fork.c 42.6 KB
Newer Older
Linus Torvalds's avatar
Linus Torvalds committed
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
/*
 *  linux/kernel/fork.c
 *
 *  Copyright (C) 1991, 1992  Linus Torvalds
 */

/*
 *  'fork.c' contains the help-routines for the 'fork' system call
 * (see also entry.S and others).
 * Fork is rather simple, once you get the hang of it, but the memory
 * management can be a bitch. See 'mm/memory.c': 'copy_page_range()'
 */

#include <linux/slab.h>
#include <linux/init.h>
#include <linux/unistd.h>
#include <linux/smp_lock.h>
#include <linux/module.h>
#include <linux/vmalloc.h>
#include <linux/completion.h>
21
#include <linux/mnt_namespace.h>
Linus Torvalds's avatar
Linus Torvalds committed
22 23 24 25 26 27 28 29
#include <linux/personality.h>
#include <linux/mempolicy.h>
#include <linux/sem.h>
#include <linux/file.h>
#include <linux/key.h>
#include <linux/binfmts.h>
#include <linux/mman.h>
#include <linux/fs.h>
30
#include <linux/nsproxy.h>
31
#include <linux/capability.h>
Linus Torvalds's avatar
Linus Torvalds committed
32 33 34 35 36 37 38
#include <linux/cpu.h>
#include <linux/cpuset.h>
#include <linux/security.h>
#include <linux/swap.h>
#include <linux/syscalls.h>
#include <linux/jiffies.h>
#include <linux/futex.h>
39
#include <linux/task_io_accounting_ops.h>
40
#include <linux/rcupdate.h>
Linus Torvalds's avatar
Linus Torvalds committed
41 42 43 44 45 46
#include <linux/ptrace.h>
#include <linux/mount.h>
#include <linux/audit.h>
#include <linux/profile.h>
#include <linux/rmap.h>
#include <linux/acct.h>
47
#include <linux/tsacct_kern.h>
48
#include <linux/cn_proc.h>
49
#include <linux/delayacct.h>
50
#include <linux/taskstats_kern.h>
51
#include <linux/random.h>
Linus Torvalds's avatar
Linus Torvalds committed
52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69

#include <asm/pgtable.h>
#include <asm/pgalloc.h>
#include <asm/uaccess.h>
#include <asm/mmu_context.h>
#include <asm/cacheflush.h>
#include <asm/tlbflush.h>

/*
 * Protected counters by write_lock_irq(&tasklist_lock)
 */
unsigned long total_forks;	/* Handle normal Linux uptimes. */
int nr_threads; 		/* The idle threads do not count.. */

int max_threads;		/* tunable limit on nr_threads */

DEFINE_PER_CPU(unsigned long, process_counts) = 0;

70
__cacheline_aligned DEFINE_RWLOCK(tasklist_lock);  /* outer */
Linus Torvalds's avatar
Linus Torvalds committed
71 72 73 74 75 76 77 78 79 80 81 82 83 84 85

int nr_processes(void)
{
	int cpu;
	int total = 0;

	for_each_online_cpu(cpu)
		total += per_cpu(process_counts, cpu);

	return total;
}

#ifndef __HAVE_ARCH_TASK_STRUCT_ALLOCATOR
# define alloc_task_struct()	kmem_cache_alloc(task_struct_cachep, GFP_KERNEL)
# define free_task_struct(tsk)	kmem_cache_free(task_struct_cachep, (tsk))
86
static struct kmem_cache *task_struct_cachep;
Linus Torvalds's avatar
Linus Torvalds committed
87 88 89
#endif

/* SLAB cache for signal_struct structures (tsk->signal) */
90
static struct kmem_cache *signal_cachep;
Linus Torvalds's avatar
Linus Torvalds committed
91 92

/* SLAB cache for sighand_struct structures (tsk->sighand) */
93
struct kmem_cache *sighand_cachep;
Linus Torvalds's avatar
Linus Torvalds committed
94 95

/* SLAB cache for files_struct structures (tsk->files) */
96
struct kmem_cache *files_cachep;
Linus Torvalds's avatar
Linus Torvalds committed
97 98

/* SLAB cache for fs_struct structures (tsk->fs) */
99
struct kmem_cache *fs_cachep;
Linus Torvalds's avatar
Linus Torvalds committed
100 101

/* SLAB cache for vm_area_struct structures */
102
struct kmem_cache *vm_area_cachep;
Linus Torvalds's avatar
Linus Torvalds committed
103 104

/* SLAB cache for mm_struct structures (tsk->mm) */
105
static struct kmem_cache *mm_cachep;
Linus Torvalds's avatar
Linus Torvalds committed
106 107 108 109

void free_task(struct task_struct *tsk)
{
	free_thread_info(tsk->thread_info);
Ingo Molnar's avatar
Ingo Molnar committed
110
	rt_mutex_debug_task_free(tsk);
Linus Torvalds's avatar
Linus Torvalds committed
111 112 113 114
	free_task_struct(tsk);
}
EXPORT_SYMBOL(free_task);

115
void __put_task_struct(struct task_struct *tsk)
Linus Torvalds's avatar
Linus Torvalds committed
116 117 118 119 120 121 122 123
{
	WARN_ON(!(tsk->exit_state & (EXIT_DEAD | EXIT_ZOMBIE)));
	WARN_ON(atomic_read(&tsk->usage));
	WARN_ON(tsk == current);

	security_task_free(tsk);
	free_uid(tsk->user);
	put_group_info(tsk->group_info);
124
	delayacct_tsk_free(tsk);
Linus Torvalds's avatar
Linus Torvalds committed
125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179

	if (!profile_handoff_task(tsk))
		free_task(tsk);
}

void __init fork_init(unsigned long mempages)
{
#ifndef __HAVE_ARCH_TASK_STRUCT_ALLOCATOR
#ifndef ARCH_MIN_TASKALIGN
#define ARCH_MIN_TASKALIGN	L1_CACHE_BYTES
#endif
	/* create a slab on which task_structs can be allocated */
	task_struct_cachep =
		kmem_cache_create("task_struct", sizeof(struct task_struct),
			ARCH_MIN_TASKALIGN, SLAB_PANIC, NULL, NULL);
#endif

	/*
	 * The default maximum number of threads is set to a safe
	 * value: the thread structures can take up at most half
	 * of memory.
	 */
	max_threads = mempages / (8 * THREAD_SIZE / PAGE_SIZE);

	/*
	 * we need to allow at least 20 threads to boot a system
	 */
	if(max_threads < 20)
		max_threads = 20;

	init_task.signal->rlim[RLIMIT_NPROC].rlim_cur = max_threads/2;
	init_task.signal->rlim[RLIMIT_NPROC].rlim_max = max_threads/2;
	init_task.signal->rlim[RLIMIT_SIGPENDING] =
		init_task.signal->rlim[RLIMIT_NPROC];
}

static struct task_struct *dup_task_struct(struct task_struct *orig)
{
	struct task_struct *tsk;
	struct thread_info *ti;

	prepare_to_copy(orig);

	tsk = alloc_task_struct();
	if (!tsk)
		return NULL;

	ti = alloc_thread_info(tsk);
	if (!ti) {
		free_task_struct(tsk);
		return NULL;
	}

	*tsk = *orig;
	tsk->thread_info = ti;
180
	setup_thread_stack(tsk, orig);
Linus Torvalds's avatar
Linus Torvalds committed
181

