NULL; |
1837 | return error; |
1838 | } |
1839 | *displaced = task->files; |
1840 | task_lock(task); |
1841 | task->files = copy; |
1842 | task_unlock(task); |
1843 | return 0; |
1844 | } |
1845 |
Branches:
ben-wpan
ben-wpan-stefan
javiroman/ks7010
jz-2.6.34
jz-2.6.34-rc5
jz-2.6.34-rc6
jz-2.6.34-rc7
jz-2.6.35
jz-2.6.36
jz-2.6.37
jz-2.6.38
jz-2.6.39
jz-3.0
jz-3.1
jz-3.11
jz-3.12
jz-3.13
jz-3.15
jz-3.16
jz-3.18-dt
jz-3.2
jz-3.3
jz-3.4
jz-3.5
jz-3.6
jz-3.6-rc2-pwm
jz-3.9
jz-3.9-clk
jz-3.9-rc8
jz47xx
jz47xx-2.6.38
master
Tags:
od-2011-09-04
od-2011-09-18
v2.6.34-rc5
v2.6.34-rc6
v2.6.34-rc7
v3.9