4 * Copyright (C) 1991, 1992 Linus Torvalds
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()'
14 #include <linux/slab.h>
15 #include <linux/init.h>
16 #include <linux/unistd.h>
17 #include <linux/module.h>
18 #include <linux/vmalloc.h>
19 #include <linux/completion.h>
20 #include <linux/mnt_namespace.h>
21 #include <linux/personality.h>
22 #include <linux/mempolicy.h>
23 #include <linux/sem.h>
24 #include <linux/file.h>
25 #include <linux/fdtable.h>
26 #include <linux/iocontext.h>
27 #include <linux/key.h>
28 #include <linux/binfmts.h>
29 #include <linux/mman.h>
30 #include <linux/mmu_notifier.h>
32 #include <linux/nsproxy.h>
33 #include <linux/capability.h>
34 #include <linux/cpu.h>
35 #include <linux/cgroup.h>
36 #include <linux/security.h>
37 #include <linux/hugetlb.h>
38 #include <linux/swap.h>
39 #include <linux/syscalls.h>
40 #include <linux/jiffies.h>
41 #include <linux/tracehook.h>
42 #include <linux/futex.h>
43 #include <linux/compat.h>
44 #include <linux/task_io_accounting_ops.h>
45 #include <linux/rcupdate.h>
46 #include <linux/ptrace.h>
47 #include <linux/mount.h>
48 #include <linux/audit.h>
49 #include <linux/memcontrol.h>
50 #include <linux/ftrace.h>
51 #include <linux/profile.h>
52 #include <linux/rmap.h>
53 #include <linux/acct.h>
54 #include <linux/tsacct_kern.h>
55 #include <linux/cn_proc.h>
56 #include <linux/freezer.h>
57 #include <linux/delayacct.h>
58 #include <linux/taskstats_kern.h>
59 #include <linux/random.h>
60 #include <linux/tty.h>
61 #include <linux/proc_fs.h>
62 #include <linux/blkdev.h>
63 #include <trace/sched.h>
65 #include <asm/pgtable.h>
66 #include <asm/pgalloc.h>
67 #include <asm/uaccess.h>
68 #include <asm/mmu_context.h>
69 #include <asm/cacheflush.h>
70 #include <asm/tlbflush.h>
73 * Protected counters by write_lock_irq(&tasklist_lock)
75 unsigned long total_forks
; /* Handle normal Linux uptimes. */
76 int nr_threads
; /* The idle threads do not count.. */
78 int max_threads
; /* tunable limit on nr_threads */
80 DEFINE_PER_CPU(unsigned long, process_counts
) = 0;
82 __cacheline_aligned
DEFINE_RWLOCK(tasklist_lock
); /* outer */
84 DEFINE_TRACE(sched_process_fork
);
86 int nr_processes(void)
91 for_each_online_cpu(cpu
)
92 total
+= per_cpu(process_counts
, cpu
);
97 #ifndef __HAVE_ARCH_TASK_STRUCT_ALLOCATOR
98 # define alloc_task_struct() kmem_cache_alloc(task_struct_cachep, GFP_KERNEL)
99 # define free_task_struct(tsk) kmem_cache_free(task_struct_cachep, (tsk))
100 static struct kmem_cache
*task_struct_cachep
;
103 #ifndef __HAVE_ARCH_THREAD_INFO_ALLOCATOR
104 static inline struct thread_info
*alloc_thread_info(struct task_struct
*tsk
)
106 #ifdef CONFIG_DEBUG_STACK_USAGE
107 gfp_t mask
= GFP_KERNEL
| __GFP_ZERO
;
109 gfp_t mask
= GFP_KERNEL
;
111 return (struct thread_info
*)__get_free_pages(mask
, THREAD_SIZE_ORDER
);
114 static inline void free_thread_info(struct thread_info
*ti
)
116 free_pages((unsigned long)ti
, THREAD_SIZE_ORDER
);
120 /* SLAB cache for signal_struct structures (tsk->signal) */
121 static struct kmem_cache
*signal_cachep
;
123 /* SLAB cache for sighand_struct structures (tsk->sighand) */
124 struct kmem_cache
*sighand_cachep
;
126 /* SLAB cache for files_struct structures (tsk->files) */
127 struct kmem_cache
*files_cachep
;
129 /* SLAB cache for fs_struct structures (tsk->fs) */
130 struct kmem_cache
*fs_cachep
;
132 /* SLAB cache for vm_area_struct structures */
133 struct kmem_cache
*vm_area_cachep
;
135 /* SLAB cache for mm_struct structures (tsk->mm) */
136 static struct kmem_cache
*mm_cachep
;
138 void free_task(struct task_struct
*tsk
)
140 prop_local_destroy_single(&tsk
->dirties
);
141 free_thread_info(tsk
->stack
);
142 rt_mutex_debug_task_free(tsk
);
143 ftrace_graph_exit_task(tsk
);
144 free_task_struct(tsk
);
146 EXPORT_SYMBOL(free_task
);
148 void __put_task_struct(struct task_struct
*tsk
)
150 WARN_ON(!tsk
->exit_state
);
151 WARN_ON(atomic_read(&tsk
->usage
));
152 WARN_ON(tsk
== current
);
154 security_task_free(tsk
);
156 put_group_info(tsk
->group_info
);
157 delayacct_tsk_free(tsk
);
159 if (!profile_handoff_task(tsk
))
164 * macro override instead of weak attribute alias, to workaround
165 * gcc 4.1.0 and 4.1.1 bugs with weak attribute and empty functions.