182 183 184 185
#ifdef CONFIG_CC_STACKPROTECTOR
	tsk->stack_canary = get_random_int();
#endif

Linus Torvalds's avatar
Linus Torvalds committed
186 187
	/* One for us, one for whoever does the "release_task()" (usually parent) */
	atomic_set(&tsk->usage,2);
188
	atomic_set(&tsk->fs_excl, 0);
189
#ifdef CONFIG_BLK_DEV_IO_TRACE
190
	tsk->btrace_seq = 0;
191
#endif
192
	tsk->splice_pipe = NULL;
Linus Torvalds's avatar
Linus Torvalds committed
193 194 195 196
	return tsk;
}

#ifdef CONFIG_MMU
197
static inline int dup_mmap(struct mm_struct *mm, struct mm_struct *oldmm)
Linus Torvalds's avatar
Linus Torvalds committed
198
{
199
	struct vm_area_struct *mpnt, *tmp, **pprev;
Linus Torvalds's avatar
Linus Torvalds committed
200 201 202 203 204 205
	struct rb_node **rb_link, *rb_parent;
	int retval;
	unsigned long charge;
	struct mempolicy *pol;

	down_write(&oldmm->mmap_sem);
206
	flush_cache_mm(oldmm);
207 208 209 210
	/*
	 * Not linked in yet - no deadlock potential:
	 */
	down_write_nested(&mm->mmap_sem, SINGLE_DEPTH_NESTING);
211

Linus Torvalds's avatar
Linus Torvalds committed
212 213 214 215
	mm->locked_vm = 0;
	mm->mmap = NULL;
	mm->mmap_cache = NULL;
	mm->free_area_cache = oldmm->mmap_base;
216
	mm->cached_hole_size = ~0UL;
Linus Torvalds's avatar
Linus Torvalds committed
217 218 219 220 221 222 223
	mm->map_count = 0;
	cpus_clear(mm->cpu_vm_mask);
	mm->mm_rb = RB_ROOT;
	rb_link = &mm->mm_rb.rb_node;
	rb_parent = NULL;
	pprev = &mm->mmap;

224
	for (mpnt = oldmm->mmap; mpnt; mpnt = mpnt->vm_next) {
Linus Torvalds's avatar
Linus Torvalds committed
225 226 227
		struct file *file;

		if (mpnt->vm_flags & VM_DONTCOPY) {
228 229
			long pages = vma_pages(mpnt);
			mm->total_vm -= pages;
230
			vm_stat_account(mm, mpnt->vm_flags, mpnt->vm_file,
231
								-pages);
Linus Torvalds's avatar
Linus Torvalds committed
232 233 234 235 236 237 238 239 240
			continue;
		}
		charge = 0;
		if (mpnt->vm_flags & VM_ACCOUNT) {
			unsigned int len = (mpnt->vm_end - mpnt->vm_start) >> PAGE_SHIFT;
			if (security_vm_enough_memory(len))
				goto fail_nomem;
			charge = len;
		}
241
		tmp = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL);
Linus Torvalds's avatar
Linus Torvalds committed
242 243 244 245 246 247 248 249 250 251 252 253 254 255
		if (!tmp)
			goto fail_nomem;
		*tmp = *mpnt;
		pol = mpol_copy(vma_policy(mpnt));
		retval = PTR_ERR(pol);
		if (IS_ERR(pol))
			goto fail_nomem_policy;
		vma_set_policy(tmp, pol);
		tmp->vm_flags &= ~VM_LOCKED;
		tmp->vm_mm = mm;
		tmp->vm_next = NULL;
		anon_vma_link(tmp);
		file = tmp->vm_file;
		if (file) {
256
			struct inode *inode = file->f_path.dentry->d_inode;
Linus Torvalds's avatar
Linus Torvalds committed
257 258 259 260 261 262 263 264 265 266 267 268 269 270
			get_file(file);
			if (tmp->vm_flags & VM_DENYWRITE)
				atomic_dec(&inode->i_writecount);
      
			/* insert tmp into the share list, just after mpnt */
			spin_lock(&file->f_mapping->i_mmap_lock);
			tmp->vm_truncate_count = mpnt->vm_truncate_count;
			flush_dcache_mmap_lock(file->f_mapping);
			vma_prio_tree_add(tmp, mpnt);
			flush_dcache_mmap_unlock(file->f_mapping);
			spin_unlock(&file->f_mapping->i_mmap_lock);
		}

		/*
271
		 * Link in the new vma and copy the page table entries.
Linus Torvalds's avatar
Linus Torvalds committed
272 273 274 275 276 277 278 279 280
		 */
		*pprev = tmp;
		pprev = &tmp->vm_next;

		__vma_link_rb(mm, tmp, rb_link, rb_parent);
		rb_link = &tmp->vm_rb.rb_right;
		rb_parent = &tmp->vm_rb;

		mm->map_count++;
281
		retval = copy_page_range(mm, oldmm, mpnt);
Linus Torvalds's avatar
Linus Torvalds committed
282 283 284 285 286 287 288 289 290

		if (tmp->vm_ops && tmp->vm_ops->open)
			tmp->vm_ops->open(tmp);

		if (retval)
			goto out;
	}
	retval = 0;
out:
291
	up_write(&mm->mmap_sem);
292
	flush_tlb_mm(oldmm);
Linus Torvalds's avatar
Linus Torvalds committed
293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322
	up_write(&oldmm->mmap_sem);
	return retval;
fail_nomem_policy:
	kmem_cache_free(vm_area_cachep, tmp);
fail_nomem:
	retval = -ENOMEM;
	vm_unacct_memory(charge);
	goto out;
}

static inline int mm_alloc_pgd(struct mm_struct * mm)
{
	mm->pgd = pgd_alloc(mm);
	if (unlikely(!mm->pgd))
		return -ENOMEM;
	return 0;
}

static inline void mm_free_pgd(struct mm_struct * mm)
{
	pgd_free(mm->pgd);
}
#else
#define dup_mmap(mm, oldmm)	(0)
#define mm_alloc_pgd(mm)	(0)
#define mm_free_pgd(mm)
#endif /* CONFIG_MMU */

 __cacheline_aligned_in_smp DEFINE_SPINLOCK(mmlist_lock);

323
#define allocate_mm()	(kmem_cache_alloc(mm_cachep, GFP_KERNEL))
Linus Torvalds's avatar
Linus Torvalds committed
324 325 326 327 328 329 330 331 332 333 334 335
#define free_mm(mm)	(kmem_cache_free(mm_cachep, (mm)))

#include <linux/init_task.h>

static struct mm_struct * mm_init(struct mm_struct * mm)
{
	atomic_set(&mm->mm_users, 1);
	atomic_set(&mm->mm_count, 1);
	init_rwsem(&mm->mmap_sem);
	INIT_LIST_HEAD(&mm->mmlist);
	mm->core_waiters = 0;
	mm->nr_ptes = 0;
336
	set_mm_counter(mm, file_rss, 0);
337
	set_mm_counter(mm, anon_rss, 0);
Linus Torvalds's avatar
Linus Torvalds committed
338 339 340 341
	spin_lock_init(&mm->page_table_lock);
	rwlock_init(&mm->ioctx_list_lock);
	mm->ioctx_list = NULL;
	mm->free_area_cache = TASK_UNMAPPED_BASE;
342
	mm->cached_hole_size = ~0UL;
Linus Torvalds's avatar
Linus Torvalds committed
343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384

	if (likely(!mm_alloc_pgd(mm))) {
		mm->def_flags = 0;
		return mm;
	}
	free_mm(mm);
	return NULL;
}

