Merge /spare/repo/linux-2.6/
[linux-2.6] / 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->cached_hole_size = ~0UL;
198         mm->map_count = 0;
199         set_mm_counter(mm, rss, 0);
200         set_mm_counter(mm, anon_rss, 0);
201         cpus_clear(mm->cpu_vm_mask);
202         mm->mm_rb = RB_ROOT;
203         rb_link = &mm->mm_rb.rb_node;
204         rb_parent = NULL;
205         pprev = &mm->mmap;
206
207         for (mpnt = current->mm->mmap ; mpnt ; mpnt = mpnt->vm_next) {
208                 struct file *file;
209
210                 if (mpnt->vm_flags & VM_DONTCOPY) {
211                         long pages = vma_pages(mpnt);
212                         mm->total_vm -= pages;
213                         __vm_stat_account(mm, mpnt->vm_flags, mpnt->vm_file,
214                                                                 -pages);
215                         continue;
216                 }
217                 charge = 0;
218                 if (mpnt->vm_flags & VM_ACCOUNT) {
219                         unsigned int len = (mpnt->vm_end - mpnt->vm_start) >> PAGE_SHIFT;
220                         if (security_vm_enough_memory(len))
221                                 goto fail_nomem;
222                         charge = len;
223                 }
224                 tmp = kmem_cache_alloc(vm_area_cachep, SLAB_KERNEL);
225                 if (!tmp)
226                         goto fail_nomem;
227                 *tmp = *mpnt;
228                 pol = mpol_copy(vma_policy(mpnt));
229                 retval = PTR_ERR(pol);
230                 if (IS_ERR(pol))
231                         goto fail_nomem_policy;
232                 vma_set_policy(tmp, pol);
233                 tmp->vm_flags &= ~VM_LOCKED;
234                 tmp->vm_mm = mm;
235                 tmp->vm_next = NULL;
236                 anon_vma_link(tmp);
237                 file = tmp->vm_file;
238                 if (file) {
239                         struct inode *inode = file->f_dentry->d_inode;
240                         get_file(file);
241                         if (tmp->vm_flags & VM_DENYWRITE)
242                                 atomic_dec(&inode->i_writecount);
243       
244                         /* insert tmp into the share list, just after mpnt */
245                         spin_lock(&file->f_mapping->i_mmap_lock);
246                         tmp->vm_truncate_count = mpnt->vm_truncate_count;
247                         flush_dcache_mmap_lock(file->f_mapping);
248                         vma_prio_tree_add(tmp, mpnt);
249                         flush_dcache_mmap_unlock(file->f_mapping);
250                         spin_unlock(&file->f_mapping->i_mmap_lock);
251                 }
252
253                 /*
254                  * Link in the new vma and copy the page table entries:
255                  * link in first so that swapoff can see swap entries.
256                  * Note that, exceptionally, here the vma is inserted
257                  * without holding mm->mmap_sem.
258                  */
259                 spin_lock(&mm->page_table_lock);
260                 *pprev = tmp;
261                 pprev = &tmp->vm_next;
262
263                 __vma_link_rb(mm, tmp, rb_link, rb_parent);
264                 rb_link = &tmp->vm_rb.rb_right;
265                 rb_parent = &tmp->vm_rb;
266
267                 mm->map_count++;
268                 retval = copy_page_range(mm, current->mm, tmp);
269                 spin_unlock(&mm->page_table_lock);
270
271                 if (tmp->vm_ops && tmp->vm_ops->open)
272                         tmp->vm_ops->open(tmp);
273
274                 if (retval)
275                         goto out;
276         }
277         retval = 0;
278
279 out:
280         flush_tlb_mm(current->mm);
281         up_write(&oldmm->mmap_sem);
282         return retval;
283 fail_nomem_policy:
284         kmem_cache_free(vm_area_cachep, tmp);
285 fail_nomem:
286         retval = -ENOMEM;
287         vm_unacct_memory(charge);
288         goto out;
289 }
290
291 static inline int mm_alloc_pgd(struct mm_struct * mm)
292 {
293         mm->pgd = pgd_alloc(mm);
294         if (unlikely(!mm->pgd))
295                 return -ENOMEM;
296         return 0;
297 }
298
299 static inline void mm_free_pgd(struct mm_struct * mm)
300 {
301         pgd_free(mm->pgd);
302 }
303 #else
304 #define dup_mmap(mm, oldmm)     (0)
305 #define mm_alloc_pgd(mm)        (0)
306 #define mm_free_pgd(mm)
307 #endif /* CONFIG_MMU */
308
309  __cacheline_aligned_in_smp DEFINE_SPINLOCK(mmlist_lock);
310
311 #define allocate_mm()   (kmem_cache_alloc(mm_cachep, SLAB_KERNEL))
312 #define free_mm(mm)     (kmem_cache_free(mm_cachep, (mm)))
313
314 #include <linux/init_task.h>
315
316 static struct mm_struct * mm_init(struct mm_struct * mm)
317 {
318         atomic_set(&mm->mm_users, 1);
319         atomic_set(&mm->mm_count, 1);
320         init_rwsem(&mm->mmap_sem);
321         INIT_LIST_HEAD(&mm->mmlist);
322         mm->core_waiters = 0;
323         mm->nr_ptes = 0;
324         spin_lock_init(&mm->page_table_lock);
325         rwlock_init(&mm->ioctx_list_lock);
326         mm->ioctx_list = NULL;
327         mm->default_kioctx = (struct kioctx)INIT_KIOCTX(mm->default_kioctx, *mm);
328         mm->free_area_cache = TASK_UNMAPPED_BASE;
329         mm->cached_hole_size = ~0UL;
330
331         if (likely(!mm_alloc_pgd(mm))) {
332                 mm->def_flags = 0;
333                 return mm;
334         }
335         free_mm(mm);
336         return NULL;
337 }
338
339 /*
340  * Allocate and initialize an mm_struct.
