fork.c 40.9 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
/*
 *  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/module.h>
#include <linux/vmalloc.h>
#include <linux/completion.h>
20
#include <linux/mnt_namespace.h>
Linus Torvalds's avatar
Linus Torvalds committed
21 22 23 24 25 26 27 28
#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>
29
#include <linux/nsproxy.h>
30
#include <linux/capability.h>
Linus Torvalds's avatar
Linus Torvalds committed
31 32 33 34 35 36 37
#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>
38
#include <linux/task_io_accounting_ops.h>
39
#include <linux/rcupdate.h>
Linus Torvalds's avatar
Linus Torvalds committed
40 41 42 43 44 45
#include <linux/ptrace.h>
#include <linux/mount.h>
#include <linux/audit.h>
#include <linux/profile.h>
#include <linux/rmap.h>
#include <linux/acct.h>
46
#include <linux/tsacct_kern.h>
47
#include <linux/cn_proc.h>
Rafael J. Wysocki's avatar
Rafael J. Wysocki committed
48
#include <linux/freezer.h>
49
#include <linux/delayacct.h>
50
#include <linux/taskstats_kern.h>
51
#include <linux/random.h>
Miloslav Trmac's avatar
Miloslav Trmac committed
52
#include <linux/tty.h>
Linus Torvalds's avatar
Linus Torvalds committed
53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70

#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;

71
__cacheline_aligned DEFINE_RWLOCK(tasklist_lock);  /* outer */
Linus Torvalds's avatar
Linus Torvalds committed
72 73 74 75 76 77 78 79 80 81 82 83 84 85 86

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))
87
static struct kmem_cache *task_struct_cachep;
Linus Torvalds's avatar
Linus Torvalds committed
88 89 90
#endif

/* SLAB cache for signal_struct structures (tsk->signal) */
91
static struct kmem_cache *signal_cachep;
Linus Torvalds's avatar
Linus Torvalds committed
92 93

/* SLAB cache for sighand_struct structures (tsk->sighand) */
94
struct kmem_cache *sighand_cachep;
Linus Torvalds's avatar
Linus Torvalds committed
95 96

/* SLAB cache for files_struct structures (tsk->files) */
97
struct kmem_cache *files_cachep;
Linus Torvalds's avatar
Linus Torvalds committed
98 99

/* SLAB cache for fs_struct structures (tsk->fs) */
100
struct kmem_cache *fs_cachep;
Linus Torvalds's avatar
Linus Torvalds committed
101 102

/* SLAB cache for vm_area_struct structures */
103
struct kmem_cache *vm_area_cachep;
Linus Torvalds's avatar
Linus Torvalds committed
104 105

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

void free_task(struct task_struct *tsk)
{
Roman Zippel's avatar
Roman Zippel committed
110
	free_thread_info(tsk->stack);
Ingo Molnar's avatar
Ingo Molnar committed
111
	rt_mutex_debug_task_free(tsk);
Linus Torvalds's avatar
Linus Torvalds committed
112 113 114 115
	free_task_struct(tsk);
}
EXPORT_SYMBOL(free_task);

116
void __put_task_struct(struct task_struct *tsk)
Linus Torvalds's avatar
Linus Torvalds committed
117 118 119 120 121 122 123 124
{
	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);
125
	delayacct_tsk_free(tsk);
Linus Torvalds's avatar
Linus Torvalds committed
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;
Roman Zippel's avatar
Roman Zippel committed
180
	tsk->stack = ti;
181
	setup_thread_stack(tsk, orig);
Linus Torvalds's avatar
Linus Torvalds committed
182

183 184 185 186
#ifdef CONFIG_CC_STACKPROTECTOR
	tsk->stack_canary = get_random_int();
#endif

Linus Torvalds's avatar
Linus Torvalds committed
187 188
	/* One for us, one for whoever does the "release_task()" (usually parent) */
	atomic_set(&tsk->usage,2);
189
	atomic_set(&tsk->fs_excl, 0);
190
#ifdef CONFIG_BLK_DEV_IO_TRACE
191
	tsk->btrace_seq = 0;
192
#endif
193
	tsk->splice_pipe = NULL;
Linus Torvalds's avatar
Linus Torvalds committed
194 195 196 197
	return tsk;
}