167 #ifndef arch_task_cache_init
168 #define arch_task_cache_init()
171 void __init
fork_init(unsigned long mempages
)
173 #ifndef __HAVE_ARCH_TASK_STRUCT_ALLOCATOR
174 #ifndef ARCH_MIN_TASKALIGN
175 #define ARCH_MIN_TASKALIGN L1_CACHE_BYTES
177 /* create a slab on which task_structs can be allocated */
179 kmem_cache_create("task_struct", sizeof(struct task_struct
),
180 ARCH_MIN_TASKALIGN
, SLAB_PANIC
, NULL
);
183 /* do the arch specific task caches init */
184 arch_task_cache_init();
187 * The default maximum number of threads is set to a safe
188 * value: the thread structures can take up at most half
191 max_threads
= mempages
/ (8 * THREAD_SIZE
/ PAGE_SIZE
);
194 * we need to allow at least 20 threads to boot a system
199 init_task
.signal
->rlim
[RLIMIT_NPROC
].rlim_cur
= max_threads
/2;
200 init_task
.signal
->rlim
[RLIMIT_NPROC
].rlim_max
= max_threads
/2;
201 init_task
.signal
->rlim
[RLIMIT_SIGPENDING
] =
202 init_task
.signal
->rlim
[RLIMIT_NPROC
];
205 int __attribute__((weak
)) arch_dup_task_struct(struct task_struct
*dst
,
206 struct task_struct
*src
)
212 static struct task_struct
*dup_task_struct(struct task_struct
*orig
)
214 struct task_struct
*tsk
;
215 struct thread_info
*ti
;
218 prepare_to_copy(orig
);
220 tsk
= alloc_task_struct();
224 ti
= alloc_thread_info(tsk
);
226 free_task_struct(tsk
);
230 err
= arch_dup_task_struct(tsk
, orig
);
236 err
= prop_local_init_single(&tsk
->dirties
);
240 setup_thread_stack(tsk
, orig
);
242 #ifdef CONFIG_CC_STACKPROTECTOR
243 tsk
->stack_canary
= get_random_int();
246 /* One for us, one for whoever does the "release_task()" (usually parent) */
247 atomic_set(&tsk
->usage
,2);
248 atomic_set(&tsk
->fs_excl
, 0);
249 #ifdef CONFIG_BLK_DEV_IO_TRACE
252 tsk
->splice_pipe
= NULL
;
256 free_thread_info(ti
);
257 free_task_struct(tsk
);
262 static int dup_mmap(struct mm_struct
*mm
, struct mm_struct
*oldmm
)
264 struct vm_area_struct
*mpnt
, *tmp
, **pprev
;
265 struct rb_node
**rb_link
, *rb_parent
;
267 unsigned long charge
;
268 struct mempolicy
*pol
;
270 down_write(&oldmm
->mmap_sem
);
271 flush_cache_dup_mm(oldmm
);
273 * Not linked in yet - no deadlock potential:
275 down_write_nested(&mm
->mmap_sem
, SINGLE_DEPTH_NESTING
);
279 mm
->mmap_cache
= NULL
;
280 mm
->free_area_cache
= oldmm
->mmap_base
;
281 mm
->cached_hole_size
= ~0UL;
283 cpus_clear(mm
->cpu_vm_mask
);
285 rb_link
= &mm
->mm_rb
.rb_node
;
289 for (mpnt
= oldmm
->mmap
; mpnt
; mpnt
= mpnt
->vm_next
) {
292 if (mpnt
->vm_flags
& VM_DONTCOPY
) {
293 long pages
= vma_pages(mpnt
);
294 mm
->total_vm
-= pages
;
295 vm_stat_account(mm
, mpnt
->vm_flags
, mpnt
->vm_file
,
300 if (mpnt
->vm_flags
& VM_ACCOUNT
) {
301 unsigned int len
= (mpnt
->vm_end
- mpnt
->vm_start
) >> PAGE_SHIFT
;
302 if (security_vm_enough_memory(len
))
306 tmp
= kmem_cache_alloc(vm_area_cachep
, GFP_KERNEL
);
310 pol
= mpol_dup(vma_policy(mpnt
));
311 retval
= PTR_ERR(pol
);
313 goto fail_nomem_policy
;
314 vma_set_policy(tmp
, pol
);
315 tmp
->vm_flags
&= ~VM_LOCKED
;
321 struct inode
*inode
= file
->f_path
.dentry
->d_inode
;
322 struct address_space
*mapping
= file
->f_mapping
;
325 if (tmp
->vm_flags
& VM_DENYWRITE
)
326 atomic_dec(&inode
->i_writecount
);
327 spin_lock(&mapping
->i_mmap_lock
);
328 if (tmp
->vm_flags
& VM_SHARED
)
329 mapping
->i_mmap_writable
++;
330 tmp
->vm_truncate_count
= mpnt
->vm_truncate_count
;
331 flush_dcache_mmap_lock(mapping
);
332 /* insert tmp into the share list, just after mpnt */
333 vma_prio_tree_add(tmp
, mpnt
);
334 flush_dcache_mmap_unlock(mapping
);
335 spin_unlock(&mapping
->i_mmap_lock
);
339 * Clear hugetlb-related page reserves for children. This only
340 * affects MAP_PRIVATE mappings. Faults generated by the child
341 * are not guaranteed to succeed, even if read-only
343 if (is_vm_hugetlb_page(tmp
))
344 reset_vma_resv_huge_pages(tmp
);
347 * Link in the new vma and copy the page table entries.
350 pprev
= &tmp
->vm_next
;
352 __vma_link_rb(mm
, tmp
, rb_link
, rb_parent
);
353 rb_link
= &tmp
->vm_rb
.rb_right
;
354 rb_parent
= &tmp
->vm_rb
;
357 retval
= copy_page_range(mm
, oldmm
, mpnt
);
359 if (tmp
->vm_ops
&& tmp
->vm_ops
->open
)
360 tmp
->vm_ops
->open(tmp
);
365 /* a new mm has just been created */
366 arch_dup_mmap(oldmm
, mm
);
369 up_write(&mm
->mmap_sem
);
371 up_write(&oldmm
->mmap_sem
);
374 kmem_cache_free(vm_area_cachep
, tmp
);
377 vm_unacct_memory(charge
);
381 static inline int mm_alloc_pgd(struct mm_struct
* mm
)
383 mm
->pgd
= pgd_alloc(mm
);
384 if (unlikely(!mm
->pgd
))
389 static inline void mm_free_pgd(struct mm_struct
* mm
)
391 pgd_free(mm
, mm
->pgd
);
394 #define dup_mmap(mm, oldmm) (0)
395 #define mm_alloc_pgd(mm) (0)
396 #define mm_free_pgd(mm)
397 #endif /* CONFIG_MMU */
399 __cacheline_aligned_in_smp
DEFINE_SPINLOCK(mmlist_lock
);
401 #define allocate_mm() (kmem_cache_alloc(mm_cachep, GFP_KERNEL))
402 #define free_mm(mm) (kmem_cache_free(mm_cachep, (mm)))
404 #include <linux/init_task.h>
406 static struct mm_struct
* mm_init(struct mm_struct
* mm
, struct task_struct
*p
)
408 atomic_set(&mm
->mm_users
, 1);
409 atomic_set(&mm
->mm_count
, 1);
410 init_rwsem(&mm
->mmap_sem
);
411 INIT_LIST_HEAD(&mm
->mmlist
);
412 mm
->flags
= (current
->mm
) ? current
->mm
->flags
413 : MMF_DUMP_FILTER_DEFAULT
;
414 mm
->core_state
= NULL
;
416 set_mm_counter(mm
, file_rss
, 0);
417 set_mm_counter(mm
, anon_rss
, 0);
418 spin_lock_init(&mm
->page_table_lock
);
419 rwlock_init(&mm
->ioctx_list_lock
);
420 mm
->ioctx_list
= NULL
;
421 mm
->free_area_cache
= TASK_UNMAPPED_BASE
;
422 mm
->cached_hole_size
= ~0UL;
423 mm_init_owner(mm
, p
);
425 if (likely(!mm_alloc_pgd(mm
))) {
427 mmu_notifier_mm_init(mm
);
436 * Allocate and initialize an mm_struct.