341  */
342 struct mm_struct * mm_alloc(void)
343 {
344         struct mm_struct * mm;
345
346         mm = allocate_mm();
347         if (mm) {
348                 memset(mm, 0, sizeof(*mm));
349                 mm = mm_init(mm);
350         }
351         return mm;
352 }
353
354 /*
355  * Called when the last reference to the mm
356  * is dropped: either by a lazy thread or by
357  * mmput. Free the page directory and the mm.
358  */
359 void fastcall __mmdrop(struct mm_struct *mm)
360 {
361         BUG_ON(mm == &init_mm);
362         mm_free_pgd(mm);
363         destroy_context(mm);
364         free_mm(mm);
365 }
366
367 /*
368  * Decrement the use count and release all resources for an mm.
369  */
370 void mmput(struct mm_struct *mm)
371 {
372         if (atomic_dec_and_test(&mm->mm_users)) {
373                 exit_aio(mm);
374                 exit_mmap(mm);
375                 if (!list_empty(&mm->mmlist)) {
376                         spin_lock(&mmlist_lock);
377                         list_del(&mm->mmlist);
378                         spin_unlock(&mmlist_lock);
379                 }
380                 put_swap_token(mm);
381                 mmdrop(mm);
382         }
383 }
384 EXPORT_SYMBOL_GPL(mmput);
385
386 /**
387  * get_task_mm - acquire a reference to the task's mm
388  *
389  * Returns %NULL if the task has no mm.  Checks PF_BORROWED_MM (meaning
390  * this kernel workthread has transiently adopted a user mm with use_mm,
391  * to do its AIO) is not set and if so returns a reference to it, after
392  * bumping up the use count.  User must release the mm via mmput()
393  * after use.  Typically used by /proc and ptrace.
394  */
395 struct mm_struct *get_task_mm(struct task_struct *task)
396 {
397         struct mm_struct *mm;
398
399         task_lock(task);
400         mm = task->mm;
401         if (mm) {
402                 if (task->flags & PF_BORROWED_MM)
403                         mm = NULL;
404                 else
405                         atomic_inc(&mm->mm_users);
406         }
407         task_unlock(task);
408         return mm;
409 }
410 EXPORT_SYMBOL_GPL(get_task_mm);
411
412 /* Please note the differences between mmput and mm_release.
413  * mmput is called whenever we stop holding onto a mm_struct,
414  * error success whatever.
415  *
416  * mm_release is called after a mm_struct has been removed
417  * from the current process.
418  *
419  * This difference is important for error handling, when we
420  * only half set up a mm_struct for a new process and need to restore
421  * the old one.  Because we mmput the new mm_struct before
422  * restoring the old one. . .
423  * Eric Biederman 10 January 1998
424  */
425 void mm_release(struct task_struct *tsk, struct mm_struct *mm)
426 {
427         struct completion *vfork_done = tsk->vfork_done;
428
429         /* Get rid of any cached register state */
430         deactivate_mm(tsk, mm);
431
432         /* notify parent sleeping on vfork() */
433         if (vfork_done) {
434                 tsk->vfork_done = NULL;
435                 complete(vfork_done);
436         }
437         if (tsk->clear_child_tid && atomic_read(&mm->mm_users) > 1) {
438                 u32 __user * tidptr = tsk->clear_child_tid;
439                 tsk->clear_child_tid = NULL;
440
441                 /*
442                  * We don't check the error code - if userspace has
443                  * not set up a proper pointer then tough luck.
444                  */
445                 put_user(0, tidptr);
446                 sys_futex(tidptr, FUTEX_WAKE, 1, NULL, NULL, 0);
447         }
448 }
449
450 static int copy_mm(unsigned long clone_flags, struct task_struct * tsk)
451 {
452         struct mm_struct * mm, *oldmm;
453         int retval;
454
455         tsk->min_flt = tsk->maj_flt = 0;
456         tsk->nvcsw = tsk->nivcsw = 0;
457
458         tsk->mm = NULL;
459         tsk->active_mm = NULL;
460
461         /*
462          * Are we cloning a kernel thread?
463          *
464          * We need to steal a active VM for that..
465          */
466         oldmm = current->mm;
467         if (!oldmm)
468                 return 0;
469
470         if (clone_flags & CLONE_VM) {
471                 atomic_inc(&oldmm->mm_users);
472                 mm = oldmm;
473                 /*
474                  * There are cases where the PTL is held to ensure no
475                  * new threads start up in user mode using an mm, which
476                  * allows optimizing out ipis; the tlb_gather_mmu code
477                  * is an example.