#ifdef CONFIG_MMU
198
static inline int dup_mmap(struct mm_struct *mm, struct mm_struct *oldmm)
Linus Torvalds's avatar
Linus Torvalds committed
199
{
200
	struct vm_area_struct *mpnt, *tmp, **pprev;
Linus Torvalds's avatar
Linus Torvalds committed
201 202 203 204 205 206
	struct rb_node **rb_link, *rb_parent;
	int retval;
	unsigned long charge;
	struct mempolicy *pol;

	down_write(&oldmm->mmap_sem);
207
	flush_cache_dup_mm(oldmm);
208 209 210 211
	/*
	 * Not linked in yet - no deadlock potential:
	 */
	down_write_nested(&mm->mmap_sem, SINGLE_DEPTH_NESTING);
212

Linus Torvalds's avatar
Linus Torvalds committed
213 214 215 216
	mm->locked_vm = 0;
	mm->mmap = NULL;
	mm->mmap_cache = NULL;
	mm->free_area_cache = oldmm->mmap_base;
217
	mm->cached_hole_size = ~0UL;
Linus Torvalds's avatar
Linus Torvalds committed
218 219 220 221 222 223 224
	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;

225
	for (mpnt = oldmm->mmap; mpnt; mpnt = mpnt->vm_next) {
Linus Torvalds's avatar
Linus Torvalds committed
226 227 228
		struct file *file;

		if (mpnt->vm_flags & VM_DONTCOPY) {
229 230
			long pages = vma_pages(mpnt);
			mm->total_vm -= pages;
231
			vm_stat_account(mm, mpnt->vm_flags, mpnt->vm_file,
232
								-pages);
Linus Torvalds's avatar
Linus Torvalds committed
233 234 235 236 237 238 239 240 241
			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;
		}
242
		tmp = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL);
Linus Torvalds's avatar
Linus Torvalds committed
243 244 245 246 247 248 249 250 251 252 253 254 255 256
		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) {
257
			struct inode *inode = file->f_path.dentry->d_inode;
Linus Torvalds's avatar
Linus Torvalds committed
258 259 260 261 262 263 264 265 266 267 268 269 270 271
			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);
		}

		/*
272
		 * Link in the new vma and copy the page table entries.
Linus Torvalds's avatar
Linus Torvalds committed
273 274 275 276 277 278 279 280 281
		 */
		*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++;
282
		retval = copy_page_range(mm, oldmm, mpnt);
Linus Torvalds's avatar
Linus Torvalds committed
283 284 285 286 287 288 289

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

		if (retval)
			goto out;
	}
290 291
	/* a new mm has just been created */
	arch_dup_mmap(oldmm, mm);
Linus Torvalds's avatar
Linus Torvalds committed
292 293
	retval = 0;
out:
294
	up_write(&mm->mmap_sem);
295
	flush_tlb_mm(oldmm);
Linus Torvalds's avatar
Linus Torvalds committed
296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325
	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);

326
#define allocate_mm()	(kmem_cache_alloc(mm_cachep, GFP_KERNEL))
Linus Torvalds's avatar
Linus Torvalds committed
327 328 329 330 331 332 333 334 335 336 337 338
#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;
339
	set_mm_counter(mm, file_rss, 0);
340
	set_mm_counter(mm, anon_rss, 0);
Linus Torvalds's avatar
Linus Torvalds committed
341 342 343 344
	spin_lock_init(&mm->page_table_lock);
	rwlock_init(&mm->ioctx_list_lock);
	mm->ioctx_list = NULL;
	mm->free_area_cache = TASK_UNMAPPED_BASE;
345
	mm->cached_hole_size = ~0UL;
Linus Torvalds's avatar
Linus Torvalds committed
346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387

	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
388 389
	might_sleep();

Linus Torvalds's avatar
Linus Torvalds committed
390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454
	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);
	}
455 456 457 458 459 460 461 462 463 464