/*
 * Allocate and initialize an mm_struct.
 */
struct mm_struct * mm_alloc(void)
{
	struct mm_struct * mm;

	mm = allocate_mm();
	if (mm) {
		memset(mm, 0, sizeof(*mm));
		mm = mm_init(mm);
	}
	return mm;
}

/*
 * Called when the last reference to the mm
 * is dropped: either by a lazy thread or by
 * mmput. Free the page directory and the mm.
 */
void fastcall __mmdrop(struct mm_struct *mm)
{
	BUG_ON(mm == &init_mm);
	mm_free_pgd(mm);
	destroy_context(mm);
	free_mm(mm);
}

/*
 * Decrement the use count and release all resources for an mm.
 */
void mmput(struct mm_struct *mm)
{
Andrew Morton's avatar
Andrew Morton committed
385 386
	might_sleep();

Linus Torvalds's avatar
Linus Torvalds committed
387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451
	if (atomic_dec_and_test(&mm->mm_users)) {
		exit_aio(mm);
		exit_mmap(mm);
		if (!list_empty(&mm->mmlist)) {
			spin_lock(&mmlist_lock);
			list_del(&mm->mmlist);
			spin_unlock(&mmlist_lock);
		}
		put_swap_token(mm);
		mmdrop(mm);
	}
}
EXPORT_SYMBOL_GPL(mmput);

/**
 * get_task_mm - acquire a reference to the task's mm
 *
 * Returns %NULL if the task has no mm.  Checks PF_BORROWED_MM (meaning
 * this kernel workthread has transiently adopted a user mm with use_mm,
 * to do its AIO) is not set and if so returns a reference to it, after
 * bumping up the use count.  User must release the mm via mmput()
 * after use.  Typically used by /proc and ptrace.
 */
struct mm_struct *get_task_mm(struct task_struct *task)
{
	struct mm_struct *mm;

	task_lock(task);
	mm = task->mm;
	if (mm) {
		if (task->flags & PF_BORROWED_MM)
			mm = NULL;
		else
			atomic_inc(&mm->mm_users);
	}
	task_unlock(task);
	return mm;
}
EXPORT_SYMBOL_GPL(get_task_mm);

/* Please note the differences between mmput and mm_release.
 * mmput is called whenever we stop holding onto a mm_struct,
 * error success whatever.
 *
 * mm_release is called after a mm_struct has been removed
 * from the current process.
 *
 * This difference is important for error handling, when we
 * only half set up a mm_struct for a new process and need to restore
 * the old one.  Because we mmput the new mm_struct before
 * restoring the old one. . .
 * Eric Biederman 10 January 1998
 */
void mm_release(struct task_struct *tsk, struct mm_struct *mm)
{
	struct completion *vfork_done = tsk->vfork_done;

	/* Get rid of any cached register state */
	deactivate_mm(tsk, mm);

	/* notify parent sleeping on vfork() */
	if (vfork_done) {
		tsk->vfork_done = NULL;
		complete(vfork_done);
	}
452 453 454 455 456 457 458 459 460 461

	/*
	 * If we're exiting normally, clear a user-space tid field if
	 * requested.  We leave this alone when dying by signal, to leave
	 * the value intact in a core dump, and to save the unnecessary
	 * trouble otherwise.  Userland only wants this done for a sys_exit.
	 */
	if (tsk->clear_child_tid
	    && !(tsk->flags & PF_SIGNALED)
	    && atomic_read(&mm->mm_users) > 1) {
Linus Torvalds's avatar
Linus Torvalds committed
462 463 464 465 466 467 468 469 470 471 472 473
		u32 __user * tidptr = tsk->clear_child_tid;
		tsk->clear_child_tid = NULL;

		/*
		 * We don't check the error code - if userspace has
		 * not set up a proper pointer then tough luck.
		 */
		put_user(0, tidptr);
		sys_futex(tidptr, FUTEX_WAKE, 1, NULL, NULL, 0);
	}
}

474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491
/*
 * Allocate a new mm structure and copy contents from the
 * mm structure of the passed in task structure.
 */
static struct mm_struct *dup_mm(struct task_struct *tsk)
{
	struct mm_struct *mm, *oldmm = current->mm;
	int err;

	if (!oldmm)
		return NULL;

	mm = allocate_mm();
	if (!mm)
		goto fail_nomem;

	memcpy(mm, oldmm, sizeof(*mm));

492 493 494 495
	/* Initializing for Swap token stuff */
	mm->token_priority = 0;
	mm->last_interval = 0;

496 497 498 499 500 501 502 503 504 505 506 507 508 509 510 511 512 513 514 515 516 517 518 519 520 521 522 523 524 525 526
	if (!mm_init(mm))
		goto fail_nomem;

	if (init_new_context(tsk, mm))
		goto fail_nocontext;

	err = dup_mmap(mm, oldmm);
	if (err)
		goto free_pt;

	mm->hiwater_rss = get_mm_rss(mm);
	mm->hiwater_vm = mm->total_vm;

	return mm;

free_pt:
	mmput(mm);

fail_nomem:
	return NULL;

fail_nocontext:
	/*
	 * If init_new_context() failed, we cannot use mmput() to free the mm
	 * because it calls destroy_context()
	 */
	mm_free_pgd(mm);
	free_mm(mm);
	return NULL;
}

Linus Torvalds's avatar
Linus Torvalds committed
527 528 529 530 531 532 533 534 535 536 537 538 539 540 541 542 543 544 545 546 547 548 549 550 551 552 553
static int copy_mm(unsigned long clone_flags, struct task_struct * tsk)
{
	struct mm_struct * mm, *oldmm;
	int retval;

	tsk->min_flt = tsk->maj_flt = 0;
	tsk->nvcsw = tsk->nivcsw = 0;

	tsk->mm = NULL;
	tsk->active_mm = NULL;

	/*
	 * Are we cloning a kernel thread?
	 *
	 * We need to steal a active VM for that..
	 */
	oldmm = current->mm;
	if (!oldmm)
		return 0;

	if (clone_flags & CLONE_VM) {
		atomic_inc(&oldmm->mm_users);
		mm = oldmm;
		goto good_mm;
	}

	retval = -ENOMEM;
554
	mm = dup_mm(tsk);
Linus Torvalds's avatar
Linus Torvalds committed
555 556 557 558
	if (!mm)
		goto fail_nomem;

good_mm:
559 560 561 562
	/* Initializing for Swap token stuff */
	mm->token_priority = 0;
	mm->last_interval = 0;

Linus Torvalds's avatar
Linus Torvalds committed
563 564 565 566 567 568 569 570 571 572 573 574 575 576 577 578 579 580 581 582 583 584 585 586 587 588 589 590 591 592 593 594 595 596 597 598 599 600 601 602 603 604 605 606 607 608 609 610 611 612 613 614
	tsk->mm = mm;
	tsk->active_mm = mm;
	return 0;

fail_nomem:
	return retval;
}

static inline struct fs_struct *__copy_fs_struct(struct fs_struct *old)
{
	struct fs_struct *fs = kmem_cache_alloc(fs_cachep, GFP_KERNEL);
	/* We don't need to lock fs - think why ;-) */
	if (fs) {
		atomic_set(&fs->count, 1);
		rwlock_init(&fs->lock);
		fs->umask = old->umask;
		read_lock(&old->lock);
		fs->rootmnt = mntget(old->rootmnt);
		fs->root = dget(old->root);
		fs->pwdmnt = mntget(old->pwdmnt);
		fs->pwd = dget(old->pwd);
		if (old->altroot) {
			fs->altrootmnt = mntget(old->altrootmnt);
			fs->altroot = dget(old->altroot);
		} else {
			fs->altrootmnt = NULL;
			fs->altroot = NULL;
		}
		read_unlock(&old->lock);
	}
	return fs;
}

struct fs_struct *copy_fs_struct(struct fs_struct *old)
{
	return __copy_fs_struct(old);
}