478                  */
479                 spin_unlock_wait(&oldmm->page_table_lock);
480                 goto good_mm;
481         }
482
483         retval = -ENOMEM;
484         mm = allocate_mm();
485         if (!mm)
486                 goto fail_nomem;
487
488         /* Copy the current MM stuff.. */
489         memcpy(mm, oldmm, sizeof(*mm));
490         if (!mm_init(mm))
491                 goto fail_nomem;
492
493         if (init_new_context(tsk,mm))
494                 goto fail_nocontext;
495
496         retval = dup_mmap(mm, oldmm);
497         if (retval)
498                 goto free_pt;
499
500         mm->hiwater_rss = get_mm_counter(mm,rss);
501         mm->hiwater_vm = mm->total_vm;
502
503 good_mm:
504         tsk->mm = mm;
505         tsk->active_mm = mm;
506         return 0;
507
508 free_pt:
509         mmput(mm);
510 fail_nomem:
511         return retval;
512
513 fail_nocontext:
514         /*
515          * If init_new_context() failed, we cannot use mmput() to free the mm
516          * because it calls destroy_context()
517          */
518         mm_free_pgd(mm);
519         free_mm(mm);
520         return retval;
521 }
522
523 static inline struct fs_struct *__copy_fs_struct(struct fs_struct *old)
524 {
525         struct fs_struct *fs = kmem_cache_alloc(fs_cachep, GFP_KERNEL);
526         /* We don't need to lock fs - think why ;-) */
527         if (fs) {
528                 atomic_set(&fs->count, 1);
529                 rwlock_init(&fs->lock);
530                 fs->umask = old->umask;
531                 read_lock(&old->lock);
532                 fs->rootmnt = mntget(old->rootmnt);
533                 fs->root = dget(old->root);
534                 fs->pwdmnt = mntget(old->pwdmnt);
535                 fs->pwd = dget(old->pwd);
536                 if (old->altroot) {
537                         fs->altrootmnt = mntget(old->altrootmnt);
538                         fs->altroot = dget(old->altroot);
539                 } else {
540                         fs->altrootmnt = NULL;
541                         fs->altroot = NULL;
542                 }
543                 read_unlock(&old->lock);
544         }
545         return fs;
546 }
547
548 struct fs_struct *copy_fs_struct(struct fs_struct *old)
549 {
550         return __copy_fs_struct(old);
551 }
552
553 EXPORT_SYMBOL_GPL(copy_fs_struct);
554
555 static inline int copy_fs(unsigned long clone_flags, struct task_struct * tsk)
556 {
557         if (clone_flags & CLONE_FS) {
558                 atomic_inc(&current->fs->count);
559                 return 0;
560         }
561         tsk->fs = __copy_fs_struct(current->fs);
562         if (!tsk->fs)
563                 return -ENOMEM;
564         return 0;
565 }
566
567 static int count_open_files(struct files_struct *files, int size)
568 {
569         int i;
570
571         /* Find the last open fd */
572         for (i = size/(8*sizeof(long)); i > 0; ) {
573                 if (files->open_fds->fds_bits[--i])
574                         break;
575         }
576         i = (i+1) * 8 * sizeof(long);
577         return i;
578 }
579
580 static int copy_files(unsigned long clone_flags, struct task_struct * tsk)
581 {
582         struct files_struct *oldf, *newf;
583         struct file **old_fds, **new_fds;
584         int open_files, size, i, error = 0, expand;
585
586         /*
587          * A background process may not have any files ...
588          */
589         oldf = current->files;
590         if (!oldf)
591                 goto out;
592
593         if (clone_flags & CLONE_FILES) {
594                 atomic_inc(&oldf->count);
595                 goto out;
596         }
597
598         /*
599          * Note: we may be using current for both targets (See exec.c)
600          * This works because we cache current->files (old) as oldf. Don't
601          * break this.
602          */
603         tsk->files = NULL;
604         error = -ENOMEM;
605         newf = kmem_cache_alloc(files_cachep, SLAB_KERNEL);
606         if (!newf) 
607                 goto out;
608
609         atomic_set(&newf->count, 1);
610
611         spin_lock_init(&newf->file_lock);
612         newf->next_fd       = 0;
613         newf->max_fds       = NR_OPEN_DEFAULT;
614         newf->max_fdset     = __FD_SETSIZE;
615         newf->close_on_exec = &newf->close_on_exec_init;
616         newf->open_fds      = &newf->open_fds_init;
617         newf->fd            = &newf->fd_array[0];
618
619         spin_lock(&oldf->file_lock);
620
621         open_files = count_open_files(oldf, oldf->max_fdset);
622         expand = 0;
623
624         /*
625          * Check whether we need to allocate a larger fd array or fd set.
626          * Note: we're not a clone task, so the open count won't  change.