	/*
	 * 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
465 466 467 468 469 470 471 472 473 474 475 476
		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);
	}
}

477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494
/*
 * 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));

495 496 497 498
	/* Initializing for Swap token stuff */
	mm->token_priority = 0;
	mm->last_interval = 0;

499 500 501 502 503 504 505 506 507 508 509 510 511 512 513 514 515 516 517 518 519 520 521 522 523 524 525 526 527 528 529
	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
530 531 532 533 534 535 536 537 538 539 540 541 542 543 544 545 546 547 548 549 550 551 552 553 554 555 556
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;
557
	mm = dup_mm(tsk);
Linus Torvalds's avatar
Linus Torvalds committed
558 559 560 561
	if (!mm)
		goto fail_nomem;

good_mm:
562 563 564 565
	/* Initializing for Swap token stuff */
	mm->token_priority = 0;
	mm->last_interval = 0;

Linus Torvalds's avatar
Linus Torvalds committed
566 567 568 569 570 571 572 573 574 575 576 577 578 579 580 581 582 583 584 585 586 587 588 589 590 591 592 593 594 595 596 597 598 599 600 601 602 603 604 605 606 607 608 609 610 611 612 613 614 615 616 617
	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;
}

618
static int count_open_files(struct fdtable *fdt)
Linus Torvalds's avatar
Linus Torvalds committed
619
{
620
	int size = fdt->max_fds;
Linus Torvalds's avatar
Linus Torvalds committed
621 622 623 624
	int i;

	/* Find the last open fd */
	for (i = size/(8*sizeof(long)); i > 0; ) {
625
		if (fdt->open_fds->fds_bits[--i])
Linus Torvalds's avatar
Linus Torvalds committed
626 627 628 629 630 631
			break;
	}
	i = (i+1) * 8 * sizeof(long);
	return i;
}

632 633 634 635 636
static struct files_struct *alloc_files(void)
{
	struct files_struct *newf;
	struct fdtable *fdt;

637
	newf = kmem_cache_alloc(files_cachep, GFP_KERNEL);
638 639 640 641 642 643
	if (!newf)
		goto out;

	atomic_set(&newf->count, 1);

	spin_lock_init(&newf->file_lock);
644
	newf->next_fd = 0;
645
	fdt = &newf->fdtab;
646
	fdt->max_fds = NR_OPEN_DEFAULT;
647 648
	fdt->close_on_exec = (fd_set *)&newf->close_on_exec_init;
	fdt->open_fds = (fd_set *)&newf->open_fds_init;
649
	fdt->fd = &newf->fd_array[0];
650 651 652
	INIT_RCU_HEAD(&fdt->rcu);
	fdt->next = NULL;
	rcu_assign_pointer(newf->fdt, fdt);
653 654 655 656
out:
	return newf;
}

657 658 659
/*
 * Allocate a new files structure and copy contents from the
 * passed in files structure.
Prasanna Meda's avatar
Prasanna Meda committed
660
 * errorp will be valid only when the returned files_struct is NULL.
661 662
 */
static struct files_struct *dup_fd(struct files_struct *oldf, int *errorp)
Linus Torvalds's avatar
Linus Torvalds committed
663
{
664
	struct files_struct *newf;
Linus Torvalds's avatar
Linus Torvalds committed
665
	struct file **old_fds, **new_fds;
666
	int open_files, size, i;
667
	struct fdtable *old_fdt, *new_fdt;
Linus Torvalds's avatar
Linus Torvalds committed
668

Prasanna Meda's avatar
Prasanna Meda committed
669
	*errorp = -ENOMEM;
670 671
	newf = alloc_files();
	if (!newf)
Linus Torvalds's avatar
Linus Torvalds committed
672 673 674
		goto out;

	spin_lock(&oldf->file_lock);
675 676
	old_fdt = files_fdtable(oldf);
	new_fdt = files_fdtable(newf);
677
	open_files = count_open_files(old_fdt);
Linus Torvalds's avatar
Linus Torvalds committed
678 679

