aboutsummaryrefslogtreecommitdiffstats
path: root/kernel/fork.c
diff options
context:
space:
mode:
Diffstat (limited to 'kernel/fork.c')
-rw-r--r--kernel/fork.c1274
1 files changed, 1274 insertions, 0 deletions
diff --git a/kernel/fork.c b/kernel/fork.c
new file mode 100644
index 000000000000..f42a17f88699
--- /dev/null
+++ b/kernel/fork.c
@@ -0,0 +1,1274 @@
1/*
2 * linux/kernel/fork.c
3 *
4 * Copyright (C) 1991, 1992 Linus Torvalds
5 */
6
7/*
8 * 'fork.c' contains the help-routines for the 'fork' system call
9 * (see also entry.S and others).
10 * Fork is rather simple, once you get the hang of it, but the memory
11 * management can be a bitch. See 'mm/memory.c': 'copy_page_range()'
12 */
13
14#include <linux/config.h>
15#include <linux/slab.h>
16#include <linux/init.h>
17#include <linux/unistd.h>
18#include <linux/smp_lock.h>
19#include <linux/module.h>
20#include <linux/vmalloc.h>
21#include <linux/completion.h>
22#include <linux/namespace.h>
23#include <linux/personality.h>
24#include <linux/mempolicy.h>
25#include <linux/sem.h>
26#include <linux/file.h>
27#include <linux/key.h>
28#include <linux/binfmts.h>
29#include <linux/mman.h>
30#include <linux/fs.h>
31#include <linux/cpu.h>
32#include <linux/cpuset.h>
33#include <linux/security.h>
34#include <linux/swap.h>
35#include <linux/syscalls.h>
36#include <linux/jiffies.h>
37#include <linux/futex.h>
38#include <linux/ptrace.h>
39#include <linux/mount.h>
40#include <linux/audit.h>
41#include <linux/profile.h>
42#include <linux/rmap.h>
43#include <linux/acct.h>
44
45#include <asm/pgtable.h>
46#include <asm/pgalloc.h>
47#include <asm/uaccess.h>
48#include <asm/mmu_context.h>
49#include <asm/cacheflush.h>
50#include <asm/tlbflush.h>
51
52/*
53 * Protected counters by write_lock_irq(&tasklist_lock)
54 */
55unsigned long total_forks; /* Handle normal Linux uptimes. */
56int nr_threads; /* The idle threads do not count.. */
57
58int max_threads; /* tunable limit on nr_threads */
59
60DEFINE_PER_CPU(unsigned long, process_counts) = 0;
61
62 __cacheline_aligned DEFINE_RWLOCK(tasklist_lock); /* outer */
63
64EXPORT_SYMBOL(tasklist_lock);
65
66int nr_processes(void)
67{
68 int cpu;
69 int total = 0;
70
71 for_each_online_cpu(cpu)
72 total += per_cpu(process_counts, cpu);
73
74 return total;
75}
76
77#ifndef __HAVE_ARCH_TASK_STRUCT_ALLOCATOR
78# define alloc_task_struct() kmem_cache_alloc(task_struct_cachep, GFP_KERNEL)
79# define free_task_struct(tsk) kmem_cache_free(task_struct_cachep, (tsk))
80static kmem_cache_t *task_struct_cachep;
81#endif
82
83/* SLAB cache for signal_struct structures (tsk->signal) */
84kmem_cache_t *signal_cachep;
85
86/* SLAB cache for sighand_struct structures (tsk->sighand) */
87kmem_cache_t *sighand_cachep;
88
89/* SLAB cache for files_struct structures (tsk->files) */
90kmem_cache_t *files_cachep;
91
92/* SLAB cache for fs_struct structures (tsk->fs) */
93kmem_cache_t *fs_cachep;
94
95/* SLAB cache for vm_area_struct structures */
96kmem_cache_t *vm_area_cachep;
97
98/* SLAB cache for mm_struct structures (tsk->mm) */
99static kmem_cache_t *mm_cachep;
100
101void free_task(struct task_struct *tsk)
102{
103 free_thread_info(tsk->thread_info);
104 free_task_struct(tsk);
105}
106EXPORT_SYMBOL(free_task);
107
108void __put_task_struct(struct task_struct *tsk)
109{
110 WARN_ON(!(tsk->exit_state & (EXIT_DEAD | EXIT_ZOMBIE)));
111 WARN_ON(atomic_read(&tsk->usage));
112 WARN_ON(tsk == current);
113
114 if (unlikely(tsk->audit_context))
115 audit_free(tsk);
116 security_task_free(tsk);
117 free_uid(tsk->user);
118 put_group_info(tsk->group_info);
119
120 if (!profile_handoff_task(tsk))
121 free_task(tsk);
122}
123
124void __init fork_init(unsigned long mempages)
125{
126#ifndef __HAVE_ARCH_TASK_STRUCT_ALLOCATOR
127#ifndef ARCH_MIN_TASKALIGN
128#define ARCH_MIN_TASKALIGN L1_CACHE_BYTES
129#endif
130 /* create a slab on which task_structs can be allocated */
131 task_struct_cachep =
132 kmem_cache_create("task_struct", sizeof(struct task_struct),
133 ARCH_MIN_TASKALIGN, SLAB_PANIC, NULL, NULL);
134#endif
135
136 /*
137 * The default maximum number of threads is set to a safe
138 * value: the thread structures can take up at most half
139 * of memory.