438 struct mm_struct
* mm_alloc(void)
440 struct mm_struct
* mm
;
444 memset(mm
, 0, sizeof(*mm
));
445 mm
= mm_init(mm
, current
);
451 * Called when the last reference to the mm
452 * is dropped: either by a lazy thread or by
453 * mmput. Free the page directory and the mm.
455 void __mmdrop(struct mm_struct
*mm
)
457 BUG_ON(mm
== &init_mm
);
460 mmu_notifier_mm_destroy(mm
);
463 EXPORT_SYMBOL_GPL(__mmdrop
);
466 * Decrement the use count and release all resources for an mm.
468 void mmput(struct mm_struct
*mm
)
472 if (atomic_dec_and_test(&mm
->mm_users
)) {
475 set_mm_exe_file(mm
, NULL
);
476 if (!list_empty(&mm
->mmlist
)) {
477 spin_lock(&mmlist_lock
);
478 list_del(&mm
->mmlist
);
479 spin_unlock(&mmlist_lock
);
485 EXPORT_SYMBOL_GPL(mmput
);
488 * get_task_mm - acquire a reference to the task's mm
490 * Returns %NULL if the task has no mm. Checks PF_KTHREAD (meaning
491 * this kernel workthread has transiently adopted a user mm with use_mm,
492 * to do its AIO) is not set and if so returns a reference to it, after
493 * bumping up the use count. User must release the mm via mmput()
494 * after use. Typically used by /proc and ptrace.
496 struct mm_struct
*get_task_mm(struct task_struct
*task
)
498 struct mm_struct
*mm
;
503 if (task
->flags
& PF_KTHREAD
)
506 atomic_inc(&mm
->mm_users
);
511 EXPORT_SYMBOL_GPL(get_task_mm
);
513 /* Please note the differences between mmput and mm_release.
514 * mmput is called whenever we stop holding onto a mm_struct,
515 * error success whatever.
517 * mm_release is called after a mm_struct has been removed
518 * from the current process.
520 * This difference is important for error handling, when we
521 * only half set up a mm_struct for a new process and need to restore
522 * the old one. Because we mmput the new mm_struct before
523 * restoring the old one. . .
524 * Eric Biederman 10 January 1998
526 void mm_release(struct task_struct
*tsk
, struct mm_struct
*mm
)
528 struct completion
*vfork_done
= tsk
->vfork_done
;
530 /* Get rid of any futexes when releasing the mm */
532 if (unlikely(tsk
->robust_list
))
533 exit_robust_list(tsk
);
535 if (unlikely(tsk
->compat_robust_list
))
536 compat_exit_robust_list(tsk
);
540 /* Get rid of any cached register state */
541 deactivate_mm(tsk
, mm
);
543 /* notify parent sleeping on vfork() */
545 tsk
->vfork_done
= NULL
;
546 complete(vfork_done
);
550 * If we're exiting normally, clear a user-space tid field if
551 * requested. We leave this alone when dying by signal, to leave
552 * the value intact in a core dump, and to save the unnecessary
553 * trouble otherwise. Userland only wants this done for a sys_exit.
555 if (tsk
->clear_child_tid
556 && !(tsk
->flags
& PF_SIGNALED
)
557 && atomic_read(&mm
->mm_users
) > 1) {
558 u32 __user
* tidptr
= tsk
->clear_child_tid
;
559 tsk
->clear_child_tid
= NULL
;
562 * We don't check the error code - if userspace has
563 * not set up a proper pointer then tough luck.
566 sys_futex(tidptr
, FUTEX_WAKE
, 1, NULL
, NULL
, 0);
571 * Allocate a new mm structure and copy contents from the
572 * mm structure of the passed in task structure.
574 struct mm_struct
*dup_mm(struct task_struct
*tsk
)
576 struct mm_struct
*mm
, *oldmm
= current
->mm
;
586 memcpy(mm
, oldmm
, sizeof(*mm
));
588 /* Initializing for Swap token stuff */
589 mm
->token_priority
= 0;
590 mm
->last_interval
= 0;
592 if (!mm_init(mm
, tsk
))
595 if (init_new_context(tsk
, mm
))
598 dup_mm_exe_file(oldmm
, mm
);
600 err
= dup_mmap(mm
, oldmm
);
604 mm
->hiwater_rss
= get_mm_rss(mm
);
605 mm
->hiwater_vm
= mm
->total_vm
;
617 * If init_new_context() failed, we cannot use mmput() to free the mm
618 * because it calls destroy_context()
625 static int copy_mm(unsigned long clone_flags
, struct task_struct
* tsk
)
627 struct mm_struct
* mm
, *oldmm
;
630 tsk
->min_flt
= tsk
->maj_flt
= 0;
631 tsk
->nvcsw
= tsk
->nivcsw
= 0;
634 tsk
->active_mm
= NULL
;
637 * Are we cloning a kernel thread?
639 * We need to steal a active VM for that..
645 if (clone_flags
& CLONE_VM
) {
646 atomic_inc(&oldmm
->mm_users
);
657 /* Initializing for Swap token stuff */
658 mm
->token_priority
= 0;
659 mm
->last_interval
= 0;
669 static struct fs_struct
*__copy_fs_struct(struct fs_struct
*old
)
671 struct fs_struct
*fs
= kmem_cache_alloc(fs_cachep
, GFP_KERNEL
);
672 /* We don't need to lock fs - think why ;-) */
674 atomic_set(&fs
->count
, 1);
675 rwlock_init(&fs
->lock
);
676 fs
->umask
= old
->umask
;
677 read_lock(&old
->lock
);
678 fs
->root
= old
->root
;
679 path_get(&old
->root
);
682 read_unlock(&old
->lock
);
687 struct fs_struct
*copy_fs_struct(struct fs_struct
*old
)
689 return __copy_fs_struct(old
);
692 EXPORT_SYMBOL_GPL(copy_fs_struct
);
694 static int copy_fs(unsigned long clone_flags
, struct task_struct
*tsk
)
696 if (clone_flags
& CLONE_FS
) {
697 atomic_inc(¤t
->fs
->count
);
700 tsk
->fs
= __copy_fs_struct(current
->fs
);
706 static int copy_files(unsigned long clone_flags
, struct task_struct
* tsk
)
708 struct files_struct
*oldf
, *newf
;
712 * A background process may not have any files ...