	/*
680 681
	 * Check whether we need to allocate a larger fd array and fd set.
	 * Note: we're not a clone task, so the open count won't change.
Linus Torvalds's avatar
Linus Torvalds committed
682
	 */
683 684
	if (open_files > new_fdt->max_fds) {
		new_fdt->max_fds = 0;
Linus Torvalds's avatar
Linus Torvalds committed
685 686
		spin_unlock(&oldf->file_lock);
		spin_lock(&newf->file_lock);
687
		*errorp = expand_files(newf, open_files-1);
Linus Torvalds's avatar
Linus Torvalds committed
688
		spin_unlock(&newf->file_lock);
689
		if (*errorp < 0)
Linus Torvalds's avatar
Linus Torvalds committed
690
			goto out_release;
691 692 693 694 695 696
		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
697
		spin_lock(&oldf->file_lock);
698
		old_fdt = files_fdtable(oldf);
Linus Torvalds's avatar
Linus Torvalds committed
699 700
	}

701 702
	old_fds = old_fdt->fd;
	new_fds = new_fdt->fd;
Linus Torvalds's avatar
Linus Torvalds committed
703

704 705 706 707
	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
708 709 710 711 712 713 714 715 716 717 718 719

	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.
			 */
720
			FD_CLR(open_files - i, new_fdt->open_fds);
Linus Torvalds's avatar
Linus Torvalds committed
721
		}
722
		rcu_assign_pointer(*new_fds++, f);
Linus Torvalds's avatar
Linus Torvalds committed
723 724 725 726
	}
	spin_unlock(&oldf->file_lock);

	/* compute the remainder to be cleared */
727
	size = (new_fdt->max_fds - open_files) * sizeof(struct file *);
Linus Torvalds's avatar
Linus Torvalds committed
728 729 730 731

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

732 733
	if (new_fdt->max_fds > open_files) {
		int left = (new_fdt->max_fds-open_files)/8;
Linus Torvalds's avatar
Linus Torvalds committed
734 735
		int start = open_files / (8 * sizeof(unsigned long));

736 737
		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
738 739
	}

740
	return newf;
Linus Torvalds's avatar
Linus Torvalds committed
741 742 743

out_release:
	kmem_cache_free(files_cachep, newf);
744
out:
745
	return NULL;
Linus Torvalds's avatar
Linus Torvalds committed
746 747
}

748 749 750 751 752 753 754 755 756 757 758 759 760 761 762 763 764 765 766 767 768 769 770 771 772 773 774 775 776 777 778 779 780
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
781 782 783 784 785 786 787 788 789 790 791
/*
 *	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;

792
	BUG_ON(!files);
Linus Torvalds's avatar
Linus Torvalds committed
793 794 795 796 797 798 799 800 801 802 803 804 805 806 807 808 809 810 811 812 813 814 815 816 817

	/* 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
818
	rcu_assign_pointer(tsk->sighand, sig);
Linus Torvalds's avatar
Linus Torvalds committed
819 820 821 822 823 824 825
	if (!sig)
		return -ENOMEM;
	atomic_set(&sig->count, 1);
	memcpy(sig->action, current->sighand->action, sizeof(sig->action));
	return 0;
}

826
void __cleanup_sighand(struct sighand_struct *sighand)
827 828 829 830 831
{
	if (atomic_dec_and_test(&sighand->count))
		kmem_cache_free(sighand_cachep, sighand);
}

Linus Torvalds's avatar
Linus Torvalds committed
832 833 834 835 836 837 838 839 840 841 842 843 844 845 846 847 848 849 850 851 852 853 854 855 856 857 858 859 860 861 862 863
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);

864
	hrtimer_init(&sig->real_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
865
	sig->it_real_incr.tv64 = 0;
Linus Torvalds's avatar
Linus Torvalds committed
866
	sig->real_timer.function = it_real_fn;
867
	sig->tsk = tsk;
Linus Torvalds's avatar
Linus Torvalds committed
868 869 870 871 872 873 874

	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 */
875
	sig->tty_old_pgrp = NULL;
Linus Torvalds's avatar
Linus Torvalds committed
876 877 878 879