627          */
628         if (open_files > newf->max_fdset) {
629                 newf->max_fdset = 0;
630                 expand = 1;
631         }
632         if (open_files > newf->max_fds) {
633                 newf->max_fds = 0;
634                 expand = 1;
635         }
636
637         /* if the old fdset gets grown now, we'll only copy up to "size" fds */
638         if (expand) {
639                 spin_unlock(&oldf->file_lock);
640                 spin_lock(&newf->file_lock);
641                 error = expand_files(newf, open_files-1);
642                 spin_unlock(&newf->file_lock);
643                 if (error < 0)
644                         goto out_release;
645                 spin_lock(&oldf->file_lock);
646         }
647
648         old_fds = oldf->fd;
649         new_fds = newf->fd;
650
651         memcpy(newf->open_fds->fds_bits, oldf->open_fds->fds_bits, open_files/8);
652         memcpy(newf->close_on_exec->fds_bits, oldf->close_on_exec->fds_bits, open_files/8);
653
654         for (i = open_files; i != 0; i--) {
655                 struct file *f = *old_fds++;
656                 if (f) {
657                         get_file(f);
658                 } else {
659                         /*
660                          * The fd may be claimed in the fd bitmap but not yet
661                          * instantiated in the files array if a sibling thread
662                          * is partway through open().  So make sure that this
663                          * fd is available to the new process.
664                          */
665                         FD_CLR(open_files - i, newf->open_fds);
666                 }
667                 *new_fds++ = f;
668         }
669         spin_unlock(&oldf->file_lock);
670
671         /* compute the remainder to be cleared */
672         size = (newf->max_fds - open_files) * sizeof(struct file *);
673
674         /* This is long word aligned thus could use a optimized version */ 
675         memset(new_fds, 0, size); 
676
677         if (newf->max_fdset > open_files) {
678                 int left = (newf->max_fdset-open_files)/8;
679                 int start = open_files / (8 * sizeof(unsigned long));
680
681                 memset(&newf->open_fds->fds_bits[start], 0, left);
682                 memset(&newf->close_on_exec->fds_bits[start], 0, left);
683         }
684
685         tsk->files = newf;
686         error = 0;
687 out:
688         return error;
689
690 out_release:
691         free_fdset (newf->close_on_exec, newf->max_fdset);
692         free_fdset (newf->open_fds, newf->max_fdset);
693         free_fd_array(newf->fd, newf->max_fds);
694         kmem_cache_free(files_cachep, newf);
695         goto out;
696 }
697
698 /*
699  *      Helper to unshare the files of the current task.
700  *      We don't want to expose copy_files internals to
701  *      the exec layer of the kernel.
702  */
703
704 int unshare_files(void)
705 {
706         struct files_struct *files  = current->files;
707         int rc;
708
709         if(!files)
710                 BUG();
711
712         /* This can race but the race causes us to copy when we don't
713            need to and drop the copy */
714         if(atomic_read(&files->count) == 1)
715         {
716                 atomic_inc(&files->count);
717                 return 0;
718         }
719         rc = copy_files(0, current);
720         if(rc)
721                 current->files = files;
722         return rc;
723 }
724
725 EXPORT_SYMBOL(unshare_files);
726
727 static inline int copy_sighand(unsigned long clone_flags, struct task_struct * tsk)
728 {
729         struct sighand_struct *sig;
730
731         if (clone_flags & (CLONE_SIGHAND | CLONE_THREAD)) {
732                 atomic_inc(&current->sighand->count);
733                 return 0;
734         }
735         sig = kmem_cache_alloc(sighand_cachep, GFP_KERNEL);
736         tsk->sighand = sig;
737         if (!sig)
738                 return -ENOMEM;
739         spin_lock_init(&sig->siglock);
740         atomic_set(&sig->count, 1);
741         memcpy(sig->action, current->sighand->action, sizeof(sig->action));
742         return 0;
743 }
744
745 static inline int copy_signal(unsigned long clone_flags, struct task_struct * tsk)
746 {
747         struct signal_struct *sig;
748         int ret;
749
750         if (clone_flags & CLONE_THREAD) {
751                 atomic_inc(&current->signal->count);
752                 atomic_inc(&current->signal->live);
753                 return 0;
754         }
755         sig = kmem_cache_alloc(signal_cachep, GFP_KERNEL);
756         tsk->signal = sig;
757         if (!sig)
758                 return -ENOMEM;
759
760         ret = copy_thread_group_keys(tsk);
761         if (ret < 0) {
762                 kmem_cache_free(signal_cachep, sig);
763                 return ret;
764         }
765
766         atomic_set(&sig->count, 1);
767         atomic_set(&sig->live, 1);
768         init_waitqueue_head(&sig->wait_chldexit);
769         sig->flags = 0;
770         sig->group_exit_code = 0;
771         sig->group_exit_task = NULL;
772         sig->group_stop_count = 0;
773         sig->curr_target = NULL;
774         init_sigpending(&sig->shared_pending);
775         INIT_LIST_HEAD(&sig->posix_timers);
776
777         sig->it_real_value = sig->it_real_incr = 0;
778         sig->real_timer.function = it_real_fn;
779         sig->real_timer.data = (unsigned long) tsk;
780         init_timer(&sig->real_timer);
781
782         sig->it_virt_expires = cputime_zero;
783         sig->it_virt_incr = cputime_zero;
784         sig->it_prof_expires = cputime_zero;
785         sig->it_prof_incr = cputime_zero;
786
787         sig->tty = current->signal->tty;
788         sig->pgrp = process_group(current);
789         sig->session = current->signal->session;
790         sig->leader = 0;        /* session leadership doesn't inherit */
791         sig->tty_old_pgrp = 0;
792
793         sig->utime = sig->stime = sig->cutime = sig->cstime = cputime_zero;
794         sig->nvcsw = sig->nivcsw = sig->cnvcsw = sig->cnivcsw = 0;
795         sig->min_flt = sig->maj_flt = sig->cmin_flt = sig->cmaj_flt = 0;
796         sig->sched_time = 0;
797         INIT_LIST_HEAD(&sig->cpu_timers[0]);
798         INIT_LIST_HEAD(&sig->cpu_timers[1]);
799         INIT_LIST_HEAD(&sig->cpu_timers[2]);
800
801         task_lock(current->group_leader);
802         memcpy(sig->rlim, current->signal->rlim, sizeof sig->rlim);
803         task_unlock(current->group_leader);
804
805         if (sig->rlim[RLIMIT_CPU].rlim_cur != RLIM_INFINITY) {
806                 /*
807                  * New sole thread in the process gets an expiry time
808                  * of the whole CPU time limit.