714 oldf
= current
->files
;
718 if (clone_flags
& CLONE_FILES
) {
719 atomic_inc(&oldf
->count
);
723 newf
= dup_fd(oldf
, &error
);
733 static int copy_io(unsigned long clone_flags
, struct task_struct
*tsk
)
736 struct io_context
*ioc
= current
->io_context
;
741 * Share io context with parent, if CLONE_IO is set
743 if (clone_flags
& CLONE_IO
) {
744 tsk
->io_context
= ioc_task_link(ioc
);
745 if (unlikely(!tsk
->io_context
))
747 } else if (ioprio_valid(ioc
->ioprio
)) {
748 tsk
->io_context
= alloc_io_context(GFP_KERNEL
, -1);
749 if (unlikely(!tsk
->io_context
))
752 tsk
->io_context
->ioprio
= ioc
->ioprio
;
758 static int copy_sighand(unsigned long clone_flags
, struct task_struct
*tsk
)
760 struct sighand_struct
*sig
;
762 if (clone_flags
& (CLONE_SIGHAND
| CLONE_THREAD
)) {
763 atomic_inc(¤t
->sighand
->count
);
766 sig
= kmem_cache_alloc(sighand_cachep
, GFP_KERNEL
);
767 rcu_assign_pointer(tsk
->sighand
, sig
);
770 atomic_set(&sig
->count
, 1);
771 memcpy(sig
->action
, current
->sighand
->action
, sizeof(sig
->action
));
775 void __cleanup_sighand(struct sighand_struct
*sighand
)
777 if (atomic_dec_and_test(&sighand
->count
))
778 kmem_cache_free(sighand_cachep
, sighand
);
783 * Initialize POSIX timer handling for a thread group.
785 static void posix_cpu_timers_init_group(struct signal_struct
*sig
)
787 /* Thread group counters. */
788 thread_group_cputime_init(sig
);
790 /* Expiration times and increments. */
791 sig
->it_virt_expires
= cputime_zero
;
792 sig
->it_virt_incr
= cputime_zero
;
793 sig
->it_prof_expires
= cputime_zero
;
794 sig
->it_prof_incr
= cputime_zero
;
796 /* Cached expiration times. */
797 sig
->cputime_expires
.prof_exp
= cputime_zero
;
798 sig
->cputime_expires
.virt_exp
= cputime_zero
;
799 sig
->cputime_expires
.sched_exp
= 0;
801 /* The timer lists. */
802 INIT_LIST_HEAD(&sig
->cpu_timers
[0]);
803 INIT_LIST_HEAD(&sig
->cpu_timers
[1]);
804 INIT_LIST_HEAD(&sig
->cpu_timers
[2]);
807 static int copy_signal(unsigned long clone_flags
, struct task_struct
*tsk
)
809 struct signal_struct
*sig
;
812 if (clone_flags
& CLONE_THREAD
) {
813 ret
= thread_group_cputime_clone_thread(current
);
815 atomic_inc(¤t
->signal
->count
);
816 atomic_inc(¤t
->signal
->live
);
820 sig
= kmem_cache_alloc(signal_cachep
, GFP_KERNEL
);
825 ret
= copy_thread_group_keys(tsk
);
827 kmem_cache_free(signal_cachep
, sig
);
831 atomic_set(&sig
->count
, 1);
832 atomic_set(&sig
->live
, 1);
833 init_waitqueue_head(&sig
->wait_chldexit
);
835 sig
->group_exit_code
= 0;
836 sig
->group_exit_task
= NULL
;
837 sig
->group_stop_count
= 0;
838 sig
->curr_target
= tsk
;
839 init_sigpending(&sig
->shared_pending
);
840 INIT_LIST_HEAD(&sig
->posix_timers
);
842 hrtimer_init(&sig
->real_timer
, CLOCK_MONOTONIC
, HRTIMER_MODE_REL
);
843 sig
->it_real_incr
.tv64
= 0;
844 sig
->real_timer
.function
= it_real_fn
;
846 sig
->leader
= 0; /* session leadership doesn't inherit */
847 sig
->tty_old_pgrp
= NULL
;
850 sig
->cutime
= sig
->cstime
= cputime_zero
;
851 sig
->gtime
= cputime_zero
;
852 sig
->cgtime
= cputime_zero
;
853 sig
->nvcsw
= sig
->nivcsw
= sig
->cnvcsw
= sig
->cnivcsw
= 0;
854 sig
->min_flt
= sig
->maj_flt
= sig
->cmin_flt
= sig
->cmaj_flt
= 0;
855 sig
->inblock
= sig
->oublock
= sig
->cinblock
= sig
->coublock
= 0;
856 task_io_accounting_init(&sig
->ioac
);
857 taskstats_tgid_init(sig
);
859 task_lock(current
->group_leader
);
860 memcpy(sig
->rlim
, current
->signal
->rlim
, sizeof sig
->rlim
);
861 task_unlock(current
->group_leader
);
863 posix_cpu_timers_init_group(sig
);
865 acct_init_pacct(&sig
->pacct
);
872 void __cleanup_signal(struct signal_struct
*sig
)
874 thread_group_cputime_free(sig
);
875 exit_thread_group_keys(sig
);
876 tty_kref_put(sig
->tty
);
877 kmem_cache_free(signal_cachep
, sig
);
880 static void cleanup_signal(struct task_struct
*tsk
)
882 struct signal_struct
*sig
= tsk
->signal
;
884 atomic_dec(&sig
->live
);
886 if (atomic_dec_and_test(&sig
->count
))
887 __cleanup_signal(sig
);
890 static void copy_flags(unsigned long clone_flags
, struct task_struct
*p
)
892 unsigned long new_flags
= p
->flags
;
894 new_flags
&= ~PF_SUPERPRIV
;
895 new_flags
|= PF_FORKNOEXEC
;
896 new_flags
|= PF_STARTING
;
897 p
->flags
= new_flags
;
898 clear_freeze_flag(p
);
901 asmlinkage
long sys_set_tid_address(int __user
*tidptr
)
903 current
->clear_child_tid
= tidptr
;
905 return task_pid_vnr(current
);
908 static void rt_mutex_init_task(struct task_struct
*p
)
910 spin_lock_init(&p
->pi_lock
);
911 #ifdef CONFIG_RT_MUTEXES
912 plist_head_init(&p
->pi_waiters
, &p
->pi_lock
);
913 p
->pi_blocked_on
= NULL
;
917 #ifdef CONFIG_MM_OWNER
918 void mm_init_owner(struct mm_struct
*mm
, struct task_struct
*p
)
922 #endif /* CONFIG_MM_OWNER */
925 * Initialize POSIX timer handling for a single task.
927 static void posix_cpu_timers_init(struct task_struct
*tsk
)
929 tsk
->cputime_expires
.prof_exp
= cputime_zero
;
930 tsk
->cputime_expires
.virt_exp
= cputime_zero
;
931 tsk
->cputime_expires
.sched_exp
= 0;
932 INIT_LIST_HEAD(&tsk
->cpu_timers
[0]);
933 INIT_LIST_HEAD(&tsk
->cpu_timers
[1]);
934 INIT_LIST_HEAD(&tsk
->cpu_timers
[2]);
938 * This creates a new process as a copy of the old one,
939 * but does not actually start it yet.