	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;
880
	sig->inblock = sig->oublock = sig->cinblock = sig->coublock = 0;
881
	sig->sum_sched_runtime = 0;
Linus Torvalds's avatar
Linus Torvalds committed
882 883 884
	INIT_LIST_HEAD(&sig->cpu_timers[0]);
	INIT_LIST_HEAD(&sig->cpu_timers[1]);
	INIT_LIST_HEAD(&sig->cpu_timers[2]);
885
	taskstats_tgid_init(sig);
Linus Torvalds's avatar
Linus Torvalds committed
886 887 888 889 890 891 892 893 894 895 896 897 898

	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);
	}
899
	acct_init_pacct(&sig->pacct);
Linus Torvalds's avatar
Linus Torvalds committed
900

Miloslav Trmac's avatar
Miloslav Trmac committed
901 902
	tty_audit_fork(sig);

Linus Torvalds's avatar
Linus Torvalds committed
903 904 905
	return 0;
}

906 907 908 909 910 911 912 913 914 915 916 917 918 919 920 921
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
922 923 924 925
static inline void copy_flags(unsigned long clone_flags, struct task_struct *p)
{
	unsigned long new_flags = p->flags;

926
	new_flags &= ~(PF_SUPERPRIV | PF_NOFREEZE);
Linus Torvalds's avatar
Linus Torvalds committed
927 928 929 930 931 932 933 934 935 936 937 938 939
	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
940 941 942
static inline void rt_mutex_init_task(struct task_struct *p)
{
	spin_lock_init(&p->pi_lock);
943
#ifdef CONFIG_RT_MUTEXES
Ingo Molnar's avatar
Ingo Molnar committed
944 945 946 947 948
	plist_head_init(&p->pi_waiters, &p->pi_lock);
	p->pi_blocked_on = NULL;
#endif
}

Linus Torvalds's avatar
Linus Torvalds committed
949 950 951 952 953 954 955 956
/*
 * 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.
 */
957 958 959 960 961 962
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,
963
					struct pid *pid)
Linus Torvalds's avatar
Linus Torvalds committed
964 965 966 967 968 969 970 971 972 973 974 975 976 977 978 979 980 981 982 983 984 985 986 987 988 989 990 991 992 993 994
{
	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;

995 996
	rt_mutex_init_task(p);

997 998 999 1000
#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
1001 1002 1003 1004 1005 1006 1007 1008 1009 1010 1011 1012 1013 1014 1015 1016 1017 1018 1019 1020
	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;

1021
	if (!try_module_get(task_thread_info(p)->exec_domain->module))
Linus Torvalds's avatar
Linus Torvalds committed
1022 1023 1024 1025 1026 1027
		goto bad_fork_cleanup_count;

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

	p->did_exec = 0;
1028
	delayacct_tsk_init(p);	/* Must remain after dup_task_struct() */
Linus Torvalds's avatar
Linus Torvalds committed
1029
	copy_flags(clone_flags, p);
1030
	p->pid = pid_nr(pid);
Linus Torvalds's avatar
Linus Torvalds committed
1031 1032 1033
	retval = -EFAULT;
	if (clone_flags & CLONE_PARENT_SETTID)
		if (put_user(p->pid, parent_tidptr))
1034
			goto bad_fork_cleanup_delays_binfmt;
Linus Torvalds's avatar
Linus Torvalds committed
1035 1036 1037 1038 1039 1040 1041 1042 1043 1044 1045