140 */
141 max_threads = mempages / (8 * THREAD_SIZE / PAGE_SIZE);
142
143 /*
144 * we need to allow at least 20 threads to boot a system
145 */
146 if(max_threads < 20)
147 max_threads = 20;
148
149 init_task.signal->rlim[RLIMIT_NPROC].rlim_cur = max_threads/2;
150 init_task.signal->rlim[RLIMIT_NPROC].rlim_max = max_threads/2;
151 init_task.signal->rlim[RLIMIT_SIGPENDING] =
152 init_task.signal->rlim[RLIMIT_NPROC];
153}
154
155static struct task_struct *dup_task_struct(struct task_struct *orig)
156{
157 struct task_struct *tsk;
158 struct thread_info *ti;
159
160 prepare_to_copy(orig);
161
162 tsk = alloc_task_struct();
163 if (!tsk)
164 return NULL;
165
166 ti = alloc_thread_info(tsk);
167 if (!ti) {
168 free_task_struct(tsk);
169 return NULL;
170 }
171
172 *ti = *orig->thread_info;
173 *tsk = *orig;
174 tsk->thread_info = ti;
175 ti->task = tsk;
176
177 /* One for us, one for whoever does the "release_task()" (usually parent) */
178 atomic_set(&tsk->usage,2);
179 return tsk;
180}
181
182#ifdef CONFIG_MMU
183static inline int dup_mmap(struct mm_struct * mm, struct mm_struct * oldmm)
184{
185 struct vm_area_struct * mpnt, *tmp, **pprev;
186 struct rb_node **rb_link, *rb_parent;
187 int retval;
188 unsigned long charge;
189 struct mempolicy *pol;
190
191 down_write(&oldmm->mmap_sem);
192 flush_cache_mm(current->mm);
193 mm->locked_vm = 0;
194 mm->mmap = NULL;
195 mm->mmap_cache = NULL;
196 mm->free_area_cache = oldmm->mmap_base;
197 mm->map_count = 0;
198 set_mm_counter(mm, rss, 0);
199 set_mm_counter(mm, anon_rss, 0);
200 cpus_clear(mm->cpu_vm_mask);
201 mm->mm_rb = RB_ROOT;
202 rb_link = &mm->mm_rb.rb_node;
203 rb_parent = NULL;
204 pprev = &mm->mmap;
205
206 for (mpnt = current->mm->mmap ; mpnt ; mpnt = mpnt->vm_next) {
207 struct file *file;
208
209 if (mpnt->vm_flags & VM_DONTCOPY) {
210 __vm_stat_account(mm, mpnt->vm_flags, mpnt->vm_file,
211 -vma_pages(mpnt));
212 continue;
213 }
214 charge = 0;
215 if (mpnt->vm_flags & VM_ACCOUNT) {
216 unsigned int len = (mpnt->vm_end - mpnt->vm_start) >> PAGE_SHIFT;
217 if (security_vm_enough_memory(len))
218 goto fail_nomem;
219 charge = len;
220 }
221 tmp = kmem_cache_alloc(vm_area_cachep, SLAB_KERNEL);
222 if (!tmp)
223 goto fail_nomem;
224 *tmp = *mpnt;
225 pol = mpol_copy(vma_policy(mpnt));
226 retval = PTR_ERR(pol);
227 if (IS_ERR(pol))
228 goto fail_nomem_policy;
229 vma_set_policy(tmp, pol);
230 tmp->vm_flags &= ~VM_LOCKED;
231 tmp->vm_mm = mm;
232 tmp->vm_next = NULL;
233 anon_vma_link(tmp);
234 file = tmp->vm_file;
235 if (file) {
236 struct inode *inode = file->f_dentry->d_inode;
237 get_file(file);
238 if (tmp->vm_flags & VM_DENYWRITE)
239 atomic_dec(&inode->i_writecount);
240
241 /* insert tmp into the share list, just after mpnt */
242 spin_lock(&file->f_mapping->i_mmap_lock);
243 tmp->vm_truncate_count = mpnt->vm_truncate_count;
244 flush_dcache_mmap_lock(file->f_mapping);
245 vma_prio_tree_add(tmp, mpnt);
246 flush_dcache_mmap_unlock(file->f_mapping);
247 spin_unlock(&file->f_mapping->i_mmap_lock);
248 }
249
250 /*
251 * Link in the new vma and copy the page table entries:
252 * link in first so that swapoff can see swap entries,
253 * and try_to_unmap_one's find_vma find the new vma.
254 */
255 spin_lock(&mm->page_table_lock);
256 *pprev = tmp;
257 pprev = &tmp->vm_next;
258
259 __vma_link_rb(mm, tmp, rb_link, rb_parent);
260 rb_link = &tmp->vm_rb.rb_right;
261 rb_parent = &tmp->vm_rb;
262
263 mm->map_count++;
264 retval = copy_page_range(mm, current->mm, tmp);
265 spin_unlock(&mm->page_table_lock);
266
267 if (tmp->vm_ops && tmp->vm_ops->open)
268 tmp->vm_ops->open(tmp);
269
270 if (retval)
271 goto out;
272 }
273 retval = 0;
274
275out:
276 flush_tlb_mm(current->mm);
277 up_write(&oldmm->mmap_sem);
278 return retval;
279fail_nomem_policy:
280 kmem_cache_free(vm_area_cachep, tmp);
281fail_nomem:
282 retval = -ENOMEM;
283 vm_unacct_memory(charge);
284 goto out;
285}
286
287static inline int mm_alloc_pgd(struct mm_struct * mm)
288{
289 mm->pgd = pgd_alloc(mm);
290 if (unlikely(!mm->pgd))
291 return -ENOMEM;
292 return 0;
293}
294
295static inline void mm_free_pgd(struct mm_struct * mm)
296{
297 pgd_free(mm->pgd);
298}
299#else
300#define dup_mmap(mm, oldmm) (0)
301#define mm_alloc_pgd(mm) (0)
302#define mm_free_pgd(mm)
303#endif /* CONFIG_MMU */
304
305 __cacheline_aligned_in_smp DEFINE_SPINLOCK(mmlist_lock);
306
307#define allocate_mm() (kmem_cache_alloc(mm_cachep, SLAB_KERNEL))
308#define free_mm(mm) (kmem_cache_free(mm_cachep, (mm)))
309
310#include <linux/init_task.h>
311
312static struct mm_struct * mm_init(struct mm_struct * mm)
313{
314 atomic_set(&mm->mm_users, 1);
315 atomic_set(&mm->mm_count, 1);
316 init_rwsem(&mm->mmap_sem);
317 INIT_LIST_HEAD(&mm->mmlist);
318 mm->core_waiters = 0;
319 mm->nr_ptes = 0;
320 spin_lock_init(&mm->page_table_lock);
321 rwlock_init(&mm->ioctx_list_lock);
322 mm->ioctx_list = NULL;
323 mm->default_kioctx = (struct kioctx)INIT_KIOCTX(mm->default_kioctx, *mm);
324 mm->free_area_cache = TASK_UNMAPPED_BASE;
325
326 if (likely(!mm_alloc_pgd(mm))) {
327 mm->def_flags = 0;
328 return mm;
329 }
330 free_mm(mm);
331 return NULL;
332}
333
334/*
335 * Allocate and initialize an mm_struct.