EXPORT_SYMBOL_GPL(copy_fs_struct);

static inline int copy_fs(unsigned long clone_flags, struct task_struct * tsk)
{
	if (clone_flags & CLONE_FS) {
		atomic_inc(&current->fs->count);
		return 0;
	}
	tsk->fs = __copy_fs_struct(current->fs);
	if (!tsk->fs)
		return -ENOMEM;
	return 0;
}

615
static int count_open_files(struct fdtable *fdt)
Linus Torvalds's avatar
Linus Torvalds committed
616
{
617
	int size = fdt->max_fdset;
Linus Torvalds's avatar
Linus Torvalds committed
618 619 620 621
	int i;

	/* Find the last open fd */
	for (i = size/(8*sizeof(long)); i > 0; ) {
622
		if (fdt->open_fds->fds_bits[--i])
Linus Torvalds's avatar
Linus Torvalds committed
623 624 625 626 627 628
			break;
	}
	i = (i+1) * 8 * sizeof(long);
	return i;
}

629 630 631 632 633
static struct files_struct *alloc_files(void)
{
	struct files_struct *newf;
	struct fdtable *fdt;

634
	newf = kmem_cache_alloc(files_cachep, GFP_KERNEL);
635 636 637 638 639 640
	if (!newf)
		goto out;

	atomic_set(&newf->count, 1);

	spin_lock_init(&newf->file_lock);
641
	newf->next_fd = 0;
642
	fdt = &newf->fdtab;
643
	fdt->max_fds = NR_OPEN_DEFAULT;
644 645 646
	fdt->max_fdset = EMBEDDED_FD_SET_SIZE;
	fdt->close_on_exec = (fd_set *)&newf->close_on_exec_init;
	fdt->open_fds = (fd_set *)&newf->open_fds_init;
647
	fdt->fd = &newf->fd_array[0];
648 649 650 651
	INIT_RCU_HEAD(&fdt->rcu);
	fdt->free_files = NULL;
	fdt->next = NULL;
	rcu_assign_pointer(newf->fdt, fdt);
652 653 654 655
out:
	return newf;
}

656 657 658
/*
 * Allocate a new files structure and copy contents from the
 * passed in files structure.
Prasanna Meda's avatar
Prasanna Meda committed
659
 * errorp will be valid only when the returned files_struct is NULL.
660 661
 */
static struct files_struct *dup_fd(struct files_struct *oldf, int *errorp)
Linus Torvalds's avatar
Linus Torvalds committed
662
{
663
	struct files_struct *newf;
Linus Torvalds's avatar
Linus Torvalds committed
664
	struct file **old_fds, **new_fds;
665
	int open_files, size, i, expand;
666
	struct fdtable *old_fdt, *new_fdt;
Linus Torvalds's avatar
Linus Torvalds committed
667

Prasanna Meda's avatar
Prasanna Meda committed
668
	*errorp = -ENOMEM;
669 670
	newf = alloc_files();
	if (!newf)
Linus Torvalds's avatar
Linus Torvalds committed
671 672 673
		goto out;

	spin_lock(&oldf->file_lock);
674 675 676
	old_fdt = files_fdtable(oldf);
	new_fdt = files_fdtable(newf);
	size = old_fdt->max_fdset;
677
	open_files = count_open_files(old_fdt);
Linus Torvalds's avatar
Linus Torvalds committed
678 679 680 681 682 683
	expand = 0;

	/*
	 * Check whether we need to allocate a larger fd array or fd set.
	 * Note: we're not a clone task, so the open count won't  change.
	 */
684 685
	if (open_files > new_fdt->max_fdset) {
		new_fdt->max_fdset = 0;
Linus Torvalds's avatar
Linus Torvalds committed
686 687
		expand = 1;
	}
688 689
	if (open_files > new_fdt->max_fds) {
		new_fdt->max_fds = 0;
Linus Torvalds's avatar
Linus Torvalds committed
690 691 692 693 694 695 696
		expand = 1;
	}

	/* if the old fdset gets grown now, we'll only copy up to "size" fds */
	if (expand) {
		spin_unlock(&oldf->file_lock);
		spin_lock(&newf->file_lock);
697
		*errorp = expand_files(newf, open_files-1);
Linus Torvalds's avatar
Linus Torvalds committed
698
		spin_unlock(&newf->file_lock);
699
		if (*errorp < 0)
Linus Torvalds's avatar
Linus Torvalds committed
700
			goto out_release;
701 702 703 704 705 706
		new_fdt = files_fdtable(newf);
		/*
		 * Reacquire the oldf lock and a pointer to its fd table
		 * who knows it may have a new bigger fd table. We need
		 * the latest pointer.
		 */
Linus Torvalds's avatar
Linus Torvalds committed
707
		spin_lock(&oldf->file_lock);
708
		old_fdt = files_fdtable(oldf);
Linus Torvalds's avatar
Linus Torvalds committed
709 710
	}

711 712
	old_fds = old_fdt->fd;
	new_fds = new_fdt->fd;
Linus Torvalds's avatar
Linus Torvalds committed
713

714 715
	memcpy(new_fdt->open_fds->fds_bits, old_fdt->open_fds->fds_bits, open_files/8);
	memcpy(new_fdt->close_on_exec->fds_bits, old_fdt->close_on_exec->fds_bits, open_files/8);
Linus Torvalds's avatar
Linus Torvalds committed
716 717 718 719 720 721 722 723 724 725 726 727

	for (i = open_files; i != 0; i--) {
		struct file *f = *old_fds++;
		if (f) {
			get_file(f);
		} else {
			/*
			 * The fd may be claimed in the fd bitmap but not yet
			 * instantiated in the files array if a sibling thread
			 * is partway through open().  So make sure that this
			 * fd is available to the new process.
			 */
728
			FD_CLR(open_files - i, new_fdt->open_fds);
Linus Torvalds's avatar
Linus Torvalds committed
729
		}
730
		rcu_assign_pointer(*new_fds++, f);
Linus Torvalds's avatar
Linus Torvalds committed
731 732 733 734
	}
	spin_unlock(&oldf->file_lock);

	/* compute the remainder to be cleared */
735
	size = (new_fdt->max_fds - open_files) * sizeof(struct file *);
Linus Torvalds's avatar
Linus Torvalds committed
736 737 738 739

	/* This is long word aligned thus could use a optimized version */ 
	memset(new_fds, 0, size); 

740 741
	if (new_fdt->max_fdset > open_files) {
		int left = (new_fdt->max_fdset-open_files)/8;
Linus Torvalds's avatar
Linus Torvalds committed
742 743
		int start = open_files / (8 * sizeof(unsigned long));