941 * It copies the registers, and all the appropriate
942 * parts of the process environment (as per the clone
943 * flags). The actual kick-off is left to the caller.
945 static struct task_struct
*copy_process(unsigned long clone_flags
,
946 unsigned long stack_start
,
947 struct pt_regs
*regs
,
948 unsigned long stack_size
,
949 int __user
*child_tidptr
,
954 struct task_struct
*p
;
955 int cgroup_callbacks_done
= 0;
957 if ((clone_flags
& (CLONE_NEWNS
|CLONE_FS
)) == (CLONE_NEWNS
|CLONE_FS
))
958 return ERR_PTR(-EINVAL
);
961 * Thread groups must share signals as well, and detached threads
962 * can only be started up within the thread group.
964 if ((clone_flags
& CLONE_THREAD
) && !(clone_flags
& CLONE_SIGHAND
))
965 return ERR_PTR(-EINVAL
);
968 * Shared signal handlers imply shared VM. By way of the above,
969 * thread groups also imply shared VM. Blocking this case allows
970 * for various simplifications in other code.
972 if ((clone_flags
& CLONE_SIGHAND
) && !(clone_flags
& CLONE_VM
))
973 return ERR_PTR(-EINVAL
);
975 retval
= security_task_create(clone_flags
);
980 p
= dup_task_struct(current
);
984 rt_mutex_init_task(p
);
986 #ifdef CONFIG_PROVE_LOCKING
987 DEBUG_LOCKS_WARN_ON(!p
->hardirqs_enabled
);
988 DEBUG_LOCKS_WARN_ON(!p
->softirqs_enabled
);
991 if (atomic_read(&p
->user
->processes
) >=
992 p
->signal
->rlim
[RLIMIT_NPROC
].rlim_cur
) {
993 if (!capable(CAP_SYS_ADMIN
) && !capable(CAP_SYS_RESOURCE
) &&
994 p
->user
!= current
->nsproxy
->user_ns
->root_user
)
998 atomic_inc(&p
->user
->__count
);
999 atomic_inc(&p
->user
->processes
);
1000 get_group_info(p
->group_info
);
1003 * If multiple threads are within copy_process(), then this check
1004 * triggers too late. This doesn't hurt, the check is only there
1005 * to stop root fork bombs.
1007 if (nr_threads
>= max_threads
)
1008 goto bad_fork_cleanup_count
;
1010 if (!try_module_get(task_thread_info(p
)->exec_domain
->module
))
1011 goto bad_fork_cleanup_count
;
1013 if (p
->binfmt
&& !try_module_get(p
->binfmt
->module
))
1014 goto bad_fork_cleanup_put_domain
;
1017 delayacct_tsk_init(p
); /* Must remain after dup_task_struct() */
1018 copy_flags(clone_flags
, p
);
1019 INIT_LIST_HEAD(&p
->children
);
1020 INIT_LIST_HEAD(&p
->sibling
);
1021 #ifdef CONFIG_PREEMPT_RCU
1022 p
->rcu_read_lock_nesting
= 0;
1023 p
->rcu_flipctr_idx
= 0;
1024 #endif /* #ifdef CONFIG_PREEMPT_RCU */
1025 p
->vfork_done
= NULL
;
1026 spin_lock_init(&p
->alloc_lock
);
1028 clear_tsk_thread_flag(p
, TIF_SIGPENDING
);
1029 init_sigpending(&p
->pending
);
1031 p
->utime
= cputime_zero
;
1032 p
->stime
= cputime_zero
;
1033 p
->gtime
= cputime_zero
;
1034 p
->utimescaled
= cputime_zero
;
1035 p
->stimescaled
= cputime_zero
;
1036 p
->prev_utime
= cputime_zero
;
1037 p
->prev_stime
= cputime_zero
;
1039 p
->default_timer_slack_ns
= current
->timer_slack_ns
;
1041 #ifdef CONFIG_DETECT_SOFTLOCKUP
1042 p
->last_switch_count
= 0;
1043 p
->last_switch_timestamp
= 0;
1046 task_io_accounting_init(&p
->ioac
);
1047 acct_clear_integrals(p
);
1049 posix_cpu_timers_init(p
);
1051 p
->lock_depth
= -1; /* -1 = no lock */
1052 do_posix_clock_monotonic_gettime(&p
->start_time
);
1053 p
->real_start_time
= p
->start_time
;
1054 monotonic_to_bootbased(&p
->real_start_time
);
1055 #ifdef CONFIG_SECURITY
1058 p
->cap_bset
= current
->cap_bset
;
1059 p
->io_context
= NULL
;
1060 p
->audit_context
= NULL
;
1063 p
->mempolicy
= mpol_dup(p
->mempolicy
);
1064 if (IS_ERR(p
->mempolicy
)) {
1065 retval
= PTR_ERR(p
->mempolicy
);
1066 p
->mempolicy
= NULL
;
1067 goto bad_fork_cleanup_cgroup
;
1069 mpol_fix_fork_child_flag(p
);
1071 #ifdef CONFIG_TRACE_IRQFLAGS
1073 #ifdef __ARCH_WANT_INTERRUPTS_ON_CTXSW
1074 p
->hardirqs_enabled
= 1;
1076 p
->hardirqs_enabled
= 0;
1078 p
->hardirq_enable_ip
= 0;
1079 p
->hardirq_enable_event
= 0;
1080 p
->hardirq_disable_ip
= _THIS_IP_
;
1081 p
->hardirq_disable_event
= 0;
1082 p
->softirqs_enabled
= 1;
1083 p
->softirq_enable_ip
= _THIS_IP_
;
1084 p
->softirq_enable_event
= 0;
1085 p
->softirq_disable_ip
= 0;
1086 p
->softirq_disable_event
= 0;
1087 p
->hardirq_context
= 0;
1088 p
->softirq_context
= 0;
1090 #ifdef CONFIG_LOCKDEP
1091 p
->lockdep_depth
= 0; /* no locks held yet */
1092 p
->curr_chain_key
= 0;
1093 p
->lockdep_recursion
= 0;
1096 #ifdef CONFIG_DEBUG_MUTEXES
1097 p
->blocked_on
= NULL
; /* not blocked yet */
1099 if (unlikely(ptrace_reparented(current
)))
1100 ptrace_fork(p
, clone_flags
);
1102 /* Perform scheduler related setup. Assign this task to a CPU. */
1103 sched_fork(p
, clone_flags
);
1105 if ((retval
= security_task_alloc(p
)))
1106 goto bad_fork_cleanup_policy
;
1107 if ((retval
= audit_alloc(p
)))
1108 goto bad_fork_cleanup_security
;
1109 /* copy all the process information */
1110 if ((retval
= copy_semundo(clone_flags
, p
)))
1111 goto bad_fork_cleanup_audit
;
1112 if ((retval
= copy_files(clone_flags
, p
)))
1113 goto bad_fork_cleanup_semundo
;
1114 if ((retval
= copy_fs(clone_flags
, p
)))
1115 goto bad_fork_cleanup_files
;
1116 if ((retval
= copy_sighand(clone_flags
, p
)))
1117 goto bad_fork_cleanup_fs
;
1118 if ((retval
= copy_signal(clone_flags
, p
)))
1119 goto bad_fork_cleanup_sighand
;
1120 if ((retval
= copy_mm(clone_flags
, p
)))
1121 goto bad_fork_cleanup_signal
;
1122 if ((retval
= copy_keys(clone_flags
, p
)))
1123 goto bad_fork_cleanup_mm
;
1124 if ((retval
= copy_namespaces(clone_flags
, p
)))
1125 goto bad_fork_cleanup_keys
;
1126 if ((retval
= copy_io(clone_flags
, p
)))
1127 goto bad_fork_cleanup_namespaces
;
1128 retval
= copy_thread(0, clone_flags
, stack_start
, stack_size
, p
, regs
);
1130 goto bad_fork_cleanup_io
;
1132 if (pid
!= &init_struct_pid
) {
1134 pid
= alloc_pid(task_active_pid_ns(p
));
1136 goto bad_fork_cleanup_io
;
1138 if (clone_flags
& CLONE_NEWPID
) {
1139 retval
= pid_ns_prepare_proc(task_active_pid_ns(p
));
1141 goto bad_fork_free_pid
;
1145 ftrace_graph_init_task(p
);
1147 p
->pid
= pid_nr(pid
);
1149 if (clone_flags
& CLONE_THREAD
)
1150 p
->tgid
= current
->tgid
;
1152 if (current
->nsproxy
!= p
->nsproxy
) {
1153 retval
= ns_cgroup_clone(p
, pid
);
1155 goto bad_fork_free_graph
;
1158 p
->set_child_tid
= (clone_flags
& CLONE_CHILD_SETTID
) ? child_tidptr
: NULL
;
1160 * Clear TID on mm_release()?