336 */
337struct mm_struct * mm_alloc(void)
338{
339 struct mm_struct * mm;
340
341 mm = allocate_mm();
342 if (mm) {
343 memset(mm, 0, sizeof(*mm));
344 mm = mm_init(mm);
345 }
346 return mm;
347}
348
349/*
350 * Called when the last reference to the mm
351 * is dropped: either by a lazy thread or by
352 * mmput. Free the page directory and the mm.
353 */
354void fastcall __mmdrop(struct mm_struct *mm)
355{
356 BUG_ON(mm == &init_mm);
357 mm_free_pgd(mm);
358 destroy_context(mm);
359 free_mm(mm);
360}
361
362/*
363 * Decrement the use count and release all resources for an mm.
364 */
365void mmput(struct mm_struct *mm)
366{
367 if (atomic_dec_and_test(&mm->mm_users)) {
368 exit_aio(mm);
369 exit_mmap(mm);
370 if (!list_empty(&mm->mmlist)) {
371 spin_lock(&mmlist_lock);
372 list_del(&mm->mmlist);
373 spin_unlock(&mmlist_lock);
374 }
375 put_swap_token(mm);
376 mmdrop(mm);
377 }
378}
379EXPORT_SYMBOL_GPL(mmput);
380
381/**
382 * get_task_mm - acquire a reference to the task's mm
383 *
384 * Returns %NULL if the task has no mm. Checks PF_BORROWED_MM (meaning
385 * this kernel workthread has transiently adopted a user mm with use_mm,
386 * to do its AIO) is not set and if so returns a reference to it, after
387 * bumping up the use count. User must release the mm via mmput()
388 * after use. Typically used by /proc and ptrace.
389 */
390struct mm_struct *get_task_mm(struct task_struct *task)
391{
392 struct mm_struct *mm;
393
394 task_lock(task);
395 mm = task->mm;
396 if (mm) {
397 if (task->flags & PF_BORROWED_MM)
398 mm = NULL;
399 else
400 atomic_inc(&mm->mm_users);
401 }
402 task_unlock(task);
403 return mm;
404}
405EXPORT_SYMBOL_GPL(get_task_mm);
406
407/* Please note the differences between mmput and mm_release.
408 * mmput is called whenever we stop holding onto a mm_struct,
409 * error success whatever.
410 *
411 * mm_release is called after a mm_struct has been removed
412 * from the current process.
413 *
414 * This difference is important for error handling, when we
415 * only half set up a mm_struct for a new process and need to restore
416 * the old one. Because we mmput the new mm_struct before
417 * restoring the old one. . .
418 * Eric Biederman 10 January 1998
419 */
420void mm_release(struct task_struct *tsk, struct mm_struct *mm)
421{
422 struct completion *vfork_done = tsk->vfork_done;
423
424 /* Get rid of any cached register state */
425 deactivate_mm(tsk, mm);
426
427 /* notify parent sleeping on vfork() */
428 if (vfork_done) {
429 tsk->vfork_done = NULL;
430 complete(vfork_done);
431 }
432 if (tsk->clear_child_tid && atomic_read(&mm->mm_users) > 1) {
433 u32 __user * tidptr = tsk->clear_child_tid;
434 tsk->clear_child_tid = NULL;
435
436 /*
437 * We don't check the error code - if userspace has
438 * not set up a proper pointer then tough luck.
439 */
440 put_user(0, tidptr);
441 sys_futex(tidptr, FUTEX_WAKE, 1, NULL, NULL, 0);
442 }
443}
444
445static int copy_mm(unsigned long clone_flags, struct task_struct * tsk)
446{
447 struct mm_struct * mm, *oldmm;
448 int retval;
449
450 tsk->min_flt = tsk->maj_flt = 0;
451 tsk->nvcsw = tsk->nivcsw = 0;
452
453 tsk->mm = NULL;
454 tsk->active_mm = NULL;
455
456 /*
457 * Are we cloning a kernel thread?
458 *
459 * We need to steal a active VM for that..
460 */
461 oldmm = current->mm;
462 if (!oldmm)
463 return 0;
464
465 if (clone_flags & CLONE_VM) {
466 atomic_inc(&oldmm->mm_users);
467 mm = oldmm;
468 /*
469 * There are cases where the PTL is held to ensure no
470 * new threads start up in user mode using an mm, which
471 * allows optimizing out ipis; the tlb_gather_mmu code
472 * is an example.