809                  */
810                 tsk->it_prof_expires =
811                         secs_to_cputime(sig->rlim[RLIMIT_CPU].rlim_cur);
812         }
813
814         return 0;
815 }
816
817 static inline void copy_flags(unsigned long clone_flags, struct task_struct *p)
818 {
819         unsigned long new_flags = p->flags;
820
821         new_flags &= ~PF_SUPERPRIV;
822         new_flags |= PF_FORKNOEXEC;
823         if (!(clone_flags & CLONE_PTRACE))
824                 p->ptrace = 0;
825         p->flags = new_flags;
826 }
827
828 asmlinkage long sys_set_tid_address(int __user *tidptr)
829 {
830         current->clear_child_tid = tidptr;
831
832         return current->pid;
833 }
834
835 /*
836  * This creates a new process as a copy of the old one,
837  * but does not actually start it yet.
838  *
839  * It copies the registers, and all the appropriate
840  * parts of the process environment (as per the clone
841  * flags). The actual kick-off is left to the caller.
842  */
843 static task_t *copy_process(unsigned long clone_flags,
844                                  unsigned long stack_start,
845                                  struct pt_regs *regs,
846                                  unsigned long stack_size,
847                                  int __user *parent_tidptr,
848                                  int __user *child_tidptr,
849                                  int pid)
850 {
851         int retval;
852         struct task_struct *p = NULL;
853
854         if ((clone_flags & (CLONE_NEWNS|CLONE_FS)) == (CLONE_NEWNS|CLONE_FS))
855                 return ERR_PTR(-EINVAL);
856
857         /*
858          * Thread groups must share signals as well, and detached threads
859          * can only be started up within the thread group.
860          */
861         if ((clone_flags & CLONE_THREAD) && !(clone_flags & CLONE_SIGHAND))
862                 return ERR_PTR(-EINVAL);
863
864         /*
865          * Shared signal handlers imply shared VM. By way of the above,
866          * thread groups also imply shared VM. Blocking this case allows
867          * for various simplifications in other code.
868          */
869         if ((clone_flags & CLONE_SIGHAND) && !(clone_flags & CLONE_VM))
870                 return ERR_PTR(-EINVAL);
871
872         retval = security_task_create(clone_flags);
873         if (retval)
874                 goto fork_out;
875
876         retval = -ENOMEM;
877         p = dup_task_struct(current);
878         if (!p)
879                 goto fork_out;
880
881         retval = -EAGAIN;
882         if (atomic_read(&p->user->processes) >=
883                         p->signal->rlim[RLIMIT_NPROC].rlim_cur) {
884                 if (!capable(CAP_SYS_ADMIN) && !capable(CAP_SYS_RESOURCE) &&
885                                 p->user != &root_user)
886                         goto bad_fork_free;
887         }
888
889         atomic_inc(&p->user->__count);
890         atomic_inc(&p->user->processes);
891         get_group_info(p->group_info);
892
893         /*
894          * If multiple threads are within copy_process(), then this check
895          * triggers too late. This doesn't hurt, the check is only there
896          * to stop root fork bombs.