1162 p
->clear_child_tid
= (clone_flags
& CLONE_CHILD_CLEARTID
) ? child_tidptr
: NULL
;
1164 p
->robust_list
= NULL
;
1165 #ifdef CONFIG_COMPAT
1166 p
->compat_robust_list
= NULL
;
1168 INIT_LIST_HEAD(&p
->pi_state_list
);
1169 p
->pi_state_cache
= NULL
;
1172 * sigaltstack should be cleared when sharing the same VM
1174 if ((clone_flags
& (CLONE_VM
|CLONE_VFORK
)) == CLONE_VM
)
1175 p
->sas_ss_sp
= p
->sas_ss_size
= 0;
1178 * Syscall tracing should be turned off in the child regardless
1181 clear_tsk_thread_flag(p
, TIF_SYSCALL_TRACE
);
1182 #ifdef TIF_SYSCALL_EMU
1183 clear_tsk_thread_flag(p
, TIF_SYSCALL_EMU
);
1185 clear_all_latency_tracing(p
);
1187 /* Our parent execution domain becomes current domain
1188 These must match for thread signalling to apply */
1189 p
->parent_exec_id
= p
->self_exec_id
;
1191 /* ok, now we should be set up.. */
1192 p
->exit_signal
= (clone_flags
& CLONE_THREAD
) ? -1 : (clone_flags
& CSIGNAL
);
1193 p
->pdeath_signal
= 0;
1197 * Ok, make it visible to the rest of the system.
1198 * We dont wake it up yet.
1200 p
->group_leader
= p
;
1201 INIT_LIST_HEAD(&p
->thread_group
);
1203 /* Now that the task is set up, run cgroup callbacks if
1204 * necessary. We need to run them before the task is visible
1205 * on the tasklist. */
1206 cgroup_fork_callbacks(p
);
1207 cgroup_callbacks_done
= 1;
1209 /* Need tasklist lock for parent etc handling! */
1210 write_lock_irq(&tasklist_lock
);
1213 * The task hasn't been attached yet, so its cpus_allowed mask will
1214 * not be changed, nor will its assigned CPU.
1216 * The cpus_allowed mask of the parent may have changed after it was
1217 * copied first time - so re-copy it here, then check the child's CPU
1218 * to ensure it is on a valid CPU (and if not, just force it back to
1219 * parent's CPU). This avoids alot of nasty races.
1221 p
->cpus_allowed
= current
->cpus_allowed
;
1222 p
->rt
.nr_cpus_allowed
= current
->rt
.nr_cpus_allowed
;
1223 if (unlikely(!cpu_isset(task_cpu(p
), p
->cpus_allowed
) ||
1224 !cpu_online(task_cpu(p
))))
1225 set_task_cpu(p
, smp_processor_id());
1227 /* CLONE_PARENT re-uses the old parent */
1228 if (clone_flags
& (CLONE_PARENT
|CLONE_THREAD
))
1229 p
->real_parent
= current
->real_parent
;
1231 p
->real_parent
= current
;
1233 spin_lock(¤t
->sighand
->siglock
);
1236 * Process group and session signals need to be delivered to just the
1237 * parent before the fork or both the parent and the child after the
1238 * fork. Restart if a signal comes in before we add the new process to
1239 * it's process group.
1240 * A fatal signal pending means that current will exit, so the new
1241 * thread can't slip out of an OOM kill (or normal SIGKILL).