	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;
1046

1047
#ifdef CONFIG_TASK_XACCT
Linus Torvalds's avatar
Linus Torvalds committed
1048 1049 1050 1051
	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 */
1052
#endif
1053
	task_io_accounting_init(p);
Linus Torvalds's avatar
Linus Torvalds committed
1054 1055 1056 1057 1058 1059 1060 1061 1062 1063 1064
	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);
1065 1066
	p->real_start_time = p->start_time;
	monotonic_to_bootbased(&p->real_start_time);
Linus Torvalds's avatar
Linus Torvalds committed
1067 1068 1069 1070
	p->security = NULL;
	p->io_context = NULL;
	p->io_wait = NULL;
	p->audit_context = NULL;
Paul Jackson's avatar
Paul Jackson committed
1071
	cpuset_fork(p);
Linus Torvalds's avatar
Linus Torvalds committed
1072 1073 1074 1075 1076
#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
1077
 		goto bad_fork_cleanup_cpuset;
Linus Torvalds's avatar
Linus Torvalds committed
1078
 	}
1079
	mpol_fix_fork_child_flag(p);
Linus Torvalds's avatar
Linus Torvalds committed
1080
#endif
1081 1082
#ifdef CONFIG_TRACE_IRQFLAGS
	p->irq_events = 0;
1083 1084 1085
#ifdef __ARCH_WANT_INTERRUPTS_ON_CTXSW
	p->hardirqs_enabled = 1;
#else
1086
	p->hardirqs_enabled = 0;
1087
#endif
1088 1089 1090 1091 1092 1093 1094 1095 1096 1097 1098 1099
	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
1100 1101 1102 1103 1104
#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
1105

1106 1107 1108 1109
#ifdef CONFIG_DEBUG_MUTEXES
	p->blocked_on = NULL; /* not blocked yet */
#endif

Linus Torvalds's avatar
Linus Torvalds committed
1110 1111 1112 1113 1114 1115 1116 1117 1118 1119 1120 1121 1122 1123 1124 1125 1126 1127 1128 1129 1130 1131 1132
	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;
1133
	if ((retval = copy_namespaces(clone_flags, p)))
Linus Torvalds's avatar
Linus Torvalds committed
1134 1135 1136
		goto bad_fork_cleanup_keys;
	retval = copy_thread(0, clone_flags, stack_start, stack_size, p, regs);
	if (retval)
1137
		goto bad_fork_cleanup_namespaces;
Linus Torvalds's avatar
Linus Torvalds committed
1138 1139 1140 1141 1142 1143

	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;
1144 1145 1146 1147
	p->robust_list = NULL;
#ifdef CONFIG_COMPAT
	p->compat_robust_list = NULL;
#endif
1148 1149 1150
	INIT_LIST_HEAD(&p->pi_state_list);
	p->pi_state_cache = NULL;

1151 1152 1153 1154 1155 1156
	/*
	 * 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
1157 1158 1159 1160 1161
	/*
	 * Syscall tracing should be turned off in the child regardless
	 * of CLONE_PTRACE.
	 */
	clear_tsk_thread_flag(p, TIF_SYSCALL_TRACE);
1162 1163 1164
#ifdef TIF_SYSCALL_EMU
	clear_tsk_thread_flag(p, TIF_SYSCALL_EMU);
#endif
Linus Torvalds's avatar
Linus Torvalds committed
1165 1166 1167 1168 1169 1170 1171 1172 1173 1174 1175 1176 1177 1178 1179

	/* 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;
1180
	INIT_LIST_HEAD(&p->thread_group);
Linus Torvalds's avatar
Linus Torvalds committed
1181 1182 1183
	INIT_LIST_HEAD(&p->ptrace_children);
	INIT_LIST_HEAD(&p->ptrace_list);

1184 1185 1186
	/* Perform scheduler related setup. Assign this task to a CPU. */
	sched_fork(p, clone_flags);

Linus Torvalds's avatar
Linus Torvalds committed
1187 1188 1189
	/* Need tasklist lock for parent etc handling! */
	write_lock_irq(&tasklist_lock);

1190 1191 1192
	/* for sys_ioprio_set(IOPRIO_WHO_PGRP) */
	p->ioprio = current->ioprio;

Linus Torvalds's avatar
Linus Torvalds committed
1193
	/*
1194 1195 1196 1197 1198 1199 1200
	 * 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
1201 1202
	 */
	p->cpus_allowed = current->cpus_allowed;
1203 1204
	if (unlikely(!cpu_isset(task_cpu(p), p->cpus_allowed) ||
			!cpu_online(task_cpu(p))))
1205
		set_task_cpu(p, smp_processor_id());
Linus Torvalds's avatar
Linus Torvalds committed
1206 1207 1208 1209 1210 1211 1212 1213