897          */
898         if (nr_threads >= max_threads)
899                 goto bad_fork_cleanup_count;
900
901         if (!try_module_get(p->thread_info->exec_domain->module))
902                 goto bad_fork_cleanup_count;
903
904         if (p->binfmt && !try_module_get(p->binfmt->module))
905                 goto bad_fork_cleanup_put_domain;
906
907         p->did_exec = 0;
908         copy_flags(clone_flags, p);
909         p->pid = pid;
910         retval = -EFAULT;
911         if (clone_flags & CLONE_PARENT_SETTID)
912                 if (put_user(p->pid, parent_tidptr))
913                         goto bad_fork_cleanup;
914
915         p->proc_dentry = NULL;
916
917         INIT_LIST_HEAD(&p->children);
918         INIT_LIST_HEAD(&p->sibling);
919         p->vfork_done = NULL;
920         spin_lock_init(&p->alloc_lock);
921         spin_lock_init(&p->proc_lock);
922
923         clear_tsk_thread_flag(p, TIF_SIGPENDING);
924         init_sigpending(&p->pending);
925
926         p->utime = cputime_zero;
927         p->stime = cputime_zero;
928         p->sched_time = 0;
929         p->rchar = 0;           /* I/O counter: bytes read */
930         p->wchar = 0;           /* I/O counter: bytes written */
931         p->syscr = 0;           /* I/O counter: read syscalls */
932         p->syscw = 0;           /* I/O counter: write syscalls */
933         acct_clear_integrals(p);
934
935         p->it_virt_expires = cputime_zero;
936         p->it_prof_expires = cputime_zero;
937         p->it_sched_expires = 0;
938         INIT_LIST_HEAD(&p->cpu_timers[0]);
939         INIT_LIST_HEAD(&p->cpu_timers[1]);
940         INIT_LIST_HEAD(&p->cpu_timers[2]);
941
942         p->lock_depth = -1;             /* -1 = no lock */
943         do_posix_clock_monotonic_gettime(&p->start_time);
944         p->security = NULL;
945         p->io_context = NULL;
946         p->io_wait = NULL;
947         p->audit_context = NULL;
948 #ifdef CONFIG_NUMA
949         p->mempolicy = mpol_copy(p->mempolicy);
950         if (IS_ERR(p->mempolicy)) {
951                 retval = PTR_ERR(p->mempolicy);
952                 p->mempolicy = NULL;
953                 goto bad_fork_cleanup;
954         }
955 #endif
956
957         p->tgid = p->pid;
958         if (clone_flags & CLONE_THREAD)
959                 p->tgid = current->tgid;
960
961         if ((retval = security_task_alloc(p)))
962                 goto bad_fork_cleanup_policy;
963         if ((retval = audit_alloc(p)))
964                 goto bad_fork_cleanup_security;
965         /* copy all the process information */
966         if ((retval = copy_semundo(clone_flags, p)))
967                 goto bad_fork_cleanup_audit;
968         if ((retval = copy_files(clone_flags, p)))
969                 goto bad_fork_cleanup_semundo;
970         if ((retval = copy_fs(clone_flags, p)))
971                 goto bad_fork_cleanup_files;
972         if ((retval = copy_sighand(clone_flags, p)))
973                 goto bad_fork_cleanup_fs;
974         if ((retval = copy_signal(clone_flags, p)))
975                 goto bad_fork_cleanup_sighand;
976         if ((retval = copy_mm(clone_flags, p)))
977                 goto bad_fork_cleanup_signal;
978         if ((retval = copy_keys(clone_flags, p)))
979                 goto bad_fork_cleanup_mm;
980         if ((retval = copy_namespace(clone_flags, p)))
981                 goto bad_fork_cleanup_keys;
982         retval = copy_thread(0, clone_flags, stack_start, stack_size, p, regs);
983         if (retval)
984                 goto bad_fork_cleanup_namespace;
985
986         p->set_child_tid = (clone_flags & CLONE_CHILD_SETTID) ? child_tidptr : NULL;
987         /*
988          * Clear TID on mm_release()?
989          */
990         p->clear_child_tid = (clone_flags & CLONE_CHILD_CLEARTID) ? child_tidptr: NULL;
991
992         /*
993          * Syscall tracing should be turned off in the child regardless
994          * of CLONE_PTRACE.
995          */
996         clear_tsk_thread_flag(p, TIF_SYSCALL_TRACE);
997 #ifdef TIF_SYSCALL_EMU
998         clear_tsk_thread_flag(p, TIF_SYSCALL_EMU);
999 #endif
1000
1001         /* Our parent execution domain becomes current domain
1002            These must match for thread signalling to apply */
1003            
1004         p->parent_exec_id = p->self_exec_id;
1005
1006         /* ok, now we should be set up.. */
1007         p->exit_signal = (clone_flags & CLONE_THREAD) ? -1 : (clone_flags & CSIGNAL);
1008         p->pdeath_signal = 0;
1009         p->exit_state = 0;
1010
1011         /*
1012          * Ok, make it visible to the rest of the system.
1013          * We dont wake it up yet.
1014          */
1015         p->group_leader = p;
1016         INIT_LIST_HEAD(&p->ptrace_children);
1017         INIT_LIST_HEAD(&p->ptrace_list);
1018
1019         /* Perform scheduler related setup. Assign this task to a CPU. */
1020         sched_fork(p, clone_flags);
1021
1022         /* Need tasklist lock for parent etc handling! */
1023         write_lock_irq(&tasklist_lock);
1024
1025         /*
1026          * The task hasn't been attached yet, so its cpus_allowed mask will
1027          * not be changed, nor will its assigned CPU.
1028          *
1029          * The cpus_allowed mask of the parent may have changed after it was
1030          * copied first time - so re-copy it here, then check the child's CPU
1031          * to ensure it is on a valid CPU (and if not, just force it back to
1032          * parent's CPU). This avoids alot of nasty races.
