Linux-2.6.12-rc2
[linux-3.10.git] / kernel / fork.c
1 /*
2  *  linux/kernel/fork.c
3  *
4  *  Copyright (C) 1991, 1992  Linus Torvalds
5  */
6
7 /*
8  *  'fork.c' contains the help-routines for the 'fork' system call
9  * (see also entry.S and others).
10  * Fork is rather simple, once you get the hang of it, but the memory
11  * management can be a bitch. See 'mm/memory.c': 'copy_page_range()'
12  */
13
14 #include <linux/config.h>
15 #include <linux/slab.h>
16 #include <linux/init.h>
17 #include <linux/unistd.h>
18 #include <linux/smp_lock.h>
19 #include <linux/module.h>
20 #include <linux/vmalloc.h>
21 #include <linux/completion.h>
22 #include <linux/namespace.h>
23 #include <linux/personality.h>
24 #include <linux/mempolicy.h>
25 #include <linux/sem.h>
26 #include <linux/file.h>
27 #include <linux/key.h>
28 #include <linux/binfmts.h>
29 #include <linux/mman.h>
30 #include <linux/fs.h>
31 #include <linux/cpu.h>
32 #include <linux/cpuset.h>
33 #include <linux/security.h>
34 #include <linux/swap.h>
35 #include <linux/syscalls.h>
36 #include <linux/jiffies.h>
37 #include <linux/futex.h>
38 #include <linux/ptrace.h>
39 #include <linux/mount.h>
40 #include <linux/audit.h>
41 #include <linux/profile.h>
42 #include <linux/rmap.h>
43 #include <linux/acct.h>
44
45 #include <asm/pgtable.h>
46 #include <asm/pgalloc.h>
47 #include <asm/uaccess.h>
48 #include <asm/mmu_context.h>
49 #include <asm/cacheflush.h>
50 #include <asm/tlbflush.h>
51
52 /*
53  * Protected counters by write_lock_irq(&tasklist_lock)
54  */
55 unsigned long total_forks;      /* Handle normal Linux uptimes. */
56 int nr_threads;                 /* The idle threads do not count.. */
57
58 int max_threads;                /* tunable limit on nr_threads */
59
60 DEFINE_PER_CPU(unsigned long, process_counts) = 0;
61
62  __cacheline_aligned DEFINE_RWLOCK(tasklist_lock);  /* outer */
63
64 EXPORT_SYMBOL(tasklist_lock);
65
66 int nr_processes(void)
67 {
68         int cpu;
69         int total = 0;
70
71         for_each_online_cpu(cpu)
72                 total += per_cpu(process_counts, cpu);
73
74         return total;
75 }
76
77 #ifndef __HAVE_ARCH_TASK_STRUCT_ALLOCATOR
78 # define alloc_task_struct()    kmem_cache_alloc(task_struct_cachep, GFP_KERNEL)
79 # define free_task_struct(tsk)  kmem_cache_free(task_struct_cachep, (tsk))
80 static kmem_cache_t *task_struct_cachep;
81 #endif
82
83 /* SLAB cache for signal_struct structures (tsk->signal) */
84 kmem_cache_t *signal_cachep;
85
86 /* SLAB cache for sighand_struct structures (tsk->sighand) */
87 kmem_cache_t *sighand_cachep;
88
89 /* SLAB cache for files_struct structures (tsk->files) */
90 kmem_cache_t *files_cachep;
91
92 /* SLAB cache for fs_struct structures (tsk->fs) */
93 kmem_cache_t *fs_cachep;
94
95 /* SLAB cache for vm_area_struct structures */
96 kmem_cache_t *vm_area_cachep;
97
98 /* SLAB cache for mm_struct structures (tsk->mm) */
99 static kmem_cache_t *mm_cachep;
100
101 void free_task(struct task_struct *tsk)
102 {
103         free_thread_info(tsk->thread_info);
104         free_task_struct(tsk);
105 }
106 EXPORT_SYMBOL(free_task);
107
108 void __put_task_struct(struct task_struct *tsk)
109 {
110         WARN_ON(!(tsk->exit_state & (EXIT_DEAD | EXIT_ZOMBIE)));
111         WARN_ON(atomic_read(&tsk->usage));
112         WARN_ON(tsk == current);
113
114         if (unlikely(tsk->audit_context))
115                 audit_free(tsk);
116         security_task_free(tsk);
117         free_uid(tsk->user);
118         put_group_info(tsk->group_info);
119
120         if (!profile_handoff_task(tsk))
121                 free_task(tsk);
122 }
123
124 void __init fork_init(unsigned long mempages)
125 {
126 #ifndef __HAVE_ARCH_TASK_STRUCT_ALLOCATOR
127 #ifndef ARCH_MIN_TASKALIGN
128 #define ARCH_MIN_TASKALIGN      L1_CACHE_BYTES
129 #endif
130         /* create a slab on which task_structs can be allocated */
131         task_struct_cachep =
132                 kmem_cache_create("task_struct", sizeof(struct task_struct),
133                         ARCH_MIN_TASKALIGN, SLAB_PANIC, NULL, NULL);
134 #endif
135
136         /*
137          * The default maximum number of threads is set to a safe
138          * value: the thread structures can take up at most half
139          * of memory.