	/* 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;

1214
	spin_lock(&current->sighand->siglock);
1215 1216 1217 1218 1219 1220 1221 1222 1223 1224 1225 1226 1227 1228

	/*
	 * 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;
1229
		goto bad_fork_cleanup_namespaces;
1230 1231
	}

Linus Torvalds's avatar
Linus Torvalds committed
1232 1233
	if (clone_flags & CLONE_THREAD) {
		p->group_leader = current->group_leader;
1234
		list_add_tail_rcu(&p->thread_group, &p->group_leader->thread_group);
Linus Torvalds's avatar
Linus Torvalds committed
1235 1236 1237 1238 1239 1240 1241 1242 1243 1244 1245 1246 1247 1248 1249 1250 1251

		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);
		}
	}

1252 1253 1254 1255 1256 1257 1258
	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;
1259
			p->signal->pgrp = process_group(current);
1260
			set_signal_session(p->signal, process_session(current));
1261 1262
			attach_pid(p, PIDTYPE_PGID, task_pgrp(current));
			attach_pid(p, PIDTYPE_SID, task_session(current));
1263

1264
			list_add_tail_rcu(&p->tasks, &init_task.tasks);
Linus Torvalds's avatar
Linus Torvalds committed
1265
			__get_cpu_var(process_counts)++;
1266
		}
1267
		attach_pid(p, PIDTYPE_PID, pid);
1268
		nr_threads++;
Linus Torvalds's avatar
Linus Torvalds committed
1269 1270 1271
	}

	total_forks++;
1272
	spin_unlock(&current->sighand->siglock);
Linus Torvalds's avatar
Linus Torvalds committed
1273
	write_unlock_irq(&tasklist_lock);
1274
	proc_fork_connector(p);
Linus Torvalds's avatar
Linus Torvalds committed
1275 1276
	return p;

1277
bad_fork_cleanup_namespaces:
1278
	exit_task_namespaces(p);
Linus Torvalds's avatar
Linus Torvalds committed
1279 1280 1281 1282 1283 1284
bad_fork_cleanup_keys:
	exit_keys(p);
bad_fork_cleanup_mm:
	if (p->mm)
		mmput(p->mm);
bad_fork_cleanup_signal:
1285
	cleanup_signal(p);
Linus Torvalds's avatar
Linus Torvalds committed
1286
bad_fork_cleanup_sighand:
1287
	__cleanup_sighand(p->sighand);
Linus Torvalds's avatar
Linus Torvalds committed
1288 1289 1290 1291 1292 1293 1294 1295 1296 1297 1298 1299 1300
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
1301
bad_fork_cleanup_cpuset:
Linus Torvalds's avatar
Linus Torvalds committed
1302
#endif
Paul Jackson's avatar
Paul Jackson committed
1303
	cpuset_exit(p);
1304 1305
bad_fork_cleanup_delays_binfmt:
	delayacct_tsk_free(p);
Linus Torvalds's avatar
Linus Torvalds committed
1306 1307 1308
	if (p->binfmt)
		module_put(p->binfmt->module);
bad_fork_cleanup_put_domain:
1309
	module_put(task_thread_info(p)->exec_domain->module);
Linus Torvalds's avatar
Linus Torvalds committed
1310 1311 1312 1313 1314 1315
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);
1316 1317
fork_out:
	return ERR_PTR(retval);
Linus Torvalds's avatar
Linus Torvalds committed
1318 1319
}

1320
noinline struct pt_regs * __devinit __attribute__((weak)) idle_regs(struct pt_regs *regs)
Linus Torvalds's avatar
Linus Torvalds committed
1321 1322 1323 1324 1325
{
	memset(regs, 0, sizeof(struct pt_regs));
	return regs;
}

1326
struct task_struct * __cpuinit fork_idle(int cpu)
Linus Torvalds's avatar
Linus Torvalds committed
1327
{