473 */
474 spin_unlock_wait(&oldmm->page_table_lock);
475 goto good_mm;
476 }
477
478 retval = -ENOMEM;
479 mm = allocate_mm();
480 if (!mm)
481 goto fail_nomem;
482
483 /* Copy the current MM stuff.. */
484 memcpy(mm, oldmm, sizeof(*mm));
485 if (!mm_init(mm))
486 goto fail_nomem;
487
488 if (init_new_context(tsk,mm))
489 goto fail_nocontext;
490
491 retval = dup_mmap(mm, oldmm);
492 if (retval)
493 goto free_pt;
494
495 mm->hiwater_rss = get_mm_counter(mm,rss);
496 mm->hiwater_vm = mm->total_vm;
497
498good_mm:
499 tsk->mm = mm;
500 tsk->active_mm = mm;
501 return 0;
502
503free_pt:
504 mmput(mm);
505fail_nomem:
506 return retval;
507
508fail_nocontext:
509 /*
510 * If init_new_context() failed, we cannot use mmput() to free the mm
511 * because it calls destroy_context()
512 */
513 mm_free_pgd(mm);
514 free_mm(mm);
515 return retval;
516}
517
518static inline struct fs_struct *__copy_fs_struct(struct fs_struct *old)
519{
520 struct fs_struct *fs = kmem_cache_alloc(fs_cachep, GFP_KERNEL);
521 /* We don't need to lock fs - think why ;-) */
522 if (fs) {
523 atomic_set(&fs->count, 1);
524 rwlock_init(&fs->lock);
525 fs->umask = old->umask;
526 read_lock(&old->lock);
527 fs->rootmnt = mntget(old->rootmnt);
528 fs->root = dget(old->root);
529 fs->pwdmnt = mntget(old->pwdmnt);
530 fs->pwd = dget(old->pwd);
531 if (old->altroot) {
532 fs->altrootmnt = mntget(old->altrootmnt);
533 fs->altroot = dget(old->altroot);
534 } else {
535 fs->altrootmnt = NULL;
536 fs->altroot = NULL;
537 }
538 read_unlock(&old->lock);
539 }
540 return fs;
541}
542
543struct fs_struct *copy_fs_struct(struct fs_struct *old)
544{
545 return __copy_fs_struct(old);
546}
547
548EXPORT_SYMBOL_GPL(copy_fs_struct);
549
550static inline int copy_fs(unsigned long clone_flags, struct task_struct * tsk)
551{
552 if (clone_flags & CLONE_FS) {
553 atomic_inc(&current->fs->count);
554 return 0;
555 }
556 tsk->fs = __copy_fs_struct(current->fs);
557 if (!tsk->fs)
558 return -ENOMEM;
559 return 0;
560}
561
562static int count_open_files(struct files_struct *files, int size)
563{
564 int i;
565
566 /* Find the last open fd */
567 for (i = size/(8*sizeof(long)); i > 0; ) {
568 if (files->open_fds->fds_bits[--i])
569 break;
570 }
571 i = (i+1) * 8 * sizeof(long);
572 return i;
573}
574
575static int copy_files(unsigned long clone_flags, struct task_struct * tsk)
576{
577 struct files_struct *oldf, *newf;
578 struct file **old_fds, **new_fds;
579 int open_files, size, i, error = 0, expand;
580
581 /*
582 * A background process may not have any files ...
583 */
584 oldf = current->files;
585 if (!oldf)
586 goto out;
587
588 if (clone_flags & CLONE_FILES) {
589 atomic_inc(&oldf->count);
590 goto out;
591 }
592
593 /*
594 * Note: we may be using current for both targets (See exec.c)
595 * This works because we cache current->files (old) as oldf. Don't
596 * break this.
597 */
598 tsk->files = NULL;
599 error = -ENOMEM;
600 newf = kmem_cache_alloc(files_cachep, SLAB_KERNEL);
601 if (!newf)
602 goto out;
603
604 atomic_set(&newf->count, 1);
605
606 spin_lock_init(&newf->file_lock);
607 newf->next_fd = 0;
608 newf->max_fds = NR_OPEN_DEFAULT;
609 newf->max_fdset = __FD_SETSIZE;
610 newf->close_on_exec = &newf->close_on_exec_init;
611 newf->open_fds = &newf->open_fds_init;
612 newf->fd = &newf->fd_array[0];
613
614 spin_lock(&oldf->file_lock);
615
616 open_files = count_open_files(oldf, oldf->max_fdset);
617 expand = 0;
618
619 /*
620 * Check whether we need to allocate a larger fd array or fd set.
621 * Note: we're not a clone task, so the open count won't change.
622 */
623 if (open_files > newf->max_fdset) {
624 newf->max_fdset = 0;
625 expand = 1;
626 }
627 if (open_files > newf->max_fds) {
628 newf->max_fds = 0;
629 expand = 1;
630 }
631
632 /* if the old fdset gets grown now, we'll only copy up to "size" fds */
633 if (expand) {
634 spin_unlock(&oldf->file_lock);
635 spin_lock(&newf->file_lock);
636 error = expand_files(newf, open_files-1);
637 spin_unlock(&newf->file_lock);
638 if (error < 0)
639 goto out_release;
640 spin_lock(&oldf->file_lock);
641 }
642
643 old_fds = oldf->fd;
644 new_fds = newf->fd;
645
646 memcpy(newf->open_fds->fds_bits, oldf->open_fds->fds_bits, open_files/8);
647 memcpy(newf->close_on_exec->fds_bits, oldf->close_on_exec->fds_bits, open_files/8);
648
649 for (i = open_files; i != 0; i--) {
650 struct file *f = *old_fds++;
651 if (f) {
652 get_file(f);
653 } else {
654 /*
655 * The fd may be claimed in the fd bitmap but not yet
656 * instantiated in the files array if a sibling thread
657 * is partway through open(). So make sure that this
658 * fd is available to the new process.