1243 recalc_sigpending();
1244 if (signal_pending(current
)) {
1245 spin_unlock(¤t
->sighand
->siglock
);
1246 write_unlock_irq(&tasklist_lock
);
1247 retval
= -ERESTARTNOINTR
;
1248 goto bad_fork_free_graph
;
1251 if (clone_flags
& CLONE_THREAD
) {
1252 p
->group_leader
= current
->group_leader
;
1253 list_add_tail_rcu(&p
->thread_group
, &p
->group_leader
->thread_group
);
1256 if (likely(p
->pid
)) {
1257 list_add_tail(&p
->sibling
, &p
->real_parent
->children
);
1258 tracehook_finish_clone(p
, clone_flags
, trace
);
1260 if (thread_group_leader(p
)) {
1261 if (clone_flags
& CLONE_NEWPID
)
1262 p
->nsproxy
->pid_ns
->child_reaper
= p
;
1264 p
->signal
->leader_pid
= pid
;
1265 tty_kref_put(p
->signal
->tty
);
1266 p
->signal
->tty
= tty_kref_get(current
->signal
->tty
);
1267 set_task_pgrp(p
, task_pgrp_nr(current
));
1268 set_task_session(p
, task_session_nr(current
));
1269 attach_pid(p
, PIDTYPE_PGID
, task_pgrp(current
));
1270 attach_pid(p
, PIDTYPE_SID
, task_session(current
));
1271 list_add_tail_rcu(&p
->tasks
, &init_task
.tasks
);
1272 __get_cpu_var(process_counts
)++;
1274 attach_pid(p
, PIDTYPE_PID
, pid
);
1279 spin_unlock(¤t
->sighand
->siglock
);
1280 write_unlock_irq(&tasklist_lock
);
1281 proc_fork_connector(p
);
1282 cgroup_post_fork(p
);
1285 bad_fork_free_graph
:
1286 ftrace_graph_exit_task(p
);
1288 if (pid
!= &init_struct_pid
)
1290 bad_fork_cleanup_io
:
1291 put_io_context(p
->io_context
);
1292 bad_fork_cleanup_namespaces
:
1293 exit_task_namespaces(p
);
1294 bad_fork_cleanup_keys
:
1296 bad_fork_cleanup_mm
:
1299 bad_fork_cleanup_signal
:
1301 bad_fork_cleanup_sighand
:
1302 __cleanup_sighand(p
->sighand
);
1303 bad_fork_cleanup_fs
:
1304 exit_fs(p
); /* blocking */
1305 bad_fork_cleanup_files
:
1306 exit_files(p
); /* blocking */
1307 bad_fork_cleanup_semundo
:
1309 bad_fork_cleanup_audit
:
1311 bad_fork_cleanup_security
:
1312 security_task_free(p
);
1313 bad_fork_cleanup_policy
:
1315 mpol_put(p
->mempolicy
);
1316 bad_fork_cleanup_cgroup
:
1318 cgroup_exit(p
, cgroup_callbacks_done
);
1319 delayacct_tsk_free(p
);
1321 module_put(p
->binfmt
->module
);
1322 bad_fork_cleanup_put_domain
:
1323 module_put(task_thread_info(p
)->exec_domain
->module
);
1324 bad_fork_cleanup_count
:
1325 put_group_info(p
->group_info
);
1326 atomic_dec(&p
->user
->processes
);
1331 return ERR_PTR(retval
);
1334 noinline
struct pt_regs
* __cpuinit
__attribute__((weak
)) idle_regs(struct pt_regs
*regs
)
1336 memset(regs
, 0, sizeof(struct pt_regs
));
1340 struct task_struct
* __cpuinit
fork_idle(int cpu
)
1342 struct task_struct
*task
;
1343 struct pt_regs regs
;
1345 task
= copy_process(CLONE_VM
, 0, idle_regs(®s
), 0, NULL
,
1346 &init_struct_pid
, 0);
1348 init_idle(task
, cpu
);
1354 * Ok, this is the main fork-routine.
1356 * It copies the process, and if successful kick-starts
1357 * it and waits for it to finish using the VM if required.
1359 long do_fork(unsigned long clone_flags
,
1360 unsigned long stack_start
,
1361 struct pt_regs
*regs
,
1362 unsigned long stack_size
,
1363 int __user
*parent_tidptr
,
1364 int __user
*child_tidptr
)
1366 struct task_struct
*p
;
1371 * We hope to recycle these flags after 2.6.26
1373 if (unlikely(clone_flags
& CLONE_STOPPED
)) {
1374 static int __read_mostly count
= 100;
1376 if (count
> 0 && printk_ratelimit()) {
1377 char comm
[TASK_COMM_LEN
];
1380 printk(KERN_INFO
"fork(): process `%s' used deprecated "
1381 "clone flags 0x%lx\n",
1382 get_task_comm(comm
, current
),
1383 clone_flags
& CLONE_STOPPED
);
1388 * When called from kernel_thread, don't do user tracing stuff.
1390 if (likely(user_mode(regs
)))
1391 trace
= tracehook_prepare_clone(clone_flags
);
1393 p
= copy_process(clone_flags
, stack_start
, regs
, stack_size
,
1394 child_tidptr
, NULL
, trace
);
1396 * Do this prior waking up the new thread - the thread pointer
1397 * might get invalid after that point, if the thread exits quickly.
1400 struct completion vfork
;
1402 trace_sched_process_fork(current
, p
);
1404 nr
= task_pid_vnr(p
);
1406 if (clone_flags
& CLONE_PARENT_SETTID
)
1407 put_user(nr
, parent_tidptr
);
1409 if (clone_flags
& CLONE_VFORK
) {
1410 p
->vfork_done
= &vfork
;
1411 init_completion(&vfork
);
1414 audit_finish_fork(p
);
1415 tracehook_report_clone(trace
, regs
, clone_flags
, nr
, p
);
1418 * We set PF_STARTING at creation in case tracing wants to
1419 * use this to distinguish a fully live task from one that
1420 * hasn't gotten to tracehook_report_clone() yet. Now we
1421 * clear it and set the child going.
1423 p
->flags
&= ~PF_STARTING
;
1425 if (unlikely(clone_flags
& CLONE_STOPPED
)) {
1427 * We'll start up with an immediate SIGSTOP.
1429 sigaddset(&p
->pending
.signal
, SIGSTOP
);
1430 set_tsk_thread_flag(p
, TIF_SIGPENDING
);
1431 __set_task_state(p
, TASK_STOPPED
);
1433 wake_up_new_task(p
, clone_flags
);
1436 tracehook_report_clone_complete(trace
, regs
,
1437 clone_flags
, nr
, p
);
1439 if (clone_flags
& CLONE_VFORK
) {
1440 freezer_do_not_count();
1441 wait_for_completion(&vfork
);
1443 tracehook_report_vfork_done(p
, nr
);
1451 #ifndef ARCH_MIN_MMSTRUCT_ALIGN
1452 #define ARCH_MIN_MMSTRUCT_ALIGN 0
1455 static void sighand_ctor(void *data
)
1457 struct sighand_struct
*sighand
= data
;
1459 spin_lock_init(&sighand
->siglock
);
1460 init_waitqueue_head(&sighand
->signalfd_wqh
);
1463 void __init
proc_caches_init(void)
1465 sighand_cachep
= kmem_cache_create("sighand_cache",
1466 sizeof(struct sighand_struct
), 0,
1467 SLAB_HWCACHE_ALIGN
|SLAB_PANIC
|SLAB_DESTROY_BY_RCU
,
1469 signal_cachep
= kmem_cache_create("signal_cache",
1470 sizeof(struct signal_struct
), 0,
1471 SLAB_HWCACHE_ALIGN
|SLAB_PANIC
, NULL
);
1472 files_cachep
= kmem_cache_create("files_cache",
1473 sizeof(struct files_struct
), 0,
1474 SLAB_HWCACHE_ALIGN
|SLAB_PANIC
, NULL
);
1475 fs_cachep
= kmem_cache_create("fs_cache",
1476 sizeof(struct fs_struct
), 0,
1477 SLAB_HWCACHE_ALIGN
|SLAB_PANIC
, NULL
);
1478 vm_area_cachep
= kmem_cache_create("vm_area_struct",
1479 sizeof(struct vm_area_struct
), 0,
1481 mm_cachep
= kmem_cache_create("mm_struct",
1482 sizeof(struct mm_struct
), ARCH_MIN_MMSTRUCT_ALIGN
,
1483 SLAB_HWCACHE_ALIGN
|SLAB_PANIC
, NULL
);
1487 * Check constraints on flags passed to the unshare system call and
1488 * force unsharing of additional process context as appropriate.