1033          */
1034         p->cpus_allowed = current->cpus_allowed;
1035         if (unlikely(!cpu_isset(task_cpu(p), p->cpus_allowed)))
1036                 set_task_cpu(p, smp_processor_id());
1037
1038         /*
1039          * Check for pending SIGKILL! The new thread should not be allowed
1040          * to slip out of an OOM kill. (or normal SIGKILL.)
1041          */
1042         if (sigismember(&current->pending.signal, SIGKILL)) {
1043                 write_unlock_irq(&tasklist_lock);
1044                 retval = -EINTR;
1045                 goto bad_fork_cleanup_namespace;
1046         }
1047
1048         /* CLONE_PARENT re-uses the old parent */
1049         if (clone_flags & (CLONE_PARENT|CLONE_THREAD))
1050                 p->real_parent = current->real_parent;
1051         else
1052                 p->real_parent = current;
1053         p->parent = p->real_parent;
1054
1055         if (clone_flags & CLONE_THREAD) {
1056                 spin_lock(&current->sighand->siglock);
1057                 /*
1058                  * Important: if an exit-all has been started then
1059                  * do not create this new thread - the whole thread
1060                  * group is supposed to exit anyway.
1061                  */
1062                 if (current->signal->flags & SIGNAL_GROUP_EXIT) {
1063                         spin_unlock(&current->sighand->siglock);
1064                         write_unlock_irq(&tasklist_lock);
1065                         retval = -EAGAIN;
1066                         goto bad_fork_cleanup_namespace;
1067                 }
1068                 p->group_leader = current->group_leader;
1069
1070                 if (current->signal->group_stop_count > 0) {
1071                         /*
1072                          * There is an all-stop in progress for the group.
1073                          * We ourselves will stop as soon as we check signals.
1074                          * Make the new thread part of that group stop too.
1075                          */
1076                         current->signal->group_stop_count++;
1077                         set_tsk_thread_flag(p, TIF_SIGPENDING);
1078                 }
1079
1080                 if (!cputime_eq(current->signal->it_virt_expires,
1081                                 cputime_zero) ||
1082                     !cputime_eq(current->signal->it_prof_expires,
1083                                 cputime_zero) ||
1084                     current->signal->rlim[RLIMIT_CPU].rlim_cur != RLIM_INFINITY ||
1085                     !list_empty(&current->signal->cpu_timers[0]) ||
1086                     !list_empty(&current->signal->cpu_timers[1]) ||
1087                     !list_empty(&current->signal->cpu_timers[2])) {
1088                         /*
1089                          * Have child wake up on its first tick to check
1090                          * for process CPU timers.
1091                          */
1092                         p->it_prof_expires = jiffies_to_cputime(1);
1093                 }
1094
1095                 spin_unlock(&current->sighand->siglock);
1096         }
1097
1098         /*
1099          * inherit ioprio
1100          */
1101         p->ioprio = current->ioprio;
1102
1103         SET_LINKS(p);
1104         if (unlikely(p->ptrace & PT_PTRACED))
1105                 __ptrace_link(p, current->parent);
1106
1107         cpuset_fork(p);
1108
1109         attach_pid(p, PIDTYPE_PID, p->pid);
1110         attach_pid(p, PIDTYPE_TGID, p->tgid);
1111         if (thread_group_leader(p)) {
1112                 attach_pid(p, PIDTYPE_PGID, process_group(p));
1113                 attach_pid(p, PIDTYPE_SID, p->signal->session);
1114                 if (p->pid)
1115                         __get_cpu_var(process_counts)++;
1116         }
1117
1118         nr_threads++;
1119         total_forks++;
1120         write_unlock_irq(&tasklist_lock);
1121         retval = 0;
1122
1123 fork_out:
1124         if (retval)
1125                 return ERR_PTR(retval);
1126         return p;
1127
1128 bad_fork_cleanup_namespace:
1129         exit_namespace(p);
1130 bad_fork_cleanup_keys:
1131         exit_keys(p);
1132 bad_fork_cleanup_mm:
1133         if (p->mm)
1134                 mmput(p->mm);
1135 bad_fork_cleanup_signal:
1136         exit_signal(p);
1137 bad_fork_cleanup_sighand:
1138         exit_sighand(p);
1139 bad_fork_cleanup_fs:
1140         exit_fs(p); /* blocking */
1141 bad_fork_cleanup_files:
1142         exit_files(p); /* blocking */
1143 bad_fork_cleanup_semundo:
1144         exit_sem(p);
1145 bad_fork_cleanup_audit:
1146         audit_free(p);
1147 bad_fork_cleanup_security:
1148         security_task_free(p);
1149 bad_fork_cleanup_policy:
1150 #ifdef CONFIG_NUMA
1151         mpol_free(p->mempolicy);
1152 #endif
1153 bad_fork_cleanup:
1154         if (p->binfmt)
1155                 module_put(p->binfmt->module);
1156 bad_fork_cleanup_put_domain:
1157         module_put(p->thread_info->exec_domain->module);
1158 bad_fork_cleanup_count:
1159         put_group_info(p->group_info);
1160         atomic_dec(&p->user->processes);
1161         free_uid(p->user);
1162 bad_fork_free:
1163         free_task(p);