659 */
660 FD_CLR(open_files - i, newf->open_fds);
661 }
662 *new_fds++ = f;
663 }
664 spin_unlock(&oldf->file_lock);
665
666 /* compute the remainder to be cleared */
667 size = (newf->max_fds - open_files) * sizeof(struct file *);
668
669 /* This is long word aligned thus could use a optimized version */
670 memset(new_fds, 0, size);
671
672 if (newf->max_fdset > open_files) {
673 int left = (newf->max_fdset-open_files)/8;
674 int start = open_files / (8 * sizeof(unsigned long));
675
676 memset(&newf->open_fds->fds_bits[start], 0, left);
677 memset(&newf->close_on_exec->fds_bits[start], 0, left);
678 }
679
680 tsk->files = newf;
681 error = 0;
682out:
683 return error;
684
685out_release:
686 free_fdset (newf->close_on_exec, newf->max_fdset);
687 free_fdset (newf->open_fds, newf->max_fdset);
688 free_fd_array(newf->fd, newf->max_fds);
689 kmem_cache_free(files_cachep, newf);
690 goto out;
691}
692
693/*
694 * Helper to unshare the files of the current task.
695 * We don't want to expose copy_files internals to
696 * the exec layer of the kernel.
697 */
698
699int unshare_files(void)
700{
701 struct files_struct *files = current->files;
702 int rc;
703
704 if(!files)
705 BUG();
706
707 /* This can race but the race causes us to copy when we don't
708 need to and drop the copy */
709 if(atomic_read(&files->count) == 1)
710 {
711 atomic_inc(&files->count);
712 return 0;
713 }
714 rc = copy_files(0, current);
715 if(rc)
716 current->files = files;
717 return rc;
718}
719
720EXPORT_SYMBOL(unshare_files);
721
722static inline int copy_sighand(unsigned long clone_flags, struct task_struct * tsk)
723{
724 struct sighand_struct *sig;
725
726 if (clone_flags & (CLONE_SIGHAND | CLONE_THREAD)) {
727 atomic_inc(&current->sighand->count);
728 return 0;
729 }
730 sig = kmem_cache_alloc(sighand_cachep, GFP_KERNEL);
731 tsk->sighand = sig;
732 if (!sig)
733 return -ENOMEM;
734 spin_lock_init(&sig->siglock);
735 atomic_set(&sig->count, 1);
736 memcpy(sig->action, current->sighand->action, sizeof(sig->action));
737 return 0;
738}
739
740static inline int copy_signal(unsigned long clone_flags, struct task_struct * tsk)
741{
742 struct signal_struct *sig;
743 int ret;
744
745 if (clone_flags & CLONE_THREAD) {
746 atomic_inc(&current->signal->count);
747 atomic_inc(&current->signal->live);
748 return 0;
749 }
750 sig = kmem_cache_alloc(signal_cachep, GFP_KERNEL);
751 tsk->signal = sig;
752 if (!sig)
753 return -ENOMEM;
754
755 ret = copy_thread_group_keys(tsk);
756 if (ret < 0) {
757 kmem_cache_free(signal_cachep, sig);
758 return ret;
759 }
760
761 atomic_set(&sig->count, 1);
762 atomic_set(&sig->live, 1);
763 init_waitqueue_head(&sig->wait_chldexit);
764 sig->flags = 0;
765 sig->group_exit_code = 0;
766 sig->group_exit_task = NULL;
767 sig->group_stop_count = 0;
768 sig->curr_target = NULL;
769 init_sigpending(&sig->shared_pending);
770 INIT_LIST_HEAD(&sig->posix_timers);
771
772 sig->it_real_value = sig->it_real_incr = 0;
773 sig->real_timer.function = it_real_fn;
774 sig->real_timer.data = (unsigned long) tsk;
775 init_timer(&sig->real_timer);
776
777 sig->it_virt_expires = cputime_zero;
778 sig->it_virt_incr = cputime_zero;
779 sig->it_prof_expires = cputime_zero;
780 sig->it_prof_incr = cputime_zero;
781
782 sig->tty = current->signal->tty;
783 sig->pgrp = process_group(current);
784 sig->session = current->signal->session;
785 sig->leader = 0; /* session leadership doesn't inherit */
786 sig->tty_old_pgrp = 0;
787
788 sig->utime = sig->stime = sig->cutime = sig->cstime = cputime_zero;
789 sig->nvcsw = sig->nivcsw = sig->cnvcsw = sig->cnivcsw = 0;
790 sig->min_flt = sig->maj_flt = sig->cmin_flt = sig->cmaj_flt = 0;
791 sig->sched_time = 0;
792 INIT_LIST_HEAD(&sig->cpu_timers[0]);
793 INIT_LIST_HEAD(&sig->cpu_timers[1]);
794 INIT_LIST_HEAD(&sig->cpu_timers[2]);
795
796 task_lock(current->group_leader);
797 memcpy(sig->rlim, current->signal->rlim, sizeof sig->rlim);
798 task_unlock(current->group_leader);
799
800 if (sig->rlim[RLIMIT_CPU].rlim_cur != RLIM_INFINITY) {
801 /*
802 * New sole thread in the process gets an expiry time
803 * of the whole CPU time limit.
804 */
805 tsk->it_prof_expires =
806 secs_to_cputime(sig->rlim[RLIMIT_CPU].rlim_cur);
807 }
808
809 return 0;
810}
811
812static inline void copy_flags(unsigned long clone_flags, struct task_struct *p)
813{
814 unsigned long new_flags = p->flags;
815
816 new_flags &= ~PF_SUPERPRIV;
817 new_flags |= PF_FORKNOEXEC;
818 if (!(clone_flags & CLONE_PTRACE))
819 p->ptrace = 0;
820 p->flags = new_flags;
821}
822
823asmlinkage long sys_set_tid_address(int __user *tidptr)
824{
825 current->clear_child_tid = tidptr;
826
827 return current->pid;
828}
829
830/*
831 * This creates a new process as a copy of the old one,
832 * but does not actually start it yet.