1490 static void check_unshare_flags(unsigned long *flags_ptr
)
1493 * If unsharing a thread from a thread group, must also
1496 if (*flags_ptr
& CLONE_THREAD
)
1497 *flags_ptr
|= CLONE_VM
;
1500 * If unsharing vm, must also unshare signal handlers.
1502 if (*flags_ptr
& CLONE_VM
)
1503 *flags_ptr
|= CLONE_SIGHAND
;
1506 * If unsharing signal handlers and the task was created
1507 * using CLONE_THREAD, then must unshare the thread
1509 if ((*flags_ptr
& CLONE_SIGHAND
) &&
1510 (atomic_read(¤t
->signal
->count
) > 1))
1511 *flags_ptr
|= CLONE_THREAD
;
1514 * If unsharing namespace, must also unshare filesystem information.
1516 if (*flags_ptr
& CLONE_NEWNS
)
1517 *flags_ptr
|= CLONE_FS
;
1521 * Unsharing of tasks created with CLONE_THREAD is not supported yet
1523 static int unshare_thread(unsigned long unshare_flags
)
1525 if (unshare_flags
& CLONE_THREAD
)
1532 * Unshare the filesystem structure if it is being shared
1534 static int unshare_fs(unsigned long unshare_flags
, struct fs_struct
**new_fsp
)
1536 struct fs_struct
*fs
= current
->fs
;
1538 if ((unshare_flags
& CLONE_FS
) &&
1539 (fs
&& atomic_read(&fs
->count
) > 1)) {
1540 *new_fsp
= __copy_fs_struct(current
->fs
);
1549 * Unsharing of sighand is not supported yet
1551 static int unshare_sighand(unsigned long unshare_flags
, struct sighand_struct
**new_sighp
)
1553 struct sighand_struct
*sigh
= current
->sighand
;
1555 if ((unshare_flags
& CLONE_SIGHAND
) && atomic_read(&sigh
->count
) > 1)
1562 * Unshare vm if it is being shared
1564 static int unshare_vm(unsigned long unshare_flags
, struct mm_struct
**new_mmp
)
1566 struct mm_struct
*mm
= current
->mm
;
1568 if ((unshare_flags
& CLONE_VM
) &&
1569 (mm
&& atomic_read(&mm
->mm_users
) > 1)) {
1577 * Unshare file descriptor table if it is being shared
1579 static int unshare_fd(unsigned long unshare_flags
, struct files_struct
**new_fdp
)
1581 struct files_struct
*fd
= current
->files
;
1584 if ((unshare_flags
& CLONE_FILES
) &&
1585 (fd
&& atomic_read(&fd
->count
) > 1)) {
1586 *new_fdp
= dup_fd(fd
, &error
);
1595 * unshare allows a process to 'unshare' part of the process
1596 * context which was originally shared using clone. copy_*
1597 * functions used by do_fork() cannot be used here directly
1598 * because they modify an inactive task_struct that is being
1599 * constructed. Here we are modifying the current, active,
1602 asmlinkage
long sys_unshare(unsigned long unshare_flags
)
1605 struct fs_struct
*fs
, *new_fs
= NULL
;
1606 struct sighand_struct
*new_sigh
= NULL
;
1607 struct mm_struct
*mm
, *new_mm
= NULL
, *active_mm
= NULL
;
1608 struct files_struct
*fd
, *new_fd
= NULL
;
1609 struct nsproxy
*new_nsproxy
= NULL
;
1612 check_unshare_flags(&unshare_flags
);
1614 /* Return -EINVAL for all unsupported flags */
1616 if (unshare_flags
& ~(CLONE_THREAD
|CLONE_FS
|CLONE_NEWNS
|CLONE_SIGHAND
|
1617 CLONE_VM
|CLONE_FILES
|CLONE_SYSVSEM
|
1618 CLONE_NEWUTS
|CLONE_NEWIPC
|CLONE_NEWUSER
|
1620 goto bad_unshare_out
;
1623 * CLONE_NEWIPC must also detach from the undolist: after switching
1624 * to a new ipc namespace, the semaphore arrays from the old
1625 * namespace are unreachable.
1627 if (unshare_flags
& (CLONE_NEWIPC
|CLONE_SYSVSEM
))
1629 if ((err
= unshare_thread(unshare_flags
)))
1630 goto bad_unshare_out
;
1631 if ((err
= unshare_fs(unshare_flags
, &new_fs
)))
1632 goto bad_unshare_cleanup_thread
;
1633 if ((err
= unshare_sighand(unshare_flags
, &new_sigh
)))
1634 goto bad_unshare_cleanup_fs
;
1635 if ((err
= unshare_vm(unshare_flags
, &new_mm
)))
1636 goto bad_unshare_cleanup_sigh
;
1637 if ((err
= unshare_fd(unshare_flags
, &new_fd
)))
1638 goto bad_unshare_cleanup_vm
;
1639 if ((err
= unshare_nsproxy_namespaces(unshare_flags
, &new_nsproxy
,
1641 goto bad_unshare_cleanup_fd
;
1643 if (new_fs
|| new_mm
|| new_fd
|| do_sysvsem
|| new_nsproxy
) {
1646 * CLONE_SYSVSEM is equivalent to sys_exit().
1652 switch_task_namespaces(current
, new_nsproxy
);
1660 current
->fs
= new_fs
;
1666 active_mm
= current
->active_mm
;
1667 current
->mm
= new_mm
;
1668 current
->active_mm
= new_mm
;
1669 activate_mm(active_mm
, new_mm
);
1674 fd
= current
->files
;
1675 current
->files
= new_fd
;
1679 task_unlock(current
);
1683 put_nsproxy(new_nsproxy
);
1685 bad_unshare_cleanup_fd
:
1687 put_files_struct(new_fd
);
1689 bad_unshare_cleanup_vm
:
1693 bad_unshare_cleanup_sigh
:
1695 if (atomic_dec_and_test(&new_sigh
->count
))
1696 kmem_cache_free(sighand_cachep
, new_sigh
);
1698 bad_unshare_cleanup_fs
:
1700 put_fs_struct(new_fs
);
1702 bad_unshare_cleanup_thread
:
1708 * Helper to unshare the files of the current task.
1709 * We don't want to expose copy_files internals to
1710 * the exec layer of the kernel.
1713 int unshare_files(struct files_struct
**displaced
)
1715 struct task_struct
*task
= current
;
1716 struct files_struct
*copy
= NULL
;
1719 error
= unshare_fd(CLONE_FILES
, ©
);
1720 if (error
|| !copy
) {
1724 *displaced
= task
->files
;