744 745
		memset(&new_fdt->open_fds->fds_bits[start], 0, left);
		memset(&new_fdt->close_on_exec->fds_bits[start], 0, left);
Linus Torvalds's avatar
Linus Torvalds committed
746 747 748
	}

out:
749
	return newf;
Linus Torvalds's avatar
Linus Torvalds committed
750 751

out_release:
752 753 754
	free_fdset (new_fdt->close_on_exec, new_fdt->max_fdset);
	free_fdset (new_fdt->open_fds, new_fdt->max_fdset);
	free_fd_array(new_fdt->fd, new_fdt->max_fds);
Linus Torvalds's avatar
Linus Torvalds committed
755
	kmem_cache_free(files_cachep, newf);
756
	return NULL;
Linus Torvalds's avatar
Linus Torvalds committed
757 758
}

759 760 761 762 763 764 765 766 767 768 769 770 771 772 773 774 775 776 777 778 779 780 781 782 783 784 785 786 787 788 789 790 791
static int copy_files(unsigned long clone_flags, struct task_struct * tsk)
{
	struct files_struct *oldf, *newf;
	int error = 0;

	/*
	 * A background process may not have any files ...
	 */
	oldf = current->files;
	if (!oldf)
		goto out;

	if (clone_flags & CLONE_FILES) {
		atomic_inc(&oldf->count);
		goto out;
	}

	/*
	 * Note: we may be using current for both targets (See exec.c)
	 * This works because we cache current->files (old) as oldf. Don't
	 * break this.
	 */
	tsk->files = NULL;
	newf = dup_fd(oldf, &error);
	if (!newf)
		goto out;

	tsk->files = newf;
	error = 0;
out:
	return error;
}

Linus Torvalds's avatar
Linus Torvalds committed
792 793 794 795 796 797 798 799 800 801 802
/*
 *	Helper to unshare the files of the current task.
 *	We don't want to expose copy_files internals to
 *	the exec layer of the kernel.
 */

int unshare_files(void)
{
	struct files_struct *files  = current->files;
	int rc;

803
	BUG_ON(!files);
Linus Torvalds's avatar
Linus Torvalds committed
804 805 806 807 808 809 810 811 812 813 814 815 816 817 818 819 820 821 822 823 824 825 826 827 828

	/* This can race but the race causes us to copy when we don't
	   need to and drop the copy */
	if(atomic_read(&files->count) == 1)
	{
		atomic_inc(&files->count);
		return 0;
	}
	rc = copy_files(0, current);
	if(rc)
		current->files = files;
	return rc;
}

EXPORT_SYMBOL(unshare_files);

static inline int copy_sighand(unsigned long clone_flags, struct task_struct * tsk)
{
	struct sighand_struct *sig;

	if (clone_flags & (CLONE_SIGHAND | CLONE_THREAD)) {
		atomic_inc(&current->sighand->count);
		return 0;
	}
	sig = kmem_cache_alloc(sighand_cachep, GFP_KERNEL);
Ingo Molnar's avatar
Ingo Molnar committed
829
	rcu_assign_pointer(tsk->sighand, sig);
Linus Torvalds's avatar
Linus Torvalds committed
830 831 832 833 834 835 836
	if (!sig)
		return -ENOMEM;
	atomic_set(&sig->count, 1);
	memcpy(sig->action, current->sighand->action, sizeof(sig->action));
	return 0;
}

837
void __cleanup_sighand(struct sighand_struct *sighand)
838 839 840 841 842
{
	if (atomic_dec_and_test(&sighand->count))
		kmem_cache_free(sighand_cachep, sighand);
}

Linus Torvalds's avatar
Linus Torvalds committed
843 844 845 846 847 848 849 850 851 852 853 854 855 856 857 858 859 860 861 862 863 864 865 866 867 868 869 870 871 872 873 874
static inline int copy_signal(unsigned long clone_flags, struct task_struct * tsk)
{
	struct signal_struct *sig;
	int ret;

	if (clone_flags & CLONE_THREAD) {
		atomic_inc(&current->signal->count);
		atomic_inc(&current->signal->live);
		return 0;
	}
	sig = kmem_cache_alloc(signal_cachep, GFP_KERNEL);
	tsk->signal = sig;
	if (!sig)
		return -ENOMEM;

	ret = copy_thread_group_keys(tsk);
	if (ret < 0) {
		kmem_cache_free(signal_cachep, sig);
		return ret;
	}

	atomic_set(&sig->count, 1);
	atomic_set(&sig->live, 1);
	init_waitqueue_head(&sig->wait_chldexit);
	sig->flags = 0;
	sig->group_exit_code = 0;
	sig->group_exit_task = NULL;
	sig->group_stop_count = 0;
	sig->curr_target = NULL;
	init_sigpending(&sig->shared_pending);
	INIT_LIST_HEAD(&sig->posix_timers);

875
	hrtimer_init(&sig->real_timer, CLOCK_MONOTONIC, HRTIMER_REL);
876
	sig->it_real_incr.tv64 = 0;
Linus Torvalds's avatar
Linus Torvalds committed
877
	sig->real_timer.function = it_real_fn;
878
	sig->tsk = tsk;
Linus Torvalds's avatar
Linus Torvalds committed
879 880 881 882 883 884 885 886 887 888 889 890 891 892 893 894

	sig->it_virt_expires = cputime_zero;
	sig->it_virt_incr = cputime_zero;
	sig->it_prof_expires = cputime_zero;
	sig->it_prof_incr = cputime_zero;

	sig->leader = 0;	/* session leadership doesn't inherit */
	sig->tty_old_pgrp = 0;

	sig->utime = sig->stime = sig->cutime = sig->cstime = cputime_zero;
	sig->nvcsw = sig->nivcsw = sig->cnvcsw = sig->cnivcsw = 0;
	sig->min_flt = sig->maj_flt = sig->cmin_flt = sig->cmaj_flt = 0;
	sig->sched_time = 0;
	INIT_LIST_HEAD(&sig->cpu_timers[0]);
	INIT_LIST_HEAD(&sig->cpu_timers[1]);
	INIT_LIST_HEAD(&sig->cpu_timers[2]);
895
	taskstats_tgid_init(sig);
Linus Torvalds's avatar
Linus Torvalds committed
896 897 898 899 900 901 902 903 904 905 906 907 908

	task_lock(current->group_leader);
	memcpy(sig->rlim, current->signal->rlim, sizeof sig->rlim);
	task_unlock(current->group_leader);

	if (sig->rlim[RLIMIT_CPU].rlim_cur != RLIM_INFINITY) {
		/*
		 * New sole thread in the process gets an expiry time
		 * of the whole CPU time limit.
		 */
		tsk->it_prof_expires =
			secs_to_cputime(sig->rlim[RLIMIT_CPU].rlim_cur);
	}
909
	acct_init_pacct(&sig->pacct);
Linus Torvalds's avatar
Linus Torvalds committed
910 911 912 913

	return 0;
}

914 915 916 917 918 919 920 921 922 923 924 925 926 927 928 929
void __cleanup_signal(struct signal_struct *sig)
{
	exit_thread_group_keys(sig);
	kmem_cache_free(signal_cachep, sig);
}

static inline void cleanup_signal(struct task_struct *tsk)
{
	struct signal_struct *sig = tsk->signal;

	atomic_dec(&sig->live);

	if (atomic_dec_and_test(&sig->count))
		__cleanup_signal(sig);
}

Linus Torvalds's avatar
Linus Torvalds committed
930 931 932 933
static inline void copy_flags(unsigned long clone_flags, struct task_struct *p)
{
	unsigned long new_flags = p->flags;