833 *
834 * It copies the registers, and all the appropriate
835 * parts of the process environment (as per the clone
836 * flags). The actual kick-off is left to the caller.
837 */
838static task_t *copy_process(unsigned long clone_flags,
839 unsigned long stack_start,
840 struct pt_regs *regs,
841 unsigned long stack_size,
842 int __user *parent_tidptr,
843 int __user *child_tidptr,
844 int pid)
845{
846 int retval;
847 struct task_struct *p = NULL;
848
849 if ((clone_flags & (CLONE_NEWNS|CLONE_FS)) == (CLONE_NEWNS|CLONE_FS))
850 return ERR_PTR(-EINVAL);
851
852 /*
853 * Thread groups must share signals as well, and detached threads
854 * can only be started up within the thread group.
855 */
856 if ((clone_flags & CLONE_THREAD) && !(clone_flags & CLONE_SIGHAND))
857 return ERR_PTR(-EINVAL);
858
859 /*
860 * Shared signal handlers imply shared VM. By way of the above,
861 * thread groups also imply shared VM. Blocking this case allows
862 * for various simplifications in other code.
863 */
864 if ((clone_flags & CLONE_SIGHAND) && !(clone_flags & CLONE_VM))
865 return ERR_PTR(-EINVAL);
866
867 retval = security_task_create(clone_flags);
868 if (retval)
869 goto fork_out;
870
871 retval = -ENOMEM;
872 p = dup_task_struct(current);
873 if (!p)
874 goto fork_out;
875
876 retval = -EAGAIN;
877 if (atomic_read(&p->user->processes) >=
878 p->signal->rlim[RLIMIT_NPROC].rlim_cur) {
879 if (!capable(CAP_SYS_ADMIN) && !capable(CAP_SYS_RESOURCE) &&
880 p->user != &root_user)
881 goto bad_fork_free;
882 }
883
884 atomic_inc(&p->user->__count);
885 atomic_inc(&p->user->processes);
886 get_group_info(p->group_info);
887
888 /*
889 * If multiple threads are within copy_process(), then this check
890 * triggers too late. This doesn't hurt, the check is only there
891 * to stop root fork bombs.
892 */
893 if (nr_threads >= max_threads)
894 goto bad_fork_cleanup_count;
895
896 if (!try_module_get(p->thread_info->exec_domain->module))
897 goto bad_fork_cleanup_count;
898
899 if (p->binfmt && !try_module_get(p->binfmt->module))
900 goto bad_fork_cleanup_put_domain;
901
902 p->did_exec = 0;
903 copy_flags(clone_flags, p);
904 p->pid = pid;
905 retval = -EFAULT;
906 if (clone_flags & CLONE_PARENT_SETTID)
907 if (put_user(p->pid, parent_tidptr))
908 goto bad_fork_cleanup;
909
910 p->proc_dentry = NULL;
911
912 INIT_LIST_HEAD(&p->children);
913 INIT_LIST_HEAD(&p->sibling);
914 p->vfork_done = NULL;
915 spin_lock_init(&p->alloc_lock);
916 spin_lock_init(&p->proc_lock);
917
918 clear_tsk_thread_flag(p, TIF_SIGPENDING);
919 init_sigpending(&p->pending);
920
921 p->utime = cputime_zero;
922 p->stime = cputime_zero;
923 p->sched_time = 0;
924 p->rchar = 0; /* I/O counter: bytes read */
925 p->wchar = 0; /* I/O counter: bytes written */
926 p->syscr = 0; /* I/O counter: read syscalls */
927 p->syscw = 0; /* I/O counter: write syscalls */
928 acct_clear_integrals(p);
929
930 p->it_virt_expires = cputime_zero;
931 p->it_prof_expires = cputime_zero;
932 p->it_sched_expires = 0;
933 INIT_LIST_HEAD(&p->cpu_timers[0]);
934 INIT_LIST_HEAD(&p->cpu_timers[1]);
935 INIT_LIST_HEAD(&p->cpu_timers[2]);
936
937 p->lock_depth = -1; /* -1 = no lock */
938 do_posix_clock_monotonic_gettime(&p->start_time);
939 p->security = NULL;
940 p->io_context = NULL;
941 p->io_wait = NULL;
942 p->audit_context = NULL;
943#ifdef CONFIG_NUMA
944 p->mempolicy = mpol_copy(p->mempolicy);
945 if (IS_ERR(p->mempolicy)) {
946 retval = PTR_ERR(p->mempolicy);
947 p->mempolicy = NULL;
948 goto bad_fork_cleanup;
949 }
950#endif
951
952 p->tgid = p->pid;
953 if (clone_flags & CLONE_THREAD)
954 p->tgid = current->tgid;
955
956 if ((retval = security_task_alloc(p)))
957 goto bad_fork_cleanup_policy;
958 if ((retval = audit_alloc(p)))
959 goto bad_fork_cleanup_security;
960 /* copy all the process information */
961 if ((retval = copy_semundo(clone_flags, p)))
962 goto bad_fork_cleanup_audit;
963 if ((retval = copy_files(clone_flags, p)))
964 goto bad_fork_cleanup_semundo;
965 if ((retval = copy_fs(clone_flags, p)))
966 goto bad_fork_cleanup_files;
967 if ((retval = copy_sighand(clone_flags, p)))
968 goto bad_fork_cleanup_fs;
969 if ((retval = copy_signal(clone_flags, p)))
970 goto bad_fork_cleanup_sighand;
971 if ((retval = copy_mm(clone_flags, p)))
972 goto bad_fork_cleanup_signal;
973 if ((retval = copy_keys(clone_flags, p)))
974 goto bad_fork_cleanup_mm;
975 if ((retval = copy_namespace(clone_flags, p)))
976 goto bad_fork_cleanup_keys;
977 retval = copy_thread(0, clone_flags, stack_start, stack_size, p, regs);
978 if (retval)
979 goto bad_fork_cleanup_namespace;
980
981 p->set_child_tid = (clone_flags & CLONE_CHILD_SETTID) ? child_tidptr : NULL;
982 /*
983 * Clear TID on mm_release()?