1164         goto fork_out;
1165 }
1166
1167 struct pt_regs * __devinit __attribute__((weak)) idle_regs(struct pt_regs *regs)
1168 {
1169         memset(regs, 0, sizeof(struct pt_regs));
1170         return regs;
1171 }
1172
1173 task_t * __devinit fork_idle(int cpu)
1174 {
1175         task_t *task;
1176         struct pt_regs regs;
1177
1178         task = copy_process(CLONE_VM, 0, idle_regs(&regs), 0, NULL, NULL, 0);
1179         if (!task)
1180                 return ERR_PTR(-ENOMEM);
1181         init_idle(task, cpu);
1182         unhash_process(task);
1183         return task;
1184 }
1185
1186 static inline int fork_traceflag (unsigned clone_flags)
1187 {
1188         if (clone_flags & CLONE_UNTRACED)
1189                 return 0;
1190         else if (clone_flags & CLONE_VFORK) {
1191                 if (current->ptrace & PT_TRACE_VFORK)
1192                         return PTRACE_EVENT_VFORK;
1193         } else if ((clone_flags & CSIGNAL) != SIGCHLD) {
1194                 if (current->ptrace & PT_TRACE_CLONE)
1195                         return PTRACE_EVENT_CLONE;
1196         } else if (current->ptrace & PT_TRACE_FORK)
1197                 return PTRACE_EVENT_FORK;
1198
1199         return 0;
1200 }
1201
1202 /*
1203  *  Ok, this is the main fork-routine.
1204  *
1205  * It copies the process, and if successful kick-starts
1206  * it and waits for it to finish using the VM if required.
1207  */
1208 long do_fork(unsigned long clone_flags,
1209               unsigned long stack_start,
1210               struct pt_regs *regs,
1211               unsigned long stack_size,
1212               int __user *parent_tidptr,
1213               int __user *child_tidptr)
1214 {
1215         struct task_struct *p;
1216         int trace = 0;
1217         long pid = alloc_pidmap();
1218
1219         if (pid < 0)
1220                 return -EAGAIN;
1221         if (unlikely(current->ptrace)) {
1222                 trace = fork_traceflag (clone_flags);
1223                 if (trace)
1224                         clone_flags |= CLONE_PTRACE;
1225         }
1226
1227         p = copy_process(clone_flags, stack_start, regs, stack_size, parent_tidptr, child_tidptr, pid);
1228         /*
1229          * Do this prior waking up the new thread - the thread pointer
1230          * might get invalid after that point, if the thread exits quickly.
1231          */
1232         if (!IS_ERR(p)) {
1233                 struct completion vfork;
1234
1235                 if (clone_flags & CLONE_VFORK) {
1236                         p->vfork_done = &vfork;
1237                         init_completion(&vfork);
1238                 }
1239
1240                 if ((p->ptrace & PT_PTRACED) || (clone_flags & CLONE_STOPPED)) {
1241                         /*
1242                          * We'll start up with an immediate SIGSTOP.
1243                          */
1244                         sigaddset(&p->pending.signal, SIGSTOP);
1245                         set_tsk_thread_flag(p, TIF_SIGPENDING);
1246                 }
1247
1248                 if (!(clone_flags & CLONE_STOPPED))
1249                         wake_up_new_task(p, clone_flags);
1250                 else
1251                         p->state = TASK_STOPPED;
1252
1253                 if (unlikely (trace)) {
1254                         current->ptrace_message = pid;
1255                         ptrace_notify ((trace << 8) | SIGTRAP);
1256                 }
1257
1258                 if (clone_flags & CLONE_VFORK) {
1259                         wait_for_completion(&vfork);
1260                         if (unlikely (current->ptrace & PT_TRACE_VFORK_DONE))
1261                                 ptrace_notify ((PTRACE_EVENT_VFORK_DONE << 8) | SIGTRAP);
1262                 }
1263         } else {
1264                 free_pidmap(pid);
1265                 pid = PTR_ERR(p);
1266         }
1267         return pid;
1268 }
1269
1270 void __init proc_caches_init(void)
1271 {
1272         sighand_cachep = kmem_cache_create("sighand_cache",
1273                         sizeof(struct sighand_struct), 0,
1274                         SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL, NULL);
1275         signal_cachep = kmem_cache_create("signal_cache",
1276                         sizeof(struct signal_struct), 0,
1277                         SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL, NULL);
1278         files_cachep = kmem_cache_create("files_cache", 
1279                         sizeof(struct files_struct), 0,
1280                         SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL, NULL);
1281         fs_cachep = kmem_cache_create("fs_cache", 
1282                         sizeof(struct fs_struct), 0,
1283                         SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL, NULL);
1284         vm_area_cachep = kmem_cache_create("vm_area_struct",
1285                         sizeof(struct vm_area_struct), 0,
1286                         SLAB_PANIC, NULL, NULL);
1287         mm_cachep = kmem_cache_create("mm_struct",
1288                         sizeof(struct mm_struct), 0,
1289                         SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL, NULL);
1290 }