934
	new_flags &= ~(PF_SUPERPRIV | PF_NOFREEZE);
Linus Torvalds's avatar
Linus Torvalds committed
935 936 937 938 939 940 941 942 943 944 945 946 947
	new_flags |= PF_FORKNOEXEC;
	if (!(clone_flags & CLONE_PTRACE))
		p->ptrace = 0;
	p->flags = new_flags;
}

asmlinkage long sys_set_tid_address(int __user *tidptr)
{
	current->clear_child_tid = tidptr;

	return current->pid;
}

Ingo Molnar's avatar
Ingo Molnar committed
948 949 950 951 952 953 954 955 956
static inline void rt_mutex_init_task(struct task_struct *p)
{
#ifdef CONFIG_RT_MUTEXES
	spin_lock_init(&p->pi_lock);
	plist_head_init(&p->pi_waiters, &p->pi_lock);
	p->pi_blocked_on = NULL;
#endif
}

Linus Torvalds's avatar
Linus Torvalds committed
957 958 959 960 961 962 963 964
/*
 * This creates a new process as a copy of the old one,
 * but does not actually start it yet.
 *
 * It copies the registers, and all the appropriate
 * parts of the process environment (as per the clone
 * flags). The actual kick-off is left to the caller.
 */
965 966 967 968 969 970 971
static struct task_struct *copy_process(unsigned long clone_flags,
					unsigned long stack_start,
					struct pt_regs *regs,
					unsigned long stack_size,
					int __user *parent_tidptr,
					int __user *child_tidptr,
					int pid)
Linus Torvalds's avatar
Linus Torvalds committed
972 973 974 975 976 977 978 979 980 981 982 983 984 985 986 987 988 989 990 991 992 993 994 995 996 997 998 999 1000 1001 1002
{
	int retval;
	struct task_struct *p = NULL;

	if ((clone_flags & (CLONE_NEWNS|CLONE_FS)) == (CLONE_NEWNS|CLONE_FS))
		return ERR_PTR(-EINVAL);

	/*
	 * Thread groups must share signals as well, and detached threads
	 * can only be started up within the thread group.
	 */
	if ((clone_flags & CLONE_THREAD) && !(clone_flags & CLONE_SIGHAND))
		return ERR_PTR(-EINVAL);

	/*
	 * Shared signal handlers imply shared VM. By way of the above,
	 * thread groups also imply shared VM. Blocking this case allows
	 * for various simplifications in other code.
	 */
	if ((clone_flags & CLONE_SIGHAND) && !(clone_flags & CLONE_VM))
		return ERR_PTR(-EINVAL);

	retval = security_task_create(clone_flags);
	if (retval)
		goto fork_out;

	retval = -ENOMEM;
	p = dup_task_struct(current);
	if (!p)
		goto fork_out;

1003 1004
	rt_mutex_init_task(p);

1005 1006 1007 1008
#ifdef CONFIG_TRACE_IRQFLAGS
	DEBUG_LOCKS_WARN_ON(!p->hardirqs_enabled);
	DEBUG_LOCKS_WARN_ON(!p->softirqs_enabled);
#endif
Linus Torvalds's avatar
Linus Torvalds committed
1009 1010 1011 1012 1013 1014 1015 1016 1017 1018 1019 1020 1021 1022 1023 1024 1025 1026 1027 1028
	retval = -EAGAIN;
	if (atomic_read(&p->user->processes) >=
			p->signal->rlim[RLIMIT_NPROC].rlim_cur) {
		if (!capable(CAP_SYS_ADMIN) && !capable(CAP_SYS_RESOURCE) &&
				p->user != &root_user)
			goto bad_fork_free;
	}

	atomic_inc(&p->user->__count);
	atomic_inc(&p->user->processes);
	get_group_info(p->group_info);

	/*
	 * If multiple threads are within copy_process(), then this check
	 * triggers too late. This doesn't hurt, the check is only there
	 * to stop root fork bombs.
	 */
	if (nr_threads >= max_threads)
		goto bad_fork_cleanup_count;

1029
	if (!try_module_get(task_thread_info(p)->exec_domain->module))
Linus Torvalds's avatar
Linus Torvalds committed
1030 1031 1032 1033 1034 1035
		goto bad_fork_cleanup_count;

	if (p->binfmt && !try_module_get(p->binfmt->module))
		goto bad_fork_cleanup_put_domain;

	p->did_exec = 0;
1036
	delayacct_tsk_init(p);	/* Must remain after dup_task_struct() */
Linus Torvalds's avatar
Linus Torvalds committed
1037 1038 1039 1040 1041
	copy_flags(clone_flags, p);
	p->pid = pid;
	retval = -EFAULT;
	if (clone_flags & CLONE_PARENT_SETTID)
		if (put_user(p->pid, parent_tidptr))
1042
			goto bad_fork_cleanup_delays_binfmt;
Linus Torvalds's avatar
Linus Torvalds committed
1043 1044 1045 1046 1047 1048 1049 1050 1051 1052 1053 1054 1055 1056 1057 1058

	INIT_LIST_HEAD(&p->children);
	INIT_LIST_HEAD(&p->sibling);
	p->vfork_done = NULL;
	spin_lock_init(&p->alloc_lock);

	clear_tsk_thread_flag(p, TIF_SIGPENDING);
	init_sigpending(&p->pending);

	p->utime = cputime_zero;
	p->stime = cputime_zero;
 	p->sched_time = 0;
	p->rchar = 0;		/* I/O counter: bytes read */
	p->wchar = 0;		/* I/O counter: bytes written */
	p->syscr = 0;		/* I/O counter: read syscalls */
	p->syscw = 0;		/* I/O counter: write syscalls */
1059
	task_io_accounting_init(p);
Linus Torvalds's avatar
Linus Torvalds committed
1060 1061 1062 1063 1064 1065 1066 1067 1068 1069 1070 1071 1072 1073 1074
	acct_clear_integrals(p);

 	p->it_virt_expires = cputime_zero;
	p->it_prof_expires = cputime_zero;
 	p->it_sched_expires = 0;
 	INIT_LIST_HEAD(&p->cpu_timers[0]);
 	INIT_LIST_HEAD(&p->cpu_timers[1]);
 	INIT_LIST_HEAD(&p->cpu_timers[2]);

	p->lock_depth = -1;		/* -1 = no lock */
	do_posix_clock_monotonic_gettime(&p->start_time);
	p->security = NULL;
	p->io_context = NULL;
	p->io_wait = NULL;
	p->audit_context = NULL;
Paul Jackson's avatar
Paul Jackson committed
1075
	cpuset_fork(p);
Linus Torvalds's avatar
Linus Torvalds committed
1076 1077 1078 1079 1080
#ifdef CONFIG_NUMA
 	p->mempolicy = mpol_copy(p->mempolicy);
 	if (IS_ERR(p->mempolicy)) {
 		retval = PTR_ERR(p->mempolicy);
 		p->mempolicy = NULL;
Paul Jackson's avatar
Paul Jackson committed
1081
 		goto bad_fork_cleanup_cpuset;
Linus Torvalds's avatar
Linus Torvalds committed
1082
 	}
1083
	mpol_fix_fork_child_flag(p);
Linus Torvalds's avatar
Linus Torvalds committed
1084
#endif
1085 1086
#ifdef CONFIG_TRACE_IRQFLAGS
	p->irq_events = 0;
1087 1088 1089
#ifdef __ARCH_WANT_INTERRUPTS_ON_CTXSW
	p->hardirqs_enabled = 1;
#else
1090
	p->hardirqs_enabled = 0;
1091
#endif
1092 1093 1094 1095 1096 1097 1098 1099 1100 1101 1102 1103
	p->hardirq_enable_ip = 0;
	p->hardirq_enable_event = 0;
	p->hardirq_disable_ip = _THIS_IP_;
	p->hardirq_disable_event = 0;
	p->softirqs_enabled = 1;
	p->softirq_enable_ip = _THIS_IP_;
	p->softirq_enable_event = 0;
	p->softirq_disable_ip = 0;
	p->softirq_disable_event = 0;
	p->hardirq_context = 0;
	p->softirq_context = 0;
#endif
Ingo Molnar's avatar
Ingo Molnar committed
1104 1105 1106 1107 1108
#ifdef CONFIG_LOCKDEP
	p->lockdep_depth = 0; /* no locks held yet */
	p->curr_chain_key = 0;
	p->lockdep_recursion = 0;
#endif
Linus Torvalds's avatar
Linus Torvalds committed
1109