984 */
985 p->clear_child_tid = (clone_flags & CLONE_CHILD_CLEARTID) ? child_tidptr: NULL;
986
987 /*
988 * Syscall tracing should be turned off in the child regardless
989 * of CLONE_PTRACE.
990 */
991 clear_tsk_thread_flag(p, TIF_SYSCALL_TRACE);
992
993 /* Our parent execution domain becomes current domain
994 These must match for thread signalling to apply */
995
996 p->parent_exec_id = p->self_exec_id;
997
998 /* ok, now we should be set up.. */
999 p->exit_signal = (clone_flags & CLONE_THREAD) ? -1 : (clone_flags & CSIGNAL);
1000 p->pdeath_signal = 0;
1001 p->exit_state = 0;
1002
1003 /* Perform scheduler related setup */
1004 sched_fork(p);
1005
1006 /*
1007 * Ok, make it visible to the rest of the system.
1008 * We dont wake it up yet.
1009 */
1010 p->group_leader = p;
1011 INIT_LIST_HEAD(&p->ptrace_children);
1012 INIT_LIST_HEAD(&p->ptrace_list);
1013
1014 /* Need tasklist lock for parent etc handling! */
1015 write_lock_irq(&tasklist_lock);
1016
1017 /*
1018 * The task hasn't been attached yet, so cpus_allowed mask cannot
1019 * have changed. The cpus_allowed mask of the parent may have
1020 * changed after it was copied first time, and it may then move to
1021 * another CPU - so we re-copy it here and set the child's CPU to
1022 * the parent's CPU. This avoids alot of nasty races.
1023 */
1024 p->cpus_allowed = current->cpus_allowed;
1025 set_task_cpu(p, smp_processor_id());
1026
1027 /*
1028 * Check for pending SIGKILL! The new thread should not be allowed
1029 * to slip out of an OOM kill. (or normal SIGKILL.)
1030 */
1031 if (sigismember(&current->pending.signal, SIGKILL)) {
1032 write_unlock_irq(&tasklist_lock);
1033 retval = -EINTR;
1034 goto bad_fork_cleanup_namespace;
1035 }
1036
1037 /* CLONE_PARENT re-uses the old parent */
1038 if (clone_flags & (CLONE_PARENT|CLONE_THREAD))
1039 p->real_parent = current->real_parent;
1040 else
1041 p->real_parent = current;
1042 p->parent = p->real_parent;
1043
1044 if (clone_flags & CLONE_THREAD) {
1045 spin_lock(&current->sighand->siglock);
1046 /*
1047 * Important: if an exit-all has been started then
1048 * do not create this new thread - the whole thread
1049 * group is supposed to exit anyway.
1050 */
1051 if (current->signal->flags & SIGNAL_GROUP_EXIT) {
1052 spin_unlock(&current->sighand->siglock);
1053 write_unlock_irq(&tasklist_lock);
1054 retval = -EAGAIN;
1055 goto bad_fork_cleanup_namespace;
1056 }
1057 p->group_leader = current->group_leader;
1058
1059 if (current->signal->group_stop_count > 0) {
1060 /*
1061 * There is an all-stop in progress for the group.
1062 * We ourselves will stop as soon as we check signals.
1063 * Make the new thread part of that group stop too.
1064 */
1065 current->signal->group_stop_count++;
1066 set_tsk_thread_flag(p, TIF_SIGPENDING);
1067 }
1068
1069 if (!cputime_eq(current->signal->it_virt_expires,
1070 cputime_zero) ||
1071 !cputime_eq(current->signal->it_prof_expires,
1072 cputime_zero) ||
1073 current->signal->rlim[RLIMIT_CPU].rlim_cur != RLIM_INFINITY ||
1074 !list_empty(&current->signal->cpu_timers[0]) ||
1075 !list_empty(&current->signal->cpu_timers[1]) ||
1076 !list_empty(&current->signal->cpu_timers[2])) {
1077 /*
1078 * Have child wake up on its first tick to check
1079 * for process CPU timers.