140          */
141         max_threads = mempages / (8 * THREAD_SIZE / PAGE_SIZE);
142
143         /*
144          * we need to allow at least 20 threads to boot a system
145          */
146         if(max_threads < 20)
147                 max_threads = 20;
148
149         init_task.signal->rlim[RLIMIT_NPROC].rlim_cur = max_threads/2;
150         init_task.signal->rlim[RLIMIT_NPROC].rlim_max = max_threads/2;
151         init_task.signal->rlim[RLIMIT_SIGPENDING] =
152                 init_task.signal->rlim[RLIMIT_NPROC];
153 }
154
155 static struct task_struct *dup_task_struct(struct task_struct *orig)
156 {
157         struct task_struct *tsk;
158         struct thread_info *ti;
159
160         prepare_to_copy(orig);
161
162         tsk = alloc_task_struct();
163         if (!tsk)
164                 return NULL;
165
166         ti = alloc_thread_info(tsk);
167         if (!ti) {
168                 free_task_struct(tsk);
169                 return NULL;
170         }
171
172         *ti = *orig->thread_info;
173         *tsk = *orig;
174         tsk->thread_info = ti;
175         ti->task = tsk;
176
177         /* One for us, one for whoever does the "release_task()" (usually parent) */
178         atomic_set(&tsk->usage,2);
179         return tsk;
180 }
181
182 #ifdef CONFIG_MMU
183 static 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
275 out:
276         flush_tlb_mm(current->mm);
277         up_write(&oldmm->mmap_sem);
278         return retval;
279 fail_nomem_policy:
280         kmem_cache_free(vm_area_cachep, tmp);
281 fail_nomem:
282         retval = -ENOMEM;
283         vm_unacct_memory(charge);
284         goto out;
285 }
286
287 static 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
295 static 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
312 static 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  */
337 struct 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  */
354 void 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  */
365 void 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 }
379 EXPORT_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  */
390 struct 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 }
405 EXPORT_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  */
420 void 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
445 static 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
498 good_mm:
499         tsk->mm = mm;
500         tsk->active_mm = mm;
501         return 0;
502
503 free_pt:
504         mmput(mm);
505 fail_nomem:
506         return retval;
507
508 fail_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
518 static 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
543 struct fs_struct *copy_fs_struct(struct fs_struct *old)
544 {
545         return __copy_fs_struct(old);
546 }
547
548 EXPORT_SYMBOL_GPL(copy_fs_struct);
549
550 static 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
562 static 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
575 static 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;
682 out:
683         return error;
684
685 out_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
699 int 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
720 EXPORT_SYMBOL(unshare_files);
721
722 static 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
740 static 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
812 static 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
823 asmlinkage 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  */
838 static 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
1107 fork_out:
1108         if (retval)
1109                 return ERR_PTR(retval);
1110         return p;
1111
1112 bad_fork_cleanup_namespace:
1113         exit_namespace(p);
1114 bad_fork_cleanup_keys:
1115         exit_keys(p);
1116 bad_fork_cleanup_mm:
1117         if (p->mm)
1118                 mmput(p->mm);
1119 bad_fork_cleanup_signal:
1120         exit_signal(p);
1121 bad_fork_cleanup_sighand:
1122         exit_sighand(p);
1123 bad_fork_cleanup_fs:
1124         exit_fs(p); /* blocking */
1125 bad_fork_cleanup_files:
1126         exit_files(p); /* blocking */
1127 bad_fork_cleanup_semundo:
1128         exit_sem(p);
1129 bad_fork_cleanup_audit:
1130         audit_free(p);
1131 bad_fork_cleanup_security:
1132         security_task_free(p);
1133 bad_fork_cleanup_policy:
1134 #ifdef CONFIG_NUMA
1135         mpol_free(p->mempolicy);
1136 #endif
1137 bad_fork_cleanup:
1138         if (p->binfmt)
1139                 module_put(p->binfmt->module);
1140 bad_fork_cleanup_put_domain:
1141         module_put(p->thread_info->exec_domain->module);
1142 bad_fork_cleanup_count:
1143         put_group_info(p->group_info);
1144         atomic_dec(&p->user->processes);
1145         free_uid(p->user);
1146 bad_fork_free:
1147         free_task(p);
1148         goto fork_out;
1149 }
1150
1151 struct 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
1157 task_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
1170 static 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  */
1192 long 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
1254 void __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 }