1110 1111 1112 1113
#ifdef CONFIG_DEBUG_MUTEXES
	p->blocked_on = NULL; /* not blocked yet */
#endif

Linus Torvalds's avatar
Linus Torvalds committed
1114 1115 1116 1117 1118 1119 1120 1121 1122 1123 1124 1125 1126 1127 1128 1129 1130 1131 1132 1133 1134 1135 1136
	p->tgid = p->pid;
	if (clone_flags & CLONE_THREAD)
		p->tgid = current->tgid;

	if ((retval = security_task_alloc(p)))
		goto bad_fork_cleanup_policy;
	if ((retval = audit_alloc(p)))
		goto bad_fork_cleanup_security;
	/* copy all the process information */
	if ((retval = copy_semundo(clone_flags, p)))
		goto bad_fork_cleanup_audit;
	if ((retval = copy_files(clone_flags, p)))
		goto bad_fork_cleanup_semundo;
	if ((retval = copy_fs(clone_flags, p)))
		goto bad_fork_cleanup_files;
	if ((retval = copy_sighand(clone_flags, p)))
		goto bad_fork_cleanup_fs;
	if ((retval = copy_signal(clone_flags, p)))
		goto bad_fork_cleanup_sighand;
	if ((retval = copy_mm(clone_flags, p)))
		goto bad_fork_cleanup_signal;
	if ((retval = copy_keys(clone_flags, p)))
		goto bad_fork_cleanup_mm;
1137
	if ((retval = copy_namespaces(clone_flags, p)))
Linus Torvalds's avatar
Linus Torvalds committed
1138 1139 1140
		goto bad_fork_cleanup_keys;
	retval = copy_thread(0, clone_flags, stack_start, stack_size, p, regs);
	if (retval)
1141
		goto bad_fork_cleanup_namespaces;
Linus Torvalds's avatar
Linus Torvalds committed
1142 1143 1144 1145 1146 1147

	p->set_child_tid = (clone_flags & CLONE_CHILD_SETTID) ? child_tidptr : NULL;
	/*
	 * Clear TID on mm_release()?
	 */
	p->clear_child_tid = (clone_flags & CLONE_CHILD_CLEARTID) ? child_tidptr: NULL;
1148 1149 1150 1151
	p->robust_list = NULL;
#ifdef CONFIG_COMPAT
	p->compat_robust_list = NULL;
#endif
1152 1153 1154
	INIT_LIST_HEAD(&p->pi_state_list);
	p->pi_state_cache = NULL;

1155 1156 1157 1158 1159 1160
	/*
	 * sigaltstack should be cleared when sharing the same VM
	 */
	if ((clone_flags & (CLONE_VM|CLONE_VFORK)) == CLONE_VM)
		p->sas_ss_sp = p->sas_ss_size = 0;

Linus Torvalds's avatar
Linus Torvalds committed
1161 1162 1163 1164 1165
	/*
	 * Syscall tracing should be turned off in the child regardless
	 * of CLONE_PTRACE.
	 */
	clear_tsk_thread_flag(p, TIF_SYSCALL_TRACE);
1166 1167 1168
#ifdef TIF_SYSCALL_EMU
	clear_tsk_thread_flag(p, TIF_SYSCALL_EMU);
#endif
Linus Torvalds's avatar
Linus Torvalds committed
1169 1170 1171 1172 1173 1174 1175 1176 1177 1178 1179 1180 1181 1182 1183

	/* Our parent execution domain becomes current domain
	   These must match for thread signalling to apply */
	p->parent_exec_id = p->self_exec_id;

	/* ok, now we should be set up.. */
	p->exit_signal = (clone_flags & CLONE_THREAD) ? -1 : (clone_flags & CSIGNAL);
	p->pdeath_signal = 0;
	p->exit_state = 0;

	/*
	 * Ok, make it visible to the rest of the system.
	 * We dont wake it up yet.
	 */
	p->group_leader = p;
1184
	INIT_LIST_HEAD(&p->thread_group);
Linus Torvalds's avatar
Linus Torvalds committed
1185 1186 1187
	INIT_LIST_HEAD(&p->ptrace_children);
	INIT_LIST_HEAD(&p->ptrace_list);

1188 1189 1190
	/* Perform scheduler related setup. Assign this task to a CPU. */
	sched_fork(p, clone_flags);

Linus Torvalds's avatar
Linus Torvalds committed
1191 1192 1193
	/* Need tasklist lock for parent etc handling! */
	write_lock_irq(&tasklist_lock);

1194 1195 1196
	/* for sys_ioprio_set(IOPRIO_WHO_PGRP) */
	p->ioprio = current->ioprio;

Linus Torvalds's avatar
Linus Torvalds committed
1197
	/*
1198 1199 1200 1201 1202 1203 1204
	 * The task hasn't been attached yet, so its cpus_allowed mask will
	 * not be changed, nor will its assigned CPU.
	 *
	 * The cpus_allowed mask of the parent may have changed after it was
	 * copied first time - so re-copy it here, then check the child's CPU
	 * to ensure it is on a valid CPU (and if not, just force it back to
	 * parent's CPU). This avoids alot of nasty races.
Linus Torvalds's avatar
Linus Torvalds committed
1205 1206
	 */
	p->cpus_allowed = current->cpus_allowed;
1207 1208
	if (unlikely(!cpu_isset(task_cpu(p), p->cpus_allowed) ||
			!cpu_online(task_cpu(p))))
1209
		set_task_cpu(p, smp_processor_id());
Linus Torvalds's avatar
Linus Torvalds committed
1210 1211 1212 1213 1214 1215 1216 1217

	/* CLONE_PARENT re-uses the old parent */
	if (clone_flags & (CLONE_PARENT|CLONE_THREAD))
		p->real_parent = current->real_parent;
	else
		p->real_parent = current;
	p->parent = p->real_parent;

1218
	spin_lock(&current->sighand->siglock);
1219 1220 1221 1222 1223 1224 1225 1226 1227 1228 1229 1230 1231 1232

	/*
	 * Process group and session signals need to be delivered to just the
	 * parent before the fork or both the parent and the child after the
	 * fork. Restart if a signal comes in before we add the new process to
	 * it's process group.
	 * A fatal signal pending means that current will exit, so the new
	 * thread can't slip out of an OOM kill (or normal SIGKILL).
 	 */
 	recalc_sigpending();
	if (signal_pending(current)) {
		spin_unlock(&current->sighand->siglock);
		write_unlock_irq(&tasklist_lock);
		retval = -ERESTARTNOINTR;
1233
		goto bad_fork_cleanup_namespaces;
1234 1235
	}