1080 */
1081 p->it_prof_expires = jiffies_to_cputime(1);
1082 }
1083
1084 spin_unlock(&current->sighand->siglock);
1085 }
1086
1087 SET_LINKS(p);
1088 if (unlikely(p->ptrace & PT_PTRACED))
1089 __ptrace_link(p, current->parent);
1090
1091 cpuset_fork(p);
1092
1093 attach_pid(p, PIDTYPE_PID, p->pid);
1094 attach_pid(p, PIDTYPE_TGID, p->tgid);
1095 if (thread_group_leader(p)) {
1096 attach_pid(p, PIDTYPE_PGID, process_group(p));
1097 attach_pid(p, PIDTYPE_SID, p->signal->session);
1098 if (p->pid)
1099 __get_cpu_var(process_counts)++;
1100 }
1101
1102 nr_threads++;
1103 total_forks++;
1104 write_unlock_irq(&tasklist_lock);
1105 retval = 0;
1106
1107fork_out:
1108 if (retval)
1109 return ERR_PTR(retval);
1110 return p;
1111
1112bad_fork_cleanup_namespace:
1113 exit_namespace(p);
1114bad_fork_cleanup_keys:
1115 exit_keys(p);
1116bad_fork_cleanup_mm:
1117 if (p->mm)
1118 mmput(p->mm);
1119bad_fork_cleanup_signal:
1120 exit_signal(p);
1121bad_fork_cleanup_sighand:
1122 exit_sighand(p);
1123bad_fork_cleanup_fs:
1124 exit_fs(p); /* blocking */
1125bad_fork_cleanup_files:
1126 exit_files(p); /* blocking */
1127bad_fork_cleanup_semundo:
1128 exit_sem(p);
1129bad_fork_cleanup_audit:
1130 audit_free(p);
1131bad_fork_cleanup_security:
1132 security_task_free(p);
1133bad_fork_cleanup_policy:
1134#ifdef CONFIG_NUMA
1135 mpol_free(p->mempolicy);
1136#endif
1137bad_fork_cleanup:
1138 if (p->binfmt)
1139 module_put(p->binfmt->module);
1140bad_fork_cleanup_put_domain:
1141 module_put(p->thread_info->exec_domain->module);
1142bad_fork_cleanup_count:
1143 put_group_info(p->group_info);
1144 atomic_dec(&p->user->processes);
1145 free_uid(p->user);
1146bad_fork_free:
1147 free_task(p);
1148 goto fork_out;
1149}
1150
1151struct pt_regs * __devinit __attribute__((weak)) idle_regs(struct pt_regs *regs)
1152{
1153 memset(regs, 0, sizeof(struct pt_regs));
1154 return regs;
1155}
1156
1157task_t * __devinit fork_idle(int cpu)
1158{
1159 task_t *task;
1160 struct pt_regs regs;
1161
1162 task = copy_process(CLONE_VM, 0, idle_regs(&regs), 0, NULL, NULL, 0);
1163 if (!task)
1164 return ERR_PTR(-ENOMEM);
1165 init_idle(task, cpu);
1166 unhash_process(task);
1167 return task;
1168}
1169
1170static inline int fork_traceflag (unsigned clone_flags)
1171{
1172 if (clone_flags & CLONE_UNTRACED)
1173 return 0;
1174 else if (clone_flags & CLONE_VFORK) {
1175 if (current->ptrace & PT_TRACE_VFORK)
1176 return PTRACE_EVENT_VFORK;
1177 } else if ((clone_flags & CSIGNAL) != SIGCHLD) {
1178 if (current->ptrace & PT_TRACE_CLONE)
1179 return PTRACE_EVENT_CLONE;
1180 } else if (current->ptrace & PT_TRACE_FORK)
1181 return PTRACE_EVENT_FORK;
1182
1183 return 0;
1184}
1185
1186/*
1187 * Ok, this is the main fork-routine.
1188 *
1189 * It copies the process, and if successful kick-starts
1190 * it and waits for it to finish using the VM if required.
1191 */
1192long do_fork(unsigned long clone_flags,
1193 unsigned long stack_start,
1194 struct pt_regs *regs,
1195 unsigned long stack_size,
1196 int __user *parent_tidptr,
1197 int __user *child_tidptr)
1198{
1199 struct task_struct *p;
1200 int trace = 0;
1201 long pid = alloc_pidmap();
1202
1203 if (pid < 0)
1204 return -EAGAIN;
1205 if (unlikely(current->ptrace)) {
1206 trace = fork_traceflag (clone_flags);
1207 if (trace)
1208 clone_flags |= CLONE_PTRACE;
1209 }
1210
1211 p = copy_process(clone_flags, stack_start, regs, stack_size, parent_tidptr, child_tidptr, pid);
1212 /*
1213 * Do this prior waking up the new thread - the thread pointer
1214 * might get invalid after that point, if the thread exits quickly.
1215 */
1216 if (!IS_ERR(p)) {
1217 struct completion vfork;
1218
1219 if (clone_flags & CLONE_VFORK) {
1220 p->vfork_done = &vfork;
1221 init_completion(&vfork);
1222 }
1223
1224 if ((p->ptrace & PT_PTRACED) || (clone_flags & CLONE_STOPPED)) {
1225 /*
1226 * We'll start up with an immediate SIGSTOP.
1227 */
1228 sigaddset(&p->pending.signal, SIGSTOP);
1229 set_tsk_thread_flag(p, TIF_SIGPENDING);
1230 }
1231
1232 if (!(clone_flags & CLONE_STOPPED))
1233 wake_up_new_task(p, clone_flags);
1234 else
1235 p->state = TASK_STOPPED;
1236
1237 if (unlikely (trace)) {
1238 current->ptrace_message = pid;
1239 ptrace_notify ((trace << 8) | SIGTRAP);
1240 }
1241
1242 if (clone_flags & CLONE_VFORK) {
1243 wait_for_completion(&vfork);
1244 if (unlikely (current->ptrace & PT_TRACE_VFORK_DONE))
1245 ptrace_notify ((PTRACE_EVENT_VFORK_DONE << 8) | SIGTRAP);
1246 }
1247 } else {
1248 free_pidmap(pid);
1249 pid = PTR_ERR(p);
1250 }
1251 return pid;
1252}
1253
1254void __init proc_caches_init(void)
1255{
1256 sighand_cachep = kmem_cache_create("sighand_cache",
1257 sizeof(struct sighand_struct), 0,
1258 SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL, NULL);
1259 signal_cachep = kmem_cache_create("signal_cache",
1260 sizeof(struct signal_struct), 0,
1261 SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL, NULL);
1262 files_cachep = kmem_cache_create("files_cache",
1263 sizeof(struct files_struct), 0,
1264 SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL, NULL);
1265 fs_cachep = kmem_cache_create("fs_cache",
1266 sizeof(struct fs_struct), 0,
1267 SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL, NULL);
1268 vm_area_cachep = kmem_cache_create("vm_area_struct",
1269 sizeof(struct vm_area_struct), 0,
1270 SLAB_PANIC, NULL, NULL);
1271 mm_cachep = kmem_cache_create("mm_struct",
1272 sizeof(struct mm_struct), 0,
1273 SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL, NULL);
1274}
generated by cgit v1.2.2 (git 2.25.0) at 2024-11-26 06:50:26 -0500