Linus Torvalds's avatar
Linus Torvalds committed
1236 1237
	if (clone_flags & CLONE_THREAD) {
		p->group_leader = current->group_leader;
1238
		list_add_tail_rcu(&p->thread_group, &p->group_leader->thread_group);
Linus Torvalds's avatar
Linus Torvalds committed
1239 1240 1241 1242 1243 1244 1245 1246 1247 1248 1249 1250 1251 1252 1253 1254 1255

		if (!cputime_eq(current->signal->it_virt_expires,
				cputime_zero) ||
		    !cputime_eq(current->signal->it_prof_expires,
				cputime_zero) ||
		    current->signal->rlim[RLIMIT_CPU].rlim_cur != RLIM_INFINITY ||
		    !list_empty(&current->signal->cpu_timers[0]) ||
		    !list_empty(&current->signal->cpu_timers[1]) ||
		    !list_empty(&current->signal->cpu_timers[2])) {
			/*
			 * Have child wake up on its first tick to check
			 * for process CPU timers.
			 */
			p->it_prof_expires = jiffies_to_cputime(1);
		}
	}

1256 1257 1258 1259 1260 1261 1262 1263
	if (likely(p->pid)) {
		add_parent(p);
		if (unlikely(p->ptrace & PT_PTRACED))
			__ptrace_link(p, current->parent);

		if (thread_group_leader(p)) {
			p->signal->tty = current->signal->tty;
			p->signal->pgrp = process_group(current);
1264
			set_signal_session(p->signal, process_session(current));
1265
			attach_pid(p, PIDTYPE_PGID, process_group(p));
1266
			attach_pid(p, PIDTYPE_SID, process_session(p));
1267

1268
			list_add_tail_rcu(&p->tasks, &init_task.tasks);
Linus Torvalds's avatar
Linus Torvalds committed
1269
			__get_cpu_var(process_counts)++;
1270 1271 1272
		}
		attach_pid(p, PIDTYPE_PID, p->pid);
		nr_threads++;
Linus Torvalds's avatar
Linus Torvalds committed
1273 1274 1275
	}

	total_forks++;
1276
	spin_unlock(&current->sighand->siglock);
Linus Torvalds's avatar
Linus Torvalds committed
1277
	write_unlock_irq(&tasklist_lock);
1278
	proc_fork_connector(p);
Linus Torvalds's avatar
Linus Torvalds committed
1279 1280
	return p;

1281 1282
bad_fork_cleanup_namespaces:
	exit_task_namespaces(p);
Linus Torvalds's avatar
Linus Torvalds committed
1283 1284 1285 1286 1287 1288
bad_fork_cleanup_keys:
	exit_keys(p);
bad_fork_cleanup_mm:
	if (p->mm)
		mmput(p->mm);
bad_fork_cleanup_signal:
1289
	cleanup_signal(p);
Linus Torvalds's avatar
Linus Torvalds committed
1290
bad_fork_cleanup_sighand:
1291
	__cleanup_sighand(p->sighand);
Linus Torvalds's avatar
Linus Torvalds committed
1292 1293 1294 1295 1296 1297 1298 1299 1300 1301 1302 1303 1304
bad_fork_cleanup_fs:
	exit_fs(p); /* blocking */
bad_fork_cleanup_files:
	exit_files(p); /* blocking */
bad_fork_cleanup_semundo:
	exit_sem(p);
bad_fork_cleanup_audit:
	audit_free(p);
bad_fork_cleanup_security:
	security_task_free(p);
bad_fork_cleanup_policy:
#ifdef CONFIG_NUMA
	mpol_free(p->mempolicy);
Paul Jackson's avatar
Paul Jackson committed
1305
bad_fork_cleanup_cpuset:
Linus Torvalds's avatar
Linus Torvalds committed
1306
#endif
Paul Jackson's avatar
Paul Jackson committed
1307
	cpuset_exit(p);
1308 1309
bad_fork_cleanup_delays_binfmt:
	delayacct_tsk_free(p);
Linus Torvalds's avatar
Linus Torvalds committed
1310 1311 1312
	if (p->binfmt)
		module_put(p->binfmt->module);
bad_fork_cleanup_put_domain:
1313
	module_put(task_thread_info(p)->exec_domain->module);
Linus Torvalds's avatar
Linus Torvalds committed
1314 1315 1316 1317 1318 1319
bad_fork_cleanup_count:
	put_group_info(p->group_info);
	atomic_dec(&p->user->processes);
	free_uid(p->user);
bad_fork_free:
	free_task(p);
1320 1321
fork_out:
	return ERR_PTR(retval);
Linus Torvalds's avatar
Linus Torvalds committed
1322 1323
}

1324
noinline struct pt_regs * __devinit __attribute__((weak)) idle_regs(struct pt_regs *regs)
Linus Torvalds's avatar
Linus Torvalds committed
1325 1326 1327 1328 1329
{
	memset(regs, 0, sizeof(struct pt_regs));
	return regs;
}

1330
struct task_struct * __devinit fork_idle(int cpu)
Linus Torvalds's avatar
Linus Torvalds committed
1331
{
1332
	struct task_struct *task;
Linus Torvalds's avatar
Linus Torvalds committed
1333 1334 1335
	struct pt_regs regs;

	task = copy_process(CLONE_VM, 0, idle_regs(&regs), 0, NULL, NULL, 0);
1336 1337
	if (!IS_ERR(task))
		init_idle(task, cpu);
1338

Linus Torvalds's avatar
Linus Torvalds committed
1339 1340 1341 1342 1343 1344 1345 1346 1347 1348 1349 1350 1351 1352 1353 1354 1355 1356 1357 1358 1359 1360 1361 1362 1363 1364 1365 1366 1367 1368 1369 1370 1371 1372
	return task;
}

static inline int fork_traceflag (unsigned clone_flags)
{
	if (clone_flags & CLONE_UNTRACED)
		return 0;
	else if (clone_flags & CLONE_VFORK) {
		if (current->ptrace & PT_TRACE_VFORK)
			return PTRACE_EVENT_VFORK;
	} else if ((clone_flags & CSIGNAL) != SIGCHLD) {
		if (current->ptrace & PT_TRACE_CLONE)
			return PTRACE_EVENT_CLONE;
	} else if (current->ptrace & PT_TRACE_FORK)
		return PTRACE_EVENT_FORK;

	return 0;
}

/*
 *  Ok, this is the main fork-routine.
 *
 * It copies the process, and if successful kick-starts
 * it and waits for it to finish using the VM if required.
 */
long do_fork(unsigned long clone_flags,
	      unsigned long stack_start,
	      struct pt_regs *regs,
	      unsigned long stack_size,
	      int __user *parent_tidptr,
	      int __user *child_tidptr)
{
	struct task_struct *p;
	int trace = 0;
1373 1374
	struct pid *pid = alloc_pid();
	long nr;
Linus Torvalds's avatar
Linus Torvalds committed
1375

1376
	if (!pid)
Linus Torvalds's avatar
Linus Torvalds committed
1377
		return -EAGAIN;
1378
	nr = pid->nr;
Linus Torvalds's avatar
Linus Torvalds committed